I.INTRODUCTION

Polymer

A polymer is a chemical compound or mixture of compounds consisting

of repeating structural units created through a process

of polymerization. The term derives from the ancient Greek word πολύς

(polus, meaning "many, much") and μέρος (meros, meaning "parts"), and

refers to a molecule whose structure is composed of multiple repeating units,

from which originates a characteristic of high relative molecular mass and

attendant properties. The units composing polymers derive, actually or

conceptually, from molecules of low relative molecular mass. The term was

coined in 1833 by Jöns Jacob Berzelius, though with a definition distinct from

the modern IUPAC definition. Polymers are studied in the fields

of biophysics andmacromolecular science, and polymer science (which

includes polymer chemistry and polymer physics).

Historically, products arising from the linkage of repeating units

by covalent chemical bonds have been the primary focus of polymer science;

emerging important areas of the science now focus on non-covalent links.

Because of the stipulation as to repeating substructures, polymers are

formally a subclass of the category of macromolecules;

the polyisoprene of latex rubber and the polystyrene of styrofoam are

examples of polymeric natural/biological and synthetic polymers,

respectively. In biological contexts, essentially all biological macromolecules

—i.e., proteins (polyamides), nucleic acids (polynucleotides), and

polysaccharides—are purely polymeric, or are composed in large part of

polymeric components—e.g., isoprenylated/lipid-modified glycoproteins,

where small lipidic molecule and oligosaccharide modifications occur on the

polyamide backbone of the protein.

Hence, the terms polymer and polymeric material encompass very

large, broad classes of compounds, both natural and synthetic, with a wide

variety of properties. Because of the extraordinary range of properties of

polymeric materials, they play essential and ubiquitous roles in everyday

life, from those of familiar synthetic plastics and other materials of day-to-

day work and home life, to the natural biopolymers that are fundamental to

biological structure and function.

Polymers are large molecules composed of many similar smaller

molecules linked together. The individual smaller molecules are called

monomers. When small organic molecules are joined together, giant

molecules are produced. These giant molecules are known as

macromolecules.

Generally speaking, all macromolecules are produced from a small set

of about 50 monomers. Different macromolecules vary because of the

arrangement of these monomers. By varying the sequence, an incredibly

large variety of macromolecules can be produced. While polymers are

responsible for the molecular "uniqueness" of an organism, the common

monomers mentioned above are nearly universal.

II. DISCUSSION

A. Common Examples of Polymers

Natural polymeric materials such as shellac, amber, wool, silk and

natural rubber have been used for centuries. A variety of other natural

polymers exist, such as cellulose, which is the main constituent of wood and

paper. The list of synthetic polymers includes synthetic rubber, phenol

formaldehyde resin (or Bakelite), neoprene, nylon, polyvinyl chloride (PVC or

vinyl), polystyrene, polyethylene, polypropylene, polyacrylonitrile, PVB,

silicone, and many more.

Most commonly, the continuously linked backbone of a polymer used

for the preparation of plastics consists mainly of carbon atoms. A simple

example is polyethylene ('polythene' in British English), whose repeating unit

is based on ethylene monomer. However, other structures do exist; for

example, elements such as silicon form familiar materials such as silicones,

examples being Silly Putty and waterproof plumbing sealant. Oxygen is also

commonly present in polymer backbones, such as those of polyethylene

glycol, polysaccharides (in glycosidic bonds), and DNA (in phosphodiester

bonds).

B. Importance of Polymer Properties

Because of their high molecular mass, polymers, as compared to small

molecules, have unique properties that are often difficult to predict. As

such, some background knowledge of the physical chemistry of polymers is

desirable for dealing with polymers and polymeric materials.

Polymer properties, like solubility behavior, are used as a guide on a

laboratory scale when analyzing or characterizing polymers or when

determining structure-property relationships. On an industrial scale,

properties, such as melt viscosity or heat capacity, are important for

establishing polymerization and processing conditions. A listing of

properties is required for selecting polymers to meet specific applications.

Polymers are ubiquitous as they are used in all applications, from

consumer products to high-temperature industrial use to medical devices,

under a wide-range of conditions. In modern polymer science and

engineering, more complex structures, such as multilayer films,

nanomaterial, electro-optical and electronic devices are being developed

that require more specialized and complex testing for end-use performance

evaluation. Furthermore, from knowledge of structure-property relations of

polymers and polymeric materials, one can begin to design and tailor make

polymers and complex polymeric structures to meet specific end-use

performance requirements.

It is sometimes difficult to accurately predict end-use performance

characteristics of the final product using tabulated data of individual

components. As a result, accurate measurements are those made on the

final product itself, rather than using model polymers or components. In

these cases, empirically derived measurements using the actual product,

verified with authentic samples, may be the best option. It should be noted

that most empirically derived data are trade secrets, and, as such, not

available. Nevertheless, compilations of properties are still valuable. 

 

C. Polymer Complexity

Because of polymer complexity, property variability must be taken into

consideration. In this section, we will discuss possible sources of polymer

inconsistency and offer suggestions to recognize and reduce these errors.

Chemical or compositional heterogeneity refers to the chemical or

structural difference among chains of the same polymer. Thus a measured

property of a chemically heterogeneous sample will be an averaged value

dependent upon sample source. For chemically homogeneous samples,

property variability will not be a concern. In a similar fashion, polymers that

are polydisperse in molecular weight have averaged property values,

while monodisperse samples will give accurate data. Obviously, samples

that are both chemically homogeneous and monodisperse will give the

most accurate and precise values.

As compared to synthetic polymers, almost all nucleic acids and

mammalian proteins are compositionally (chemically) homogeneous

and monodisperse, if not there would be no life; biopolymers carry highly

specific and selective information. Mammalian polysaccharides, for the

most part, are also compositionally homogeneous, but are polydisperse in

molecular weight; whereas plant polysaccharides are polydisperse.

Chemically modified cellulose (cellulosics) are typically both compositionally

heterogeneous and polydisperse in molecular weight. Starches (α-amylose

and amylopectin), another major class of polysaccharides, are highly

polydisperse in molecular weight, but quite compositionally homogeneous.

In addition, amylopectin and many other polysaccharides are highly

branched, which may further complicate listed property values.

Synthetic polymers can be quite complex and, as such, tabulated and

measured property data must be interpreted with

care. Homogeneous synthetic polymers are those produced from

condensation polymerization reactions, in which all polymer chains

are chemically indistinguishable from another. Even though these types of

polymers show a finite polydispersity of two, accuracy and precision will not

be compromised since all samples (and reference standards) will have the

same degree of polydispersity. Lastly, synthetic polymers produced by

addition polymerization (i.e., ionic, complex coordination catalytic, or free-

radical copolymerization), will have the greatest amount of compositional

heterogeneity, and with the exception of anionically polymerized samples,

will also have a large molecular weight polydispersity. For these polymers,

tabulated data must be interpreted with caution, unless users establish

their own data sets with reference polymers obtained from the same

polymerization conditions.

Sequence distribution or polymer microstructure is the next higher

level of complexity in which the average arrangement of monomers along a

chain is considered. The polymerization mechanism and reactivity ratios of

monomers dictate this parameter. Monomers can be randomly arranged

along chains in the case of statistic or random copolymers or in the

extreme form a block copolymers. In any event, the microstructure of

reference polymers should be defined when properties are listed.

Next in line of complexity is macromolecular architecture, or polymer

configuration, in which the topological nature of the chain is of interest.

Thus polymer branching can take on a wide range of configurations

including short- and long-chain branching, and comb, star, and dendritic

structures with or without comonomer segregation or blockiness. Because

of the strong influence of polymer configuration on properties, this

parameter needs to be defined, and care taken when comparing tabulated

data to those of actual samples.

In summary, polymers may have up to two or more distributed

characteristics depending on the number of different monomers used in the

polymerization, the type of polymerization mechanism, and whether or not

the sample was fractionated during isolation. As a rough estimate, polymer

"complexity" increases exponentially with the number of distributive

properties, making it more difficult to measure accurate polymer properties.

Some polymers are modified after polymerization; however, this

process can be somewhat difficult to control. Because polymer chain

segments can influence the chemistry of a neighboring groups. Chemical

modifications are done mainly on cellulosics and other polysaccharides to

tailor-make specific property characteristics. Thus tabulated property data

given for cellulosics and polysaccharides represent average values of the

entire sample ensemble of polymer chains that differ in composition. To

complicate matters further, insoluble gels, comprised of three-dimensional

networks, may form if chains are allowed to chemically or physically (via

hydrogen bonding) react with one another, either during or after

polymerization.

Post-polymerization processes are also accomplished via vulcanization,

irradiation, or through the addition of a low molecular weight cross-linking

agent. The resulting polymer (i.e., rubber, elastomer, resin, or gel) in

essence, is one super or giant molecule approaching infinite molecular

weight. Theseviscoelastic materials have wonderful consumer, industrial,

and aerospace end-use applications when properly formulated.

The next level of polymer complexity is polymer blends and

multicomponent systems. To adjust the glass-transition temperature,

plasticizers are added, often times at high concentrations. To increase

polymer strength, reinforced polymeric materials are used that consist of

added inorganic material, the most common being carbon black or glass

fibers. Laminated structures are also produced for increased material

strength.

High-value added, specialty products with controlled molecular weight,

branching, or architecture are being developed for high-technology

industries, most notably electronic and optical devices, printing inks, and

coatings in the aerospace industry. Because of their specialized uses, most

of these polymeric materials are not listed in this compilation. 

D. Regulatory Agencies

Most industries issue testing protocols and polymer property

specifications to the trade. To ensure uniformity, national regulatory

agencies have formed to deal with standardized methods and testing

approaches. In the United States, ASTM is the most prominent independent

agency supported by industry with about 100 test methods in place

specifically for polymers and polymeric materials. API specializes in the

development of procedures for petroleum products, some of which are

polymeric. In Britain, BSI is the key agency for testing, while in Europe, DIN

procedures are followed. Many of these agencies are overseen by ISO, a

federation of national regulatory bodies. (See Table 1 for complete names

and acronyms.)

Governmental departments of commerce, defense, and military are

also involved in issuing protocols and specifications. For example, the FDA

is responsible for establishing acceptable limits of extractable components

from polymeric materials in contact with food and drugs. 

Table 1. Key agencies involved in

standardized testing of polymers and

polymeric materials under the umbrella of

ISO.

Abbreviatio

nOrganization

API American Petroleum Institute

ASTM American Society for Testing and Materials

BSI British Standards Institution

DIN Deutsches Institut fur Normung

FDA Food and Drug Agency

ISOInternational Organization for Standardization

*

*Global federation of national standards

bodies representing 100 countries.

 D. Reference Polymers and Specialty Materials

Sources of reference polymer standards that can be used for

instrument calibration and validating methods are listed in Table 2. In the

United States NIST is responsible for distributing a number of well-

characterized polymer standards.

These standards have well-defined chemical composition and

molecular weight, and are also suitable for formulating materials for R&D.

All reference standards and polymeric material should come with

certificates of analysis. (Since water content in polymers, especially

hydrophilic ones and polysaccharides, may affect properties, it is advisable

to vacuum dry and properly store them to prevent moisture buildup and

degradation.) 

Table 2. Sources of polymer standards used

for instrument calibration, method

development and verification, and

formulating R&D samples

American Polymer Standards Corp USA

Gearing Scientific Ltd UK

National Institute of Standards and Technology USA

Polymer Laboratories Varian UK

Polymer Source Inc Canada

Polymer Standards Service (PSS) Germany

Pressure Chemical Co. USA

Putus Macromolecular China

Sigma-Aldrich USA

Tosoh Corporation Japan

Waters Corporation USA

E. Polymer Properties

In this section we discuss and list polymer properties that are included

in data tables of this book. Some properties reviewed in this section are not

listed in this text, but they are included for completeness. Specific

properties for certain classes of polymers are not given, especially those

used for optical, electronic and magnetic devices.

Much of this section and the book's content is based on van Krevelen's

(1976) property schemes, with modification. His book should be consulted

for more detailed discussions. Other books of interest are listed at the end

of this chapter.

Basic information that characterizes polymers is listed in Table 3.

These properties can be estimated from the expected outcome of the

polymerization, measured, or calculated from group contributions (see van

Krevelen, 1976). Methods for measuring these properties can be found in

the reference list (for example, see Barth and Mays, 1991; Brady, 2003;

Wu, 1995). Some of the more important properties will be considered here.

The most useful average molecular weights are the number- (Mn),

weight- (Mw), and z-averages (Mz). These averages are easily determined

from the molecular weight distribution obtained using size exclusion

chromatography (Mori and Barth, 2001). Oftentimes just the viscosity-

average molecular weight (Mv) is available, which can be conveniently

determined from the measured intrinsic viscosity of the polymer in a given

solvent at a specified temperature using tabulated Mark-Houwink

coefficients. Alternatively, Mw can be determined from light scattering and

Mn from osmometry. 

Table 3. Basic Polymer Information

Property measured Remarks

CAS registration number  

Physical state at rt  

Chemical composition of

repeat units 

Structural formula of repeat

group 

Comonomer molar ratios For copolymers

Molar substitution For cellulosics

Molecular weight of repeat

unit 

Statistical average molecular

weights

Mn, Mv, Mw, Mz, and

polydispersity

Percent added inorganic or

carbon filler or plasticizer

Polymer additives used to

impart selected performance

Polymer additives, e.g.,

antioxidants, UV stabilizers,

etc.

 

Moisture level If applicable

Branching, degree

(frequency) and extent

(length)

Short- or long-chain

branching if applicable, as

estimated

Polymer architecture

(topology), other than linear

or branched, if applicable

graft, star, comb, or

dendritic

Crystallinity  

Tacticity  

Microstructure, i.e.,

monomer sequence

distribution

Block, random, or alternate

Toxicity and stability Should be determined or at

least estimated from

structure of corresponding

comonomers

Environmental impactMust be known or at least

estimated for safe disposal

Branching, molecular topology, and comonomer sequence distribution

along the chain are more difficult to estimate; these properties are best

estimated by the chemistry of the polymerization procedure, with support

from NMR measurements. Polymer toxicity and stability must be known or

at least estimated from functional group and comonomer chemistry. It

should be realized that polymer toxicity, to a first approximation, is lower,

than the corresponding comonomer toxicity; because of the low polymer

diffusion coefficient, macromolecules cannot readily pass through

biomembranes, thus have limited bioavailability.

The effect of molecular weight of a polymer in solution on its colligative

properties, summarized in Table 4, is a well-established phenomeon. These

properties are dependent on the number of macromolecules in solution,

independent on molecular weight and chemical composition. In fact, the

number-average molecular weight of a polymer can be determined by

measuring one of its colligative properties. 

Table 4. Colligative Polymer Properties

Property measured Remarks

Freezing point depression MW dependent

Boiling point elevation MW dependent

Vapour pressure depression MW dependent

Osmotic pressure elevation MW dependent

Table 5 lists volumetric properties of polymers in the liquid or solid

state as a function of temperature; these properties are related to the

compactness of chains and the interaction of comonomers within and

among neighboring chains. These properties are more dependent on

chemical composition, than molecular weight. Volumetric properties also

depend on factors influenced by comonomer sequence distribution, such as

tacticity, branching, and polymer crystallinity. 

Table 5. Volumetric Properties

Property measured Remarks

Specific volume (reciprocal

of specific density)Depends on polymer state

Molar volume (reciprocal of

molar density)Depends on polymer state

Specific thermal expansivity Depends on polymer state

Molar thermal expansivity Depends on polymer state

Specific melt expansivityApplicable to crystalline

polymers

Molar melt expansivityApplicable to crystalline

polymers

Table 6 lists thermodynamic and calorimetric attributes of a polymer,

while Table 7 deals with polymer solubility and cohesive energy. Except for

molar entropy, all these properties depend mainly of chemical composition,

rather than molecular weight. Furthermore, polymer crystallinity, in

addition to the chemical nature of a polymer, plays a major role in dictating

solubility behavior. In order to effect solubility in the case of crystalline or

semicrystalline polymers, the solution must be heated near or above its

melting point to break up crystalline regions. 

Table 6. Calorimetric and Thermodynamic

Properties Including Transition Temperatures

Property measured Remarks

Molar entropy  

Molar enthalpy  

Molar heat capacity  

Latent heat of crystallization  

Thermal conductivity  

Melting temperature, Tm

Disappearance of polymeric

crystalline phase

Glass-transition

temperature, Tg

Onset of extensive

macromolecular motion

Secondary transition

temperaturesOther than Tm and Tg

Deflection temperature (heat

distortion)

Highest continuous

temperature material will

withstand

Vicat softening pointTemperature at which a

needle penetrates material

Brittleness temperature  

Table 7. Cohesive Properties and Solubilities

Property measured Remarks

Cohesive energy  

Cohesive energy density

Related to the "internal

pressure" of a polymer in

solution

Surface and interfacial

energy 

Solubility parameterEqual to the square root of

the cohesive energy density

Good Solvency

Good solvent imparts

solubility via polymer

solvation

NonsolvencyPoor solvent cannot solvate

polymer

Theta temperature

The temperature at which

polymer-polymer, polymer-

solvent, and solvent-solvent

interactions are equal

Theta solvent

A solvent in which polymer-

polymer, polymer-solvent,

and solvent-solvent

interactions are equal

Light scattering and inherent viscosity measurements made at infinite

dilution are used to determine polymer size parameters, conformation,

2nd virial coefficient, weight-average molecular weight, and long-chain

branching parameters (Table 8). These are fundamental parameters that

allow us to probe structural features of polymer molecules. These

properties are dependent on molecular mass and shape, rather than

polymer composition. 

Table 8. Dilute Solution Properties

Property measured Remarks

Intrinsic viscosity

Measured quantity related to

the hydrodynamic shape and

molecular volume of a

polymer in solution

Mark-Houwink coefficients

Coefficients related to the

shape of macromolecules in

solution.

Molecular conformation Molecular shape parameter

Specific refractive index

Parameter needed for

calculating Mw from light

scattering data

Polymer-solvent 2nd virial

coefficient

Determined from light

scattering measurements

Radius of gyrationMacromolecular size

parameter

End-to-end distance Macromolecular size

parameter

Hydrodynamic volumeMacromolecular volume

parameter

Melt index and viscosity are critical parameters needed for polymer

processing. These and other polymer transport properties are listed in Table

9. As in the case of other viscosity measurements, these properties depend

mainly on higher statistical molecular weight averages, such as Mw and Mz. 

Table 9. Transport Properties

Property measured Remarks

Melt viscosity

Depends on molecular

weight and chain

entanglement

Melt indexInversely proportional to

viscosity

Gas permeability across a

polymer film or membrane

Usually water vapor, oxygen,

nitrogen, or carbon dioxide,

or specialty gases

Diffusion coefficient

Diffusion of polymer in a

given solvent at defined

conditions

Water absorption Water content taken up at

specified relative humidity

and temperature

Tables 10 to 13 list polymer characteristics directly involved with end-

use properties: mechanical properties (Table 10), electric and magnetic

properties (Table 11), optical properties (Table 12), and polymer stability

(Table 13). (A more complete discussion of these properties is given in

selected references at the end of this chapter.) 

Table 10. Mechanical Properties

Property measured Remarks

Adhesion (tackiness)  

Ball indentation hardness  

Bulk modulus (reciprocal of

compressibility) 

Coefficient of friction  

Compression strengthForce needed to rupture

material

Tensile creep Shape change of material

caused by suspended weight

DampingAbsorption or dissipation of

vibrations

Dynamic mechanical

behavior

 

Elastic modulus  

Elongation  

Fatigue Number of cycles required

for fracture

Flexural stiffness  

Flexural strength at break Amount of stress needed to

break material

Fracture mechanical

properties

Fracture energy, fatigue

resistance, fatigue crack

growth, void coalescence

Friction abrasion and

resistance

 

Hardness Resistance to compression,

indentation, and scratch

Impact strength Energy absorbed by sample

prior to fracture

Indention hardness  

Load deformation  

Mar resistance  

Mold shrinkage  

Poisson's ratio  

Scratch resistance  

Shear strengthMaximum load to produce a

fracture by shearing

Surface abrasion resistance  

Tear resistance  

Tensile strength break

(yield)See Young's modulus

Toughness

Amount of energy to break a

material (area under stress-

strain curve)

Ultimate strength  

Viscoelastic behavior  

Young's modulus(Tensile

strength)

Modulus of elasticity or

tensile modulus

Table 11. Electrical and Magnetic Properties

Property measured Remarks

Arc Resistance

Time needed for current to

make material surface

conductive because of

carbonization

Dielectric constant

Ability of material to store

electric energy for capacitor

application

Dielectric permittivity  

Dielectric strengthVoltage required to break

down or arc material

Dissipation power factor

(loss tangent)

Watts (power) lost in

material used as insulator

Insulation resistance  

Magnetic susceptibility  

Resistivity  

Volume resistivity  

Tables 10 to 13 list polymer characteristics directly involved with end-

use properties: mechanical properties (Table 10), electric and magnetic

properties (Table 11), optical properties (Table 12), and polymer stability

(Table 13). (A more complete discussion of these properties is given in

selected references at the end of this chapter.) 

Table 12. Optical Properties

Property measured Remarks

Colour

Physiological response;

measured using three

parameters: lightness,

chroma, and delta

Luminous transmittanceMeasure of plastic haze or

clarity

Molar refraction  

Percent transmission Transparency

Refractive index  

Specular glossSurface "flatness"; mirror

"finish"

Total internal reflectanceUV-visible absorbance

spectrum

Table 13. Polymer Stability

Property measured Remarks

Accelerated aging studies  

Biological stabilityStability in the presence of

microorganisms

Burning rate  

Chemical resistance

Hydrolytic stability (extreme

pH conditions), exposure to

chemicals and solvents

Flammability Flame resistance

Flash ignition temperature  

Long-term immersion  

PermeabilityAmount of gas or liquid

penetrating film

Recyclability  

Resistance to cold  

Self-extinguishing

temperature 

Stress cracking Caused by weathering

III.CRITIQUE

Polymers are made up of many many molecules all strung together to

form really long chains (and sometimes more complicated structures, too).

What makes polymers so fun is that how they act depends on what

kinds of molecules they're made up of and how they're put together. The

properties of anything made out of polymers really reflect what's going on at

the ultra-tiny (molecular) level. So, things that are made of polymers look,

feel, and act depending on how their atoms and molecules are connected, as

well as which ones we use to begin with! Some are rubbery, like a bouncy

ball, some are sticky and gooey, and some are hard and tough, like a

skateboard.

IV. CONCLUSIONS

Polymer science can be viewed as an applied branch of chemistry

based on deliverable properties. It is of interest to note that most of these

properties depend on just four attributes: 1. polymer molecular weight, 2.

crystallinity, 3. chemical composition, and 4. macromolecular topology or

architecture; furthermore, these parameters interact with one another in a

complex manner. By varying these parameters, polymers can be tailor-

made to fit a list of desirable characteristics. It is hoped that this polymer

property database will serve as a guideline to help pave the way for the

development of newer materials of improved characteristics.

V. REFERENCES

http://www.polymersdatabase.com/intro/index.jsp

http://en.wikipedia.org/wiki/Polymer

http://biology.about.com/od/molecularbiology/ss/polymers.htm

http://www.merriam-webster.com/dictionary/polymer

DON MARIANO MARCOS MEMORIAL STATE UNIVERSITY

MID-LA UNION CAMPUS

COLLEGE OF ENGINEERING

CITY OF SAN FERNANDO, LA UNION

REPORT IN

MATERIALS ENGINEERING LECTURE

“POLYMERS”

REPORTED BY:

MHAR JOHN G. GALON

JOSE T. CORPUZ

SUBMITTED TO:

ENGR. JULIUS RAUL C. SAMPAGA