EPA STAR award # RD-83090401 under 2002 Environmental Futures Research in Nanoscale Science Engineering and Technology

PROJECT TITLE:PROJECT TITLE:

Sustainable Biodegradable Sustainable Biodegradable Green Nanocomposites From Green Nanocomposites From

Bacterial Bioplastic For Bacterial Bioplastic For Automotive ApplicationsAutomotive Applications

Lawrence T. DrzalLawrence T. DrzalComposite Material and Structures Center

Michigan State UniversityEast Lansing, MI 48824

drzal@msu.eduhttp://www.egr.msu.edu/cmsc/biomaterials/index.html

Research TeamResearch TeamPI: Lawrence T. Drzal1Co- PIs: Amar K. Mohanty2 , Manjusri Misra1

Senior Personnel: Satish Joshi3,Postdoc(1st year only): Shrojal Desai1Graduate Students: Yashodhan Parulekar 2 and Dana G. Miloaga1

1Composite Materials and Structures Center,The Department of Chemical Engineering and Materials Science, 2100 Engineering Building, 2The School of Packaging, 130 Packaging Building, 3 Department of Agricultural Economics, 301C Agriculture Hall,Michigan State University, East Lansing, MI 48824

Industrial Partners: General Motors, Metabolix Inc and Nanocor

Giant Pollution Mass at SeaWhen an oceanic garbage patch the size of Texas dumps some of its treasures along the West Coast this summer, By Marsha Walton -- CNN

Plastic Litter and Waste

Cleanup Costs Approach a

Billion Dollars …

TRASHED !!!!Across the Pacific Ocean, Plastics, Plastics, EverywhereTexas sized trash mass floating in the North Pacific Ocean. An "eyes-on" report . . . Charles Moore/ Natural History v.112, n.9, Nov. 2003

▲ To overcome the problems due to plastic wastes.

▲ To substitute non-degradable petroleum based polymers with biodegradable plastics.

▲ To introduce bioplastics from renewable resources into market.

RenewableRenewableResourceResource--basedbased

MicrobialMicrobialsynthesizedsynthesized

•• Aliphatic polyesterAliphatic polyester

•• AliphaticAliphatic--aromatic aromatic polyesterspolyesters

•• PolyesteramidesPolyesteramides

•• Polyvinyl alcoholsPolyvinyl alcohols

•• Polyhydroxy Polyhydroxy alkanoates (PHAs)alkanoates (PHAs)

•• PolyhydoxybutyratePolyhydoxybutyratecoco--valerate (PHBV)valerate (PHBV)

•• PLA PolymerPLA Polymer(From Corn)(From Corn)

•• Cellulosic plasticsCellulosic plastics•• SoySoy--based plasticsbased plastics•• Starch plasticsStarch plastics

PetroPetro--Bio Bio (Mixed) Sources(Mixed) Sources

•• SoronaSorona

•• BiobasedBiobasedPolyurethanePolyurethane

•• Biobased Biobased epoxyepoxy

•• Blends etcBlends etc

BIOPOLYMERS: CLASSIFICATIONBIOPOLYMERS: CLASSIFICATION

PetroPetro--basedbasedsyntheticsynthetic

PolyhydroxybutyratePolyhydroxybutyrate (PHB)(PHB)

Carbon source

PHB in cell wall

Extraction

Bacteria

fermentation

O C

H O

2 nH

R

• Polyhydroxybutyrate (PHB) is a linear thermoplastic polyester produced by controlled bacterial fermentation process.

• Discovered by French microbiologist Maurice Lemoigne in 1923.

• Next generation PHB will come from Transgenic plants/micro-organisms

• Typical cost ranges from 1-2 $/lb

Ref: Marchessualt, R. H.; TRIP, 1994, 4, 163

Bacterial Polyester DevelopmentsBacterial Polyester Developments

Direct route

PHA Polymers

PlasticProducts

Sunlight

FermentationProcess

Plant Crops

BiodegradationCarbohydrates

White patches in microorganism White patches in microorganism

PHBPHB

PHA RPHB - CH3PHV -CH2CH3PHBV (Biopol®) - CH3 & CH2CH3PHBHx -CH3 & - CH2CH2CH3PHBO -CH3 & -(CH2)4CH3

O

R

OH

OH

xn

R = Hydrocarbon(up to C13)

x = 1 to 3 or morePHA structure

Courtesy: Metabolix & BiomerCourtesy: Metabolix & Biomer

BACTERIAL BIOPLASTICBACTERIAL BIOPLASTICADVANATAGES

▲ Eco-friendly synthesis▲ Biodegradable

▲ Good mechanical properties

▲ Excellent processability▲ From renewable resource

SHORTCOMINGS

▲ Poor interaction with fibers

▲ Narrow processing window

▲ Lack of reactive groups

▲ Thermal degradation

▲ Brittleness

OBJECTIVESOBJECTIVES

▲ To overcome some of the inherent material limitations of PHB/PHA bioplastics.

▲ To study the effect of PHB/PHAs modification on its Thermal and Morphological properties.

▲ To synthesize functionalized PHB/PHAs as a compatibilizer in PHB/PHAs based blends, and nanocomposites.

PART – I“Functionalization and characterization of

PHB and its derivatives via Solvent-free Reactive Extrusion”

MATERIALS & PROCESSINGMATERIALS & PROCESSING

•• PHBPHB--P226P226-- from Biomer Germanyfrom Biomer Germany•• Maleic Anhydride:MA Maleic Anhydride:MA •• Octadecenyl Succinic Anhydride: ODSAOctadecenyl Succinic Anhydride: ODSA•• TrigonoxTrigonox 101 45B (2,5101 45B (2,5--dimethylhexanedimethylhexane--2,52,5--

ditertbutyl peroxide)ditertbutyl peroxide)

EXPERIMENTAL SETUPEXPERIMENTAL SETUP

Feeder Twin Screw Extruder

DSM MICRO 15, HOLLANDDSM MICRO 15, HOLLAND

MA T 101 PHB P226

MECHANISMMECHANISM

O C CH 2

CH 3

C

O

H PH B

O C CH 2

CH 3

C

O

Initiator

o ooo oo

R

o

O C

CH3

C

O

CH2

R

oo

CH

CCO OO

O C

CH2

CH3

C

O

CH2

ODSAMA

PHB g MAPHB g ODSA

US PATENT APPLIED

US PATENT APPLIED

Free radical grafting of MA/ODSA onto PHB via reactive extrusion

1900 1850 1800

0.5

1.0

1.5

14 hrs

Purification of PHBMA pellets

PHBMA-vacuum purified 10 hrs

PHBMA-impure

Wave numbers (cm-1)

Abs

orba

nce

1600170018001900

1

2

3

Abs

orba

nce

wave numbers (cm-1)

PHBP226

PHBSA4

PHBMA4

1782

FTIR spectra of functionalized PHB

1.31481.8PHBSA4

% AN

ACID No.

MA/ ODSAwt%

Initiator wt%

NAME

2.02341.8PHBMA4

▲ Peak at 1782 cm-1 indicates anhydride groups grafted onto PHB backbone.

FT-IR

▲ Peak at 1850 cm-1 corresponds to unreacted MA in the PHB matrix.▲ Vacuum drying of pellets at 80 oC for > 12 hrs ensures complete removal

of unreacted MA.

OPTICAL MICROSCOPY

• Large spherulites with distinct maltase patterns and well defined boundaries are due to highly regular arrangement of pristine PHB chains

• Drastic decrease in spherulite size upon maleation results from hindered / irregular rearrangement of PHB chains bearing large anhydride groups

• Smaller spherulites size results in less brittle material

PHB PHB PHBP226PHBP226PHBMA4PHBMA4 PHBSA4PHBSA4

Thin (25 µ) films heated and cooled @ 20 oC/min

XRD FT-IR

117011851200

1.2

1.8

2.4

Crystalinity changes in PHB

1185 cm-1

Abs

orba

nce

wave numbers (cm-1)

PHB P226

Unplasticized PHB

PHBMA4

12 14

0

300

600

Inte

nsity

XRD Overlay of thin PHB films

Unplasticized PHB

PHB P226

Degree 2θ

*

PHBMA4

13.3

020

• XRD peak at 2θ =13.3o corresponding to crystalline region decreases upon maleation of PHB.

• Decrease in crystallinity of PHB upon maleation is evident from depletion of 1185 cm-1 peak intensity in FTIR spectral overlay.

• Intensity of crystalline peaks in both the graphs depend on % anhydride in the PHB backbone.

PART – I: CONCLUSIONS

Reactive extrusion can be successfully employed for the grafting of functional groups onto PHB backbone by a solvent free process.

Degree of grafting can be controlled by varying the reagent concentrations and residence time of melt in the extruder.

Desired changes in the thermal and morphological properties of PHB can be achieved upon its functionalization.

Decrease in PHB spherulite size with the grafting degree is due to the imperfect crystal formation and irregular rearrangement of PHB chains bearing bulky anhydride groups.

Smaller crystal size leads to a less brittle material.

PART – II-A

COMPTIBILIZED COMPTIBILIZED GREENGREEN--NANOCOMPOSITES FROM PHB NANOCOMPOSITES FROM PHB

and NANOCLAYand NANOCLAY

MECHANISM

CH3-N+-TCH2CH2

CH2CH2OH

O OO ..O

OO

OHOH

Organo modifierCH3-N+-T

CH2CH2OH

18 44Αo

Αo

Expansion of clay gallery

PHB g MA

XRD ANALYSIS

0 1 2 3 4 5 6 7 8 9

0

100

200

300

400

500

600

700

XRD paterns of PHB-Clay Nanocomposites

coun

ts

2 theta (deg)

PHB/clay 5%/PHBMA 5% PHB+ 5 wt% clay

PHB

PHB + 9 wt% clayPHB/clay 9%/PHBMA 5%

Closite 30B

The d001 spacing in organo-clay sample is 18 Å, and that of the PHB/clay sample is 44 Å.

Upon intercalation, peak corresponding to clay crystallites shifts from 5° to 2° on 2θ axis

Decrease in the intensity of intercalation peak at 2θ = 2° indicates more number of exfoliated clay plates

TEM ANALYSIS

PHB + 9 wt% clay(arrow indicates clay tactoid)

PHB + 9 wt% clay+ 5 wt% PHB-g-MA(arrow indicates exfoliated clay)

Clay tends to remain as tactoids in the PHB matrixAddition of small of amount of PHB-g-MA facilitates Clay exfoliation

PART – II-A : CONCLUSION

PHB-MA is a good compatibilizer for PHB Nanocomposites

PART – IIB Automotive application of Automotive application of

nanocompositesnanocomposites

OBJECTIVESPP’s low impact strength led to the development of

TPO but at the cost of flexural strength and scratch resistance.

Clay-reinforced TPO has overcome these drawbacks and was the first instance of a nanocomposite being used for exterior automotive applications.

However PP and subsequently TPO are both non-biodegradable and also petroleum-based.

This project aims to replace these conventional petroleum-based clay-reinforced toughened polyolefin (TPO) materials with alternative ‘Green’ materials which will have comparable properties with TPO and also be biodegradable and recyclable.

Results (Results (Patent application on processPatent application on process ))40% X does not affect the impact strength of PHB. But addition of 10 % additive Y improves the impact strength by 440% (50%more than TPO)

The modulus of PHB is reduced by only 50% when X and Y were added together and is only 20% lower than TPO.

0

20

40

60

80

100

120

140

PHB PHB + X PHB + X + Y TPO

Impa

ct s

tren

gth

J/m

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Mod

ulus

(GPa

)

PHB PHB + X PHB + X + Y TPO

Conclusions from Part II B:

Toughened Green-nanocomposites

Toughening of PHB resulted in improvement in Impact properties with a loss in modulus.

Nanoclay platelets were added to regain the stiffness to some degree.

Optimum clay exfoliation and surface chemical modification produced nanocomposites with enhanced properties capable of competing with TPO.

PART-III(New Research Approach Underway)

Ionic liquids (ILs) to be used as:New plasticizer for PHA polymer matrix (replace

phthalates)

Exfoliating agent for layered silicates in ‘green nanocomposites’ preparation from PHAs

Project Schedule

Tasks Spr.2003 Sum.2003Fall02003Spr.2004 Sum.2004Fall2004 Spr.2005 Sum.2005Fall2005

Bioplastic Maleation

Bioplastic plasticization

Natural Rubber blending

Green Nanocomposite

fabrication

Characterization and

performance optimizations

Effect of extent of grafting

on compatibilization

Biodegradability study

Life Cycle Analysis

Integration of Education

AcknowledgementsAcknowledgements

EPA STAR award # RD-83090401 FORD, GM, METABOLIX, EASTMAN & NANOCORFORD, GM, METABOLIX, EASTMAN & NANOCOR