Thames Research Group School of Polymers and High Performance Materials Rebirth of Bio-based Polymer Development Dr. Shelby F. Thames The University of

Thames Research GroupSchool of Polymers and High Performance Materials

Rebirth of Bio-based Polymer Development

Dr. Shelby F. Thames

The University of Southern Mississippi


Applications Coatings Fibers Plastics Adhesives Cosmetics Oil Industry Paper Textiles/clothing Water treatment Biomedical Pharmaceutical Automotive Rubber


Polymers

Polymers are broadly classified into: Synthetic Natural

Synthetic polymers are obtained via polymerization of petroleum-based raw materials through engineered industrial processes using catalysts and heat


Synthetic Polymers Polyethylene Polypropylene Polytetrafluoroethylene

(Teflon®) Polyvinylchloride Polyvinylidenechloride Polystyrene Polyvinylacetate Polymethylmethacrylate

(Plexiglas®) Polyacrylonitrile

Polybutadiene Polyisoprene Polycarbonate Polyester Polyamide (nylons) Polyurethane Polyimide Polyureas Polysiloxanes Polysilanes Polyethers


Natural Polymers Natural polymeric materials have been used

throughout history for clothing, decoration, shelter, tools, weapons, and writing materials

Examples of natural polymers: Starch Cellulose (wood) Protein Hair Silk DNA and RNA Horn Rubber


Chronological Development Natural resins From early

history Modified phenolic 1910 Nitrocellulose 1920 Air-drying oil-modified polyesters 1927 Urea-formaldehyde polymers 1929 Chlorinated rubber 1930 Acrylates 1931 Cellulose derivatives 1935 Polystyrene 1937 Melamine formaldehyde 1939 Polytetrafluoroethylene 1946 Polyethylene 1946


Biopolymers Biopolymers are obtained via polymerization

of biobased raw materials through engineered industrial processes

The raw materials of biopolymers are either isolated from plants and animals or synthesized from biomass using enzymes/ microorganisms


Examples of Biopolymers Polyesters

Polylactic acid Polyhydroxyalkanoates

Proteins Silk Soy protein Corn protein (zein)

Polysaccharides Xanthan Gellan Cellulose Starch Chitin

Polyphenols Lignin Tannin Humic acid

Lipids Waxes Surfactants

Specialty polymers Shellac Natural rubber Nylon (from castor oil)


Why Biopolymers? Fossil fuels (oil, gas, coal) are in finite supply and

alternative renewable sources of raw materials are needed

USDA's Bioproduct Chemistry & Engineering Research Unit focuses on creating new polymer technologies in which underutilized components of crops and their residues are processed into value-added biobased products.

Most synthetic polymers are not biodegradable


Sustainability

Sustainability is defined as a development that meets the needs of the present world without compromising the needs of future generations. Agricultural products offers this capability.

World Commission on Environment and Development


Biodegradable Polymers Polymers such as polyethylene and

polypropylene persist in the environment for many years after their disposal

Physical recycling of plastics soiled by food and other biological substances is often impractical and undesirable

Biodegradable polymers break down in a bioactive environment to natural substances by enzymatic processes and/or hydrolysis


Where are BiodegradablePolymers Needed?

Packaging materials (e.g., trash bags, loose-fill foam, food containers)

Consumer goods (e.g., egg cartons, razor handles, toys)

Medical applications (e.g., drug delivery systems, sutures, bandages, orthopedic implants)

Cosmetics Coatings Hygiene products

Biodegradable Polymers Market

Global consumption of biodegradable polymers increased from 14 million kg (30.8 million lbs) in 1996 to 68 million kg (149.6 million lbs) in 2001

U.S. demand for biopolymers is expected to reach $600 million by 2005 according to a Freedonia Group study

U.S. Congress, Office of Technology Assessment, Biopolymers: Making Materials Nature’s Way-Background Paper, OTA-BP-E-102 (Washington, DC: U.S. Government Printing Office, September 1993


Opportunities for Biodegradable Polymers: Vegetable Oils

Oils are triglyceride esters of mixed fatty acids

where R1, R2, and R3 are saturated or unsaturated fatty acids

CH2 O C

O

R1

CH O C

O

R2

CH2 O C

O

R3

Fatty Acid Composition of Vegetable Oils

Oil Saturated Oleic Linoleic Linolenic Others Iodine Value

Sunflower 10 30 60 - - 125 - 136

Soybean 14 30 50 6 - 120 - 141

Safflower 7 15 78 - - 140 - 150

Oiticica 10 6 6 - 78f 147 - 165

Chinese Melon 33 2 4 1 58g 120 - 130

Tung 4 7 9 - 80g 160 - 175

Linseed 8 20 19 52 - 165 - 202

Castor 3 7 5 - 85k 81 - 91

Coffee ? 9 46 - 45h,i,j 100 - 111

f) Licanic acid g) Eleostearic acid h) Palmitic i) Estearic j) Araquidic k) Ricinoleic acid

Unsaturated Fatty Acids in Vegetable Oils

HOOC (CH2)7 CH CH (CH2)7 CH3

9-Oleic Acid

HOOC (CH2)7 CH CH CH2 CH CH (CH2)4 CH3

9,12-Linoleic Acid

HOOC (CH2)7 CH CH CH2 CH CH CH2 CH CH CH2 CH3

9,12,15-Linolenic Acid

HOOC (CH2)7 CH CH CH2 CH (CH2)5 CH3

OH

Ricinoleic Acid


Oil-Modified Polyesters Oil-modified polyesters (alkyds) are

synthesized by reacting oils, polyhydric alcohols, and polyfunctional acids

Single largest quantity of solvent-soluble polymers manufactured for use in surface coatings industry

2n+ H2O+ C

O

HO R OH

O

CHO R OH C

O

ORO R

O

Cn n


Oil-Modified Polyesters (continued)Oil-modified polyesters are classified into

four categories based on their oil content: Very long oil polyesters (>75%)

Used in printing inks and as plasticizers for nitrocellulose coatings

Long oil polyesters (60-75%) Used in architectural and maintenance coatings as brushing

enamels, undercoats, and primers Medium oil polyesters (45-60%)

Used in anti-corrosive primers and general maintenance coatings

Short oil polyesters (<45%) Used with amino resins in heat-cured OEM coatings

Dimer Acid Polyamides (R) Long chain fatty acid dimers derived from

vegetable oils are reacted with slight excess of primary amines to synthesize polyamides

(CH2)7

C O

OH

CHCH

CHCHCH

CH

HC

HC

(CH2)7 C

O

OH

(CH2)5

CH3 (CH2)5

CH3

(CH2)7

C O

CHCH

CHCHCH

CH

HC

HC

(CH2)7 C

O

(CH2)5

CH3 (CH2)5

CH3

R NH2NH

R NH2NH

H2N R NH2+ 2

Dimer Acid Polyamides (continued)

Polyamide-epoxy systems are the workhorse of high performance protective coatings

H2C CH CH2

O

O C

CH3

CH3

O CH2 CH CH2

O

+ H2N R NH22

OCH2CHCH2NR

H

H2N

OH

C

CH3

CH3

O CH2 CH

OH

CH2 N

H

R NH2


Epoxidized Oils Epoxidized oils are synthesized by reacting

vegetable oils (typically soybean and linseed oils) with peracids or hydrogen peroxide

Epoxidized oils are employed as plasticizers for polyvinyl chloride and as high temperature lubricants

CH2 O C

O

CH O C

O

R2

CH2 O C

O

R3

(CH2)7 CH CH CH2 CH CH (CH2)4 CH3

O O


As early as 1973, it was shown that poly(-caprolactone) degrades in bioactive environments such as soil

Poly(-caprolactone) and related polyesters are water resistant and can be melt-extruded into sheets and bottles

Poly(-caprolactone)

O (CH2)5 C

O[ ]

n


Polyhydroxyalkanoates (PHA) accumulate as granules within cell cytoplasm

PHAs are thermoplastic polyesters with m.p. 50–180ºC (Biopol

TM

)

Properties can be tailored to resemble elastic rubber (long side chains) or hard crystalline plastic (short side chains)

Polyhydroxyalkanoates

H O C

O

(CH2) C

O

OHn[ ]


PHA ProductionRaw materials

Media preparation

Fermentation

Cell disruption

Washing

Centrifugation

Drying

PHA

Carbon source

Bacteria growth and polymer accumulation

Polymer purification


PHB-V Polyhydroxybutyrate – polyhydroxyvalerate

(PHB-V) is formed when bacteria is fed a precise combination of glucose and propionic acid

PHB-V

has properties similar to polyethylene but degrades into water and carbon dioxide under aerobic conditions


Starch Starch is the principal carbohydrate

storage product of plants

Starch is extracted primarily from corn; with lesser sources being potatoes, rice, barley, sorghum, and wheat

All starches are mixtures of two glucan polymers – amylose and amylopectin, at ratios that vary with the source

Starch (continued) ~75% of industrial corn starch is made

into adhesives for use in the paper industry

Corn starch absorbs up to 1,000 times its weight in moisture and is used in diapers (>200 million lb annually)

Starch-plastic blends are used in packaging and garbage bag applications

U.S. Congress, Office of Technology Assessment, Biopolymers: Making Materials Nature’s Way-Background Paper, OTA-BP-E-102 (Washington, DC: U.S. Government Printing Office, September 1993


Starch (continued)

Starch blended or grafted with biodegradable polymers such as polycaprolactone are available in the form of films

Blends with more than 85% starch are used as foams in lieu of polystyrene


Cellulose Cotton contains 90% cellulose while wood

contains 50% cellulose

Cellulose derivatives are employed in a variety of applications

Carboxymethyl cellulose is used in coatings, detergents, food, toothpaste, adhesives, and cosmetics applications

O

ORO

ROH2C

RO ORO

ORRO

O R

ROH2C

n


Cellulose (continued) Hydroxyethyl cellulose and its derivatives

are used as thickeners in coatings and drilling fluids

Methyl cellulose is used in foods, adhesives, and cosmetics

Cellulose acetate is a plastic employed in packaging, fabrics, and pressure-sensitive tapes

Chitin Chitin, a polysaccharide, is almost as common as

cellulose in nature, and is an important structural component of the exoskeleton of insects and shellfish

Chitin and its derivative, chitosan, possess high strength, biodegradability, and nontoxicity

The principal source of chitin is shellfish waste

O

OHO

HO

CH2OH

NHCOCH3

O

O

CH2OH

NHCOCH3

n

O

CH2OH

NHCOCH3OH

OH


Chitosan Chitosan forms a tough, water-absorbent,

oxygen permeable, biocompatible films, and is used in bandages and sutures

Chitosan is used in cosmetics and for drug delivery in cancer chemotherapy

Chitosan carries a positive charge (cationic) in aqueous solution and is used as a flocculating agent to purify drinking water


Lactic Acid Lactic acid is produced principally via

microbial fermentation of sugar feedstocks

Variation in polymerization conditions and L- to D- isomer ratios permit the synthesis of various grades of polylactic acid

Polylactide polymers are the most widely used biodegradable polyesters

CH3 CH

OH

COOH


Polylactic Acid Polylactic acid (PLA) degrades primarily by

hydrolysis and not microbial attack

PLA fabrics have a silky feel and good moisture management properties (draws moisture away and keeps the wearer comfortable)

Copolymers of lactic acid and glycolic acid are used in sutures, controlled drug release, and as prostheses in orthopedic surgery


Polyamino Acids

Polyamino acids (polypeptides) are found in naturally occurring proteins

20 amino acids form the building blocks of a variety of polymers

Polypeptides based on glutamic acid, aspartic acid, leucine, and valine are the most frequently used


Amino Acid Structures

CH3 CH

CH3

CH2 CH

NH2

COOH

Leucine

HOOC CH

NH2

CH2 CH2 COOH

Glutamic acid

HOOC CH2 CH COOH

NH2

Aspartic acid

CH3 CH

CH3

CH

NH2

COOH

Valine


Polyamino Acids (continued)

Glutamic acid and aspartamic acid are hydrophilic whereas leucine and valine are hydrophobic in nature

Combination of these amino acids in different ratios permits the development of copolymers with varying rates of biodegradability (for use as drug delivery systems)


Polyamino Acids (continued)

Amino acid polymers are particularly attractive for medical applications since they are nonimmunogenic (i.e., do not produce any immune response in animals)

Homopolymers of aspartic acid and glutamic acid are water-soluble, biodegradable polymers


Protein Soybeans are grown primarily for their

protein content and secondarily for their oil

A 60-pound bushel of soybeans yields about 48 pounds of protein-rich meal and 11 pounds of oil

U.S. soybean production exceeded 2,500 million bushels in 2002

www.unitedsoybean.org

Soybean ProteinSoybean protein consists mainly of the

acidic amino acids (aspartic and glutamic acids), and their amides, nonpolar amino acids (alanine, valine, and leucine), basic amino acids (lysine and arginine), and uncharged polar amino acid (glycine)

CH3 CH

NH2

COOH

Alanine

NH2 C

NH

NH (CH2)3 CH

NH2

COOH

Arginine

NH2CH2COOH

Glycine


Soybean Protein (continued)

Soybean protein is available as soy protein concentrate, soy protein isolate, and defatted soy flour

Soybean protein is employed in paper coatings, with casein in adhesive formulations, wood bonding agents, and composites


Corn Protein

Corn protein (zein) is a bright yellow, water-insoluble powder

Zein forms odorless, tasteless, clear, hard, and almost invisible edible films, and is therefore used as coatings for food and pharmaceutical ingredients


Polyvinyl Alcohol

Polyvinyl alcohol is the only polymer with exclusively carbon atoms in the main chain that is regarded as biodegradable

Polyvinyl alcohol is used in textile, paper, and packaging industries

CH2 CH

OH

n


Sorona®

Sorona® is a biopolyester marketed by DuPont for use in fibers and fabrics and is based on 1,3-propanediol (derived from fermentation of corn sugar)

Sorona offers advantages over both nylon and PET by virtue of softer feel, better dyeability, excellent wash fastness, and UV resistance


Thames Research Group

Castor Acrylated MonomerAcrylate group

reactswith growing

polymerradicals

Alkyl moieties provideinternal plasticization

Residual unsaturationprovides mechanism for

ambient cure

O

H3CO

OOH H

H H

United States Marines Utilize USM Technology

New fatigues are treated with a latex-based product


VOMM-Based Textile Latex

12,000 Marine Corps uniforms are treated monthly by a Mississippi-based company

Over 100 new jobs created

7,500 uniforms are being evaluated by the Air Force

USM Waterborne Water Repellant

USM Soy-Based Waterborne Water Repellent

Commercial Solvent-Based Water Repellent

Formaldehyde-Free Biodegradable Wood Composites

RenewableBiodegradableFormaldehyde-free Environmentally-friendly


Wood CompositesMechanical properties were tested as per

ANSI specifications A208.1-1999 (M-2 grade) following ASTM D 1037-96a

Boards with ag-based adhesive met and even exceeded commercial particleboard specifications

The adhesive is ready for a trial run in a commercial facility


Looking Ahead


Challenges for Biopolymers Competition with inexpensive commodity

polymers familiar to the consumer

Disposal of biodegradable polymers require an infrastructure and capital investment

In absence of suitable bioconversion facilities, biodegradable polymers are discarded in dry landfills and do not degrade as rapidly as intended


Farm Bill The Federal Biobased Procurement Program

was authorized by Section 9002 of the 2002 Farm Bill

Agencies will be required to purchase biobased industrial products whenever their cost is not substantially higher than fossil energy based alternatives, when biobased industrial products are available, and when biobased industrial products meet the performance requirements of the federal user


Life Cycle Analysis Life-cycle analysis is a technique used to

quantify the environmental impact of products during their entire life cycle from raw material extraction, manufacture, transport, use, and through waste processing

Life cycle analysis helps identify where improvement can be made to benefit the environment


Life Cycle Analysis (continued) Plastics production consumes energy and

releases emissions which negatively affect the environment

On the other hand, plastics being light weight result in reduced material use and lower energy costs in transport

Many companies are now undertaking life cycle analysis of their products

Life Cycle Analysis (continued) The concept of product responsibility is gaining

importance as manufacturers and end-users must now consider the cradle to grave pathway of each product

Life cycle analysis offers economic advantages for biopolymers because of their environmental friendliness

Environmentally friendly products also have a marketing advantage, as consumers are becoming increasingly aware of 'green' issues


References ‘Biodegradable Polymers for the Environment’, Richard A. Gross and Bhanu

Kalra, Science, Vol. 297, 2 Aug 2002, p. 803–807 www.metabolix.com www.biobased.com Protective Coatings: Fundamentals of Chemistry and Composition, Clive H.

Hare, 1st ed., Technology Publishing Co., NY, 1994 www.unitedsoybean.org U.S. Congress, Office of Technology Assessment, Biopolymers: Making

Materials Nature’s Way-Background Paper, OTA-BP-E-102 (Washington, DC: U.S. Government Printing Office, September 1993)

‘Adhesives and Plastics Based on Soy Protein Products’, Rakesh Kumar, Veena Choudhary, Saroj Mishra, I. K. Varma, and Bo Mattiason, Industrial Crops and Products, 16 (2002) 155-172

www.freemanllc.com ‘Biodegradable Binders and Cross-linking Agents from Renewable

Resources’, G. J. H. Buisman, Surface Coatings International, 1999(3), 127-130

‘Life Cycle Assessment and Environmental Impact of Plastic Products’, T. J. O’Neill, ISBN 1-85957-364-9 (www.chemtec.org)


Contact Information

The University of Southern Mississippi School of Polymers and

High Performance Materials118 College Drive, #10037

Hattiesburg, MS 39406-0001601-266-4080

www.psrc.usm.edu

Documents

Thames Research Group School of Polymers and High Performance Materials Rebirth of Bio-based Polymer Development Dr. Shelby F. Thames The University of