Fiber Reinforced Phenolic Foam: Effects of Extreme · PDF fileBibliography 129 . Appendix A: Glossary 135 . viii List of Tables . Table 1 ... Figure 2.6: Adidas Village, Portland,

FIBER REINFORCED PHENOLIC FOAM:

CLIMATIC EFFECTS ON MECHANICAL PROPERTIES

AND BUILDING APPLICATIONS IN NORTHERN THAILAND

by

John Paul Basbagill

A Thesis Presented to the FACULTY OF THE SCHOOL OF ARCHITECTURE

UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the

Requirements for the Degree MASTER OF BUILDING SCIENCE

May 2008

Copyright 2008 John Paul Basbagill

ii

Dedication This thesis is dedicated to my grandfather, John Marzinski, who passed away

during the early stages of this project. My grandfather was a lifelong builder and

engineer and an inspiration in helping me seek my interests. He laid down the

bricks on this journey, and I follow in his footsteps.

~ ever the engineer ~

iii

Acknowledgments I would like to thank my thesis committee for their patience and support. My

thesis chair, Professor Goetz Schierle, provided me with technical guidance and

timely advice on structural topics; Professor Thomas Spiegelhalter offered help

on sustainability issues; Professor Marc Schiler listened to my grievances

throughout the year, helped me keep the “big picture” in perspective, and kept me

on course; and Professor Steven Nutt allowed me to conduct my project in the

composite materials department in the Viterbi School of Engineering at the

University of Southern California. I am grateful to the department for providing

funding for the project. Professor Nutt helped me in narrowing my project topic,

and his in depth knowledge on materials science topics was invaluable. I am also

indebted to Warren Haby, whose handyman expertise in the composite materials

laboratory got me through several unforeseen challenges while conducting my

experiments. Finally, I would like to thank Amit Desai and Hongbin Shen,

current and former composite materials doctoral students at USC, from whose

previous work I was able to build and who provided helpful tips in my project

methodology.

Table of Contents Dedication ii

Acknowledgments iii

List of Tables viii

List of Figures xi

Abstract xiii

Chapter 1: Introduction 1 1.1 The Problem 3 1.2 Potential Solution 3 1.3 Objective 4 1.4 Final Product 5 1.5 Hypothesis 5 1.6 Scope 5

1.6.1 Base Material 7 1.6.2 Reinforcement Fibers: Synthetic Versus Natural 8

1.6.2.1 Synthetic Fibers 9 1.6.2.2 Natural Fibers 9

1.6.3 Tests 10 1.6.4 Thai Climate Simulations 10 1.6.5 Comparison Materials 12 1.6.6 Environmental Impact 12 1.6.7 Costs 13

1.7 Applications 13 Chapter 2: Background 14

2.1 The Problem 14 2.1.1 Living Conditions in northern Thailand 15

2.1.1.1 Climate 15 2.1.1.2 Thai Climate, Economy, and Building

Practices 17 2.1.2 Insulation and the Environment 19 2.1.3 Insulation Materials: Overview 20

2.1.3.1 Cellulose 21 2.1.3.2 Mineral Wool 22 2.1.3.3 Fiberglass 23 2.1.3.4 Polystyrene 23 2.1.3.5 Polyisocyanurate 24 2.1.3.6 Radiant Barriers 24

2.1.4 Insulation Materials: Other Environmental Factors 24 2.2 Cladding 25

2.3 Structural Insulation 26 2.4 Phenolic Foam 27 2.5 Previous Work 28

Chapter 3: Methodology 30

3.1 Fabrication 31 3.1.1 Materials 31 3.1.2 Mixer 32 3.1.3 Fabrication Process 33 3.1.4 Problems 35

3.1.4.1 Thermal Control 35 3.1.4.2 Batch Process 36 3.1.4.3 Fiber Dispersion 36 3.1.4.4 Non-Uniform Density 36 3.1.4.5 Low Density Values 39

3.2 Cutting Samples 39 3.3 Density Measurements 40 3.4 Climate Conditioning 40

3.4.1 Climate Simulation I: Water Immersion 40 3.4.2 Climate Simulation II: Accelerated Aging 42

3.5 Testing 43 3.5.1 Test I: Compression 44 3.5.2 Test II: Shear 45 3.5.3 Test III: Cell Length (SEM) 47 3.5.4 Test IV: Flammability 48 3.5.5 Test V: Conductivity 49

3.6 Results 53 3.6.1 Mechanical and Thermal Tests 54 3.6.2 Environmental Impact Assessment 54 3.6.3 Costs 55

Chapter 4: Results 56

4.1 Density 57 4.2 Strength Tests 60

4.2.1 Compression 60 4.2.1.1 Can Phenolic Foam Be Used as a 62

Load-Bearing Material in Thailand? 4.2.1.2 Do Climate Stresses Weaken Phenolic 65

Foam? 4.2.1.3 Do Natural or Synthetic Fibers Add Greater 65

Strength to Phenolic Foam? 4.2.2 Shear 65

4.3 Climate Simulations 67 4.3.1 Water Immersion 68 4.3.2 Accelerated Aging 71

4.4 Other Tests 72 4.4.1 Cell Length (SEM) 72 4.4.2 Fire Resistance 75

4.4.3 Conductivity 76 4.5 Summary 81

Chapter 5: Environmental Impact 82

5.1 Prior Environmental Impact Studies on Insulation 83 5.2 Difficulty in Assessing the Environmental Impact of 83

Phenolic Foam 5.3 Method 84 5.4 Results: Environmental Impact Assessment of Phenolic 85

Foam 5.4.1 Heat Loss 85

5.4.1.1 Building the Model 86 5.4.1.2 Calculating Heat Loss 88

5.4.2 Moisture Resistance 90 5.4.3 Embodied Energy 92 5.4.4 Emissions 93

5.4.4.1 Phenolic Foam 94 5.4.4.2 EPS 97 5.4.4.3 Phenolic Foam Versus EPS 97

5.4.5 Toxicity 98 5.4.5.1 Phenolic Foam 98 5.4.5.2 EPS 99

5.5 Summary 99 Chapter 6: Costs 101

6.1 Method 101 6.2 Production Site 102 6.3 Construction Site 102 6.4 Suppliers 104 6.5 Raw Materials 105 6.6 Transportation 107

6.6.1 Cost to Ship Raw Materials to the Production Site 107 6.6.2 Cost to Ship End Product to the Construction Site 108

6.7 Machinery 109 6.8 Labor 110

6.8.1 Manufacturing 110 6.8.2 Installation 111

6.9 Electricity Costs Associated with Production 111 6.10 Lifetime Energy Savings 112 6.11 Summary 113

Chapter 7: Conclusion 115

7.1 Mechanical and Thermal Tests 115 7.1.1 Load-Bearing Applications 117 7.1.2 Climate Stresses 117 7.1.3 Natural or Synthetic Fibers 118 7.1.4 Best Performing Fiber 118 7.1.5 Phenolic Foam or EPS 119

7.1.6 Summary 119 7.2 Environmental Impact 120

7.2.1 Heat Loss 120 7.2.2 Moisture Resistance 120 7.2.3 Embodied Energy 121 7.2.4 Emissions 121 7.2.5 Toxicity 121 7.2.6 Summary 121

7.3 Costs 122 7.4 Recommendation 122

Chapter 8: Future Work 124

8.1 Fabrication 124 8.2 Testing 126 8.3 Comparison Materials 127 8.4 Environmental Impact Assessment 127 8.5 Cost Assessment 128

Bibliography 129 Appendix A: Glossary 135

viii

List of Tables Table 1.1: Uses of indigenous woods: Ban Tun village, Northern 1

Thailand Table 2.1: Precipitation in various U.S. climate regions 15 Table 2.2: Heat loss distribution for heating a typical residence 19

Table 2.3: Heat loss distribution for cooling a typical residence 20

Table 2.4: Embodied energy of common insulation materials 21

Table 3.1: Density of fiber reinforced phenolic foam samples 38

Table 3.2: Tests conducted for each material 44

Table 4.1: Density results for all materials 57

Table 4.2: Densities of common load-bearing materials 58

Table 4.3: Percentage increase in density after 8-week water exposure for 59 all materials

Table 4.4: Compression results: climatic effects on compressive strength 61

Table 4.5: Compression results: climatic effects on Young’s modulus 61

Table 4.6: Young’s modulus values for common building materials 64 Table 4.7: Shear results: climatic effects on maximum shear load 66

Table 4.8: Water absorption rates for phenolic foam and EPS expressed 69 as mass of water absorbed as a percentage of mass of material

Table 4.9: Mass of water absorbed expressed as percentage of mass of 69

sample Table 4.10: Water absorption values for some common insulation 70

materials

ix

Table 4.11: Accelerated aging results: mass lost as a percentage of initial 71 mass

Table 4.12: SEM images showing cell length across climatic stress 73 Table 4.13: SEM results: cell length across climatic stress 74

Table 4.14: Flammability test results: volume lost as a percentage of 75 initial volume

Table 4.15: Flammability test results: UL94 ratings assigned to materials 76

Table 4.16: R-values recorded by Oak Ridge National Laboratory per 76 ASTM C 518

Table 4.17: Conductivity results: temperature drop across dry materials 77

Table 4.18: Conductivity results: temperature drop across wet materials 78 (one week immersion) Table 4.19: Conductivity test results: R-values 79

Table 4.20: R-values of common materials 80

Table 5.1: U-values entered into HEED to obtain energy loss data on 88 each separate material Table 5.2: Effect of water exposure on energy losses in a northern 89

Thai home Table 5.3: Water absorption rates for phenolic foam and EPS expressed 91

as mass of water absorbed as a percentage of mass of materials

Table 5.4: Embodied energy of common insulation materials 93

Table 5.5: Hydrofluorocarbon (HFC) emissions in phenolic foam, in the 96 case where HFCs are used as blowing agents

Table 5.6: Toxicity concentrations in phenolic foam 98

Table 6.1: Suppliers of phenolic foam raw materials 104

Table 6.2: Raw materials costs for phenolic foam 106

x

Table 6.3: Cost to ship phenolic foam raw materials to production site 108

Table 6.4: Costs of providing phenolic foam and EPS insulation for a 113 typical house in northern rural Thailand

Table 7.1: Summary of mechanical and thermal results 116

xi

List of Figures Figure 1.1: Weather worn house in northern Thailand with degraded paper 2

and bamboo walls Figure 1.2: Local woods and grasses used as posts, walls, doors, and 9

floors in rural Thai construction Figure 2.1: Prevailing air streams in Thailand 17

Figure 2.2: Rural Thai wall construction: the author holding a panel 18 composed of cellulose-based bags woven between bamboo

strips Figure 2.3: Cellulose insulation 22

Figure 2.4: Rock wool insulation 22

Figure 2.5: Fiberglass insulation 23

Figure 2.6: Adidas Village, Portland, Oregon 26

Figure 3.1: Keyence hybrid mixer used to mix phenolic foam chemicals 32

Figure 3.2: The author cutting bamboo fiber into ¼” lengths 34

Figure 3.3: Adding aramid fibers to the resin-surfactant mixture 34

Figure 3.4: Styrofoam mold covered in aluminum foil 35

Figure 3.5: Samples being prepared for water absorption testing 41

Figure 3.6: Samples in USC’s environmental testing chamber 42

Figure 3.7: Instron machine loaded with two stainless steel platens for 45 compression testing

Figure 3.8: Shear samples being glued between shear plates 46

Figure 3.9: Shear sample undergoing testing 47

xii

Figure 3.10 Cambridge 360 Scanning Electron Microscope 48

Figure 3.11: Sample loaded into fire testing chamber 49

Figure 3.12: Conductivity samples being glued together in 12” wooden 50 frames

Figure 3.13: Cellulose fiber conductivity sample 51 Figure 3.14: Conductivity test apparatus 53

Figure 4.1: Assumed typical 40’ x 50’ house plan in northern Thailand 62 Figure 5.1: Simple one-story house in northern Thailand constructed in 87

HEED Figure 6.1: Construction site chosen as a case study to estimate 103

insulation costs

xiii

Abstract Phenolic foam warrants consideration as a building material because of several

characteristic features. For example, low thermal conductivity allows for

applications as a building insulation material. Moreover, the material has low

flammability, low smoke toxicity, no dripping during combustion, and is cost-

competitive with conventional foams, such as polyurethane and expanded

polystyrene (EPS).

This paper demonstrated the mechanical and insulation properties, sustainable

benefits, and costs of fiber-reinforced phenolic foam when used as an insulation

material in the hot, arid, wet region of northern Thailand. Four types of fiber

reinforced phenolic foams were fabricated: bamboo, aramid, glass, and cellulose.

Choosing these materials provided a comparison study of natural and synthetic

materials.

Foam samples were fabricated using ¼” fibers. Water absorption and accelerated

aging tests were conducted on composite foam samples to simulate the flooding

and extreme heat and humidity conditions of northern Thailand. Compression,

shear, and conductivity tests were performed after these climate simulations.

Measurements of retained mechanical properties were performed to determine if

the material would be a suitable insulation and/or load-bearing material. Fire

resistance testing was also performed on the samples. In addition to testing, an

environmental impact assessment was performed on the composite foams.

xiv

Finally, costs to insulate a home in northern Thailand with the materials were

evaluated.

Results were compared with expanded polystyrene, a common insulation

material. The results showed that neither the fabricated fiber reinforced phenolic

foam nor EPS is comparable in strength to conventional load-bearing materials

and do not retain their mechanical properties after extreme climate exposure.

Little distinction could be drawn between natural and synthetic fibers. Results

also showed phenolic foam’s stronger fire resistance and insulative properties

under dry conditions than EPS. However, EPS exhibited a higher R-value and

slower R-value degradation under wet conditions. Comparison of environmental

impacts showed that, due to fiber reinforced phenolic foams’ relatively low

embodied energy, the material warrants consideration as a sustainable alternative

to conventional building insulation materials such as EPS. Finally, cost

considerations show that neither phenolic foam nor EPS can feasibly be used as

building insulation in low-income areas of northern Thailand.

Keywords: Design of fiber reinforced phenolic foam, strengthening of composite materials, environmental impact

Chapter 1: Introduction Building methods and materials in the developing regions of northern Thailand and

Laos are often the most basic. Construction methods are rudimentary since, as

subsistence farmers, few people can afford any sort of sturdy walled protection or

insulation from the elements. Residents are industrious, however, as use of

indigenous timber is common in shelter construction here. Shelter walls, when they

do exist, are usually composed of locally available wood materials such as bamboo

and eucalyptus. For example, in Ban Tun, a highland village about 150km southwest

of Chiang Mai, residents make use of 49 of 78 indigenous tree species found in the

village (Schmidt-Vogt 2000). Construction and firewood are some of the most

common uses highlighted in Table 1.1.

Ecolocial Significance and Use of Forest Trees: Ban Tun Village, Northern Thailand

05

1015202530

Constr

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n

Fence

s

Firewoo

dToo

lsFoo

d

Animal

Food

Medicin

al

Ceremon

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Decora

tion

Uses

Num

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f Tre

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s

Table 1.1: Uses of indigenous woods: Ban Tun village, Northern Thailand

http://www.etfrn.org/etfrn/workshop/users/chapter_13.pdf

1

Construction methods here must also consider climate, as the northern regions of

Thailand and Laos receive tremendous amounts of rain in the summer. Monthly

averages often exceed ten inches per month (Global Historical Climatology Network

1992). Humidity swells as well with temperatures climbing to over 35º C (Simply-

Thai.com 2007).

Unfortunately, shelters are often left susceptible to these harsh weather conditions.

Despite assiduous use of local materials such as in Ban Tun, tattered, weather-worn

materials revealing gaping holes are common sights throughout the region. Living

quarters are often left exposed to harsh weather conditions, and families are left to

fend against severe rainstorms (see Figure 1.1).

Figure 1.1: Weather worn house in northern Thailand with degraded paper and bamboo walls

Photograph produced by the author, 2008

2

3

1.1 The Problem

These observations suggest better insulation and more durable wall materials are

needed in underdeveloped areas prone to extreme weather. This thesis set out to

produce a low-cost, environmentally-sensitive, hybrid load-bearing insulation

material made of natural materials and capable of withstanding extreme heat,

humidity, and rain.

1.2 Potential Solution

Members of Dr. Steven Nutt’s composite materials department within the chemical

engineering school at the University of Southern California have been exploring the

use of phenolic foam as both an insulation and structural material. Building materials

are one application with which they have been working. Yet three significant gaps in

scientific data exist regarding the material. The primary question this thesis explored

is how phenolic foam compares with expanded polystyrene (EPS), a common

insulation material. Which material is stronger and more insulative, more

environmentally sensitive, and cheaper? Chapter 4 (results), chapter 5

(environmental impact), and chapter 6 (costs), respectively, answer these three

questions. Second, few studies have examined phenolic foam’s response to extreme

climate conditions. How does this material perform under heavy rains or extreme

heat and humidity? Chapter 4 returns an answer to this question. Third, although

structural benefits of fiber reinforcement in phenolic foam have been documented,

comparison studies of natural versus synthetic reinforcement fibers have not been

4

conducted. Do natural fibers offer a stronger, more insulative, cheaper, and more

sustainable solution to synthetic fibers? Chapters 4, 5, and 6 address these questions.

Therefore, this thesis’s primary endeavor is to compare natural and synthetic fiber

reinforced phenolic foams’ response to various climate conditions, then compare the

results to EPS’s performance. A secondary objective is to examine the viability of

phenolic foam load-bearing applications in buildings. The thesis is valuable because

it provides a recommendation on which material is better suited as an insulation

material in extreme weather conditions such as in northern Thailand: phenolic foam

reinforced with natural or synthetic fibers or EPS.

Note: Appendix A: Glossary defines all acronyms, tests, and important concepts

throughout the thesis. For example, EPS will be used throughout this thesis to refer

to expanded polystyrene.

1.3 Objective

The objective of this thesis was to determine whether phenolic foam is suitable as a

hybrid structural insulation material in hot, humid, and rainy underdeveloped regions

with better mechanical, thermal, and sustainable properties and cost considerations

than currently used structural and insulation materials. As part of this determination,

the benefits of using various fibers as reinforcing agents were investigated.

5

1.4 Final Product

The final product of this thesis is two recommendations. A statement is produced in

Chapter 7 on whether:

• phenolic foam or EPS is better suited as an insulation material in hot, humid,

rainy underdeveloped regions such as in northern Thailand

• phenolic foam is well suited as a load bearing material in hot, humid, rainy

underdeveloped regions such as in northern Thailand.

1.5 Hypothesis

Phenolic foam’s mechanical and thermal properties, environmental impact, and costs

demonstrate the material’s superiority as a hybrid structural insulation material. This

will be tested by evaluating the mechanical and thermal properties and assessing the

environmental impact and costs of fabricated unreinforced and fiber reinforced

phenolic foam against common structural and insulation materials.

1.6 Scope

The thesis involved six steps:

Step 1: Obtain materials. Fabricate phenolic foam, both un-reinforced and with

various natural and synthetic fibers: bamboo, cellulose, glass, and aramid. Purchase

EPS.

6

Step 2: Condition samples in either a water or aging chamber. Control samples for

fiber reinforced phenolic foam, unreinforced phenolic foam, and EPS will not be

conditioned in a water or aging chamber.

Step 3: Perform mechanical and thermal tests on both conditioned and unconditioned

(control) samples.

Step 4: Conduct an environmental impact assessment on phenolic foam.

Step 5: Analyze the cost to insulate a home in northern Thailand with phenolic foam

insulation.

Step 6: Compare results of steps 3 through 5 with common structural materials as

well as EPS.

Several choices were made in order to narrow the scope of the project. These

included choosing:

• a base material

• reinforcement fibers

• mechanical and thermal tests

• climate simulations

• a common insulation material with which to test alongside and draw

comparisons with the base material

• environmental impact assessment categories

• cost categories related to insulating a home in northern Thailand.

Each of these choices is described in the following sections.

7

1.6.1 Base Material

Phenolic foam was chosen as the core insulation material with which to experiment.

Its excellent insulation and fire resistant properties were extensively taken advantage

of during World War II as a material in German aircraft. The material was also

widely used in the 1970s as a roof insulation material. In the late 1980s and early

1990s, however, residues of an acid catalyst in the foam, when activated by moisture

in the air, caused corrosion in metal decking in contact with the foam (Greenwald

2008). As a result, phenolic foam’s use as an insulation material faded.

Despite such problems, Shen has noted in his dissertation Toughening of Phenolic

Foam that effective solutions have been found to reduce phenolic foam’s corrosion

problems (2003, p.25). In addition, its structural applications are being explored. The

main reason that phenolic foam was chosen, then, was to mechanically and thermally

experiment with a material that could rival current structural and insulation

materials. Fire resistance could also be measured and a sustainability profile could be

created, the results of which could be compared with common building materials to

reinforce the material’s superiority in building applications.

Phenolic foam was also chosen to compare the benefits of natural and synthetic

fibers. These fibers might not only strengthen phenolic foam for load-bearing

applications but also provide additional mechanical and/or thermal benefits;

consequently, a broad range of tests were conducted on the fibers. Fibers were also

8

used to compare the benefits of natural, locally available versus synthetic materials,

in an effort to keep the resources of developing regions in mind.

Finally, phenolic foam was chosen because little data existed on how the material

responded to extreme climate conditions. Could the material withstand heavy rain

and extreme heat and humidity? Coupled with environmental impact and cost data,

the project would ultimately determine whether phenolic foam yielded a viable

structural insulation choice for poor communities in hot, humid, rainy climates.

1.6.2 Reinforcement Fibers: Natural Versus Synthetic

Various fibers were chosen with which to experiment in order to evaluate natural

versus synthetic fibers. The reason fibers were chosen in the first place was to

confirm whether fibers found in developing regions could strengthen phenolic foam

enough for use as a load-bearing building material. Secondary reasons examined

whether fibers offered any thermal benefits or improved unreinforced phenolic

foam’s response to climate stresses.

Natural and synthetic fibers of similar lengths were compared in order to determine

the potential benefits of using indigenous, locally available materials. For example,

bamboo forests and plantations cover the landscape throughout Southeast Asia,

India, and China (Lehmer 1997). In addition, several types of cellulose-based wood

materials are used as posts, walls, and doors in Thai buildings (see Figure 1.2). By

using materials available in residents’ own backyards, this thesis would hopefully

yield a cheaper, more natural, and more sustainable product.

Figure 1.2: Local woods and grasses used as posts, walls, doors, and floors in rural Thai

construction


1.6.2.1 Synthetic Fibers

The synthetic reinforcing fibers chosen were glass and aramid. Glass fibers,

commonly used in building insulation materials, were ¼” long cut fibers supplied by

Owens-Corning Inc. Aramid fibers, a plastic often used as a strengthening agent in

fiber reinforced polymers, were ¼” cut Nomex® fibers made by DuPont.

1.6.2.2 Natural Fibers

9

Bamboo and cellulose were chosen as the natural reinforcing fibers. These

represented materials widely available in northern Thailand used in many aspects of

10

life. Woven bamboo fibers were obtained from Habu Textiles in New York and were

cut into ¼” pieces. The cellulose fibers were obtained from Advanced Fiber

Technology Company in Ohio. They were recycled from industrial grade newsprint,

clumped together in small bunches about ¼” long, and not cut.

1.6.3 Tests

Five tests were conducted in order to evaluate phenolic foam’s mechanical and

thermal performance. A compression test was chosen to test the material’s

compressive strength and Young’s modulus, and a shear test was chosen to test

maximum shear strength. Scanning electron microscopy (SEM) was used to measure

samples’ cell diameters before and after being placed in water or aging chambers, in

order to measure the effect of environmental stresses on cell length. The purpose of

obtaining this data was to see if longer cell diameters correlated with greater water

absorption rates and shorter cell diameters correlated with smaller absorption rates.

SEM data would therefore hopefully serve as a predictor of phenolic foam’s water

resistance ability. A conductivity test was also designed in order to measure phenolic

foam’s R-value, or how easily the material resists heat flow. Finally, a flammability

test was chosen in order to measure how well the material resists fire.

1.6.4 Thai Climate Simulations

Two climate simulations were run in order to model the effects of harsh Thai

weather conditions on phenolic foam’s mechanical and thermal properties. Water

immersion, an eight week test, was chosen for five reasons. First, it modeled wet

climate conditions in northern Thailand during the summer wet season. Second, this

11

simulation measured how much water phenolic foam would absorb over an extended

period of time, thereby indicating how well the foam could resist water. Third,

compression and shear values were compared before and after the water immersion

simulation in order to see if extended water exposure would weaken the material.

Fourth, cell lengths measured through SEM were compared before and after the

water simulation to see if cell size correlated with water resistance. A positive

correlation would suggest cell length as a good predictor of water resistance rates in

phenolic foam. Finally, R-values were measured before and after water immersion,

in order to see how flooding conditions may impact the thermal performance of the

material.

Accelerated aging was the second climate simulation, a six week test chosen for

three reasons. As with the water test, compression and shear values were compared

before and after the simulation in order to see if extended exposure to intense heat

and humidity would weaken the material. Second, cell lengths obtained through

SEM were compared before and after the simulation in order to see if aging altered

cell size. This SEM data could then be a useful predictor of phenolic foam’s water

resistance, assuming a positive correlation between cell size and water resistance

derived from the first climate simulation. Third, the test was chosen to indicate

phenolic foam’s durability by measuring the percentage of mass lost throughout the

test.

12

1.6.5 Comparison Materials

Data for various structural materials was referenced throughout the thesis in order to

evaluate phenolic foam’s potential as a load-bearing material. Although testing these

materials was beyond the scope of this study, the values referenced are well

established and offered a reliable comparison method.

Expanded polystyrene (EPS) was chosen as a commonly used insulation material in

the building industry with which to compare phenolic foam. The material was bought

at Home Depot and subjected to the same five tests and two climate simulations as

phenolic foam. Its environmental impact and cost to insulate a home in northern

Thailand were also compared against phenolic foam. The intention in choosing this

material was to directly compare phenolic foam’s effectiveness against a competing

building insulation material.

1.6.6 Environmental Impact

The environmental impact of phenolic foam as an insulation material was compared

with EPS. Since data relating to phenolic foam’s environmental impact is scarce,

only categories in which data was readily available and which provided an easy

comparison with EPS were chosen. These categories included heat loss, moisture

resistance, embodied energy, emissions, and toxicity.

13

1.6.7 Costs

The cost to insulate a home in northern Thailand is not widely published or readily

available. Consequently, several estimates had to be made in several cost categories,

including raw materials, transportation, machinery, labor, and electricity.

1.7 Applications

Phenolic foam has historically been used as a roofing insulation material. Recent

research also supports fiber reinforced phenolic foam’s use as a load-bearing

material (Shen & Nutt 2003). The objective of this project was to prove phenolic

foam’s viability as a hybrid structural insulation material. Various applications

relevant to this objective, such as load-bearing walls, rain screens, and cladding

systems, are discussed as background material in Chapter 2.

14

Chapter 2: Background The initial goal of this project was to create a low-cost hybrid structural insulation

material with superior mechanical, thermal, and sustainable properties for use in hot,

humid, and wet underdeveloped regions like northern Thailand. The chapter begins

by examining the necessity for such a material. After defining the problem, the

chapter continues with an overview of current insulation materials as well as

cladding and structural applications. The chapter concludes with background

material on phenolic foam, its potential as a low-cost, environmentally sensitive

structural insulation material for use in hot, arid, wet climates, and a brief discussion

of previous studies involving phenolic foam.

2.1 The Problem

The problem addressed is twofold. First, many residents in northern Thailand and

northern Laos are too poor to afford insulation or quality home construction. This

fact, coupled with a hot, rainy climate in the summer months, means millions must

fend against the elements. The problem extends to other developing regions in Asia,

Africa, and South America. Therefore, a solution is needed to better protect

residents. The second problem involves improving on current insulation materials’

mechanical properties, environmental impact, and cost. Whereas current materials

have high R-values, are environmentally sensitive, or are cheap, no single material

15

outperforms all others in these categories. Consequently, this thesis sought to

produce a material that performed well in all three categories.

2.1.1 Living Conditions in Northern Thailand

Inhabitants of northern Thailand experience a harsh rainy season. Rural areas rely on

farming and generate little disposable income; therefore, residents often do not have

the resources to use quality materials in homes or make basic home improvements.

An affordable, environmentally sensitive insulation material is therefore needed to

protect people in this region from extreme weather conditions.

2.1.1.1 Climate

Thailand is located in the northern hemisphere and lies along the Southeast Asian

tropical rain belt during the region’s wet season from April to September. This rain

belt is home to the world’s second largest rain forest, and the climate is hot and

humid for the entire year. Seasonal shifting winds, or monsoons, bring heavy rainfall

in the wet months. The region’s climate statistics are especially formidable. The

average yearly temperature is 80ºF, the average humidity is between 70 and 90%,

and the average rainfall is between 60 to 100 inches (F 2002). Comparison with three

regions in the United States shows just how extreme this rainfall is:

16

U.S. Region Climate Category Average Annual Precipitation (in.)

Eastern U.S. Moist continental 32

(abundant precipitation)

Central and southern Mediterranean (wet 17 California winter-dry summer) Rocky Mountain Range Highland 9

Table 2.1: Precipitation in various U.S. climate regions

http://www.blueplanetbiomes.org/calif_chap_climate_page.htm

The region is surrounded on several sides by ocean, and shifting air streams

throughout the year - particularly in Thailand, which borders ocean water on two

sides - dominate climatic conditions and contribute to the high rainfall (see Figure

2.1).

Figure 2.1: Prevailing air streams in Thailand

http://www.cig.ensmp.fr/~iahs/hsj/250/hysj_25_02_0167.pdf

2.1.1.2 Thai Climate, Economy, and Building Practices

Such extreme weather conditions define relationships between rainfall, the economy,

and building practices in northern Thailand. Residents derive their income primarily

from farming. Yet the non-uniform distribution of rainfall throughout the year

creates severe shortages of irrigation water during many months, and severe floods

wash over the region at other times (Phien et al. 1980). Consequently, water resource

management directly impacts living conditions, and the efficient use of available

water for farming is critical to economic and physical survival.

17

Because of such extreme weather conditions, income in rural areas goes toward such

expenses as irrigation and land maintenance. Yet Thailand’s GNP per capita is only

$2712 - a figure presumably less in the north, where livelihood is dominated by

subsistence farming (Earth Trends 2003). Therefore, in such poorer regions, living

conditions and buildings are often the most basic and utilize indigenous materials

such as bamboo and other woods. Because many residents cannot afford insulation

or wall enclosures, entire building faces are sometimes left open to the elements. In

other cases, walls - often made of cheap, cellulose-based materials - are flimsy or

severely degraded (see Figure 2.2). Given the large amount of rain in the region,

walls made of such materials typically do not stay intact much longer than ten years

(T Kongchumchuen 2007, pers. comm., 21 Aug.).

Figure 2.2: Rural Thai wall construction: the author holding a panel composed of cellulose-

based bags woven between bamboo strips

Photograph produced by author, 2008

18

19

Materials used in walls also often have poor strength, insulative and water and fire

resistant properties. These conditions, coupled with the fact that residents’ homes

face exposure to extreme elements, suggest a low-cost wall or insulation material is

essential in improving the long-term living conditions of people in this area.

2.1.2 Insulation and the Environment

Creating a low-cost structural insulation material is also important for environmental

reasons. As energy costs rise, energy conservation in buildings is becoming

increasingly important. Heat is principally lost through ceilings, walls, windows,

doors, floors, and foundations as well as through air infiltration. A large reduction in

heat loss, however, can be realized by insulating attics and ceilings (Klempner 2004,

p.220). Tables 2.2 and 2.3 compare heat losses for an un-insulated and insulated

house during heating and air-conditioning periods.

Un-insulated Insulated Peak hour1 Day Peak hour1 Day KW*h % kW*h % kW*h % KW*h % Ceiling 5.4 42 99.3 43 0.8 12 15.8 14 Wall 2.1 16 51.9 22 0.8 12 20.1 17 Glass conduction 2.7 22 38.1 16 2.7 40 38.1 33 and convection Infiltration 2.5 20 42.4 19 2.5 36 42.4 36 Total load 12.6 231.6 6.8 116.4

Table 2.2: Heat loss distribution for heating a typical residence (Klempner 2004, p. 220)

1Peak hour is the hour of day that corresponds to the highest thermal load.

20

Un-insulated Insulated Peak hour1 Day Peak hour1 Day KW*h % kW*h % kW*h % KW*h % Ceiling 1.6 18 24.6 22 0.5 7 6.7 8 Wall 0.8 10 12.9 12 0.3 5 4.4 6 Glass conduction 0.6 7 8.6 8 0.6 9 8.6 10 and convection Infiltration 1.5 16 29.7 27 1.5 19 29.7 35 Total load 8.9 110.3 6.9 83.9

Table 2.3: Heat loss distribution for cooling a typical residence (Klempner 2004, p. 221)

1Peak hour is the hour of day that corresponds to the highest thermal load.

The tables show that insulation can save on energy costs by up to 50%, with roofs

the most effective location to place insulation (Khemani 1997, p.224). However,

several factors need to be considered when choosing an insulation material, given the

important part insulation plays in a building’s energy conservation. Are insulation

materials manufactured with CFCs? How lightweight is the material? What is the R-

value of the material, and does it degrade over time? These are just three questions to

consider when evaluating a material’s environmental impact. Chapter 5 gives further

background information on chemicals used in the foam industry and their

environmental impact.

2.1.3 Insulation Materials: Overview

Decisions about insulation are among the most important in the environmental

impact of buildings. Although insulation reduces building energy consumption and

provides other ongoing environmental benefits throughout a building’s lifetime,

insulation materials greatly differ in their environmental advantages. For example,

Table 2.4 reveals a tremendous difference in embodied energy of the most

commonly used insulation materials.

Table 2.4: Embodied energy of common insulation materials

http://www.afcee.brooks.af.mil/green/case/accsfguide.pdf

1http://www.canadianarchitect.com/asf/perspectives_sustainibility/measures_of_sustainablity/measur

es_of_sustainablity_embodied.htm

The table shows that EPS has an embodied energy value over 35 times greater than

cellulose. The data suggests that use of natural, locally available or recycled

materials can drastically reduce embodied energy costs. This section gives an

overview of the most common insulation materials and recent efforts to reduce

embodied energy through the use of recycled materials.

2.1.3.1 Cellulose

Cellulose insulation is usually comprised of 80% post-consumer recycled newspaper

by weight, while the rest is made of fire retardant chemicals (see Figure 2.3). Efforts

have been made in the last decade to produce a lower-density cellulose material by

breaking down newspaper into individual fibers that are fluffier, resulting in a

21

“greener” product. The material is cleaner with a higher R-value (Building Green

1995).

Figure 2.3: Cellulose insulation

http://www.daviddarling.info/encyclopedia/C/AE_cellulose_insulation.html

2.1.3.2 Mineral Wool

Mineral wool was at one time the most common insulation material until fiberglass

gained favor in the 1960s and 1970s. The material consists of up to 75% post-

industrial recycled content and is classified either as slag wool or rock wool (see

Figure 2.4). Slag wool comprises about 80% of the mineral wool industry and is

made from iron ore blast furnace slag, an industrial waste product. Rock wool is

made from natural molten rocks such as basalt and diabase (Building Green 1995).

Figure 2.4: Rock wool insulation

http://science.howstuffworks.com/plasma-converter2.htm

22

2.1.3.3 Fiberglass

Fiberglass is the most common insulation material and is made from molten glass

spun into microfibers (see Figure 2.5). The primary manufacturers of fiberglass have

been using 20% recycled glass materials in their products for decades, with the

largest manufacturer, Owens Corning, using 30% recycled glass (Building Green

1995). The relatively high percentage of manufactured materials used in fiberglass is

reflected in the material’s high embodied energy cost shown in Table 2.4.

Figure 2.5: Fiberglass insulation

http://img.alibaba.com/photo/12283858/FiberGlass_wool_Insulation.jpg

2.1.3.4 Polystyrene

Polystyrene is another common insulation material made from synthetic materials,

and recycled plastic resin has been used by some of the largest manufacturers such as

Dow and Amoco Foam Products. Expanded polystyrene (EPS) can be made out of

recycled polystyrene by crumbling then re-molding the old EPS (Building Green

1995). Expandable polystyrene beads are typically impregnated with pentane, a

23

24

hydrocarbon that contributes to smog but not global warming or ozone depletion.

EPS is also the only rigid foam insulation made without CFCs or HCFCs.

EPS was chosen as the material with which to compare phenolic foam for several

reasons. Like phenolic foam, it is lightweight, cheap, comes in rigid board form, and

uses pentane as an expanding agent. It offered a good “challenge” in the insulation

market, as it is well established as an insulation material with known R-values, cheap

and easily accessible to the public, and widely used.

2.1.3.5 Polyisocyanurate

Manufacturers of polyisocyanurate foam insulation also use recycled materials, but

instead of using recycled foam, the chemical components themselves contain

recycled content.

2.1.3.6 Radiant Barriers

Aluminum used in radiant barriers is mostly recycled and sometimes uses recycled

plastic in its foam core.

2.1.4 Insulation Materials: Other Environmental Factors

R-value, durability, water resistance, fire resistance, weight, and cost are other

environmental factors besides embodied energy to consider when choosing an

insulation material. R-value is a measure of how well a material retards the flow of

energy through the material itself. The higher the R-value, the better the insulation,

and the SI units are in K*m²/W. R-value degradation, particularly after exposure to

wet weather, is a factor when evaluating an insulation material’s environmental

25

performance. Durability, or how well a material resists compression, moisture, and

physical degradation, is also important when considering insulation materials. A

strong insulation material might find application as a structural member within a

building, and a material that resists environmental deterioration and moisture may be

well suited to wet regions. Likewise, fire resistance may be an important factor when

considering building in dry areas prone to fires. Finally, lightweight insulation

materials are generally cheaper than heavier materials and may find application as

exterior cladding boards or structural members.

2.2 Cladding

Cladding systems are an important weatherproofing feature of buildings. They often

help keep water out of buildings and reduce mold growth and leaking. They may also

reduce energy losses of a building because of good insulative properties. Other

important characteristics of cladding materials are weight and fire resistance.

Some of the most common cladding materials are ceramic stone, glass fiber concrete,

terracotta, brick, and various woods, stones, and metals. They are typically

watertight and durable. Alucobond is a relatively new and popular sandwich system

made of two sheets of aluminum metal adhered to a thermoplastic core material. The

material has exceptional resistance to water and extreme temperatures.

Cladding systems consist of core insulative materials and outer skin layers and may

be used in exterior applications. For example, the Adidas Village in Portland, OR

uses multi-colored alucobond panels on its buildings (see Figure 2.6). The panels

form a curtain wall and act as a rain screen. The attachment system has an internal

gutter that routes condensation out at the joints, and the panel system also

accommodates seismic movement (Alcan 2004).

Figure 2.6: Adidas Village, Portland, Oregon

http://www.aia.org/aiarchitect/thisweek04/tw0116/0116aia_portland.htm

2.3 Structural Insulation

Structural insulated panels (SIPs) consist of foam insulation sandwiched between

two layers of a structural board. The foam is usually expanded polystyrene, extruded

polystrene, or polyurethane, and the composite material has structural properties

similar to an I-beam or I-column. SIPs are extremely versatile and can be used in

floors, roofs, walls, or foundations and replace such building components as studs

26

27

and joists, insulation, and vapor barriers (Structural Insulated Panel Association

2007).

Efforts have been made to use unique materials in SIPs. For example, the addition of

glass and aramid fibers to phenolic foam has been shown to increase its strength

(Shen & Nutt 2003, p. 906). The resulting composite material is tough, fire-retardant,

strong, insulative, and has potential for use in various structural applications.

2.4 Phenolic Foam

Phenolic foam is a synthetic cellular solid made up of closed cells, or an

interconnected network of plates forming the edges and faces of cells (Klempner

2004, p. 37). This hollow infrastructure has several implications. First, it allows for

lightweight design options as an insulation material. Second, values of various

mechanical and thermal properties - including Young’s modulus, conductivity, and

strength - can be controlled by altering the density of the cellular solids.

The material is a polymer foam that typically consists of phenolic resin (the base

matrix), surfactants, an acid catalyst, and pentane, a blowing agent used to expand

the matrix. Fibers may also be added as reinforcing agents to increase the strength to

weight ratio.

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Phenolic foam has several important properties. First, as with most cellular materials,

it has very low thermal conductivity and is a good choice as an insulation material.

The material also has low mass, low cost, and is exceptionally fire resistant and

thermally stable. Finally, it has low smoke density, low smoke toxicity, and non-

dripping during combustion. Disadvantages to the material are that it is fairly water

absorbent, corrosive to metal, and brittle (Shen 2003, p. 22).

Severe brittleness has prevented the material from being used extensively in load-

bearing applications. Sandwich panels with a phenolic foam core have achieved only

modest success, due to difficulty in bonding the foam to other materials. However,

previous work done at the University of Southern California (described below) has

shown that fibers embedded in the material make it stronger, more ductile and

competitive with structural foams such as polyurethane or PVC (Shen & Nutt 2003,

p. 904).

2.5 Previous Work

Previous studies with phenolic foam have focused primarily on using fibers in the

foam as reinforcing agents. Fibers have the potential to increase foam strength and

reduce brittleness. In particular, short chopped glass and aramid fibers have been

used to increase phenolic foam toughness (Desai et. al 2008). In another study,

various approaches to toughening phenolic foam and a comprehensive evaluation of

its mechanical performance were undertaken (Shen 2003). Short fiber reinforcements

29

demonstrated significant improvement in mechanical performance, and aramid fibers

were shown to best enhance toughness. Additional topics explored included: peel

resistance of reinforced phenolic foam, anisotropy and the effect of fiber orientation

on strength, and the mechanics of phenolic foam sandwich structures.

Most recent work at the University of Southern California that has built off the

previous studies involves mechanical behavior of hybrid composite foam (Desai et.

al 2008). Phenolic foam was reinforced with chopped glass and aramid in varied

proportions, in order to increase its toughness, and various mechanical properties

were assessed. The above studies all confirm that fibers can effectively be used as

reinforcing agents to strengthen phenolic foam. Current work at USC is considering

specific load-bearing applications of fiber reinforced phenolic foam.

This thesis built off the previously described studies and attempted to produce a low

density load-bearing material. The thesis also examined three topics not considered

in previous studies, the methods of analyses of which are outlined in Chapter 3:

• comparison of phenolic foam versus EPS: mechanical, thermal, and

environmental impact properties and costs

• effects of various climate simulations on mechanical properties

• strength and conductivity differences between natural and synthetic fibers.

30

Chapter 3: Methodology This thesis’s goal was to determine whether phenolic foam is suitable as a hybrid

structural insulation material in hot, humid, and rainy underdeveloped regions like

northern Thailand. Methodology in pursuing this goal involved eight steps:

• Obtain materials: fabricate phenolic foam, buy EPS, and cut samples.

• Record pre-conditioning measurements (length and weight). Conditioning is

defined as exposing materials to environmental conditions that simulate

Thailand’s hot, arid, rainy summer climate (see Appendix A: Glossary).

• Condition samples with one of two climate simulations (water immersion or

accelerated aging).

• Record post-conditioning measurements (length and weight).

• Test samples, both unconditioned and post-conditioned, in compression,

shear, cell length, flammability, or conductivity.

• Assess environmental impact of materials.

• Assess cost of insulating a typical home in northern Thailand with the

materials.

• Compare results with common structural and insulation materials.

Climate tests were included in the methodology since they may alter materials’

mechanical properties (American Society for Testing and Materials 1998, p. 35;

American Society for Testing and Materials 2004b, p. 532). In most tests, three

31

samples were tested in order to obtain a meaningful average. Environmental impact

and cost were assessed to provide a sustainability profile of phenolic foam. Several

materials and equipment items were purchased in order to execute this methodology.

The project also required the use of materials from various suppliers as well as

several laboratory facilities at the University of Southern California.

3.1 Fabrication

The first step in the project was fabricating phenolic foam. The proprietary formula

belongs to M.C. Gill Corporation, a company in El Monte, California, which

develops high performance composite products and has sponsored previous projects

involving phenolic foam at USC.

3.1.1 Materials

The formula to make phenolic foam consists primarily of phenolic resin (HRJ-

14489, supplied by Schenectedy International Inc.). The resin was stored in a

refrigerator at 4ºC to prolong its lifetime and prevent curing. The resin provided the

base matrix.

Two surfactants (Pel-stab, supplied by Pelron Corp., France, and Dabco, DC193,

supplied by Air Products and Chemicals Inc., Pennsylvania) served to stabilize the

material and refine the cell sizes.

Phenolsulfonic acid (CRC-608, supplied by Capital Resin Corp., Ohio) acted as a

catalyst and created heat during foam formation.

Fibers added reinforcement and were supplied by Owens Corning (glass), DuPont

(aramid), Advanced Fiber Technology (cellulose), and Habu Textiles (bamboo).

N-pentane, a blowing agent supplied by Aldrich Chemical Co., provided gas to

expand the foam. The amount of pentane largely determined foam density.

3.1.2 Mixer

A mixer (Keyence hybrid mixer HM-560) involving two simultaneous rotation types

combined the phenolic foam chemicals (see Figure 3.1).

Figure 3.1: Keyence hybrid mixer used to mix phenolic foam chemicals


The centrifugal force drove the resin flow in the container, which provided a shear

force necessary for mixing and dispersing fibers. The advantage of using this mixing 32

33

method was that it eliminated air voids in the mixture. Because temperatures of the

dispersed fiber mixtures increased after mixing, the containers were cooled for ten

minutes before fibers were added.

3.1.3 Fabrication Process

Five types of foams were fabricated: un-reinforced phenolic foam, glass fiber

reinforced phenolic foam, bamboo fiber reinforced phenolic foam, aramid fiber

reinforced phenolic foam, and cellulose fiber reinforced phenolic foam. Proportions

of chemicals were kept constant in order to maintain uniform composition across

foam type: acid was 5% of the resin mass (5 wt%), surfactants were 1.5 wt% (Pel-

stab) and .5 wt% (Dabco), pentane was 4 wt%, and glass, aramid, and cellulose fiber

were 4 wt%. Bamboo fibers were only 2 wt%, since greater proportions of bamboo

created high heat and viscosity when mixing the fibers into the resin. Section 3.1.4

describes problems with the mixing process.

The fabrication process began by weighing resin and surfactants in a polyethylene

container and mixing for two minutes in the mixer. Fibers were cut into ¼” lengths

(see Figure 3.2).

Figure 3.2: The author cutting bamboo fiber into ¼” lengths


The fibers were then added to the mixture, and the materials were mixed again for

two minutes and then cooled (see Figure 3.3).

Figure 3.3: Adding aramid fibers to the resin-surfactant mixture


34

Next, pentane and acid were added to the cold container and mixed together for two

minutes. Hand mixing, followed by one minute of additional mixing in the mixer,

was sometimes necessary to thoroughly combine the chemicals. The final mixture

was transferred into a Styrofoam mold (see Figure 3.4).

Figure 3.4: Styrofoam mold covered in aluminum foil


Five containers were typically combined in the mold to create a final mixture, which

was heated in the open mold in an oven at 80ºC for one hour. A similar process was

followed for un-reinforced foam, although the containers did not need to be cooled.

3.1.4 Problems

Several problems arose while fabricating phenolic foam, including thermal control,

problems with the batch process, fiber dispersion, and the creation of uniformly

dense samples.

3.1.4.1 Thermal Control

Thermal control proved to be the biggest challenge while fabricating fiber reinforced

phenolic foam. The addition of fibers created great friction and a highly viscous

35

36

mixture generating much heat. As a result, the top of the polyethylene container

sometimes burst while in the mixture, creating a huge mess. The best solution was to

cool the containers in a refrigerator at 4ºC for ten minutes after adding the fibers but

before adding the acid and pentane.

3.1.4.2 Batch Process

A second fabrication problem was working with a batch process. Since the

containers were small (holding about 200 grams), several containers – typically four

or five – had to be combined in the mold. The resulting mixture was non-uniform,

due to slight variations in chemical amounts or mixing times. The solution was to

keep amounts and mixing times precisely identical before combining the individual

batches. Amounts were measured to the nearest hundredth of a gram.

3.1.4.3 Fiber Dispersion

A third problem was fiber dispersion. Bamboo fibers generated much friction, heat

and eruptions in the mixer, despite cooling. Hand mixing proved the easiest method

of dispersing bamboo fibers, although this did not uniformly distribute the fibers.

The other fiber types were only slightly less difficult to uniformly mix in the mixer.

Non-uniform fiber dispersion, caused in part by hand versus machined mixing, could

explain why certain fiber reinforced phenolic foam samples did not perform well in

the strength tests.

3.1.4.4 Non-Uniform Density

A fourth problem was creating uniformly dense samples. Foams with different

reinforcing fibers should have reasonably close densities in order to facilitate

37

comparisons between their mechanical properties (Shen et al. 2003, p.942). For

example, Paraskevopoulos (1962, 4.4) has noted that mechanical properties of

foams, including compression and shear strengths, are related to density as follows:

S = A(D)C

where S = the mechanical property in question

D = density

A and C = constants varying with the type of property under consideration,

but independent of D.

Thus, materials should have similar densities in order to accurately compare their

mechanical properties.

Unfortunately, maintaining uniform densities across fiber type was a difficult task

during fabrication. Density does not stay constant within the volume of a foam block

but may be much greater at the surface layers, due mainly to processing conditions

(Klempner 2004, p.27). Table 3.1 shows that although the densities of glass, aramid,

cellulose, and un-reinforced phenolic foam samples were within 6% of 4.22 pcf,

bamboo foam density was 41% less than this value at 2.51 pcf. This was likely

because of the aforementioned problems with mixing and fiber dispersion.

Table 3.1: Density of fiber reinforced phenolic foam samples

The implications of Table 3.1 were severe for my thesis goals. Because the density

of bamboo samples was significantly less than the density of other foam samples,

mechanical properties of bamboo fiber reinforced phenolic foam could not be fairly

compared with the other samples. Therefore, bamboo fiber reinforced phenolic foam

did not undergo strength testing and was not considered for structural applications.

However, it was assumed that water absorption, aging, flammability, cell length, and

conductivity would be less related to density (although still related) than strength

38

39

properties, and these tests were conducted for bamboo fiber reinforced phenolic

foam. Remediation of this density problem is discussed in Chapter 8: Future Work.

3.1.4.5 Low Density Values

Table 3.1 reveals a final problem: samples’ density values were ultimately too low

for the materials to be considered for structural applications. A study looking at

structural applications of phenolic foam formulated sample densities between 12 and

15 pcf (Desai et al. 2008, p. 20). The values in Table 3.1 fall well below this range.

Because strength is proportional to density, it was concluded that phenolic foam as

fabricated in this thesis would not be suitable for structural applications. As a result,

the project goal narrowed in scope: only insulation applications would be considered

for phenolic foam. However, structural tests were still carried out to confirm that

phenolic foam would not be strong enough to serve as a load-bearing material.

3.2 Cutting Samples

After fabrication, phenolic foam blocks were allowed to cool for 20 minutes. The

blocks were then cut into samples of various sizes, depending on the American

Society for Testing and Materials (ASTM) testing standard. A metal handsaw was

used to cut the foam, and a band saw and sandpaper were used to create precise

dimensions.

40

3.3 Density Measurements

Length, width, height, and weight measurements were recorded after samples were

cut. These measurements were compared to measurements taken after climate

conditioning. As mentioned, due to problems in creating uniformly dense samples

across fiber type, strength tests for bamboo fiber reinforced phenolic foam were not

conducted.

3.4 Climate Conditioning

After measurement, samples underwent climate conditioning by being placed either

in a water absorption or accelerated aging chamber. Control samples were not

conditioned. The water absorption test was chosen to model heavy rain conditions in

northern Thailand. Likewise, the aging test was chosen to model extreme heat and

humidity conditions in the region.

3.4.1 Climate Simulation I: Water Immersion

ASTM D570 (long-term immersion) was followed in order to conduct water

absorption, the first climate simulation. The procedure served two purposes. First, it

yielded water absorption rates, as samples were weighed at various intervals

throughout the test. Second, it prepared samples for four post-conditioning tests:

compression, shear, cell measurement (conducted with scanning electron

microscopy), and conductivity.

The first step in the water absorption test was to condition the cut samples in an oven

at 50 ºC for 24 hours. Next, samples were placed in a flat-bottomed glass bowl,

which was then filled with de-ionized water. Samples were kept at room temperature

and submerged by placing aluminum foil on top of the water, aluminum cans on top

of the foil, and a five pound weight on top of the cans. Samples were weighed at

various intervals by removing samples from the container and wiping surface

moisture with a dry cloth. Figure 3.5 shows samples being submersed in the water

chamber.

Figure 3.5: Samples being prepared for water absorption testing


Deviations from ASTM D570 were as follows. The water sample sizes were

dependent on the post-conditioning test: 1”x1”x1” for compression, 1”x1”x¼” for

shear, 1”x1”x1” for SEM, and 4½”x4½”x1” for conductivity. Samples were weighed

at 24 hours, 48 hours, one week, two weeks, three weeks, four weeks, five weeks,

and six weeks after initial submersion. Conductivity samples were submersed in

water for only one week due to time constraints. Samples were not re-conditioned in 41

an oven, as a large quantity of sediment was not observed after six weeks. The

amount of absorbed water was calculated as the increase in weight = (wet weight –

conditioned weight) / conditioned weight. Three samples were conditioned for each

fiber type to obtain a meaningful average for both water absorption results as well as

results for each of the three post-conditioning tests.

3.4.2 Climate Simulation II: Accelerated Aging

Accelerating aging was performed per ASTM D 2126 specifications. The test

prepared samples for three post-conditioning tests: compression, shear, and cell

measurement.

Samples were first conditioned in an oven at 50 ºC for 24 hours. Next, samples were

placed in an environmental testing chamber, or humidity oven, at USC’s mechanical

engineering lab (see Figure 3.6). Controls were set at 40ºC and 85% humidity.

Samples were conditioned for six weeks then weighed.

Figure 3.6: Samples in USC’s environmental testing chamber


42

43

Deviations from ASTM D 2126 were as follows. As with the water absorption test,

the sample size was dependent on the post-conditiong test: 1”x1”x1” for

compression, 1”x1”x¼” for shear, and 1”x1”x1” for SEM. Samples were not

conditioned in an oven (to extract moisture) before being placed in the chamber. No

measurements were taken during the six week duration. Three samples were placed

in the aging chamber for each fiber type to obtain a meaningful average for results of

the post-conditioning tests.

3.5 Testing

Following climate conditioning, samples were subjected to one of five tests designed

to measure mechanical or thermal properties. Control samples that had undergone no

climate conditioning were also tested in order to compare phenolic foam’s properties

in both conditioned and unconditioned environments. Such a comparison showed the

effects of water, heat, and humidity on phenolic foam’s properties. Table 3.2

summarizes the tests conducted.

44

Glass No Fibers Bamboo Aramid Cellulose EPS Compression No stress 3 3 3 3 3 3 Water 3 3 3 3 3 3 Aging 3 3 3 3 3 3 Shear No stress 3 3 3 3 3 3 Water 3 3 3 3 3 3 Aging 3 3 3 3 3 3 Conductivity No stress 1 1 1 1 1 1 Water 1 1 1 1 1 1 Flammability 3 3 3 3 3 3 Cell Length (measured with SEM) No stress 1 1 1 1 1 1 Water 1 1 1 1 1 1 Aging 1 1 1 1 1 1

Table 3.2: Tests conducted for each material. Numbers indicate numbers of samples tested.

3.5.1 Test I: Compression

Compression testing was performed per ASTM D 1621 specifications. An Instron

machine in USC’s engineering department provided the necessary equipment and

software (see Figure 3.7). Specimens were compressed between an upper and lower

stainless steel platen, and load was applied at a crosshead speed of 0.5 mm/min. The

sample was loaded in the direction of the foam rise direction since, because of the

anisotropy of foam properties, load direction can yield drastically different results

(Shen & Nutt 2003, p. 903). The Instron program automatically provided load-

deformation curves as well as maximum load, yield strength, compressive strength,

Young’s modulus, and ultimate stress for each specimen.

Figure 3.7: Instron machine loaded with two stainless steel platens for compression testing


Deviations from ASTM 1621 were as follows. Sample size was 1”x1”x1” instead of

2”x2”x1”. At least three samples were tested for each specimen, and the results were

averaged. Specimens were either not conditioned or conditioned in water or aging

chambers as described above.

3.5.2 Test II: Shear

Shear testing was performed per ASTM C 273 specifications. As with the

compression test, an Instron machine provided the necessary equipment and

software. Shear samples had to be glued between a bottom and top metal shear plate

(see Fig. 3.8).

45

Figure 3.8: Shear samples being glued between shear plates


Two-ton epoxy was used to adhere the sample ¼” away from each metal plate’s

edge. Two-pound lead fishing weights were placed on the uppermost metal plate.

After the epoxy dried for 12 hours, the sample was tested: the two plates were loaded

in the machine, the upper plate was pulled in one direction, and the lower shear plate

was pulled in the opposite direction (see Figure 3.9). The Instron program

automatically provided outputs of maximum load and extension at maximum load.

46

Figure 3.9: Shear sample undergoing testing


Deviations from ASTM C 273 were as follows. Sample size was 1”x1”x¼” instead

of 2”x12”x1”. At least three samples were tested for each specimen, and the results

were averaged. Specimens were either not conditioned or conditioned in water or

aging chambers as described above.

3.5.3 Test III: Cell Length (SEM)

Scanning electron microscopy (SEM) was used to compare cell lengths in phenolic

foam both before and after climate conditioning. This test was important because cell

size can have considerable influence on the properties of phenolic foam. For

example, thermal conductivity increases as cell size increases, since there are more

paths available for heat transfer by radiation and convection. The Young’s modulus

also increases as cell size increases (Klempner 2004, p.37).

47

A Cambridge 360 SEM machine was used at USC to conduct the test (see Figure

3.10). Samples were carefully cut using a razor blade. Small samples about

1/8”x1/2”x1/8” were cut from 1”x1”x1” cubes and adhered to a metal disk. The disk

was placed in a gold sputtering chamber for about 15 minutes to impart electrical

conductivity and then loaded into the SEM machine. The machine’s operating

voltage was 10kV. Images were recorded in a high-resolution electronic format and

processed with computer software. The machine provided zoom and measurement

capabilities in order to measure cell length.

Figure 3.10 Cambridge 360 Scanning Electron Microscope


3.5.4 Test IV: Flammability

UL 94 vertical burn test was followed in order to measure flammability. Samples

were loaded into the metal fire chamber, and a Bunsen burner was lit and slid

beneath the sample (see Figure 3.11). The flame was applied to samples for two 10

second intervals separated by the time it took (if any) for the combustion to cease

48

after the first application. The length of time that the sample retained flame for each

application was measured.

Figure 3.11: Sample loaded into fire testing chamber


Deviations from UL94 were as follows. Sample size was 1”x1”x5” instead of

½”x½”x5”. Three samples were tested per specimen. In addition to combustion time,

the volume of each sample was measured before and after the test in order to

determine the percent volume of material consumed by flame.

3.5.5 Test V: Conductivity

R-values were measured both before and after water immersion. The purpose was to

measure R-value degradation due to water, an important factor when considering the

long term performance of building materials exposed to the elements.

Two separate tests were conducted. First, ASTM C 518 was conducted by Oak Ridge

National Lab in Oak Ridge, Tennessee yielding R-values.

49

Deviations from ASTM C 518 were as follows. Sample size was 11”x11”x1” instead

of 12”x12”x1”. A big challenge in this test was fabricating large samples, since Oak

Ridge Laboratory requires sizes of 8”x8”x1” or larger. Four smaller squares sized

5 ½”x5 ½”x1” were glued together to form the larger square. The four squares were

glued together by constructing wooden frames about 12”x12” (see Figure 3.12).

Warren Haby, USC’s composite materials lab technician, constructed the frames.

Two-ton epoxy was applied to each square, and four squares were laid in the wooden

frame. Screws were inserted in the frames every 2” and tightened so each small

square pressed against each other. Wax paper and a thin piece of wood were

sandwiched between each sample and screw to prevent deformation.

Figure 3.12: Conductivity samples being glued together in 12” wooden frames


After the glue dried for four hours, the screws were released and the final samples

were shipped to Oak Ridge National Laboratory. Figure 3.13 shows how the overall

50

sample size of 11”x11”x1” was created by gluing four smaller panels together of size

5 ½”x5 ½”x1”.

Figure 3.13: Cellulose fiber conductivity sample


A modified conductivity test was also executed. The strategy was to compare

temperature drops across the foam samples with temperature drops across a material

of known R-value. By assuming that temperature and R-value had a linear relation,

the R-value of the foam samples could be deduced.

Samples - both conditioned after one week of water immersion and unconditioned -

were separately placed inside a box consisting of three layers of materials. EPS

panels comprised the outer two layers. The inner layer consisted of five EPS panels

and one test panel: either unreinforced phenolic foam, fiber reinforced phenolic

foam, or EPS. A 4W light bulb served as a heat source inside the box. Two iButtons

(DS1921L) were positioned: inside the box and embedded in an EPS panel between

the inner and middle layers. The inner iButton logged the temperature inside the box,

and the middle iButton logged the temperature against the outer face of the test 51

52

panel. Finally, a radiant barrier consisting of an aluminum foil sheet was placed

between the heat source and the test panel in order to minimize radiant gain. This

configuration (see Figure 3.14) was used to calculate the temperature drop across the

test panel. The R-value of phenolic foam under both dry and wet conditions could be

deduced using the following formula:

R-value (test panel) = R-value (EPS) * Temperature Difference (test panel) /

Temperature Difference (EPS).

The R-value of EPS was specified on the product wrapping as 3.85 m²*K/W.

Figure 3.14: Conductivity test apparatus


3.6 Results

Chapters 4, 5, and 6 present thesis results. Each chapter compares phenolic foam

with EPS. Goals and key questions are first established. An application is chosen: the

use of phenolic foam as an insulation material. Assumptions, limitations, and

deviations from standard testing methods are outlined. Environmental impact

categories are defined, and relevant data is referenced in order to provide quantitative

results. Appropriate conclusions are drawn in Chapter 7, and a recommendation is

53

54

ultimately provided to meet the thesis goal. Future work building on these results is

presented in Chapter 8.

3.6.1 Mechanical and Thermal Tests

Chapter 4 presents results and analysis of the mechanical and thermal test data.

Three sets of data comparisons were made: climate simulations, phenolic foam

versus EPS, and fiber type. The Instron machine provided compression and shear

data, the SEM machine measured cell lengths, iButtons measured temperature

values, and a caliper obtained length measurements associated with the fire test.

All data was arranged in excel spreadsheets. Three samples were tested for most tests

and climate simulations across each fiber type. The results were averaged in order to

get a more meaningful result than just one sample. Bar graphs were constructed to

aid in data analysis.

3.6.2 Environmental Impact Assessment

Chapter 5 presents results of the environmental impact assessment. Various lifecycle

cost assessment software programs were attempted to conduct a lifecycle cost

analysis of phenolic foam and EPS, including Athena, Gemis, and GaBi. However,

none of the programs included phenolic foam as a material to analyze. Instead, data

was obtained by researching published information on phenolic foam’s and EPS’s

embodied energy, emissions, and toxicity. In addition, the heat loss of each material

was calculated by inputting the R-value of each material (obtained from the

55

conductivity test) into HEED (Home Energy Efficient Design), a energy analysis

software tool.

3.6.3 Costs

Chapter 6 presents results of the cost assessment to insulate a home in northern

Thailand with either phenolic foam or EPS. Cost categories included raw materials,

transportation, machinery, labor, and electricity. Both published data and estimates

were used to arrive at a final cost estimate for each material.

56

Chapter 4: Test Results Test results compared various mechanical and thermal properties of phenolic foam

and EPS. Density measurements were obtained, and then all materials underwent two

environmental simulations: water and accelerated aging. Common sense dictated that

only fiber materials with a density of 3.0 pcf underwent compression and shear

testing. Materials below this value compressed quite easily when squeezed between

index finger and thumb. Materials also underwent three other tests tied to various

environmental responses: SEM cell length measurement, flammability, and

conductivity.

As described in Chapter 1, the objective of this thesis was to determine whether

phenolic foam is suitable as a hybrid structural insulation material in hot, rainy

climates like northern Thailand. Therefore, answers to the following five key

questions were sought throughout analysis of the test results:

• Are load-bearing applications possible?

• Did phenolic foam withstand climatic stresses well?

• Which material performed better in the tests, phenolic foam or EPS?

• Did natural or synthetic fibers fare better?

• Which material performed best overall?

4.1 Density

After fabricating each type of fiber reinforced phenolic foam, length, width, height,

and weight were measured. Density measurements were also taken after the two

climate simulations. Table 4.1 shows density results for each fiber type (glass,

bamboo, aramid, and cellulose) embedded in phenolic foam. Water and aging

represent the two climate stresses. EPS represents the comparison material.

Climatic Effects on Density

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

Material

Dens

ity (p

cf)

No stressWaterAging

No stress 3.08 4.29 2.42 4.93 4.01 0.95

Water 36.06 33.79 13.09 26.20 27.71 7.31

Aging 4.29 4.00 2.31 4.57 3.79 0.95

Glass No fiber Bamboo Aramid Cellulose EPS

Table 4.1: Density results for all materials

The table shows that the density of bamboo fiber reinforced phenolic foam was

significantly less than the other fibers. As described in Chapter 3, the creation of

uniform density samples was difficult due to mixing and fiber dispersion problems.

Because mechanical properties of foam materials vary according to density, strength 57

testing was therefore not undertaken for bamboo fiber reinforced phenolic foam. The

density of bamboo fiber reinforced phenolic foam also fell well below density values

of common load-bearing materials (see Table 4.2).

Table 4.2: Densities of common load-bearing materials

http://www.engineersedge.com/manufacturing_spec/average_properties_structural_materials.htm

1http://hypertextbook.com/facts/2004/KarenSutherland.shtml

The remaining materials underwent compression and shear testing, both before and

after water and aging simulations, in order to determine their viability as load-

bearing materials under extreme weather conditions.

It should be noted that the density of EPS was significantly less than fiber reinforced

phenolic foam. For example, Table 4.1 indicates that EPS was 69% less dense than

glass fiber reinforced phenolic foam. Despite this disparity, this thesis tested EPS

against the same set of tests as phenolic foam, since one of the project goals was to

compare mechanical properties of phenolic foam and commonly available insulation

materials regardless of density differences. EPS was also bought at Home Depot, and

therefore its density value could not be adjusted through the fabrication process as

with phenolic foam.

58

Table 4.1 also shows the effect of water and aging climate simulations on density.

The table suggests that neither phenolic foam nor EPS is a very water resistant

material, with the density of glass fiber reinforced phenolic foam exceeding 36 pcf

after the water absorption test.

Table 4.3 shows the percentage increase in density after water exposure.

Density, % Increase after Water Exposure

0.00

200.00

400.00

600.00

800.00

1000.00

1200.00

Material

Dens

ity, %

Incr

ease

afte

r W

ater

Exp

osur

e

Water Density, % Increase 1070.78 687.65 440.91 431.44 591.02 669.47


Table 4.3: Percentage increase in density after 8-week water exposure for all materials

Bamboo and aramid showed the least increase in density, although both materials

still increased their weight by a significant percentage. Glass performed the worst,

and EPS performed better than some fibers but not as well as others. Similarly,

natural fibers (cellulose and bamboo) performed better than some but not all of the

materials. These observations on density increase after water exposure suggest no

clear advantage when comparing phenolic foam versus EPS or natural versus

synthetic fibers. Further discussion of water and aging tests follows in Section 4.3.

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4.2 Strength Tests

Results of strength tests determined whether phenolic foam could serve as a load-

bearing material.

4.2.1 Compression

Fiber reinforced phenolic foams with a density value of 3.0 pcf or higher as well as

EPS underwent compression and shear testing. Sample sizes were 1”x1”x1”.

Compression results are shown in Tables 4.4 and 4.5. Compressive strength is

defined as the maximum stress a material can sustain under crush loading. For

samples that do not shatter in compression, the compressive strength is the amount of

stress required to distort the material an arbitrary amount. Compressive strength is

calculated by dividing the maximum load by the original cross-sectional area of the

sample (Instron 2008).

http://www.instron.us/wa/resourcecenter/glossaryterm.aspx?ID=145

Climatic Effects on Compressive Strength

0.00

20.00

40.00

60.00

80.00

Material

Com

pres

sive

Str

engt

h (p

si)

No stress

Water

Aging

No stress 21.47 44.64 47.47 49.04 12.85

Water 47.76 33.63 30.83 36.78 12.33

Aging 74.08 44.36 54.27 34.07 12.69

Glass No Fiber Aramid Cellulose EPS

Table 4.4: Compression results: climatic effects on compressive strength

Climatic Effects on Young's Modulus

0.00

500.00

1000.00

1500.00

2000.00

2500.00

Material

Youn

g's

Mod

ulus

(psi

)

No stress

Water

Aging

No stress 615.80 1935.57 2226.79 933.99 83.63

Water 1140.81 1093.53 1200.85 1043.73 153.25

Aging 937.76 1301.21 1318.61 523.56 92.82

Glass No fiber Aramid Cellulose EPS

Table 4.5: Compression results: climatic effects on Young’s modulus

The results of Tables 4.4 and 4.5 were used to evaluate the following three questions:

• Can phenolic foam be used as a load-bearing material in Thailand?

61

• Do climate stresses weaken phenolic foam?

• Do natural or synthetic fibers add greater strength to phenolic foam?

4.2.1.1 Can Phenolic Foam Be Used as a Load-Bearing Material in Thailand?

A simple calculation using the results from Tables 4.4 and 4.5 shows whether

phenolic foam could be used as a load-bearing material in northern Thailand.

Assume a typical one-story house in the region has wood floors having weight 25 psf

and dimensions 40’ x 50’. The house consists of four rooms each 20’x 25’(see Figure

5.1). A 1’ wide wall strip is analyzed.

Figure 4.1: Assumed typical 40’ x 50’ house plan in northern Thailand

Diagram courtesy of G.G. Schierle, 2008

The tributary area is 1’ x 20’ = 20 ft2.

62

The resisting area is 8” x 12” = 96 in².

The tributary length is 20’.

P = uniform load x tributary area = 25 psf x 20’ x 1’ = 500 lb

Wall stress f = P/A = 500 lb / 96 in² = 5.2 psi

The average compressive value for all phenolic foam materials in Table 4.4 is used =

43.2 psi. A reasonable safety factor is 10, considering the data has a high standard

deviation (more consistent strength results would yield a lower safety factor).

43.2 psi / 10 = 4.32 psi

4.32 < 5.2, NOT OK

This result shows that phenolic foam is not strong enough to be used as a load-

bearing material.

Consider also Table 4.6, which gives Young’s modulus values for common load-

bearing materials. Published values for industrial grade phenolic resin and

polystyrene are included for comparison purposes.

63

http://www.diracdelta.co.uk/science/source/y/o/youngs%20modulus/source.html

2Schierle, Structure and Design

Table 4.6: Young’s modulus values for common building materials

Industrial grade phenolic foam is significantly less stiff than almost all common

building materials. Aramid fiber reinforced phenolic foam, the strongest material

fabricated in Table 4.5 at 2227 psi, is over 700 times less stiff than Douglas fir-larch

wood and is comparable to concrete. This is likely due to the low density of phenolic

foam produced in this thesis. The table also shows that phenolic resin has a stiffness

about 200 times greater than the fabricated phenolic foam. Again, the most likely

reason for the difference is that the fabricated phenolic foam was not very dense. In

addition, the foam contained a low percentage of fibers (4% for glass, aramid, and

cellulose; 2% for bamboo) due to mixing difficulties; a higher fiber percentage

would have increased the density and, correspondingly, the strength values. As noted

in Chapter 3, non-uniform fiber distribution also likely contributed to low strength

values. See Chapter 8: Future Work for further discussion about phenolic foam’s

potential as a load-bearing material.

64

65

4.2.1.2 Do Climate Stresses Weaken Phenolic Foam?

Compressive results are inconclusive when evaluating phenolic foam’s ability to

withstand climate stresses. Tables 4.4 and 4.5 show that, in some cases, phenolic

foam’s post-stressed strength values were higher than with no stress. In other cases,

the unstressed samples were strongest. This phenomenon may have occurred because

the same exact sample was not tested for each stress condition: unstressed, water,

and aging. Each sample varied in its fiber content, fiber dispersion, and overall

density, likely leading to the flux in strength values across climate simulation. This

problem could be remedied by creating more uniform samples. Compressive strength

of EPS was only slightly affected by climatic stresses, although this is hardly an

advantage over phenolic foam considering unstressed EPS was much weaker than

phenolic foam in the first place.

4.2.1.3 Do Natural or Synthetic Fibers Provide Greater Strength to Phenolic

Foam?

Compression results are also inconclusive as to whether natural or synthetic fibers

withstood climate stresses better, and the distinction appeared somewhat arbitrary.

For example, cellulose fiber reinforced phenolic foam had a higher compressive

strength and Young’s modulus across climate stress than some fibers but had lower

values than other fibers.

4.2.2 Shear

Shear results are shown in Table 4.7.

Climatic Effects on Maximum Load

0.00

50.00

100.00

150.00

Material

Max

imum

Loa

d (N

)No climate stressWaterAging

No climate stress 90.97 79.09 112.88 69.58 89.30

Water 84.80 74.30 119.69 91.43 45.56

Aging 97.24 71.53 84.27 86.53 62.56

Glass No fiber Aramid Cellulose EPS

Table 4.7: Shear results: climatic effects on maximum shear load

Shear results reinforce phenolic foam’s inability to act as a load-bearing member.

For example, plywood with steel stud backing (24” O.C. spacing) has a maximum

shear load of 3225 N (Dietrich Metal Framing Company n.d.). This value is over 30

times the measured shear load of phenolic foam. As with the compression test,

greater shear strength could be achieved by creating samples with a higher

percentage of fiber reinforcements. This issue is discussed in Chapter 8: Future

Work.

Shear results are inconclusive when evaluating phenolic foam’s ability to withstand

climatic stresses. Water and aging would presumably reduce shear stress maximum

load, yet only unreinforced phenolic foam showed a progressive drop in shear values

(6% after the water test and 10% after the aging test). The reason again likely relates

66

67

to the non-uniform fiber dispersion in the samples; more uniform samples would

have to be fabricated in order to create more informative results.

Finally, shear results are largely inconclusive when evaluating phenolic foam versus

EPS and natural versus synthetic fibers, as no one material or fiber type performed

consistently well across climate stress.

4.3 Climate Simulations

Strength tests outlined in 4.2 showed that phenolic foam is not strong enough to act

as a load-bearing material. Non-load bearing applications were then considered. In

order to determine how suitable the material is for non-load bearing insulation and

cladding applications, the material’s response to water immersion and accelerated

aging was measured. The water simulation determined how well the material would

perform under long-term water exposure, and accelerated aging determined how well

the material would perform under intense heat and humidity. Bamboo fiber

reinforced phenolic foam was considered for these applications since, even though

the material had a low density, load-bearing applications were not being considered.

Glass, aramid, and cellulose fibers were also evaluated along with unreinforced

phenolic foam and EPS.

Climate simulation results answered the following questions:

• How well does phenolic foam withstand extreme weather conditions?

68

• Does phenolic foam or EPS perform better under extreme weather?

• Do natural or synthetic fibers perform better under extreme weather?

4.3.1 Water Immersion

Two tables were used to express water absorption values. First, Table 4.8 gives water

absorption rates, where weekly amount of water absorbed was calculated according

to the following equation:

Water absorption rate = (wet weight – conditioned weight) / initial mass * 100. The

conditioned weight represented the sample weight after being placed in an oven at

50ºC for one hour but before being placed in the water immersion chamber.

Water Absorption Rates

0100200300400500600700800900

1000

Weeks Elapsed

Wat

er A

bsor

bed,

% (m

ass/

mas

s)

GlassNo FibersBambooAramidCelluloseEPS

Glass 0 285.01 388.21 463.92 631.38 696.39 741.81 758.68 772.02No Fibers 0 272.53 406.5 494.23 676.56 754.31 812.67 847.33 869.14Bamboo 0 218.92 323.51 416.71 492.67 534.76 534.76 534.76 534.76Aramid 0 267.36 347.90 401.98 585.74 636.63 678.45 703.56 709.39Cellulose 0 453.67 672.59 750.21 792.16 817.42 817.42 817.42 817.42EPS 0 643.55 660.41 691.54 691.54 691.54 691.54 691.54 691.54

0 1 2 3 4 5 6 7 8

Table 4.8: Water absorption rates for phenolic foam and EPS expressed as mass of water

absorbed as a percentage of mass of material

Table 4.9 presents water absorption values after both 24 hours and 8 weeks.

Water Absorption, %

0

200400

600800

1000

Material

Wat

er A

bsor

ptio

n, %

(m

ass/

mas

s)

24-Hour Immersion8-Week Immersion

24-Hour Immersion 155.42 156.21 102.96 159.35 183.91 435.56

8-Week Immersion 772.02 869.14 534.76 709.39 817.42 691.54

Glass No fibers Bamboo Aramid Cellulose EPS

Table 4.9: Mass of water absorbed expressed as percentage of mass of sample

69

The results show that both phenolic foam and EPS absorbed water at a rapid rate.

The EPS value, however, tapered off fairly quickly. The phenolic foam absorption

rate took several weeks to slow down and converge towards a value. Also, the

addition of fibers in all cases reduced water absorption after eight weeks when

compared to unreinforced phenolic foam. Finally, natural fibers performed better

than synthetic fibers in one case and worse in another case, as bamboo absorbed the

least amount of water and cellulose absorbed the most amount of water. These

results suggest that bamboo fibers used to reinforce phenolic foam may be an

effective method of reducing water absorption in rain screen or other cladding

applications. This is reinforced by the fact that bamboo fiber reinforced foam

absorbed the least amount of water of all materials tested.

Table 4.10 compares 24-hour water absorption values for some common insulation

materials.

Table 4.10: Water absorption values for some common insulation materials

http://www.buildingscience.com/bsc/designsthatwork/buildingmaterials.htm

70

The 24-hour immersion values in Table 4.9 may be compared with the values in

Table 4.10. Common insulation materials absorb far less water than phenolic foam or

EPS; bamboo was the least water resistant fiber yet doubled its weight in the first 24

hours of exposure. Because northern Thailand receives significant amounts of rain in

the wet season, exterior cladding applications such as rain screens using phenolic

foam as a core material would require a skin layer adhered to the foam.

4.3.2 Accelerated Aging

Results of the accelerated aging test are summarized in Table 4.11. Mass lost as a

percentage of initial mass was calculated by subtracting the final mass of each

sample after six weeks in the environmental chamber from the initial mass then

dividing by the initial mass and multiplying by 100.

Accelerated Aging Results

0

5

10

15

20

Material

Mas

s Lo

st, %

of I

nitia

l Mas

s

Mass Lost, % 6.42 5.31 6.05 5.79 14.46 2.33

Glass No fibers Bamboo Aramid Cellulose EPS

Table 4.11: Accelerated aging results: mass lost as a percentage of initial mass

71

72

The results show that phenolic foam lost a fair amount of material over the six weeks

at 40ºC and 85% humidity. EPS performed somewhat better and lost half as much

mass as phenolic foam. Aramid performed best among fibers, and cellulose

performed the worst, suggesting natural fiber reinforced phenolic foam may not be

the best choice of cladding material to withstand extreme heat and humidity.

4.4 Other Tests

The three remaining tests measured cell length (measured through SEM), fire

resistance, and conductivity. These tests were performed to further evaluate phenolic

foam’s potential as an insulation or cladding material.

4.4.1 Cell Length (SEM)

SEM was used in order to measure cell length of samples before and after climate

conditioning. The test was important because it determined whether extreme weather

altered materials’ cell length as well as whether a correlation could be drawn

between cell length and water resistance. Table 4.12 shows SEM images of the

various samples before and after climatic stresses. The numbers next to the images

indicate the magnification level of the microscope.

Table 4.12: SEM images showing cell length across climatic stress

Table 4.13 quantifies the cell lengths. Measurements were taken using software

accompanying the Cambridge 360 SEM machine.

73

SEM Results: Climatic Effects on Cell Length

0

200

400

600

Material

Cel

l len

gth

(mic

rons

)No stressWaterAging

No stress 140 330 150 170 186 140

Water 164 445 176 157 144 121

Aging 188 412 224 245 211 162


Table 4.13: SEM results: cell length across climatic stress

The results indicate that unreinforced phenolic foam’s cell length is much greater

than the other materials’ cell lengths. This result is important because it suggests that

fiber reinforcement has the benefit of reducing cell size. Comparison of Table 4.13

with Table 4.8 (water absorption results) confirms that a correlation can be drawn

between cell length and water resistance. Reduced cell length therefore offers an

explanation of why water absorption values for fiber reinforced phenolic foam are

less than unreinforced phenolic foam values.

Less informative cell length conclusions are as follows. For most fibers,

environmental stress had little, if any, effect on cell size. EPS cell lengths were equal

to or slightly less than phenolic foam cell lengths, and natural and synthetic fibers’

cell lengths were about the same.

74

4.4.2 Fire Resistance

Table 4.14 gives results of the flammability test.

Table 4.14: Flammability test results: volume lost as a percentage of initial volume

Results show that fire resistance is one of phenolic foam’s biggest advantages over

EPS. Phenolic foam was not consumed by fire whereas EPS was consumed. This

result has significant implications when considering whether to use phenolic foam or

EPS as an insulation material.

Table 4.15 gives another result obtained by using the classification system defined

by testing standard UL 94. VO is the best rating, and V1 is not as good.

75

Table 4.15: Flammability test results: UL 94 ratings assigned to materials

Results clearly show that phenolic foam rates as a more fire resistant material than

EPS.

4.4.3 Conductivity

Two sets of conductivity results were obtained: those recorded by Oak Ridge

National Laboratory per ASTM C 518, and those recorded by the author using a

homemade conductivity apparatus to measure temperature drops across materials

(see Chapter 3).

Table 4.16 presents R-values recorded by Oak Ridge National Laboratory.

R-values obtained by Oak Ridge National Laboratory

0.00

2.00

4.00

6.00

Material

R-va

lue

(m2*

K/W

)

No Stress 4.00 4.07 4.05 4.00

Glass No Fibers Aramid Cellulose

Table 4.16: R-values recorded by Oak Ridge National Laboratory per ASTM C 518

76

Oak Ridge was only able to record reliable values for glass fiber, aramid fiber,

cellulose fiber, and unreinforced phenolic foam. The values were nearly identical,

and the test offered no comparison with EPS.

The conductivity test conducted by the author was more useful by providing EPS and

water immersion R-values. Tables 4.17 and 4.18 show results of the conductivity test

for both unconditioned materials and materials immersed in water for one week. The

tables show the temperature change across each material as a function of time.

Conductivity Results: Temperature Drop (No Water Immersion)

010203040506070

1 10 19 28 37 46 55 64 73 82 91 100

Time (minutes)

Tem

pera

ture

Cha

nge

(°F)


Table 4.17: Conductivity results: temperature drop across dry materials

77

Conductivity Results: Temperature Drop After Water Immersion

010203040506070

1 10 19 28 37 46 55 64 73 82 91 100

Time (minutes)

Tem

pera

ture

Cha

nge

(°F)


Table 4.18: Conductivity results: temperature drop across wet materials (one week immersion)

R-values are shown in Table 4.19, calculated using the following equation:

R-value (unknown material) = Maximum temperature drop (unknown material) /

Maximum temperature drop (known material) * R-value (known material). EPS

served as the known material.

78

R-values

0

2

4

6

Material

R-v

alue

(m2*

K/W

)No Stress

Water

No Stress 5.22 5.13 5.3 5.65 4.62 3.85

Water 2.31 2.31 1.97 2.82 1.97 3.08

Glass No Fibers

Bamboo Aramid Cellulose EPS

Table 4.19: Conductivity test results: R-values

The most significant result is that water greatly affects R-value degradation, and EPS

outperformed phenolic foam in this respect. Although EPS without any water

exposure has a lower R-value than phenolic foam, the material has a higher R-value

than phenolic foam after water exposure. This result shows that R-values should be

carefully considered when insulating buildings. Just because a material has a lower

published R-value than another material does not mean that it will not insulate better

after exposure to climate stresses. Phenolic foam’s poor thermal response to climate

stress therefore suggests it may not be the best insulation material in wet regions like

northern Thailand.

Other conclusions include aramid fiber reinforced phenolic foam performed the best

among fibers, and no significant differences separated natural and synthetic fibers.

79

Also, the phenolic foam R-values recorded by Oak Ridge National Laboratory were

slightly less than the values recorded by the author. This was likely for two reasons:

first, Oak Ridge followed ASTM C 518, whereas the author measured temperature

drops using no ASTM standard. Second, each test used different samples, which

likely had different densities and fiber composition.

R-values of common insulation materials under no water stress are provided in Table

4.20.

Table 4.20: R-values of common materials

http://www.buildingscience.com/bsc/designsthatwork/buildingmaterials.htm

Unstressed phenolic foam has R-values that are competitive with these materials,

with only rigid polyisocyanurate insulation having a higher value. However,

phenolic foam’s good insulative value is only retained when not exposed to climate

stresses such as water.

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R-value degradation is also important when considering energy losses and costs of

building insulation. These issues are more thoroughly discussed in Chapter 5:

Environmental Impact and Chapter 6: Costs.

4.5 Summary

Results show that phenolic foam cannot be used as a load-bearing material given the

low densities and strength values of the samples tested. However, phenolic foam has

potential as an insulation and/or cladding material. It is lightweight, fire resistant,

and insulative (under no climate stresses) and performs reasonably well after

extended exposure to intense heat and humidity. Neither natural nor synthetic fibers

display any consistent advantage, suggesting this distinction is somewhat arbitrary as

far as mechanical tests are concerned. Bamboo fiber reinforced phenolic foam,

however, has fair water resistance. Aramid fiber reinforced phenolic foam was also

the strongest and most insulative material. Another useful conclusion is that cell

length can be correlated with water resistance, suggesting denser materials should be

better at resisting water. Chapter 8 discusses ways of increasing the density of

phenolic foam. Finally, phenolic foam’s best advantages over EPS are its fire

resistance and insulative value, although the material’s R-value deteriorates severely

when exposed to extreme flooding conditions.

82

Chapter 5: Environmental Impact An environmental impact assessment of insulation materials is essential when

comparing and choosing insulation materials. The result should benefit the

environment, as a well-informed decision can reduce building energy consumption

costs dramatically. This is important because buildings are a huge source of energy

consumption. For example, homes account for 21% of all energy used in the United

States every year, and the average annual utility bill is $1767.00 (United States

Department of Energy 2008). Therefore, as an energy-saving tool, insulation plays a

critical role in determining building operations costs.

Insulation material selection is broad. The most popular insulation materials

comprising about 90% of the insulation market are inorganic fibrous (glass wool and

stone wool) and organic foamy (EPS, extruded polystyrene, and polyurethane)

materials (Papadopoulos & Giama 2006, p. 2178). Environmentally friendly

materials based on agricultural raw materials have found limited market share due to

high cost and limited accessibility of information. Environmental impact assessments

can therefore better inform the public on insulation material selection and ultimately

help citizens make “greener” insulation choices.

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5.1 Prior Environmental Impact Studies on Insulation

Limited data exists on the environmental impact of insulation materials. Data on

phenolic foam is especially lacking. Schmidt performed a life cycle assessment of

stone wool, flax, and cellulose wool insulation (2003). Paper wool had the lowest

global and regional environmental impacts, and flax insulation had the highest. Stone

wool had the lowest total energy use, followed by cellulose and flax. Stone wool was

also found to be the most occupationally healthy material, mainly because of the

absence of carcinogenic properties. Aside from Schmidt’s results, however, no

studies rigorously and comprehensively evaluate the environmental advantages and

disadvantages of various insulation materials and systems.

5.2 Difficulty in Assessing the Environmental Impact of Phenolic Foam

Instead of using existing studies, then, raw data was researched in order to assess the

environmental impact of phenolic foam. However, perhaps because of phenolic

foam’s extremely limited market share, raw data is also limited. The United States

Department of the Interior notes that the environmental characteristics of foam are

complex and not well understood (2008). Moreover, lifecycle cost analysis software

such at Athena, Gemis, and GaBi do not list phenolic foam as an insulation material,

and the material is often not found in data specification sheets on insulation

materials. A thorough lifecycle cost assessment model would supply all first and

future costs, including production, manufacturing, transportation, maintenance,

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labor, installation, and repair costs. However, estimating such costs in this thesis

would have required considerable guesswork and assumptions.

Another reason producing a comprehensive environmental impact assessment of

phenolic foam proved quite a challenge is because chemicals used in phenolic foam

production have frequently changed in the last 30 years, especially as hydrocarbons

have become a more appealing and environmentally sensitive substitute for

hydrofluorocarbons. Section 5.4.4.1 details the evolving nature of phenolic foam’s

production process.

5.3 Method

The approach this thesis took on assessing the environmental impact of phenolic

foam was to use two sources:

• data generated in Chapter 4: Results

• published data.

These two sources were used to compare the environmental impact of phenolic foam

with EPS. R-values calculated in Chapter 4 were found to be particularly useful in

this assessment. By building on its own previously acquired data, the thesis

succeeded in providing an environmental impact assessment. Several environmental

impact categories, including embodied energy, CO2 emissions, and the correlation

between R-value and heat loss, helped determine which material was more

environmentally sensitive.

85

Data estimates from suppliers were also used in estimating the cost of insulating a

home in northern Thailand with phenolic foam, including production, transportation,

labor, and purchase costs. This assessment is presented in Chapter 6 and helped

determine which material was not only environmentally friendly but also

economically viable. A final recommendation is presented in Chapter 7, which

combines results of this chapter, the test results of Chapter 4, and the cost results of

Chapter 6. This conclusion yields the thesis’s goal of providing a recommendation

on which insulation material is best suited for use in hot, rainy regions such as

northern Thailand.

5.4 Results: Environmental Impact Assessment of Phenolic Foam

Several considerations were taken into account when determining the environmental

impact of phenolic foam. Heat loss, moisture resistance, embodied energy, emissions

in the form of hydrochlorofluorocarbons (HCFCs) and CO2, and toxicity were used

to compare the environmental impact of phenolic foam with EPS. Thesis data helped

analyze the first two factors, and published data were used for the final three factors.

5.4.1 Heat Loss

Which material would produce more heat loss in a building in northern Thailand,

phenolic foam or EPS? The energy software program HEED (Home Energy Efficient

Design) was used to answer this question. R-values for materials both before and

after water stress were used. This was important since, as Chapter 4 showed, EPS’s

R-value degrades more slowly than phenolic foam’s R-value. Therefore, pre- and

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post-water stress R-values used in heat loss calculations would presumably yield

different results.

5.4.1.1 Building the Model

Since only relative heat loss data was desired, the following basic specifications were

inputted into HEED to create a rough model of a rural house in northern Thailand:

• one-story

• 40’x52’ (modeled after figure 4.1; note: HEED dimensions are in multiples

of 4, so 40’x50’ was not possible; 40’x52’ was used.)

• 8’ tall ceilings

• 4 residents

• no garage

• windows:

o 7 on south façade, 2 on east façade, 3 on north façade, 2 on west

facade

o clear single pane 1/8” glass in aluminum frame (“no glass”, typical of

homes in rural northern Thailand, was not an option)

• insulated attic and raised floor; radiant barrier installed in attic

• walls: wood siding on 2x6 wood studs at 24”, plaster board interior

• roof: white (cool roof) elastomeric membrane; flat roof

• floors: wood floors exposed

• under first floor condition: area open to exterior

• infiltration: very poorly sealed older building

• ventilation: good natural ventilation (up to 5.0 air changes per hour) by

opening windows as needed (no fans)

• heating: no furnace

• cooling: no air conditioner

• overhangs: fixed all year long, never retracted

Additionally, since only climate regions in the United States were options, Los

Angeles (zip code: 90007) was chosen as the location. Both northern Thailand and

Los Angeles have warm temperatures year-round.

The HEED model of this house is shown in Figure 5.1:

Figure 5.1: Simple one-story house in northern Thailand constructed in HEED

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5.4.1.2 Calculating Heat Loss

In order to calculate heat loss, wall U-values had to be entered into HEED. U-values

calculated in the conductivity section of Chapter 4 before and after water stress were

used. It was assumed that the average wall U-value was equal to the U-value of a

wall constructed entirely of 1” thick phenolic foam. No interior or exterior layers

were applied. Only relative heat losses were desired, so the U-value of the windows

was not factored in to the calculation. It is recognized that this does not give data on

the magnitude of the net impact, only relative impact between the two foams.

Table 5.1 presents U-values of phenolic foam and EPS before and after water stress.

These values were obtained by inverting the R-values obtained in the conductivity

results in Chapter 4 (see Table 4.18).

U-values

0.000

0.200

0.400

0.600

Material

U-v

alue

(W/m

2*K

)

No Stress 0.192 0.195 0.189 0.177 0.216 0.260

Water 0.433 0.433 0.508 0.355 0.508 0.325

Glass No Fibers Bamboo Aramid Cellulose EPS

Table 5.1: U-values entered into HEED to obtain energy loss data on each separate material

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These values were entered into HEED, and Table 5.2 presents the resulting energy

losses of the building both before and after the materials had been exposed to water.

Energy Losses in a Northern Thai House

0

20000

40000

60000

80000

Material

BTU

H

No stress 44134 44270 43997 43452 45225 47226

Water 55093 55093 58503 51546 58503 50182

Glass No Fibers Bamboo Aramid Cellulose EPS

Table 5.2: Effect of water exposure on energy losses in a northern Thai house

Results show that EPS performed about 8.7% worse than aramid, the best-

performing material, before water exposure. EPS performed 2.6% better than aramid,

however, after water exposure. These results suggest that EPS would retain energy

slightly better than phenolic foam after prolonged exposure to rain.

Heat loss, however, is not too relevant as northern Thailand has a warm climate for

most of the year. The analysis could be more useful in colder regions or regions

which use heaters. Still, the results show moisture effects on relative energy losses of

homes insulated with phenolic foam and EPS.

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90

The results of Table 5.2 were used in Chapter 6: Costs to estimate costs related to

energy losses in buildings.

5.4.2 Moisture Resistance

Moisture resistance is a more relevant indicator of the environmental impact of

phenolic foam, as northern Thailand receives tremendous amounts of rain during the

rainy season from April to September. The ability to resist both infiltration and

absorption of water plays a critical factor in long-term thermal performance of

building materials in the region. Most importantly, a stable R-value is linked to high

resistance of water moisture absorption (Fabian et al. 2004). This translates to less

energy loss. Table 5.3 reproduces the results of Table 4.8, which show water

absorption rates of phenolic foam and EPS.

Water Absorption Rates

0100200300400500600700800900

1000

Weeks Elapsed

Wat

er A

bsor

bed,

% (m

ass/

mas

s)


Glass 0 285.01 388.21 463.92 631.38 696.39 741.81 758.68 772.02No Fibers 0 272.53 406.5 494.23 676.56 754.31 812.67 847.33 869.14Bamboo 0 218.92 323.51 416.71 492.67 534.76 534.76 534.76 534.76Aramid 0 267.36 347.90 401.98 585.74 636.63 678.45 703.56 709.39Cellulose 0 453.67 672.59 750.21 792.16 817.42 817.42 817.42 817.42EPS 0 643.55 660.41 691.54 691.54 691.54 691.54 691.54 691.54

0 1 2 3 4 5 6 7 8

Table 5.3: Water absorption rates for phenolic foam and EPS expressed as mass of water

absorbed as a percentage of mass of material

As noted in Chapter 4, bamboo and aramid fiber reinforced phenolic foam and EPS

resisted water the best, and unreinforced phenolic foam resisted water the worst. EPS

initially absorbed more water, but its absorption rate quickly tapered off and the

material ultimately absorbed less water than all other materials except bamboo

reinforced phenolic foam. Overall, neither phenolic foam nor EPS faired well in

resisting water, since all materials showed a threefold increase in weight after water

immersion. In addition, both phenolic foam and EPS R-values significantly

decreased after water exposure, hurting the thermal performance of buildings

insulated with these materials. As noted in Table 5.1, phenolic foam’s R-value 91

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deteriorated more than EPS’s R-value, suggesting buildings insulated with phenolic

foam would experience slighter greater energy losses after prolonged exposure to

rain.

5.4.3 Embodied Energy

Embodied energy is perhaps a more useful indicator than heat loss of the

environmental impact of phenolic foam insulation in northern Thai homes. As the

United States Department of the Interior notes, insulation manufacturing processes

generate pollution as a result of fossil fuel combustion. The simplest way the

Department recommends comparing manufacturing impacts is to compare the

manufacturing energy required, or embodied energy (2008).

John Barry Associates Architects and the United States Air Force Air Combat

Command have produced a “Sustainable Facility Guide” to creating energy efficient

buildings (2000). Besides weighing the advantages of using spray, blow-in, or rigid

insulation under different applications, the guide includes a table of embodied energy

values for the most common insulation materials (see Table 5.4; first appears as

Table 2.4).

Table 5.4: Embodied energy of common insulation materials

1http://www.canadianarchitect.com/asf/perspectives_sustainibility/measures_of_sustainablity/measur

es_of_sustainablity_embodied.htm

The guide also describes the production of phenolic resins used in plastic materials

and gives the embodied energy as 34,383 Btu/lb. This value is 28% less than the

value for EPS. Assuming phenolic foam has an embodied energy comparable to

plastic materials made out of phenolic resin (a reasonable assumption given plastics

and foam are typically 60% or more phenolic resin by mass), phenolic foam’s

embodied energy is considerably less, and has a considerably less environmental

impact, than EPS’s embodied energy.

5.4.4 Emissions

Phenolic foam and EPS are closed-cell foam insulation materials, meaning they

consist of cells closed to prevent the passage of air. These cells contain air or gas-

filled pockets arranged to retard heat flow, and blowing agents are required to

expand these materials and create the pockets. Cellular foam insulation is typically

classified as either thermoplastic foams (EPS and extruded polystyrene) or thermoset

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plastic foams (phenolic, polyurethane, and polyisocyanurate) (Kalinger & Drouin

2001). As long as phenolic foam and EPS use pentane as a blowing agent, they are

considered CFC (chlorofluorocarbon)-free insulation and exhibit low levels of toxic

chemical emissions. However, the use of HFCs would increase the level of toxic

emissions. The following investigation gives a historical look at foam emissions,

provides specific quantitative data on HFC emissions, and offers a basis for

comparing carbon emissions in phenolic foam and EPS.

5.4.4.1 Phenolic Foam

Chlorofluorocarbons (CFCs) were used up until the 1980s as blowing agents for

phenolic and other thermoset foams. Since the conductivity of CFCs is lower than

air, the conductivity of the insulation was lower than air-filled materials. CFCs in

phenolic foam also had low toxicity and were odorless and nonflammable. Their

biggest drawback was that chlorine in CFCs degraded the Earth’s ozone layer.

Hydrochlorofluorocarbons (HCFCs) appeared to be a solution, as their ozone

depleting potential (ODP) was only 5-10% of CFCs (Kalinger & Drouin 2001).

However, HCFCs or CFCs were still emitted into the atmosphere during foam

manufacturing or on-site application, while in use, or when discarded. For example,

as the foams aged, blowing agents migrated out of the foam according to a leakage

rate defined mainly by foam cell structure and solubility (United States

Environmental Protection Agency 2001). The Copenhagen Amendment of 1992

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restricted their use and production, and they are planned to be phased out of foam

production by 2030.

Hydrocarbons and hydrofluorocarbons (HFCs) have been used as substitute blowing

agents. For example, n-pentane is a hydrocarbon that was used in the fabrication of

phenolic foam in this thesis (see Chapter 3). This material has high availability, low

cost, and zero ODP. In addition, its low solubility means it has a low diffusion rate

out of foam (Grimminger & Muha 1995). This translates into minimum carbon

emissions.

Unfortunately, n-pentane is not always used as a blowing agent in commercially

manufactured phenolic foam, as HFCs and other ozone depleting substitutes are

commonly used. The United States Environmental Protection Agency has created an

emissions profile for HFC blowing agents used in phenolic foam (see Table 5.5)

(Godwin 2003). The values were calculated using the following equation:

Ej = O (efi x Qcj-i+1) for i = 1 -> k

Where E = Emissions. Total emissions of a specific chemical in year j for

closed-cell foam blowing, by weight.

Ef = Emission Factor. Percent of foam’s original charge emitted in

each year (1 -> k). This factor includes a rate for manufacturing

emissions (occurs during the first year of foam life), annual emissions

(every year throughout the foam lifetime), and disposal emissions

(occurs during the final year of foam life).

Qc = Quantity of Chemical. Total amount of a specific chemical used

in closed-cell foams in year j.

k = Lifetime. Average lifetime of foam product.

HFC Emissions in Phenolic Foam

25%

36%

39%

Loss at Manufacturing (%) Leakage (%) Loss at Disposal (%)

Table 5.5: Hydrofluorocarbon (HFC) emissions in phenolic foam, in the case where HFCs are

used as blowing agents. The leakage rate is 1.125% per year, and the leakage lifetime is 32

years.

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The table shows that emissions are greatest during the final year of foam life.

Emissions during the product lifetime are slightly less than this value, and emissions

during manufacturing are the least.

5.4.4.2 EPS

The Environmental Protection Agency describes EPS as a non-emissive plastic. It is

made with neither CFCs nor HCFCs and is expanded with the hydrocarbon n-

pentane, similar to the fabrication of phenolic foam in this thesis. The United States

Department of the Interior notes that pentane contributes to smog but not ozone

depletion or global warming (2008). The pentane leaks out of the EPS and is

replaced with air. The Department further notes that in California, many plants used

to manufacture EPS now recover up to 95% of pentane used in production.

5.4.4.3 Phenolic Foam Versus EPS

The emissions profiles of phenolic foam and EPS production, therefore, largely

depend on the chemicals used. Assuming phenolic foam production uses HFCs as

blowing agents, EPS would have the better emissions profile. Assuming both use the

hydrocarbon n-pentane, the environmental impact of the two materials based on

emissions would be similar.

One final distinction the United States Environmental Protection Agency draws

between the two materials is the carbon content of phenolic and EPS resins. Phenolic

resin (phenol) has a somewhat lower carbon content at 77%, whereas polystyrene’s

carbon content is 92% (2007). Uncertainty in these values, particularly in phenolic

foam’s carbon content, is high. Some of the carbon may be released into the

atmosphere during the life of the products, but the Environmental Protection Agency

notes that this amount is likely to be small (2007). Therefore, this analysis suggests

that carbon emissions during the life of both phenolic foam and EPS are difficult to

compare and are assumed to be reasonably similar.

5.4.5 Toxicity

Both phenolic foam and EPS exhibit low toxicity. Analysis of two separate studies

on toxic properties shows that no significant toxic differences separate the two

materials.

5.4.5.1 Phenolic Foam

Composite Building Structures, a manufacturer of homes, prepared a fire, smoke,

and toxicity (FST) study of phenolic foam (2007). The material was burned, and

toxins were measured against the target values for the International Maritime

Organization’s fire test procedures code (IMO FTP code). Table 5.6 presents the

results.

Table 5.6: Toxicity concentrations in phenolic foam

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Phenolic foam gas concentrations fall below the IMO FTO Code values for every

toxin. The test also confirmed flammability results shown in Table 4.14, which

demonstrated that phenolic foam has a low flame spread.

5.4.5.2 EPS

Airlite Plastics Company manufacturers various materials for home construction

projects. The company published EPS toxicity data undertaken by Underwriters

Laboratories (Fox Blocks 2008). Some of the report’s key results were:

• no HCFCs or CFCs emitted during manufacturing

• no toxins or formaldehyde produced

• low flame spread

• low smoke density

The report suggested that EPS emits relatively low quantities of toxins.

Consequently, phenolic foam and EPS are comparable in terms of toxicity

assessments. The only clear advantage that phenolic foam has over EPS as far as

burn characteristics is its much greater fire resistance.

5.5 Summary

A comprehensive environmental impact comparison of phenolic foam and EPS is

difficult due to limited data. However, the environmental impact of the materials can

be compared in a few categories. The method of comparison used data compiled in

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this thesis as well as in published reports. Results can be broken down into five

categories: heat loss, moisture resistance, embodied energy, emissions, and toxicity.

Phenolic foam has a higher R-value and conserves more energy, except after

prolonged exposure to water when EPS has the advantage in these two categories.

EPS initially absorbs more water than phenolic foam, but its absorption rate quickly

tapers off and becomes less in the long term than phenolic foam’s absorption rate.

Phenolic foam has 28% less embodied energy than EPS, the strongest indicator that

phenolic foam is a better insulation material for the environment. Phenolic foam also

burns much less easily. Emissions and toxicity are assumed comparable between the

two materials, largely because of the difficulty in generating precise emissions

estimates.

In addition to environmental impact and mechanical and thermal properties,

however, the various costs associated with insulating a home in northern Thailand

with both phenolic foam and EPS must be considered. This data, when included with

environmental impact considerations and mechanical and thermal test results, is

helpful when making a final recommendation on which material is best suited as an

insulation material in northern Thailand. The following chapter assesses cost.

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Chapter 6: Costs The goal of this chapter is to compare the cost of insulating a typical house in

northern Thailand with phenolic foam and EPS. Chapter 7 builds on this chapter and

the prior two chapters (test results and environmental impact) to provide a final

recommendation regarding which material is better suited as an insulation material.

Here, raw material, transportation, labor, machinery, and electric power costs as well

as energy savings are presented.

6.1 Method

A scenario was created to evaluate phenolic foam versus EPS insulation costs in

northern Thailand. The scenario was as follows. First, raw materials were shipped to

a production site, where the final product was manufactured and then shipped to a

chosen construction site in northern Thailand. Here, the product was installed in a

house. Since EPS was assumed to be available at any of three large home

improvement stores near the site, the only costs considered for EPS were end product

retail and installation costs. It was assumed phenolic foam insulation would not be

available in end product form near the site, and its costs were broken down into raw

materials, production, transportation, and labor.

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6.2 Production Site

Bangkok was chosen as the production site, since many of phenolic foam’s raw

materials are supplied here (see Section 6.4). The city is a major transportation and

manufacturing hub for Southeast Asia, and shipping the end product from here to the

construction site would be convenient and cheap.

6.3 Construction Site

The chosen construction site was in Udon Thani in Thailand’s developing tropical

rain belt region near the Laos border (see Figure 6.1). A railroad line runs from the

city directly to Bangkok, providing a convenient method of shipping materials. Costs

were estimated for phenolic foam and EPS insulation installed in the walls and roof

of a one-story home in the rural outskirts of the city.

Figure 6.1: Construction site chosen as a case study to estimate insulation costs

http://www.lib.utexas.edu/maps/middle_east_and_asia/thailand_pol88.jpg

The chosen building was a simple one-story 40’x50’ home. The walls were 8’ high,

and 1” thick insulation covered 80% of four exterior walls and 100% of the roof

area. Note this is identical to the building used to calculate compression loads in

Section 4.2.1.1. The total insulation coverage was:

• 80% x (2 walls x 40’x8’x1”x1’/12”) = 43 ft3 (north and south exterior walls)

• 80% x (2 walls x 50’x8’x1”x1’/12”) = 53 ft3 (east and west exterior walls)

• 100% x 40’x50’x1”x1’/12” = 167 ft3 (roof)

Total insulation coverage = 263 ft3.

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104

6.4 Suppliers

Various suppliers were researched which provide raw materials for phenolic foam

manufacturing. The strategy was to find suppliers nearest to the construction site in

order to reduce shipping costs. Table 6.1 lists raw materials, the various suppliers,

and their proximity to the construction site.

Raw material Supplier nearest construction site Location Distance to site (miles)Phenolic resin Thai GCI Resitop Co.,Ltd Rayong, Thailand 341 Surfactants Pel-stab Pelron Corp. France 5,785 Dabco Air Products and Chemicals, Inc. Pennsylvania 8,482 n-Pentane NGL Chemicals Bangkok 294 Phenolsulphonic Nanjing Yinqi Biological Engineering Nanjing, China 1,420 acid Co., Ltd. Fibers Aramid Dupont Tokyo 2,589 Glass Fabulous Fiber Bangkok 294 Cellulose Eikonik Bangkok 294 Bamboo Kongkiat Textile Co., Ltd. Bangkok 294

Table 6.1: Suppliers of phenolic foam raw materials

The table shows that many of the materials would come from Asia, and several of

the fibers would come from the production site in Bangkok. Dabco would be shipped

from North America, since no Asian vendors were discovered. Fortunately, Dabco

was only 1% of the final product mass, and so limited quantities would not inflate

transportation expenses. It should be noted that if phenolic insulation becomes more

common, Asian producers would likely emerge. This assumes the startup case.

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6.5 Raw Materials

Raw material costs were calculated for the one-story house as follows. Total

insulation coverage = 263 ft3 (calculated above in Section 6.3). Aramid was chosen

as the reinforcing fiber, as the overall best-performing material in strength, thermal,

and climate tests described in Chapter 4. Costs were based on online published data

from suppliers different from those listed in Table 6.1. As most of the suppliers in

Table 6.1 did not publish or make known raw material costs, it was assumed their

raw materials costs would be similar to costs published by other suppliers. Bulk cost

values, based on a 40,000 lb order (roughly the size of a freight container), were

considered when available and are noted in the discussion. As a final note on the

table values, the only available published data on bamboo fibers came from a

company in New York. The Bangkok-based company in Table 6.1 would likely

supply bamboo fibers at a cost considerably cheaper than this value. Table 6.2

presents the raw materials’ cost results.

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Material Cost ($/lb) % of end product Cost/batch ($) Cost/house ($)Phenolic resin 1.251 87 2.07 272.75 Surfactants Pel-stab 2.252 1 0.04 5.64 Dabco 107.403 1 2.04 269.36 n-Pentane 7.953 4 0.60 79.75 Phenolsulphonic acid 29.633 4 2.25 297.25 Fibers Aramid 11.504 3 0.66 86.53 Glass 1.365 3 0.08 10.23 Cellulose 0.206 3 0.01 1.50 Bamboo 58.247 3 3.88 511.63 Total ($) 7.66 1011.28

Table 6.2: Raw materials costs for phenolic foam

1 (J Fisher 2008, pers. comm., 8 Feb.)

2 (Sabatini 1996)

3 (Sigma-Aldrich 2007)

4 (Maleniak 2001)

5 (Cripps n.d.)

6 (Marcin & Klungness 1992)

7 (Habu Textiles 2007, pers. comm., 8 Sept.)

The second column represents the per pound cost of each material. Cost for phenolic

resin was reduced from $1.60/lb to $1.25/lb based on a bulk order (J Fisher 2008,

pers. comm., 8 Feb). The third column gives each raw material’s percentage of the

final foam product. Costs were then calculated based on production of one 1.9 lb

batch of foam. This value represented a typical foam block size produced in USC’s

engineering lab, and figuring costs using this relatively small size was the most

manageable. For example, phenolic resin made up 87% of one batch of foam, or .87

x 1.9 lb = 1.65 lb. At a cost of $1.25/lb, it cost $2.07 in phenolic resin to make one

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batch of foam. Following this cost procedure for the remaining raw materials and

adding the results, one batch of aramid fiber reinforced phenolic foam cost $7.66 in

raw materials.

The final column represents the cost to insulate the house walls and roof, based on

263 ft3 of coverage. Since the density of EPS purchased from Home Depot was .95

pcf (see Table 4.1), this value became the target density of phenolic foam as well.

Therefore, a 1.9 lb batch of foam at .95 pcf would yield 1.9 lb/.95 pcf = 2 ft3 of foam.

Since the total coverage was 263 ft3, it would take 263 ft3 / (2ft3 / batch) = 132

batches of foam to insulate the house. Since each batch cost $7.66 worth of raw

materials, the total raw material cost to insulate the house was $7.66 x 132 batches =

$1011.28.

6.6 Transportation

Transportation costs for the insulation materials were broken down as follows:

• cost to ship raw materials to the production site

• cost to ship end product to the construction site.

6.6.1 Cost to Ship Raw Materials to the Production Site

The bulk cost to ship raw materials to the production site was $0.10/lb of material, an

estimate provided by Schenectedy International, Inc., the supplier of phenolic resin

for this thesis (J Fisher 2008, pers. comm., 8 Feb.). Note that this cost was not

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estimated for EPS, since it was assumed EPS was available as an end product near

the construction site. Table 6.3 presents the results.

Material Weight/house (lb) Cost/house ($) Phenolic resin 218.20 21.82 Surfactants Pel-stab 2.51 0.25 Dabco 2.51 0.25 n-Pentane 10.03 1.00 Phenolsulphonic acid 10.03 1.00 Fibers Aramid 7.52 0.75 Glass 7.52 0.75 Cellulose 7.52 0.75 Bamboo 7.52 0.75 Total ($) 250.80 25.08

Table 6.3: Cost to ship phenolic foam raw materials to production site

The second column represents the per house weight of each raw material. The

equation used in this column was: percent of each raw material within the final

product x mass of one batch of foam (1.9 lb) x total number of batches per house

(132). The second column represents the per house cost to ship raw material (in bulk)

to the production site, based on a shipping cost of $0.10/lb. For example, the cost to

ship enough phenolic resin to produce insulation for one house was 218.20 lb x

$0.10/lb = $21.82. The total cost to ship enough phenolic foam raw materials to the

production site for one house, based on a bulk order of 40,000 lb of material, was

$25.08.

6.6.2 Cost to Ship End Product to the Construction Site

The cost to ship the final insulation product to the construction site varied according

to the distance of the construction site from the production site. Since the

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construction site was much closer to the supplier site for EPS (Udon Thani) than the

production site for phenolic foam (Bangkok, about 300 miles further), common sense

dictated that the cost to transport EPS would be cheaper than the cost to transport

phenolic foam. Therefore, $0.10/lb and $0.05/lb were used as shipping costs for

phenolic foam and EPS, respectively, from the production site to the construction

site.

The equation used to calculate end product shipping costs was: density of material x

volume of material needed x per pound shipping cost.

• Results for phenolic foam were: .95 pcf x 263 ft3 x $0.10/lb = $25.00.

• Results for EPS were: .95 pcf x 263 ft3 x $0.05/lb = $12.50.

Therefore, the cost to ship EPS insulation to the construction site was 50% cheaper

than the cost to ship phenolic foam insulation.

6.7 Machinery

Machinery costs only involved phenolic foam, as it was assumed EPS was already

available in end product form. Costs were broken down as follows, with the

assumption that production machinery consisted primarily of mixing machines,

ovens, and cutting machines. In order to produce enough insulation material for one

house as quickly and cost efficiently as possible, the number of machines had to be

optimized. It was assumed each machine had enough working capacity to handle 25

lbs of material (or, at .95 pcf, about 26 ft3). Table 6.3 shows that about 250 lb of

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insulation were needed to insulate one house. Therefore, 250 lb / (25lb/machine) =

10 machines needed to produce enough phenolic foam insulation for one house.

Estimated machinery costs were as follows:

• mixer = $100,000

• oven = $100,000

• cutting machine = $50,000

It was assumed each machine could be used to help produce enough insulation

product for 5,000 homes before significant repair or replacement costs were

necessary. Therefore, the machinery cost for producing insulation for one house =

($100,000 + $100,000 + $50,000) / 5000 = $50.

6.8 Labor

Labor costs were broken down into cost to manufacture the end product and the cost

to install the end product. Wages were assumed to be $1.25/hour, based on the

author’s experience with working on construction projects in the region.

6.8.1 Manufacturing

The cost to manufacture the end product involved only phenolic foam, since it was

assumed EPS would already be available in end product form. It was assumed it

would take two hours to produce enough insulation for one home, based on one hour

of mixing time and one hour of baking and cutting time. Ten workers were assumed

to be needed to operate the ten mixers, ovens, and cutting machines for these two

hours. Therefore, the labor cost was $1.25/hour x 2 hours x 10 workers = $25.00.

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6.8.2 Installation

Installation costs for phenolic foam and EPS were assumed to be similar. Twelve

workers were assumed to be the optimal number to install both materials. This was

based on two workers installing insulation on each of the four walls and four workers

installing insulation on the roof. It was assumed this job would take four hours.

Therefore, the installation cost for both materials was $1.25/hour x 4 hours x 12

workers = $60.00.

6.9 Electric Power Costs Associated with Production

Cost estimates for the energy needed to produce the insulation only involved

phenolic foam, since it was assumed EPS was available in end product form near the

construction site. The electricity rate for a small business at voltage greater than

22kV is 2.4649 Baht / kWh or about $0.07 / kWh (Board of Investment, Thailand

2005). It was assumed that about 1000 kWh were needed to produce enough

phenolic foam insulation for one house. Therefore, the total electricity cost to

produce enough phenolic foam insulation for one house is $0.07 x 1000 kWh = $70.

Note: the monthly service charge is 228.18 Baht or about $6.52. Relative to the

electricity rate, however, this charge was negligible and not included in energy cost

calculations.

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6.10 Lifetime Energy Savings

Energy savings over product lifetime must also be considered. Table 5.2 showed

how prolonged water exposure affects energy losses of phenolic foam and EPS. This

data was based on the result shown in Chapter 4 that EPS’s R-value - initially lower

than phenolic foam’s R-value - degrades less rapidly when exposed to water.

Consequently, aramid reinforced phenolic foam insulation saves 3,774 BTUH of

energy over EPS without any water exposure, but EPS saves 1,364 BTUH of energy

over aramid foam after water exposure. The Board of Investment, Thailand shows

that electricity costs 2.4649 (Thai baht/kWh) ~ $.000018/BTUH (2005). Assume the

lifetime of EPS and phenolic foam insulation is 20 years. Therefore, the energy

savings of phenolic foam over EPS without water exposure = 3,774 BTUH x

$.000018/BTUH x 20 years = $11,901.69. The energy savings of EPS over phenolic

foam after long term water exposure = $4,301.51.

The problem with this assessment is that energy losses are most relevant in a cold

climate, and northern Thailand is hot and arid. Therefore, it is assumed that neither

phenolic foam nor EPS provides any cost savings when considering energy losses in

this region. However, the analysis does show the relative advantages of each material

in cold climates: phenolic foam is favored in the short term without any water

exposure, and EPS is favored in the long term after R-value degradation due to

prolonged water exposure.

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6.11 Summary

Table 6.4 summarizes the above cost categories and energy savings.

Costs ($) Phenolic Foam EPS Raw materials 1011.28 n/a Transportation (to production site) 25.00 n/a Transportation (to construction site) 25.00 12.50 Labor (manufacturing) 25.00 n/a Labor (installation) 60.00 60.00 Machinery (manufacturing) 50.00 n/a Energy (manufacturing) 70.00 n/a Product selling price 1417.54 1083.56 Total cost for one house 1502.54 1156.06 Lifetime energy savings1 11901.69 4301.51 Overall savings 23.06%

Table 6.4: Costs of providing phenolic foam and EPS insulation for a typical house in northern

rural Thailand

1Assumes cold climate. Not used in overall savings calculation.

As noted throughout the chapter, several categories were not applicable to EPS since

it was assumed EPS was available in end product form near the construction site. Its

product selling price was based on the cost of an 8’ x 4’ x 1” thick sheet at Home

Depot = $11.00. The product cost for a 40’x50’x8’ house would be $1083.56.

Transportation and installation costs were added to this value to reach a final cost of

$1156.06.

Costs for phenolic foam insulation, on the other hand, also included raw materials

and manufacturing. The product selling cost was based on the sum of the raw

materials, the cost to transport raw materials to the production site, labor costs to

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manufacture the material, and the machinery and electricity costs to produce the

material. A 20% profit mark-up was included in the product selling price.

Transportation costs to the construction site and installation costs were added to the

product selling price to reach a final cost of $1502.54.

The results show that installing EPS represented a 23% savings. However, cost and

energy savings are only two factors to consider when choosing an insulation

material. Strength, durability, water resistance, and other mechanical and thermal

properties evaluated in previous chapters, as well as the environmental impact of

each material must also be considered before making a final recommendation. The

following chapter presents conclusions and offers a recommendation based on the

results of the previous three chapters.

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Chapter 7: Conclusion This thesis evaluated phenolic foam’s potential as a hybrid structural insulation

material in homes in northern Thailand. Strength tests were conducted in order to

assess the material’s load-bearing potential. Climatic effects on mechanical

properties were considered in order to determinate whether the foam could endure

the harsh weather of Thailand’s hot, humid, rainy season. The benefits of natural

versus synthetic fibers were also considered. In addition, the environmental impact

and costs of the material were considered to broaden the scope of the evaluation.

EPS was used as a comparison insulation material. The ultimate goal of the thesis

was to provide a recommendation on which material would be best suited as an

insulation material in northern Thai homes.

This chapter provides this recommendation by drawing conclusions from three

primary areas of analysis: mechanical and thermal tests, environmental impact, and

costs. Each area is evaluated separately according to which material exhibited

stronger performance. The relative weights of each of these three areas are then

considered before producing a final recommendation.

7.1 Mechanical and Thermal Tests

Results of the mechanical and thermal tests answered the following questions:

• Can phenolic foam be used as a load-bearing material?

• Can phenolic foam withstand climate stresses well?

• Do natural or synthetic fibers perform better?

• Which fiber performs best?

• Does phenolic foam or EPS perform better?

Table 7.1 summarizes the mechanical and thermal results presented in Chapter 4.

Table 7.1: Summary of mechanical and thermal results

Before considering each of the above questions, several notes accompanying the

table must be addressed. First, conclusions cannot be drawn for climatic effects on

compression and shear values. The reason is that in some cases phenolic foam was

not weakened by one condition, such as water absorption, but was weakened by the

other condition, such as accelerated aging. Second, shear testing showed that neither

phenolic foam nor EPS exhibited a clear advantage over the other material. Finally,

the separation of fibers into natural versus synthetic types proved to be somewhat

arbitrary, since neither type consistently performed well in mechanical and thermal

tests. In other words, finding one “good” natural fiber was not offset by finding a

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“bad” one. In practical terms, the good fiber would be used, the bad one would be

discarded, and the attention to natural versus synthetic would be ignored.

7.1.1 Load-bearing Applications

The second column of Table 7.1 suggests that load-bearing applications of phenolic

foam are not practical. Strength values were low primarily because of low density

values of samples; non-uniform fiber dispersion could also explain why some

samples were weaker than others. Chapter 8 discusses alternate conditions under

which load-bearing applications may be possible. It should also be noted that

previous work has shown that phenolic foam is strong enough to act as a load-

bearing member (Desai et al. 2008). Samples were fabricated at significantly higher

densities than in this thesis, however, demonstrating the relation between strength

and density. Fabricating higher density samples for load-bearing applications was not

the exclusive end goal of this thesis. Because of the difficulty in fabricating high

density materials, insulation applications became the focus.

7.1.2 Climate Stresses

The third column of Table 7.1 suggests that in most cases phenolic foam did not

perform well under climatic stresses or no conclusion could be drawn. One trend

noted was that fibers reduce cell length, and this length remained fairly constant

across climatic stress. As described in Chapter 1, the purpose of measuring cell

length was to derive a correlation between cell length and water resistance: materials

with little water resistance would presumably have larger cell lengths, and materials

with great water resistance would presumably have smaller cell lengths. Examination

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of Tables 4.8 (water resistance) and 4.13 (cell length) confirms a correlation between

cell length and water resistance. Therefore, reduced cell length explains why water

absorption values for fiber reinforced phenolic foam are less than unreinforced

phenolic foam values.

In conclusion, phenolic foam’s poor response to climate stresses suggests the

material should not be used for exterior applications. Exceptions would be if a skin,

perhaps made of plastic, were applied to the foam so that weather would not degrade

the material or its R-value.

7.1.3 Natural or Synthetic Fibers

Neither natural nor synthetic fibers had any conclusive advantage over the other, and

the distinction proved largely arbitrary. Bamboo did demonstrate strong water

resistance. However, bamboo proved difficult to fabricate in the lab above a density

of 3 pcf; therefore, its strength properties could not be fairly compared with the other

fibers (all at densities near 4 pcf). The creation of a stronger, denser, more water

resistant bamboo fiber reinforced phenolic foam material has strong potential and is

addressed in Chapter 8: Future Work.

7.1.4 Best Performing Fiber

Aramid performed the best of all fibers. Its strength, water resistance, aging

properties, fire resistance, and conductivity values suggest the strongest potential as

an insulation material. In addition, if fabricated at a high enough density (12 pcf to

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15 pcf), aramid fiber reinforced phenolic foam may be used effectively as a hybrid

structural insulation material.

7.1.5 Phenolic Foam or EPS

Both phenolic foam and EPS have mechanical advantages. EPS’s greatest advantage

is that it is lightweight and would be the better choice if a building application called

for a lightweight material. EPS is a better exterior insulation choice due to slower R-

value degradation due to moisture ingress. EPS also showed slightly better long-term

durability. Phenolic foam’s advantages are that it is stronger and has greater potential

as a load-bearing material. Phenolic foam is also much more fire resistant and has

better conductivity when not exposed to water. Therefore, phenolic foam should be

considered when a strong, fire resistant, or highly insulative material (under low

moisture exposure applications) is needed.

7.1.6 Summary

In conclusion, phenolic foam cannot be used as a load-bearing material unless

fabricated at a density considerably higher than those values tested in this thesis. The

material does not weather particularly well under climatic stresses, and the

distinction between natural and synthetic fibers proved arbitrary when considering

mechanical properties. EPS is more lightweight and has slower R-value degradation

than phenolic foam, whereas phenolic foam is a stronger, more fire resistant, and

more insulative material when not exposed to moisture.

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In Thailand, residents often cook in enclosed, interior kitchen spaces. Phenolic

foam’s fire resistance would suit well for this application. However, summer Thai

rains are intense, suggesting EPS would be a better insulation choice unless a skin

layer was applied to phenolic foam. Environmental impact and costs of phenolic

foam and EPS must also be examined before producing a final recommendation.

7.2 Environmental Impact

Several factors were considered when evaluating the environmental impact of

phenolic foam: heat loss, moisture resistance and R-value degradation, embodied

energy, emissions, and toxicity.

7.2.1 Heat Loss

Results from Chapter 5 showed that phenolic foam resists heat loss fairly well under

dry conditions, and EPS resists heat loss better under wet conditions. These results

were produced by correlating R-values calculated in Chapter 4 with heat losses

calculated in HEED in Chapter 5. However, these results are most relevant in cold

climates. Since Thailand’s summer climate is hot and humid and heaters are not

popular in the rural north, other environmental impact categories proved more

informative in recommending a material.

7.2.2 Moisture Resistance

Neither phenolic foam nor EPS resisted moisture well. However, EPS demonstrated

slower R-value degradation due to moisture exposure. Since R-value degradation is

an important factor when considering a building’s energy losses, EPS would have a

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better environmental impact in wet environments where energy retention within a

building - such as in cold regions - was important.

7.2.3 Embodied Energy

The “Sustainable Facility Guide” produced by the United States Air Force Air

Combat Command and John Barry Associates Architects shows that phenolic foam

has a clear advantage over EPS when embodied energy is considered (2000).

Phenolic foam’s embodied energy is 28% less than EPS and comparable to or better

than many other common insulation materials.

7.2.4 Emissions

Predicting the emissions of foam products is a difficult task. The United States

Environmental Protection Agency has shown that phenolic foam has a lower carbon

content than EPS (2007). However, the organization estimates that both products are

low-emissive and their emissions rates are ultimately quite comparable.

7.2.5 Toxicity

No distinction based on toxicity levels appears to separate phenolic foam or EPS.

7.2.6 Summary

In summary, both phenolic foam and EPS appear to have advantages when

environmental impact factors are considered. Phenolic foam has a lower embodied

energy, and EPS’s R-value degrades more slowly when exposed to water – an

advantage in cold climates. When building homes in Thailand, choosing phenolic

foam as the material with lower embodied energy should yield less environmental

strain.

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7.3 Costs

EPS is about 23% cheaper than phenolic foam to use as an insulation material in

northern Thailand. Phenolic foam’s raw materials and transportation costs are

relatively expensive, but these expenses would likely decrease relative to EPS if

phenolic foam gained a greater share in the market. If phenolic foam’s raw materials

were produced in Thailand, then the cost to insulate a house here using either

phenolic foam or EPS insulation would likely be similar.

The more practical issue is whether insulation can be afforded by Thai residents in

the first place. Unfortunately, the cost of both EPS and phenolic foam is

prohibitively out of the budget of most northern Thai citizens. Significant raw

material cost decreases (or GNP increases) would have to be realized before such

insulation products could realistically be installed in northern Thai homes.

7.4 Recommendation

The relative importance of mechanical properties, environmental impact, and cost

must be considered before providing a recommendation on whether phenolic foam or

EPS should be used as an insulation material in northern Thailand. The most

practical category is cost. Given that Thailand’s GNP per capita is $2712, these

materials are currently too expensive to be considered. Cost considerations aside,

phenolic foam is recommended based on its environmental impact. When

mechanical properties are considered, phenolic foam is more beneficial when fire

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resistance and strength are important. Phenolic foam is also more insulative, but only

under dry conditions. EPS’s biggest advantages are that it is more lightweight and

durable than phenolic foam. Between these two materials, then, phenolic foam

should be used for applications calling for a fire resistant, strong, insulative material

under dry conditions, whereas EPS should be used for applications calling for a

lightweight, durable, cheap, insulative material under wet conditions.

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Chapter 8: Future Work Several areas of research can be further explored with phenolic foam. The categories

can be broken down as follows:

• fabrication

• testing

• comparison materials

• environmental impact

• costs

8.1 Fabrication

Future experiments can explore more reliable methods of fabricating phenolic foam

at a constant density. As noted in Chapter 3, creating foam samples at the same

density - which allows fair comparison of mechanical properties - represented the

biggest challenge of this thesis. Problems included mixing materials, dispersing

fibers, regulating thermal control while mixing, and keeping the weight percentage

of fibers constant. It is suggested that future work fabricate phenolic foam using a

larger mixer. This would likely alleviate many of these problems and produce

samples at approximately equal densities. From there, strength and climate tests

would hopefully yield a more definitive separation of materials’ mechanical and

thermal properties when comparing phenolic foam versus EPS or other insulation

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materials. This thesis saw little separation of these properties in part because of

fabrication difficulties.

Another area to explore is fabricating phenolic foam with bamboo fibers. For

example, the strength properties of bamboo fiber reinforced phenolic foam were not

fully explored, since the material proved difficult to fabricate at a density above 3

pcf. Structural and other building applications with bamboo fiber reinforced phenolic

foam would be good possibilities to explore.

The use of other fibers may also be investigated. For example, palm fibers and flax

may offer strength or water resistant advantages.

Another possibility is exploring load-bearing applications of phenolic foam. Given

that strength is related to density, the material should be fabricated at a high enough

density (12 to 15 pcf or higher). In addition, a greater proportion of fibers should be

used in the fabrication process. This thesis used 4 weight percent of fibers, and a

value two or three times that would significantly increase strength. From there, a

thesis project could explore using the material as a structural member within a

building.

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8.2 Testing

Phenolic foam could also undergo different sorts of tests than examined in this

thesis. Tests could be modeled based on a certain climate or case study. For example,

northern Thailand was chosen as a case study in this thesis, and tests were chosen to

measure the effects of the region’s extreme heat, humidity, and rain on phenolic

foams mechanical properties. Instead, a colder climate could be chosen, and tests

could be chosen to model the effects of cold weather on the material’s properties. R-

value degradation due to moisture exposure would have more relevance here.

Another possibility would be examining how well phenolic foam withstood

freeze/thaw conditions.

Testing could also look at hygrothermal effects, or the change in properties due to

moisture absorption and temperature change. Little work has been explored on this

topic, especially with phenolic foam. Oak Ridge National Laboratory performed a

study two years ago on the hygrothermal performance of various cladding materials

and concluded that EPS was superior over brick, concrete block, and other materials

in terms of moisture resistance and thermal performance (Karagiozis 2006). Phenolic

foam could be integrated into a similar study. A thesis could also look at various

weather schemes based on geographical location and determine under what

temperature conditions phenolic foam best resists moisture.

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8.3 Comparison Materials

Other materials could be chosen with which to compare phenolic foam. This thesis

chose EPS as a common insulation material to compare its mechanical and thermal

properties as well as environmental impact and costs. As described in Chapter 2,

however, numerous other insulation materials exist. Structural materials could also

be chosen with which to compare phenolic foam’s load-bearing properties.

8.4 Environmental Impact Assessment

Limited data exists on the environmental impact of phenolic foam. For example,

none of the lifecycle cost assessment software programs examined in this thesis

listed phenolic foam in their database of materials. Instead, this thesis had to extract

data from several sources in order to create a rough environmental impact profile.

Future work could focus on creating a website or software program on the

environmental impact of phenolic foam. The tool could take a more rigorous

approach to evaluating the environmental impact of phenolic foam and include more

comprehensive data than included here. Such a tool would fill a missing niche in the

sustainable assessment of building materials. The tool could also broaden its scope to

include other insulation materials, thereby creating a central database. This could be

especially valuable for homeowners when considering the environmental impact and

cost savings of various insulation materials.

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8.5 Cost Assessment

Significant gaps exist in data showing the cost to insulate a home with phenolic

foam. This is largely due to its limited use and availability, especially in the United

States. As with its environmental impact, the various costs of phenolic foam could be

assembled in a central database or website. Other insulation materials could be

compared on the site.

Further work could also explore the economics of phenolic foam in developing

regions like Thailand. How could developing regions be able to afford this material?

How can costs such as raw materials and production be reduced? Various cost-

benefit scenarios could be analyzed. For example, the economic and physical health

benefits of installing weather resistant insulation in homes in developing regions

could be weighed against economic, health and lifestyle costs associated with not

having insulation. This is especially relevant when considering that several

developing regions in Asia and worldwide are prone to tsunamis and flooding, the

effects of which adversely affect the lives of millions of people living in sub-

standard housing conditions.

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Appendix A: Glossary 1. climate conditioning – exposing materials to one of two environmental conditions

simulating northern Thailand’s hot and humid rainy season

• water immersion

• accelerated aging

2. conditioning – see climate conditioning

3. EPS – expanded polystyrene, or the primary insulation material whose mechanical

and thermal properties were compared with phenolic foam

4. SEM – scanning electron microscopy, or the method used to measure the cell

length of phenolic foam and EPS samples

5. SIPs – structural insulated panels, or boards that serve dual structural and thermal

purposes

6. fiber reinforcement – the use of two types of fibers to improve the mechanical and,

possibly, thermal characteristics of phenolic foam

• natural

o bamboo

136

o cellulose

• synthetic

o glass

o aramid

7. stress – one of two environmental conditions imposed on samples

• water immersion

• accelerated aging

8. tests – methods used to evaluate phenolic foam’s properties

• environmental

o water immersion

o accelerated aging

• mechanical

o strength

compression

shear

o cell length measurement through SEM

• thermal – conductivity

• other – flammability

9. underdeveloped – describing a poor, rural region, such as in areas of northern

137

Thailand, where subsistence farming and rudimentary construction methods

and materials are common

Documents

Fiber Reinforced Phenolic Foam: Effects of Extreme · PDF fileBibliography 129 . Appendix A: Glossary 135 . viii List of Tables . Table 1 ... Figure 2.6: Adidas Village, Portland,