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Rebirth of Bio-based Polymer Development Dr. Shelby F. Thames The University of Southern Mississippi Thames Research Group School of Polymers and High Performance Materials Applications Coatings Fibers Plastics Adhesives Cosmetics Oil Industry Paper Textiles/clothing Water treatment Biomedical Pharmaceutical Automotive Rubber Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials Examples of Biopolymers Polyesters Polylactic acid Polyhydroxyalkanoates Proteins Silk Soy protein Corn protein (zein) Xanthan Gellan Cellulose Starch Chitin Polysaccharides Polyphenols Lignin Tannin Humic acid Lipids Waxes Surfactants Specialty polymers Shellac Natural rubber Nylon (from castor oil) Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials Where are Biodegradable Polymers Needed? Packaging materials (e.g., trash bags, loosefill 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 Thames Research Group School of Polymers and High Performance Materials 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, OTABP-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 O CH2 O C R1 O CH O C R2 O CH2 where R1, R2, and R3 are saturated or unsaturated fatty acids O C R3 Thames Research Group School of Polymers and High Performance Materials 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 f) Licanic acid g) Eleostearic acid h) Palmitic i) Estearic j) Araquidic k) Ricinoleic acid 100 - 111 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 OH HOOC (CH2)7 CH CH CH2 CH Ricinoleic Acid (CH2)5 CH3 Oil-Modified Polyesters Oil-modified polyesters (alkyds) are synthesized by reacting oils, polyhydric alcohols, and polyfunctional acids O O n HO R OH + n HO C R C OH O O O R O C R C Single + 2n H2O largest quantity of solvent-soluble polymers manufactured for use in surface coatings industry Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials Dimer Acid Polyamides (R) Long chain fatty acid dimers derived from vegetable oils are reacted with slight excess of primary amines to synthesize polyamides OH NH R NH 2 C O C O (CH 2)7 (CH 2)7 O CH HC CH (CH 2)7 HC CH CH CH (CH 2)5 CH CH 3 (CH 2)5 CH 3 + C OH 2 H2N R NH2 O CH HC CH (CH 2)7 HC CH CH CH (CH 2)5 CH CH 3 (CH 2)5 CH 3 C NH R NH 2 Dimer Acid Polyamides (continued) Polyamide-epoxy systems are the workhorse of high performance protective coatings O H2C CH CH2 O CH3 C O CH2 O CH CH2 + 2 H2N R NH2 CH3 OH H2N R N CH2 CH CH2 O H CH3 C CH3 OH O CH2 CH CH2 N R NH2 H Epoxidized Oils Epoxidized oils are synthesized by reacting vegetable oils (typically soybean and linseed oils) with peracids or hydrogen peroxide O O CH2 O C O (CH2)7 CH O CH CH2 CH CH (CH2)4 CH3 CH O C R2 O CH2 O C R3 Epoxidized oils are employed as plasticizers for polyvinyl chloride and as high temperature lubricants Thames Research Group School of Polymers and High Performance Materials Poly(e-caprolactone) As early as 1973, it was shown that poly(e-caprolactone) degrades in bioactive environments such as soil O [ O (CH2)5 C ] n Poly(e-caprolactone) and related polyesters are water resistant and can be melt-extruded into sheets and bottles Thames Research Group School of Polymers and High Performance Materials Polyhydroxyalkanoates Polyhydroxyalkanoates (PHA) accumulate as granules within cell cytoplasm O H [O C O (CH2)n C ] OH PHAs are thermoplastic polyesters with TM m.p. 50–180ºC (Biopol ) Properties can be tailored to resemble elastic rubber (long side chains) or hard crystalline plastic (short side chains) Thames Research Group School of Polymers and High Performance Materials PHA Production Raw materials Media preparation Fermentation Carbon source Bacteria growth and polymer accumulation Cell disruption Washing Centrifugation Polymer purification Drying PHA Thames Research Group School of Polymers and High Performance Materials PHB-V – polyhydroxyvalerate (PHB-V) is formed when bacteria is fed a precise combination of glucose and propionic acid Polyhydroxybutyrate PHB-V has properties similar to polyethylene but degrades into water and carbon dioxide under aerobic conditions Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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, OTABP-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 Thames Research Group School of Polymers and High Performance Materials Cellulose Cotton contains 90% cellulose while wood contains 50% cellulose Cellulose derivatives are employed in a variety of applications RO ROH2C OR O RO O n R O O RO OR ROH2C Carboxymethyl cellulose is used in coatings, detergents, food, toothpaste, adhesives, and cosmetics applications Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 CH2OH NHCOCH3 O HO CH2OH O O O OH O HO NHCOCH3 CH2OH n OH NHCOCH3 Chitin and its derivative, chitosan, possess high strength, biodegradability, and nontoxicity The principal source of chitin is shellfish waste 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 Thames Research Group School of Polymers and High Performance Materials Lactic Acid Lactic acid is produced principally via microbial fermentation of sugar feedstocks OH CH3 CH COOH 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials Amino Acid Structures CH3 CH3 NH2 CH CH2 CH COOH NH2 HOOC CH CH2 Leucine CH COOH Aspartic acid COOH Glutamic acid NH2 HOOC CH2 CH2 CH3 CH3 NH2 CH CH COOH Valine Thames Research Group School of Polymers and High Performance Materials 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) Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials Soybean Protein Soybean 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) NH NH2 CH3 CH COOH Alanine NH2 C NH NH2 (CH2)3 CH 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials Polyvinyl Alcohol Polyvinyl alcohol is the only polymer with exclusively carbon atoms in the main chain that is regarded as biodegradable OH CH2 CH n Polyvinyl alcohol is used in textile, paper, and packaging industries Thames Research Group School of Polymers and High Performance Materials 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 School of Polymers and High Performance Materials Thames Research Group Thames Research Group School of Polymers and High Performance Materials Castor Acrylated Monomer O H H H3CO O H H O Residual unsaturation provides mechanism for ambient cure Acrylate group reacts with growing polymer radicals Alkyl moieties provide internal plasticization 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 Mississippibased company Over 100 new jobs created 7,500 uniforms are being evaluated by the Air Force Thames Research Group School of Polymers and High Performance Materials USM Waterborne Water Repellant USM Soy-Based Waterborne Water Repellent Commercial Solvent-Based Water Repellent Formaldehyde-Free Biodegradable Wood Composites Renewable Biodegradable Formaldehyde-free Environmentally-friendly Wood Composites Mechanical 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 Thames Research Group School of Polymers and High Performance Materials Looking Ahead Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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 Thames Research Group School of Polymers and High Performance Materials 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), 127130 ‘Life Cycle Assessment and Environmental Impact of Plastic Products’, T. J. O’Neill, ISBN 1-85957-364-9 (www.chemtec.org) Thames Research Group School of Polymers and High Performance Materials Contact Information The University of Southern Mississippi School of Polymers and High Performance Materials 118 College Drive, #10037 Hattiesburg, MS 39406-0001 601-266-4080 www.psrc.usm.edu Thames Research Group School of Polymers and High Performance Materials
