In

L I

1.2 Types of Biopolymers 2

1

1.12 Diene Polymers 39

1.14 Biopolymer Compositions 421.14.1 Blends 421.14.2 Additives and Modifiers 45

1of Biopolymers

One of the fastest-growing materials sectors in thelast several years has been the production of polymersfrom renewable resources. Their development isfueled by the potential these polymers hold to replace

lfuel resources; (2) pricing volatility of fossil fuel; (3)

change; (4) its occasional role as a political weapon;and (5) its association with the waste disposal problemcreated by the fossil fuel-derived polymers.

Polymers derived from renewable resources draw

fossil fuel-based polymers. The main reasons for this attention as environment-friendly resins because theyB

Ccontribution of fossil fuel as a feedstock to climate.1 Rationale for Use1.10 Polysaccharides 31(Bio-Based PUs) 29

1.9 Polyurethanes1.8 Poly(ether amide)s 291.7 Poly(ester amide)s 281.6.3 Poly(a-amino acid)s 25

Acids or Lactams 25Dicarboxylic Acids 251.6.2 Polycondensation of u-Amino Carboxylic1.6.1 Polycondensation of Diamines and1.5 Aliphatic Polycarbonates 23

1.6 Polyamides 241.4 Poly(ether-ester)s 221.3.2.3 Aromatic polyesters (bio-based) 20

1.3.2.2 Aliphatic-aromatic copolyesters 201.3.2 Poly(alkylene dicarboxylate)s 171.3.2.1 Aliphatic (co)polyesters 17(PHAs) 111.3.1.3 Poly(u-hydroxyalkanoate)s 161.3.1.1 Poly(a-hydroxyalkanoic acid)s 51.3.1.2 Poly(b-, g-, d-hydroxyalkanoate)siopolymers: Reuse, Recycling, and Disposal. http://dx.doi.org/10.1016/B

opyright 2013 Elsevier Inc. All rights reserved.drive can be summarized as follows: (1) limited fossiReferences 571.18 Sources of Scrap and Waste Biopolymers 561.17.11 Other Applications of Biopolymers 55

1.17.10 Building/Construction Industry 55

1.17.9 Outdoor Sports 55

1.17.8 Cosmetics 55

1.17.7 Medical and Pharmaceutical Sectors 54

1.17.6 Textiles/Fibers 54

1.17.5 Automotive Industry 53

1.17.4 Consumer Electronics 52

1.17.3 Agriculture/Forestry/Horticulture 52

1.17.2 Food Services 51

1.17.1 Service Packaging 511.17 Applications and Parts 501.16 Sources of Biopolymers 481.15 Biodegradable Biopolymer Additives 481.3 Polyesters 51.3.1 Poly(hydroxy acid)s 5

1.13 Other Biodegradable Polymers 391

O U T

1.1 Rationale for Use of Biopolymers 197troduction to Biopolymers

N E

.11 Vinyl Polymers 378-1-4557-3145-9.00001-4

1

to biodegrade in the environment. They offer a lotof advantages, such as increased soil fertility, low

2 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALare produced without relying on fossil fuel resources.In addition, the plants which provide the raw mate-rials for these polymers absorb carbon dioxide asthey grow, while the polymers themselves emitsmaller quantities of CO2 when they are disposed ofwith an incinerator. The polymers that are based onrenewable raw materials, as well as the polymers thatare produced by biological routes, are generallybiodegradable. The bio-based polymers, however, donot necessarily need to be biodegradable. This meansthat polymers that contribute to the protection of theenvironment include not only the bio-based polymersthat are not biodegradable, but also biodegradablepolymers. For this reason, the terms environmentalpolymer, enviropolymer, and biopolymer werecoined for the sake of convenience in order to givea generic name to the bio-based polymers that are notbiodegradable, and to the biodegradable polymers(including fossil fuel-based and bio-based polymers;see Chapter 2: Definitions and Assessment of (Bio)-degradation; Section 2.1: Define the Terms).

The main property that distinguishes biopolymersfrom fossil fuel-derived polymers is their sustain-ability, especially when combined with biodegrad-ability. Biodegradable biopolymers from renewableresources have been synthesized toprovide alternativesto fossil fuel-based polymers. They are often synthe-sized from starch, sugar, natural fibers, or other organicbiodegradable components in varying compositions.The biopolymers are degraded by exposure to bacteriain soil, compost, or marine sediment. When thebiodegradable biopolymers are subjected to wastedisposal by utilizing their characteristic of beingdegradable by the bacteria in the ground, it signifi-cantly reduces emission of CO2 compared with con-ventional incineration. Therefore, attention is drawn tothe use of biodegradable biopolymers from the view-point of global warming prevention. In recent years,with the critical situation of the global environmentworsening due to global warming, the construction ofsystems with sustainable use of materials has beenaccelerated from the viewpoint of effectively usinglimited carbon resources and conserving limitedenergy resources. The Kyoto protocol, together withthe desire to reduce societys dependence on importedcrude oil, has directed researchers efforts toward theuse of biomass as a source of energy and of commoditychemicals. Furthermore, the cost of petroleum feed-stocks has risen dramatically and there is a risingconsumer interest in using green (or renewable

resources) as the basis for consumer products.accumulation of bulky plastic materials in theenvironment, and reduction in the cost of wastemanagement. But there have been several obstacles sofar. Depending on the type and ratios of the compo-nents in biodegradable biopolymers, and dependingon the environmentwhere biodegradable biopolymersare disposed of, the rate of biodegradationmay be lessthan desired. Another obstacle is that as the thicknessof the product containing biodegradable biopolymerincreases, its biodegradability property is diminished.A greater problem still is that many biopolymers haveinferior properties, and it is often necessary to eitherblend themwith other polymers or to compound themwith various additives. As a result, many biopolymerblends or composites do not have uniformmechanicalproperties. Also,most knownbiodegradable polymersare aliphatic polyesters that have low softeningtemperatures (Tm), which prevents their use ina variety of fields.

In spite of several setbacks, biodegradable poly-mers are moving into the mainstream becauseconventional polymers are nondegradable and theyexhaust fossil fuel sources. However, biopolymersstill face a number of challenges, including costreduction, wider availability, the need to improvetheir thermomechanical and barrier properties, speedof biodegradability, and availability and optimizationof composting processes. As the demand for bio-polymers increases, it is expected that their produc-tion capacity will expand and their prices will fall,and eventually, a denser network of industrial com-posting facilities will be created. But the ultimateissue is whether the performance properties andprocessability of biopolymers will ever be able tocompete with the nonrenewable polymers.

1.2 Types of Biopolymers

Biopolymers are classified in several differentways at different scales. As explained in Chapter 2:Definitions and Assessment of (Bio)degradation;Section 2.1: Define the Terms, biopolymers can beBiodegradable biopolymers offer promise insolving the problem of conventional polymerdisposal. In principle, it is not necessary to collectarticles made of biodegradable biopolymers afterthe end of their useful life because they can be leftdivided into two broad groups, namely biodegradable

INTRODUCTION TO BIOPOLYMERS 3and non-biodegradable, and alternatively, into bio-based and non-bio-based biopolymers.

On the basis of their polymer backbone, biopoly-mers can be classified roughly into the followinggroups, each of which is subdivided into severalsubgroups (this list is not exhaustive):

PolyestersPoly(hydroxy acid)s top the list, and they include

biopolymers such as the following:

Poly(a-hydroxyalkanoic acid)s Polylactide (PLA, PLLA, PDLA) Polyglycolide (PGA) Poly(lactide-co-glycolide) (PLGA) Poly(tetramethyl glycolide) (PTMG) Poly(glycolide-co-trimethylene carbonate)(PGA/PTMC)

Poly(2-hydroxybutyrate) (P2HB) a-type polymalic acid (a-PMA)

Poly(b-, g-, d-hydroxyalkanoate)s (PHAs) Poly(3-hydroxypropionate (P3HP or PHP) Poly(3-hydroxybutyrate (P3HB or PHB) Poly(3-hydroxyvalerate) (P3HV or PHV) Poly(3-hydroxyhexanoate) (P3HH or PHH) Poly(3-hydroxyheptanoate) (P3HHp orPHHp)

Poly(3-hydroxyoctanoate) (P3HO or PHO) Poly(3-hydroxynonanoate) (P3HN or PHN) Poly(3-hydroxydecanoate) (P3HD or PHD) Poly(4-hydroxypropionate (P4HP) Poly(4-hydroxybutyrate) (P4HB) Poly(4-hydroxyvalerate) (P4HV) Poly(3-hydroxybutyrate-co-hydroxypropio-nate) (PHBHP)

Poly(3-hydroxybutyrate-co-3-hydroxyhexa-noate) (P3HB/P3HVor PHB/PHVorPHBHx)

Poly(3-hydroxybutyrate-co-3-hydroxyocta-noate) (P3HB/3HO or PHBO)

Poly(3-hydroxybutyrate-co-3-hydroxyvaler-ate) (P3HB/P3HVor PHBHV)

Poly(3-hydroxyoctanoate-co-3-hydroxyhex-

anoate) (P3HO/3HH or PHO/HH) Poly(3-hydroxybutyrate-co-3-hydroxydeca-noate) (PHBHD)

Poly(3-hydroxybutyrate-co-4-hydroxybuty-rate) (P3HB/P4HB)

b-type polymalic acid (b-PMA) Poly(5-hydroxyvalerate) (P5HV)

Poly(u-hydroxyalkanoate)s Poly(b-propiolactone) (b-PPL) Poly(b-butyrolactone) (b-PBL) Poly(e-caprolactone) (PCL)

Poly(alkylene dicarboxylate)s Poly(ethylene succinate) (PES) Poly(propylene succinate) (PPS) Poly(butylene succinate) (PBS) Poly(tetramethylene succinate) (PTeMS) Poly(ethylene adipate) (PEA) Poly(butylene adipate) (PBA) Poly(tetramethylene adipate) (PTA) Poly(hexamethylene adipate) Poly(ethylene succinate-co-adipate) (PESA) Poly(butylene succinate-co-adipate) (PBSA) Poly(butylene pimelate) (PBP) Poly(hexamethylene malonate) Poly(ethylene diethyl glutarate) Poly(tetramethylene glutarate) Poly(hexamethylene glutarate) Poly(hexamethylene diethyl glutarate) Poly(ethylene azelate) (PEAz) Poly(ethylene sebacate) (PESE) Poly(butylene sebacate) (PBSE) Poly(tetramethylene sebacate) (PTSE) Poly(hexamethylene sebacate) (PHSE) Poly(ethylene decamethylate) (PEDe) Poly(ethylene suberate) (PESu) Polyoxalate [poly(ethylene oxalate)(PEOx)]

Poly(propylene fumarate) (PPF) Aliphatic-aromatic copolyesters

Poly(butylene adipate-co-terephthalate)

(PBAT)

4 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSAL Poly(butylene succinate-co-terephthalate)(PBST)

Poly(tetramethylene glutarate-co-terephthalate-co-diglycolate)

Poly(tetramethylene glutarate-co-terephtha-late)

Poly(ethylene glutarate-co-terephthalate) Poly(tetramethylene adipate-co-terephthalate)(PTeMAT)

Poly(tetramethylene succinate-co-terephtha-late)

Poly(tetramethylene-co-ethylene glutarate-co-terephthalate)

Aromatic (co)polyesters Poly(ethylene terephthalate) (bio-based PET) Poly(ethylene furanoate) (PEF) Poly(trimethylene terephthalate) (bio-basedPTT)

Poly(ether-ester)s

Polydioxanone (PDO or PDS)Polycarbonates, aliphatic

Poly(ethylene carbonate) (PEC) Poly(propylene carbonate) (PPC) Poly(trimethylene carbonate) (PTMC) Poly(butylene carbonate) (PBC) Poly(tetramethylene carbonate) (PTeMC) Poly(cyclohexene carbonate) (PCHC) Poly(propylene carbonate)/poly(cyclohexenecarbonate) (PPC/PCHC)

Poly[(tetramethylene succinate)-co-(tetramethy-lene carbonate)] (PTMS/PTeMC)

Poly(glycolide-co-trimethylene carbonate)(PGA/PTMC)

Polyamides

By polycondensation of diamines and dicarbox-ylic acids:

Polyamide 1010 (PA 1010) Polyamide 1012 (PA 1012) Polyamide 410 (PA 410) Polyamide 610 (PA 610)

Polyphthalamides (PPA) By polycondensation of u-amino carboxylicacids or lactams:

Polyamide 11 (PA 11) Poly(a-amino acid)s

Poly(g-glutamic acid) (g-PGA) Poly(a-aspartic acid) e-Poly(L-lysine) (e-PL) Polypeptides (collagen, casein, fibrin,gelatin)

ProteinsPoly(ester amide)s

Poly(butylene adipate-co-caproamide) Hyperbranched poly(ester amide)sPolyurethanes (bio-based PU)

Poly(ester urethane)s Poly(ether urethane)sPolysaccharides

Cellulose derivatives Methyl cellulose Ethyl cellulose Propyl cellulose Hydroxyethyl cellulose Carboxymethyl cellulose Hydroxypropyl cellulose Cellulose acetate (CA) Cellulose acetate butyrate (CAB) Cellulose acetate propionate (CAP) Cellulose nitrate (CN) Cellulose-chitosan

Starch Lignin Chitin, chitosanVinyl Polymers

Polyolefins (bio-based polyethylene, PE, LDPE,HDPE; bio-based polypropylene, PP)

Poly(vinyl chloride) (bio-based PVC)

Poly(vinyl alcohol) (PVOH)

polymerization of cyclic monomers, eR-COOe. The

even g-, d-, and e-hydroxyalkanoic acids.

D-lactides results in LD-lactide (rac-lactide) (seeScheme 1.3).

Polylactide resins are classified into poly(L-lac-tide) (PLLA), poly(D-lactide) (PDLA), syndiotacticpoly(D,L-lactide) (syndiotactic PDLLA), attacticpoly(D,L-lactide) (attactic PDLLA), and copolymerswith other polymers, depending on the type ofconstitutive monomer (see Scheme 1.4). There is also

INTRODUCTION TO BIOPOLYMERS 51.3.1.1 Poly(a-hydroxyalkanoic acid)s

Poly(a-hydroxyalkanoic acid)s are poly(a-ester)sderived from a-hydroxyalkanoic acids (see Scheme1.1). A list of common a-hydroxyalkanoic acids isshown in Table 1.1.

Common a-hydroxyalkanoic acids includelactic acid, glycolic acid, tartaric acid, malic acid,mandelic acid, benzylic acid, valeric acid, a-hydroxy-butyric acid, a-hydroxyoctanoic acid, a-hydroxy-stearic acid, and mixtures thereof. The most useda-hydroxyalkanoic acids are lactic acid, glycolic acid,second group consists of the poly(alkylene dicar-boxylate)s. These are polyesters prepared by poly-condensation of diols and dicarboxylic acids.

1.3.1 Poly(hydroxy acid)s

A series of hydroxy acids are the hydroxyalkanoicacids, and the corresponding polymers are subdividedinto three categories: poly(a-hydroxyalkanoic acid)s,poly(b-hydroxyalkanoic acid)s and poly(u-hydroxy-alkanoate)s. The term polyhydroxyalkanoate is nor-mally used for poly(hydroxyalkanoic acid)s derivedfrom b-hydroxyalkanoic acids, and in certain cases,Other Biodegradable Polymers

Polyorthoesters I, II, III, IV (POE) Polyanhydrides

Poly(carboxyphenoxy hexane-sebacic acid) Poly(fumaric acid-sebacic acid) Poly(imide-sebacic acid) Poly(imide-carboxyphenoxy hexane)

Polyphosphazenes (PPHOSs)

1.3 Polyesters

Polyesters, especially the aliphatic ones, are themost extensively studied class of biopolymers [1].They can be classified into two groups according tothe bonding of the constituent monomers [2]. The firstgroup consists of the poly(hydroxy acid)s. These arepolyesters synthesized from hydroxy acids (hydroxy-carboxylic acids), HO-R-COOH, or by ring-openingand mixtures thereof; the corresponding polymers,polylactide (PLA) and polyglycolide (PGA), andcopolymers thereof, have been known for years.

Polylactide (PLA)Polylactide or polylactic acid (PLA) is a linear

aliphatic poly(a-ester) or a-hydroxyalkanoic acid-derived polyester (see Scheme 1.2).

PLA is obtainable primarily by the ionic poly-merization of lactide, a ring closure of two lactic acidmolecules. At temperatures between 140 and 180Cand under the action of catalytic tin compounds(such as tin oxide), a ring-opening polymerizationtakes place. Lactide itself can be made throughlactic acid fermentation from renewable resourcessuch as starch by means of various bacteria. PLAcan also be produced directly from lactic acid bypolycondensation. However, this process yields lowmolecular weight polymers, and the disposal of thesolvent is a problem in the industrial production.Various procedures for synthesizing, purifying, andpolymerizing lactide are disclosed in US4057537 A(1977, GULF OIL CORP), EP0261572 A1 (1988,BOEHRINGER INGELHEIM KG; BOEHRINGERINGELHEIM INT) and described in the literature[3e5].

There are two optically active forms of lactic acid:L-lactic acid and D-lactic acid. Consequently, thelactide, the cyclic dimer of lactic acid, may occurin three isomeric forms depending on whether itconsists of: (1) two L-lactic acid molecules, L-lac-tide; (2) two D-lactic acid molecules, D-lactide; or(3) one L-lactic acid molecule and one D-lactic acidmolecule, meso-lactide. The meso-lactide is charac-terized by a melting point (Tm) of around 50

C,whereas the melting point of the L- and D-lactideisomers is 97C. An equimolar mixture of the L- and

HO OH

O

Scheme 1.1 a-Hydroxyalkanoic acid.another form of PLA known as isotactic

Table 1.1 List of a-hydroxyalkanoic acid

a-Hydroxyethanoic acid(glycolic acid)

a-Hydroxypropanoic acid(a-lactic acid)

2,3-Dihydroxybutanedioic acid(tartaric acid)

Hydroxybutanedioic acid(malic acid)

2-Hydroxy-2-phenylacetic acid(mandelic acid)

2-Hydroxy-2,2-di(phenyl)acetic acid(benzylic acid)

a-Hydroxypentanoic acid(2-hydroxyvaleric acid)

1-Hydroxy-1-cyclohexane carboxylic ac

2-Hydroxy-2-(2-tetrahydrofuranyl)ethanoic acid

2-Hydroxy-2-(2-furanyl) ethanoic acid

2-Hydroxy-2-phenylpropanoic acid

2-Hydroxy-2-methylpropanoic acid

2-Hydroxy-2-methylbutanoic acid

2-Hydroxy-2-ethylhexylcarboxylic acid

a-Hydroxybutanoic acid(a-hydroxybutyric acid)

a-Hydroxypentanoic acid(a-hydroxyenanthoic acid)

a-Hydroxyheptanoic acid(a-hydroxyenanthoic acid)

a-Hydroxyoctanoic acid(a-hydroxycaprylic acid)

a-Hydroxynonanoic acid(a-hydroxypelargonic acid)

O CH

O

n

CH3

Scheme 1.2 Polylactide (PLA).

6 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALs

a-Hydroxydecanoic acid(a-hydroxycapric acid)

a-Hydroxyundecanoic acid(a-hydroxyhendecanoic acid)

a-Hydroxydodecanoic acid(a-hydroxylauric acid)stereocomplex, prepared from rac-lactide usinga racemic catalyst (isopropoxide), which has theadded advantage of possessing a melting pointapproximately 50C higher than the homochiralpolymers [6]. The mechanical properties of all thesetypes of PLA are as different as their degradationtimes [7]. Thus, a regular PLLA is a hard, transparentpolymer; it has a Tm of 165e185

C, a glass transitiontemperature (Tg) of 53e63

C, and a crystallization

a-Hydroxytridecanoic acid

a-Hydroxytetradecanoic acid(a-hydroxymyristic acid)

a-Hydroxypentadecanoic acid

a-Hydroxyhexadecanoic acid(a-hydroxypalmitic acid)

id a-Hydroxyheptadecanoic acid

a-Hydroxynonadecanoic acid

a-Hydroxystearic acid

a-Hydroxyarachidic acid

a-Hydroxybehenic acid

a-Hydroxylignoceric acid

a-Hydroxycerotic acid

a-Hydroxyoleic acid

a-Hydroxylinoleic acid

a-Hydroxylinolenic acid

a-Hydroxyarachidonic acid

OO

O

O

CH3

R

SO

O

O

O

H3C H3C

CH3

R

RO

O

O

O

H3C

CH3

SS

L-lactide D-lactide meso-lactide

O

O

O

O

H3C

CH3

R

RO

O

O

O

H3C

CH3

SS

L-lactide D-lactide

LD-lactide (rac-lactide): equimolar mixture of L-lactide and D-lactide

+

Scheme 1.3 Stereoisomeric forms of lactide.

OO

OO

O

O O

O

OO

OO

O

O O

O

OO

OO

O

O O

O

OO

OO

O

O O

O

isotacticpoly(L-lactide) (PLLA)

isotacticpoly(D-lactide) (PDLA)

heterotactic poly(D,L-lactide)(heterotactic PDLLA)

syndiotactic poly(D,L-lactide)(syndiotactic PDLLA)

Scheme 1.4 Stereoisomeric forms of polylactide (PLA).

INTRODUCTION TO BIOPOLYMERS 7

8 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALtemperature (Tc) of 100e120C. On the other hand,

attactic PDLLA has no melting point, a Tg around55C, and it shows much lower tensile strength [8].

The properties of PLA depend primarily on themolecular mass, the degree of crystallinity, andpossibly the proportion of co-monomers. A highermolecular mass raises Tg, as well as Tm, tensilestrength, elastic modulus, and lowers the strain afterfracture. Due to the CH3 side group (see Scheme 1.2),the material has water-repellent or hydrophobicbehavior. PLA is soluble in many organic solvents,such as dichloromethane or the like. PLA has highertransparency than other biodegradable polymers, andis superior in weather resistance and workability.

PLA has low melt viscosity, which is required forthe shaping of a molding. PLA is, however, slow inthe crystallization rate with long molding cycles andhas poor gas properties; furthermore, it has inferiorthermal resistance and mechanical characteristics(toughness, impact resistance, and the like) comparedwith those of existing synthetic resin molded articles.To solve these problems, many countermeasures areused in forming PLA, including blending PLA withother polymers, and compounding various kinds ofsubstances as filler; thus, PLA products have beenentering practical applications.

PLA is gaining a lot of interest due to its biode-gradability, biocompatibility, and renewable resource-based origin. It can be said that PLA is a lowenvironment load polymer that does not cause a directincrease in the total amount of carbon dioxide gas,even if the polymer is finally biodegraded or burnedup. The biodegradability of PLA, however, has bothpositive and negative aspects. The positive aspects ofPLA are its ability to form non-hazardous productswhen PLA polymers or articles are discarded orcomposted after completing their useful life, and itsslow degradation period (several weeks up to aboutone year), which is advantageous for some applica-tions as it leads to a relatively good shelf life. Thenegative aspects are that the thermal degradation ofPLA during processing causes deterioration of prop-erties, and that the degradation rate of PLA is still lowas compared to the waste accumulation rate, whichmeans that a large amount of PLA left untreatedoutdoors may cause a new environmental problem.Thus, the same properties that make PLA polymersdesirable as replacements for nondegradable fossilfuel-based polymers also create undesirable effectswhich must be overcome. PLA has a considerably

lower biodegradability than poly(e-caprolactone)(PCL) or poly(3-hydroxybutyrate) (PHB). PLA is themost common biopolymer currently on the market. Assuch, it has a variety of brand names associated with it(see Table 1.2).

Polyglycolide (PGA)Polyglycolide (PGA) is the simplest linear

aliphatic polyester (see Scheme 1.5). Glycolidemonomer is synthesized from the dimerization ofglycolic acid. Ring-opening polymerization yieldshigh molecular weight materials, with approximately1e3% residual monomer present. PGA is highlycrystalline (45e55%), with a high Tm (220e225

C)and a Tg of 35e40

C [9]. Because of its high degreeof crystallinity, it is not soluble in most organicsolvents, the exceptions being highly fluorinatedorganics such as hexafluoroisopropanol.

PGA has an extremely high gas-barrier property,as high as ca. 3 times or higher (i.e., ca. 1/3 or lowerin terms of an oxygen transmission coefficient) thanthat of ethylene-vinyl alcohol copolymer (PEVOH),which is a representative gas-barrier resin usedheretofore. This means that a bottle (especially onemade of PET) with a remarkably improved gas-barrier property can be obtained by including a thinlayer of PGA in addition to the principal resin layer.Accordingly, it becomes possible to effectivelyprevent the degradation of contents due to oxidationor poorer quality due to dissipation of carbon dioxidegas. Furthermore, PGA has a substantial hydro-lyzability with alkaline washing liquid, water(particularly warmed water), or acidic water. Incontrast, PLA does not exhibit gas-barrier propertieslike that of PGA, and can only show a slowerhydrolyzation speed with alkaline water, water, oracidic water (WO03097468 A1, 2003, KUREHACHEM IND CO LTD). Fibers from PGA exhibit highstrength and modulus and are too stiff to be used assutures except in the form of braided material.Sutures of PGA lose about 50% of their strength aftertwo weeks and 100% at four weeks, and arecompletely absorbed in 4e6 months. Glycolide hasbeen copolymerized with other monomers to reducethe stiffness of the resulting fibers. PGA can beutilized as a packaging material (e.g., lightweightPET bottles) as well as for oil recovery and otherindustrial and medical applications.

Poly(lactide-co-glycolide) (PLGA)Poly(lactide-co-glycolide) (PLGA) is a copolymer

of hydrophobic PLA and hydrophilic PGA (seeScheme 1.6). L-lactide and D,L-lactide have been

used for copolymerization with glycolide. Amorphous

Table 1.2 Commercial a-hydroxycarboxylic acid-derived polyesters

Biopolymer Commercial name Manufacturer Application

PLA Ingeo gradesNatureWorks 2000 series:2003D TDS

NatureWorks 3000 series:3001D SDS, 3052D SDS,3251D SDS, 3801X SDS

NatureWorks 4000 series:4032D TDS, 4043D TDS,4060D TDS

NatureWorks 6000 series:6060D TDS, 6201D TDS,6202D TDS, 6204D TDS,6400D TDS, 6251D TDS,6252D TDS, 6302D TDS,6751D TDS, 6752D TDS

NatureWorks 7000 series:7001D TDS, 7032D TDS

NatureWorks LLC (USA) 2003D TDS: food packaging;

2003D TDS, 3001D TDS,3052D TDS, 3251D TDS:service ware;

3001D SDS, 3052D SDS,3251D SDS, 3801X SDS:durable goods;

4032D TDS, 4043D TDS,4060D TDS: films, cards,folded cartons;

6201D TDS, 6204D TDS:apparel;

6201D TDS, 6202D TDS,6204D TDS, 6400D TDS:home textiles (woven andknitted);

6060D TDS, 6202D TDS,6251D TDS, 6252D TDS,6302D TDS, 6751D TDS,6752D TDS: nonwovens;

7001D TDS, 7032D TDS:bottles

PLA Econstrong Far Eastern Textiles (TW) Catering products (cups,trays, cutlery)

PLA Eco plastic Toyota (JP) Floor mats in cars

PLA Heplon Chronopol (USA) Bags

PLA Lacea H-100Lacea H-280Lacea H-400Lacea H-440

Mitsui Chemicals (JP) Bags, containers, films,nonwovens, packaging(stationery, cosmeticcontainers, pots forseedlings)

PLA Lacty 5000 seriesLacty 9000 seriesLacty 9800 series

Shimadzu Corp. (JP) Injection molding, fibers,films, sheets

PLA Terramac

Unitika Ltd. (JP)

TE-2000TE-1030TE-1070

Injection: smaller goods,containers, various plasticparts, etc.

TE-7000TE-7307

Injection: containers, tablewear, chassis, etc.

(Continued )

INTRODUCTION TO BIOPOLYMERS 9

Table 1.2 Commercial a-hydroxycarboxylic acid-derived polyesters (Continued )

Biopolymer Commercial name Manufacturer Application

TE-7300TE-8210TE-8300

TP-4000TP-4030HV-6250H

Extrusion, blown, and foam:containers, bottles, pipes,foam sheet, etc.

PLA Ecoloju S series Mitsubishi Plastics, Inc. (JP) Films, sheets

PLA, recycled LOOPLA

GalacidGalactic (BE)Futerro Total/Galactic (BE)

Recycled PLA grades arenot suitable for food-gradeapplications

PLA Palgreen Mitsui Chemicals Tohcello Films

PLA L-PLAD-PLAPDLA

PURALACT

Purac (NL) & SulzerChemtech

Molded plastic parts, fibers,films, foam, heat-stableapplications

PDLLA BIOFRONT Teijin (JP) Fibers, injection molding,eyeglass frames; films andsheets

PLA REVODE 100 seriesREVODE 200 series

Daishin Pharma-Chem Co.,Ltd./ Zhejiang HisunBiomaterials Co., Ltd. (CN)

Fixed installations such asbone plates, bone screws,surgical sutures, spinning

PLA, PCL blend VYLOECOL BE-400y

VYLOECOL BE-600VYLOECOL BE-910VYLOECOL HYD-306VYLOECOL BE-450VYLOECOL BE-410VYLOECOL HYD-006

Toyobo (JP) Printing ink, adhesive, paint,master batch resin, etc; BE-400 (pellet): general purposegrade, agent for variouscoating; BE-600 (sheet):anchor coating for vapordeposition film, anchorcoating for printing ink;BE-910 (sheet): adhesive fordry lamination

PLA (co)polymers

Ecodear series:Ecodear L4E6Ecodear V351X51 (glassfiber reinforcement, 30%)Ecodear V554R10 (glassfiber reinforcement, 30%)Ecodear V554X51Ecodear V751X52 (glassfiber reinforcement, 30%)Ecodear V911X51 (glassfiber reinforcement, 30%)

Toray Industries (JP) Electric, commodityappliances;film, bags, fibers;food packaging applications(frozen foods, snacks,cookies, cereal and nutritionbars, and confectioneryitems); packaging fornonfood items (personalcare items, fashionaccessories, promotionalitems, toys, office supplies,and other retail goods)

PGA Kuredux

KuresurgeKureha (JP) Kuredux: used in multilayer

PET bottles for carbonateddrinks;Kuresurge: used forsurgical sutures

(Continued )

10 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSAL

Table 1.2 Commercial a-hydroxycarboxylic acid-derived polyesters (Continued )

Biopolymer Commercial name Manufacturer Application

PGA PURASORB PG 20 Purac (NL) Medical device andpharmaceutical industry

PLGA PURASORB PLG 8531PURASORB PLG 8523

Purac (NL) Medical device andpharmaceutical industry

icon

icon

ctone

arkete

INTRODUCTION TO BIOPOLYMERS 11PURASORB PLG 8560PURASORB PLG 8218PURASORB PLG 8055PURASORB PLG 1017

PLGA Coated VICRYL RAPIDE(polyglactin 910)

Eth

PGCL MONOCRYL PlusAntibacterial (poliglecaprone25) Suture

Eth

Abbreviations: PGA, Polyglycolide; PGCL, Poly(glycolide-co-caprola

PLGA, Poly(lactide-co-glycolide).yVYLOECOL is made from lactides supplied by Purac. They are m

Opolymers are obtained for a 25 lactide/75 glycolidemonomer ratio. A copolymer with a monomer ratio of80 lactide/20 glycolide is semicrystalline. When theratio of monomer lactide/glycolide increases, thedegradation rate of the copolymer decreases [1].

PLGA is useful in drug delivery and tissue regen-eration applications since it degrades into harmlesssubstances. Since polymers of lactic acid and glycolicacid and their copolymers (PLGA) degrade quickly inthe body into nontoxic products, PLGA is used forbiodegradable sutures and can potentially be used inimplantable screws, intravascular stents, pins, drugdelivery devices, and as a temporary scaffold for tissueand bone repair. Additionally, PLGA has good

O CH2n

Scheme 1.5 Polyglycolide (PGA).

OO

O

O

CH3

CH3

O m

Scheme 1.6 Poly(lactide-co-glycolide) (PLGA).mechanical properties that improve the structuralintegrity of such devices. However, since PLGAdegrades completely by bulk erosion, it loses morethan 50% of its mechanical strength in less than twomonths, which can lead to uncontrollable drug releaserates and biocompatibility problems; this is probablydue to an accumulation of lactic and glycolic acidsduring degradation (US6077916 A, 2000, PENNSTATE RES FOUND)., Inc. (USA) Coated absorbable sutures

, Inc. (USA) Monofilament absorbablesutures

); PLA, Polylactide; PLCL, Poly(lactide-co-caprolactone);

d under the brand name PURALACT.1.3.1.2 Poly(b-, g-, d-hydroxyalkanoate)s(PHAs)

Polyhydroxyalkanoates (PHAs) are polyesters inwhich the hydroxyl group and the carboxyl group ofhydroxyalkanoic acids are linked via oxoester bonds.The general formula of polyhydroxyalkanoates isgiven in Scheme 1.7. The hydroxyalkanoic acidsare distinguished mainly by the position of thehydroxyl group in relation to the carboxyl group (seeScheme 1.8a and b), by the length of the side-alkylchain, by a large variety of substituents in the

O

H

O H

O n

12 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALO CH2

O

m

R H

n

Scheme 1.7 General formula of polyhydroxyalka-

noates; wherein m 1, R H, (un)substituted alkyl.

OH

O

OH

Scheme 1.8a b-Hydroxyalkanoic acid.

OH

Oside chains, and by one additional methyl groupat carbon atoms between the hydroxyl and thecarboxyl groups [10]. Unlike polymers derived froma-hydroxyalkanoic acids, like PLA and PGA, thepolyhydroxyalkanoates are normally comprised ofb-hydroxyalkanoic acids, and in certain cases, eveng- and d-hydroxyalkanoic acids.

To date, more than 150 hydroxyalkanoic acidshave been detected as constituents in bacterial PHAs;these constituents are produced by microorganismsgrown on carbon substrates containing different typesof chemical structures [10e12]. Beside linear andbranched b-, g-, d-, and e-hydroxyalkanoates,various constituents such as PHAs containing halo-genated or aromatic side chains have been described[13,14]. A list of b-, g-, and d-hydroxyalkanoic acidsis given in Table 1.3.

PHAs are commercially produced by severalbacteria as intercellular carbon and energy storagematerials [15]. PHAs may constitute up to 90% of thedry cell weight of bacteria, and are found as discretegranules inside the bacterial cells. Produced naturallyby soil bacteria, PHAs are degraded upon subsequentexposure to these same bacteria in soil, compost,

OH

Scheme 1.8b g-Hydroxyalkanoic acid.or marine sediment. Biodegradation begins whenmicroorganisms start growing on the surface of PHAand secrete enzymes that break down the biopolymerinto hydroxy acid monomeric units. The hydroxyacids are then taken up by the microorganisms andused as carbon sources for growth. The monomersand polymers can also be produced chemically.

In addition to commercial use as a biodegradablereplacement for synthetic commodity resins, PHAshave been extensively studied for use in biomedicalapplications. These studies range from potentialapplications in controlled release, to use in formu-lation of tablets, surgical sutures, wound dressings,lubricating powders, blood vessels, tissue scaffolds,surgical implants to join tubular body parts, bonefracture fixation plates, and other orthopedic uses(WO9932536 A1, 1999, METABOLIX INC).

Because of their great compositional diversity,PHAs with a range of physical properties can be pro-duced [16]. There are currently several commerciallyavailable PHAs, including poly-3-hydroxybutyrate(PHB), poly-(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV), poly(3-hydroxybutyrate-co-4-hydroxybuty-rate) (P3HB4HB), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx), which are derived frombacterial fermentations (Table 1.4).

This class of polyesters is attractive as a potentialalternative to conventional fossil fuel-based poly-mers. PHAs can be processed by traditional polymertechniques for use in an enormous variety of appli-cations, including consumer packaging, disposablediaper linings, garbage bags, and food and medicalproducts [15,17].

Polyhydroxybutyrate (PHB or P3HB)Polyhydroxybutyrate (PHB or P3HB) is synthe-

sized and stored within cells as an energy source forvarious microorganisms [18,19]. PHB can be extrac-ted from themicroorganisms. Example techniques aredisclosed in AU5560680 A (1980, ICI PLC) andEP0046335 A2 (1982, ICI PLC) (Scheme 1.9).

PHB is a homopolymer having stereoregularstructurewith high crystallinity. The high crystallinityleads to a rather stiff and brittle material. PHB has lowmelt viscosity and a narrow processing window. Itsinherent brittleness and thermal instability duringmelt processing impedes its commercial applications[20]. Plasticization of PHB or addition of processingadditives (e.g., nucleants) is often practiced in order toovercome its brittleness (see Section 1.14.2:Additivesand Modifiers). The commercial products of PHB are

outlined in Table 1.4.

oxy

anon

noic aric ac

anoicric ac

noicoic a

anoicthoic

INTRODUCTION TO BIOPOLYMERS 13Table 1.3 List of b-, g- and d-hydroxycarboxylic acids

b-Hydroxycarboxylic acids g-Hydroxycarb

b-Hydroxypropanoic acid(hydracrylic acid)

g-Hydroxyprop

b-Hydroxybutanoic acid(b-hydroxybutyric acid)

g-Hydroxybuta(g-hydroxybuty

3-Hydroxy-2-methylpropanoic acid(3-hydroxyisobutyric acid)

b-Hydroxypentanoic acid(b-hydroxyvaleric acid)

g-Hydroxypent(g-hydroxyvale

3-Hydroxy-3-methylpentanoic acid(3-hydroxy-3-methylvaleric acid)

b-Hydroxyhexanoic acid(b-hydroxycaproic acid)

g-Hydroxyhexa(g-hydroxycapr

b-Hydroxyheptanoic acid(b-hydroxyenanthoic acid)

g-Hydroxyhept(g-hydroxyenanPHB is used in themanufacture of body-waste bags,whether alone or as a coating on a water-solublepolymer, because of its good impermeability to waterand vapor (US4372311 A, 1983, UNION CARBIDECORP). Films or coatings of PHB may be made bysolution-coating techniques or bymelt extrusion.Upondegradation of PHB, the water-soluble polymer candissolve, thus avoiding obstruction of sewage pipesand sewage treatment plants. However, it is claimedthat the degradation rate of PHB is often too slow toavoid the formation of the aforementioned obstructions(AU3521984 A, 1985, ICI PLC). The rate of degra-dation can be markedly increased by modification ofthe pH of the bag contents (see Chapter 7: Degrad-ability on Demand; Section 7.3.4: Compounds WhichCan Initiate and/or Propagate Depolymerization).

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) is a copolymer in which 3-hydroxyvalerate

b-Hydroxyoctanoic acid(b-hydroxycaprylic acid)

b-Hydroxynonanoic acid g-Hydroxynonanoic

g-Hydroxydecanoic(g-hydroxycapric ac

b-Hydroxydodecanoic acid(b-hydroxylauric acid)

g-Hydroxydodecano(g-hydroxylauric acid

g-Hydroxytridecanoi

g-Hydroxyhexadeca(a-hydroxypalmitic alic acids d-Hydroxycarboxylic acids

ic acid

cidid)

acidid)

d-Hydroxypentanoic acid(d-hydroxyvaleric acid)

acidcid)

d-Hydroxyhexanoic acid(d-hydroxycaproic acid)

acidacid)

d-Hydroxyheptanoic acid(d-hydroxyenanthoic acid)(HV) units are incorporated in the PHB backboneduring the fermentation process (see Scheme 1.10).Microbiologically produced PHBV can be made bythe techniques described in EP0052459 A1 (1982)and EP0069497 A2 (1983, ICI PLC). The use ofcopolymers (e.g., containing 10 to 25, and particu-larly 15 to 20 mol% of HV units) may in some casesbe advantageous for lowering the modulus of thePHB since bags made from a film of such copolymerswould be less likely to make rustling noises uponmovement by the wearer.

PHBV has improved flexibility and toughness anda lower processing temperature than PHB. Presently,PHBV with an HV content below 15 mol% is com-mercially available, while large-scale productionof PHBV with higher HV content is presently notcommercially viable due to the surprisingly highproduction cost [21]. The available PHBV (with anHV content of less than 15mol%) has a low toughnessand elongation at break. PHBV has achieved a certain

acid

acidid)

d-Hydroxydecanoic acid(d-hydroxycapric acid)

ic acid)

c acid

noic acidcid)

Table 1.4 Commercial polyhydroxyalkanoates (PHAs)

Biopolymer Commercial name Manufacturer Applications

PHB Biogreen Mitsubishi Gas ChemicalCompany Inc (JP)

As component material forbiodegradable polymers; (cast)films, in natural latex gloves

PHB Mirel 3000 series(P and F versions)1

Mirel 400 series(P and F versions)

Telles (ADM/Metabolix)(USA)2

Mirel 3000: thermoformingMirel 400: sheet applications

PHB Biocycle

-B1000-B18BC-1-B189C-1-B189D-1

PHB Industrial S/A (BR) Films, disposables, medicalapplications

PHBV andPHB

Biomer 300-P300E-P300F-P300EF

Biomer Inc (DE) P300E: for extrusion, but not forfilm blowing;P300F: for food contact (EU only);P300EF: for extrusion and foodcontact, not for film blowing

PHBV,PHBV/PLA

ENMAT Y1000ENMAT Y1010 (withnucleating and stabilizingagent)ENMAT Y1000PENMAT Y3000ENMAT Y3000PENMAT F9000P

Tianan Biologic,Ningbo (CH)

Thermoplastics: injection molding,extrusion, thermoforming, blownfilms;fiber & nonwovens;denitrification: water treatment

PHBHx Nodax3 Meredian (USA) Packaging, laminates, coatings,nonwoven fibers

PHBHx Kaneka PHBH Kaneka Co. (JP) Film, sheets, foam, injectionmoldings, fibers, etc.; expected tobe used in agricultural andconstruction interior materials,automotive interior materials,electrical devices, packaging, etc.

P3HB4HB GreenBio Tianjin Green Bio-ScienceCo. (CN)/DSM (NL)

Fresh film, mulch film, laminatingfilm, wrapping film, heat shrinkablefilm, etc.; food packaging,shopping bags, garbage bags, giftbags, produce bags, etc.

PHBHx AONILEX Kaneka Co. (JP) High-durability molded products:bottles and containers, autointeriors, electrical equipment

PHBV BIOPOL4 Metabolix, Inc. (USA) Disposable products used in thefood industry (utensils, cups andplates);plastic wrap for packaging,coatings for paper and cardboard,moisture barrier films for hygienic

(Continued )

14 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSAL

) (Co

ctur

INTRODUCTION TO BIOPOLYMERS 15Table 1.4 Commercial polyhydroxyalkanoates (PHAs

Biopolymer Commercial name Manufaeconomic importance because of its polypropylene-like properties. Its commercial products are outlinedin Table 1.4. They have the potential to replacepolypropylene (PP) and other conventional fossil-based polymers if the PHB and PHBV-based materialscan be developed with a balance of properties such asstiffness and toughness. PHB and PHBV often haveunsatisfactory properties. PHB tends to be thermallyunstable, while PHB and PHBV often have slowcrystallization rates and flow properties that makeprocessing difficult. For example, PHBV remainstacky for long periods of time, and may stick to itselfwhen being processed into films.

Commercially available PHB and PHBV representonly a small component of the property sets available

P4HB TephaFLEX Tepha, Inc.

Abbreviations: PHB, Polyhydroxybutyrate; PHBV, Poly(3-hydroxybutyrate

hydroxybutyrate); PHBHx, Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate1The P and F versions refer to general purpose and food contact appli2On 12 January 2012Metabolix announced that Archer Daniels Midland Co

venture for PHA bioplastics. Telles was established as a joint venture betw

based bioplastics, including Mirel and Mvera, in the US, Europe and other3Meredian, Inc. bought Nodax PHA technology from Procter & Gamble Co4Monsantos rights to BIOPOL were sold to the American company Meta

O

CH3 O n

Scheme 1.9 Poly(3-hydroxybutyrate) (PHB or P3HB).ntinued )

er Applications

products, disposable containersfor shampoo and cosmetics, anddisposable items (razors, garbagebags and disposable nappies);agricultural uses include a carrierfor slow release of pesticides,herbicides or fertilizers;medical and pharmaceutical uses(gauzes, sutures, filaments,implants, drug carriers, andcoatings for drugs);

to PHAs. For example, the elongation at break of PHBand PHBV ranges from around 4 to 42%, whereasthe same property for poly-4-hydroxybutyrate (P4HB)is about 1000%. Similarly, the values of Youngsmodulus and tensile strength for PHB and PHBV are3.5 to 0.5 GPa and 40 to 16 MPa (for increasing HVcontent to 25 mol%), respectively, compared to 149MPa and 104 MPa, respectively, for P4HB [22].

In addition to finding commercial use as a biode-gradable replacement for synthetic commodity resins,PHB and PHBV have been extensively studied for usein biomedical applications. These studies range frompotential uses in controlled drug delivery [23,24], touse in formulation of tablets, surgical sutures, wounddressings, lubricating powders, blood vessels, tissue

bicycle helmet with BIOPOLfibers and cellulose highperformance fibers

Monofilament suture; absorbablesurgical film

-co-3-hydroxy valerate); P3HB4HB, Poly(3-hydroxybutyrate-co-4-

).

cations, respectively.

mpany (ADM) had given notice of termination of the Telles, LLC joint

een Metabolix and ADM in July 2006. The joint venture sold PHA-

countries.

.

bolix in 2001.

O

CH3 O

O

CH2H5 O mn

Scheme 1.10 Poly(3-hydroxybutyrate-co-3-hydroxy-

valerate) (PHBV).

scaffolds, surgical implants to join tubular body parts,bone fracture fixation plates, and other orthopedicuses, as described in WO9851812 A2 (1998,METABOLIX INC). PHB and PHBVare also used forpreparation of a porous, bioresorbable flexible sheetfor tissue separation and stimulation of tissue regen-eration in injured soft tissue as disclosed in

hydroxyalkanoate) owing to the possibility of

manufactured by ring-opening polymerization ofe-caprolactone in the presence of a tin octoate cata-lyst (see Scheme 1.14). PCL is a semicrystallinepolymer with a degree of crystallinity of about 50%.It has a rather low Tg (60C) and Tm (60C).Examples of commercially available products ofPCL are shown in Table 1.5.

A block copolymer of e-caprolactone with glyco-lide, which offers reduced stiffness compared to pure

O

CO2H O

n

Scheme 1.12 Poly(b-malic acid) (PMLA).

O

O

n

16 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALEP0349505 A2 (1990, ASTRA MEDITEC AB).Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

(P3HB4HB)Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

(P3HB4HB) was first found in 1988 from Ralstoniaeutropha cultivated with 4-hydroxybutyric or 4-chlorobutyric acid as carbon sources. The incorpo-ration of 4-hydroxybutyrate (4HB) units into PHB (orP3HB) improves the material application potential,and the copolymer shows a wide range of physicalproperties ranging from highly crystalline polymer toelastic rubber, depending on the polymer composi-tion (see Scheme 1.11). Generally, carbon sourcesstructurally related to 4HB are required to generate4HB-containing PHA, such as 4-hydroxybutyric acid,g-butyrolactone, and 1,4-butanediol. However, thesecarbon sources aremuchmore expensive than glucoseor other 3HB-generating carbon sources. The highcost of raw material for the copolymer productionhas become an obstacle for the wide production andapplication of P3HB4HB. US2012214213 A1 (2012,TIANJIN GREENBIO MATERIAL CO LTD) dis-closes methods of producing P3HB4HB with high4HB monomer content using carbon sources whichare structurally unrelated to 4-hydroxybutyrate.

Poly(b-malic acid) (PMLA)Poly(b-malic acid) (PMLA) is a biodegradable and

bioabsorbable water-soluble aliphatic polyester withmodifiable pendant carboxyl groups (see Scheme1.12). PMLA has been reported to be producedby Penicillum cyclopium, Physarum polycephalum,and Aureobasidium [25]. Various representativeindustrial methods for producing PMLA are describedin CN102002148 A (2011, ZHANGJIAGANGCHAINENG BIOLOG SCIENCE CO LTD),

O

CH3 O

O

m

n

O

Scheme 1.11 Poly(3-hydroxybutyrate-co-4-hydroxy-butyrate) (P3HB4BH).blending this aliphatic polyester with a number ofmiscible commercial polymers such as PVC, chlori-nated polyethylene, styrene-co-acrylonitrile copoly-mers, and bisphenol-A polycarbonate [26].

PCL is a fossil fuel-based aliphatic polyester,JP2004175999 A (2004) and JP2005320426 A(2005, NAT INST FOR MATERIALS SCIENCE).PMLA has various important applications in thebiomedical field.

1.3.1.3 Poly(u-hydroxyalkanoate)s

The general formula of poly(u-hydroxyalkanoate)sis given in Scheme 1.13. A representative example ofpoly(u-hydroxyalkanoate)s is poly(e-caprolactone)(PCL).

Poly(e-caprolactone) (PCL)PCL is the most thoroughly investigated poly(u-

OCH2

O

x n

Scheme 1.13 Poly(u-hydroxyalkanoate)s.Scheme 1.14 Poly(e-caprolactone) (PCL).

anuf

ow Cx UnSA)

Capa 6200Capa 6250

ersto

INTRODUCTION TO BIOPOLYMERS 17Capa 6400Capa 6430Capa 6500Table 1.5 Commercial polylactones

Biopolymer Commercial name M

PCL Tone series1

Tone P-300Tone P-700Tone P-767Tone P-787Tone UC-261

D(e(U

PCL Capa 6000 series

PPGA, is being sold as a monofilament suture byEthicon, Inc. under the trade name MONOCRYL.

1.3.2 Poly(alkylene dicarboxylate)s

Poly(alkylene dicarboxylate)s are polyesters derivedfrom dicarboxylic acids and dihydroxy compounds.These biodegradable polyesters can be characterized asbelonging to three general classes: (1) aliphatic poly-esters (derived solely fromaliphatic dicarboxylic acids);(2) aliphatic-aromatic polyesters (derived from amixture of aliphatic dicarboxylic acids and aromaticdicarboxylic acids); and (3) aromatic polyesters.Commercially available industrial poly(alkylene dicar-boxylate)s are shown in Table 1.6.

Capa 6500CCapa 6506Capa 6800Capa FB100Capa 7000 series(copolymers)

PCL Celgreen PH Daicel(JP)

PCL, PCLderivatives

Placcel 200 seriesPlaccel 300 seriesPlaccel F Series(macro-monomers)Placcel H1P (Mw 10,000)

Daicel(JP)

PGCL MONOCRYL PlusAntibacterial(poliglecaprone 25)

Ethico

Abbreviations: PCL, Poly(e-caprolactone); PGCL, Poly(glycolide-co-capro1The production of Tone has been stopped or sold.acturer Applications

hemicals Co.ion Carbide)

Coatings, elastomers, agriculturalfilms, drug delivery systems,matrices for the controlled releaseof pesticides, herbicides andfertilizers

rp (UK) Medical applications: alternative totraditional plaster, orthopedicsplints, dental impressions, andoncology immobilizationsystems;Films and laminates: blown films,1.3.2.1 Aliphatic (co)polyesters

The polyesters derived solely from aliphaticdicarboxylic acids, also called poly(alkylene alka-noate)s, are polyesters prepared from a dicarboxylicacid containing four to ten carbon atoms and a diolcontaining two to six carbon atoms; two or morekinds of each dicarboxylic acid and diol may beemployed. Examples include poly(ethylene adipate)(PEA), poly(ethylene succinate) (PES), and poly-(butylene succinate) (PBS).

Poly(ethylene succinate) (PES)Polyethylene succinate (PES) is chemically

synthesized either by polycondensation of ethyleneglycol and succinic acid or by ring-opening poly-merization of succinic anhydride with ethylene

laminates and packaging (e.g.,foamed packaging or wrapping forboth direct and indirect foodcontactOther applications: universalmaster batches

Corporation Mulch films, loose fill packaging,developing foam products, etc.

Corporation Chemical compounds for use in oras coating materials orpolyurethanes; modifiers forplastics; electric insulatingmaterials; ink binders; additivesfor adhesives

n, Inc. (USA) Monofilament absorbable suture

lactone).

Table 1.6 Poly(alkylene alkanoate)s

Applications

(KR) Injection molding, disposable goods,fibers

Ltd. (KR) Enpol G4560: disposable goods(forks, spoons, knives, golf tees),horticulture equipment (plant pot,

lyme

18 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALBiopolymer Commercial name Manufacturer

PBS Skygreen SG100 SK Chemicals

PBS EnPol G4000seriesEnPol G4560EnPol G4560J(> MFI)

IRE Chemical

PBS Bionolle 1000seriesBionolle 1001MD1

Bionolle 1020MDBionolle 1903MD

Showa HighpoCo., Ltd. (JP)oxide [27,28] (JPH0931174 A, 1997, UNITIKALTD; CN101628972 A, 2010, QINGDAO INST OFBIOMASS ENERGY) (see Scheme 1.15). PES hasa Tm of 103e106

C and good mechanical properties,especially elongation [29,30]. It has a high oxygen gasbarrier property, which is an advantageous propertywhen taking film utility into consideration, and ithas excellent biodegradability (EP1564235A1, 2005;JP2005264155 A, 2005, NIPPON CATALYTICCHEM IND).

Poly(butylene succinate) (PBS)Poly(butylene succinate) (PBS)1 is chemically

synthesized by polycondensation of 1,4-butanediol

PBSA Bionolle 3000seriesBionolle 3001Bionolle 3003Bionolle 3020Bionolle 3900Bionolle 5000

Showa HighpolymeCo., Ltd. (JP)

PBSA Skygreen SG200 SK Chemicals (KR)

PBSL GS Pla AD92WGS Pla AZ91TGS Pla GZ95T

Mitsubishi Chemica

Abbreviations: PBA, Poly(butylene adipate); PBS, Poly(butylene-co-succin

butylene succinate-co-lactide); PES, Poly(ethylene succinate); PESA, Pol1Bionolle 1001 is synthesized from succinic acid and 1,4-butanediol usin

1 Poly(tetramethylene succinate) (PTeMS) has the samestructure as PBS, but a different CAS number.clip), fishing gear

r Bionolle 1001MD: blown film (mulchfilms, compost bags), monofilament,blow molding, sheets, flat yarns;Bionolle 1020MD: injection molding,staple fiber;Bionolle 1903MD: foamed sheet,and succinic acid or its anhydride in the presence ofa catalyst [27] (JPH083302A, 1996, UNITIKALTD;JPH0931176 A, 1997, SHOWA HIGHPOLYMER;SHOWA DENKO KK; JP2001098065 A, 2001,MITSUBISHI CHEM CORP; WO2010123095 A1,2010, HITACHI PLANT TECHNOLOGIES LTD)(Scheme 1.16).

extrusion coating, uses for additive

r Bionolle 3001MD: blown film (mulchfilms, compost bags), monofilament,blow molding, sheets, flat yarns;Bionolle 3020MD: injection molding,staple fiber

Extrusion films, sheets, extrusioncoating

l (JP) Biodegradable multi-films foragriculture;disposable table utensils

ate); PBSA, Poly(butylene succinate-co-adipate); PBSL, Poly(-

y(ethylene succinate-co-adipate).

g 1,6-hexamethylene diisocyanate as a chain-extending agent.

O

O

nO

O

Scheme 1.15 Poly(ethylene succinate) (PES).

The succinic acid can be manufactured byfermentation of a saccharide such as sugarcane or corn(maize) (JP2005211041 A, 2005, NIPPON CATA-LYTIC CHEM IND). Showa Denko K.K. (SDK)announced that it has succeeded in producing its PBSunder the trademark Bionolle using bio-basedsuccinic acid. Another company already producingbio-based PBS (containing bio-succinic acid) is

with samples becoming completely metabolized infour to six weeks without any observable untowardeffects (US5439688 A, 1995, DEBIO RECHPHARMA SA).

Poly(butylene adipate) (PBA)PBA is chemically synthesized through poly-

condensation of adipic acid or its lower alkyl ester with1,4-butanediol in the presence of a polymerizationcatalyst such as a titanium compound (JPS63251424A, 1988, UNITIKA LTD; JPH08301996 A, 1996,KANEBO LTD; JP2001098065 A, 2001, MITSU-BISHI CHEM CORP) (see Scheme 1.17).

Poly(butylene succinate adipate) (PBSA)Poly(butylene succinate-co-butylene adipate)

(PBSA) is a combination of 1,4-butanediol, succinicacid, and adipic acid [27] (see Scheme 1.18). PBSA

O

n

OO

O

O

Scheme 1.16 Poly(butylene succinate) (PBS).

INTRODUCTION TO BIOPOLYMERS 19Mitsubishi Chemical Company [31].PBS has a relatively high melting temperature

(Tm 113C) and favorable mechanical properties,which are comparable to those of such widely usedpolymers as polyethylene and polypropylene [32].PBS has a relatively low biodegradation rate becauseof its high crystallization rate and high crystallinity.The enzymatic degradability of PBS was reportedto be lower than that of PCL, a low-melting-point(62C) aliphatic polyester [33]. Examples ofcommercially available products of PBS are shown inTable 1.6.

Another form of poly(butylene succinate) ispoly(2,3-butylene succinate), which is an amorphousPBS with a relatively low softening point (45 to50C) that is used in pharmaceutical applications.It has relatively fast in vivo bioresorption rates,

OOScheme 1.17 Poly(butylene adipate) (PBA).

OO

O

O m

Scheme 1.18 Poly(butylene succinate adipate (PBSA).is prepared by adding adipic acid to source materialsduring PBS synthesis. Although usually synthesizedfrom fossil fuel, it is also possible for the monomersthat make up PBSA to be produced from bio-basedfeedstock. PBSA degrades faster than PBS. Further-more, PBS and PBSA are known to biodegrade moreslowly than PHAs. Of the two, PBS has highercrystallinity and is better suited for molding, whilePBSA has lower crystallinity and is better suited tofilm applications. Both polymers have a low (sub-zero) Tg, and their processing temperatures overlapwith PHAs.

PolyoxalatesThe synthesis of polyoxalate polymers was first

reported by Carothers et al. [34]. They described theester interchange reaction of diols, such as ethyleneglycol, 1,3-propanediol, or 1,4-butanediol, with

O n

n

OO

O

O

Bio-based poly(ethylene terephthalate) (PET) is

20 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALdiethyl oxalate to yield amixture ofmonomer, solublepolymer, and insoluble polymer. The reaction ofoxalic acid and an alkylene glycol to form polyesterresins is described in US2111762 A (1938, ELLISFOSTER CO), while methods for the preparation ofpolyoxalates of fiber-forming quality, and theformation of sutures from filaments made of poly-oxalates are described in US4141087 A (1979) andGB1590261 A (1981, ETHIKON INC).

The synthesis of a poly(ethylene oxalate) (PEOx)(see Scheme 1.19) is also described in WO

O

O

O n

Scheme 1.19 Poly(ethylene oxalate) (PEOx).

OO

O

O CH3

HO

CH3

OH

n

Scheme 1.20 Poly(propylene fumarate) (PPF).2008038648 A1 (2008, TOYO SEIKAN KAISHALTD) (see Chapter 7: Degradability on Demand;Section 7.3.7: Blending with other Polymers).

Poly(propylene fumarate) (PPF)Poly(propylene fumarate) (PPF) is a biodegrad-

able unsaturated linear polyester that is typicallysynthesized via transesterification (see Scheme 1.20).The fumarate double bonds in PPF can be cross-linked at low temperatures to form polymernetworks. The high mechanical strength of cross-linked PPF matrices and their ability to be cross-linked in situ make them especially suitable fororthopedic applications. PPF degrades in the pres-ence of water into propylene glycol and fumaric acid,degradation products that are easily cleared from thehuman body by normal metabolic processes.

Representative synthethic methods and applica-tions for PPF are described in WO0062630 A1(2000, UNIV WMMARSH RICE) andWO9529710A1 (1995, RICE UNIVERSITY) and US2004023028A1 (2004, MAYO FOUNDATION).made from ethylene glycol and terephthalic acid orits ester-forming derivative, wherein at least one ofthe diol component or terephthalate component isderived from at least one bio-based material (seeScheme 1.21).

WO2009120457 A2 (2009, COCA COLA CO)and US2010028512 A1 (2010, COCA COLA CO)disclose such a bio-based PET. This bio-based PET iscomprised of about 25 to about 75 wt.% of a tere-phthalate component and about 20 to about 50 wt.%of a diol component, wherein at least 1 wt.% (pref-erably 10 wt.%) of the diol component and/or tere-phthalate component are derived from at least onebio-based material (e.g., corn and potato). The bio-based PET is useful for making bio-based containersfor packaging food products, soft drinks, alcoholicbeverages, detergents, cosmetics, pharmaceuticalproducts, and edible oils.

Coca-Colas current renewable bottle, named1.3.2.2 Aliphatic-aromatic copolyesters

Aliphatic-aromatic polyesters are obtained bycondensing aliphatic diols, aliphatic dicarboxylicacids, and aromatic dicarboxylic acids/esters. Thealiphatic-aromatic copolyesters are syntheticallypolymerized and therefore are not generallyrenewable. Some well known biodegradablealiphatic-aromatic copolyesters are poly(butylenesuccinate-co-terephthalate) (PBST) and, poly(butylene adipate-co-terephthalate) (PBAT). Variousrepresentative industrial methods for producingaliphatic-aromatic copolyesters are described inUS5171308 A (1992, DU PONT), WO9514740 A1(1995, DU PONT), WO9625446 A1 (1996, BASFAG), EP1108737 A2 (2001, IRE CHEMICAL LTD),and EP1106640 A2 (2001, IRE CHEMICAL LTD).Examples of commercially available aliphatic-aromatic polyesters are shown in Table 1.7.

1.3.2.3 Aromatic polyesters (bio-based)

Bio-based aromatic polyesters are capable ofreducing the use of fossil fuel resources and theaccompanying increase in carbon dioxide, but theyare not biodegradable. Examples of commerciallyavailable bio-based aromatic polyester are shown inTable 1.8.

Poly(ethylene terephthalate) (PET) (bio-based)PlantBottle , is made by converting sugarcane intoethylene glycol, which represents 30 wt.% of the total

Table 1.7 Aliphatic-aromatic (co)polyesters

Biopolymer Commercial name Manufac

PBAT EnPol G8000 Series:EnPol G8002; Enpol G8060;EnPol G8060F (G8060 &biomass)

IRE Che

PBAT Skygreen SG300 SK Chem

PBAT FEPOL 1000 seriesFEPOL 2000 series:FEPOL 2024

Far EastCo. (TW

PBAT Ecoflex series:Ecoflex F 1200;Ecoflex F BX 7011

BASF (D

PBAT Origo-Bi (ex Eastar Bio1) Novamo

PBST Biomax (modified PET) DuPont (

PEST Green Ecopet (recycled PETfiber/resin)

Teijin (JP

Abbreviations: PBAT, Poly(butylene adipate-co-terephthalate); PBST, Pol

succinate-co-terephthalate).1The Eastman Chemicals Eastar Bio technology was bought in 2004 by N

Table 1.8 Aromatic polyesters

Biopolymer Commercial name Manufacture

PET bio-based Up to 30% bio-basedPET (PlantBottle)

Coca-ColaCo. (USA)

PTT Sorona DuPont (USA

PTT Biomax PTT 1100Biomax PTT 1002

DuPont (USA

Abbreviations: PET (bio-based), Poly(ethylene terephthalate); PTT, Poly(t

OO

OO

n

Scheme 1.21 Poly(ethylene terephthalate) (PET).

INTRODUCTION TO BIOPOLYMERS 21turer Applications

mical Ltd. (KR) Enpol G8060: packagingfilms, plastic bags, PLAmodifier; EnPol G8060F: highcomposition of PET [35]. Deriving terephthalic acidfromnature hasbeenmuchmore difficult. InNovember2011, Japanese industrial group Toray announced thatit had produced the worlds first fully renewablebio-based PET fiber with terephthalic acid made fromp-xylene derived from biomass via isobutanol fromGevo (USA) [36]. Gevos yeast-based fermentation

quality films

icals (KR) Extrusion, film, sheet

ern New Century)

Packaging films, agriculturalfilms and compost bags

E) Packaging films, agriculturalfilms, compost bags, coatedapplications

nt (IT) Plastic bags, plastic sacks,plastic envelopes

USA) Fast food disposablepackaging, yard-waste bags,diaper backing, agriculturalfilms, flowerpots, bottles

) Fibers

y(butylene succinate-co-terephthalate); PEST, Poly(ethylene

ovamont.

r Applications

Containers for packaging food products, softdrinks, alcoholic beverages, detergents,cosmetics, pharmaceutical products andedible oils

) Fibers, multifilament surgical devices (suture,mesh, sternal closure device, cable and tape)

) Biomax PTT 1002: packaging and industrialapplications;Biomax PTT 1100: injection-molded containers,cosmetic packaging and other parts wherepolyesters are used

rimethylene terephthalate).

which results in several excellent properties such ashigh elastic recovery and dyeing ability [38]. InitiallyPTTwas intended for the carpeting market, but due toits processability, like spinning and dyeing properties,it turned out to be more suitable for the fiber market in

PONT). As disclosed in WO0111070 A2 (2001, DU

O

O

n

OO

O

22 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALprocess converts cornstarch-derived sugar into iso-butanol, which after subsequent chemical reactions istransformed into a stream of aromatics containingmore than 90% p-xylene. Its technology is easilyretrofitted into existing ethanol plants.

JP2011219736 A (2011, TORAY IND INC)discloses a bio-based poly(alkylene terephthalate)obtained by using as raw materials biomass resource-derived glycol and biomass resource-derived tereph-thalic acid and/or its ester-forming derivative. Aphosphorus compound was also included.

Poly(ethylene furanoate) (PEF)Poly(ethylene furanoate) (PEF) is made from

ethylene glycol and 2,5-furan dicarboxylic acid(FDCA) (see Scheme 1.22). Avantium (NL) devel-oped a process using catalytic reactions to createFDCA, which reacts with ethylene glycol to makePEF. PEF is a bio-based alternative to PET; the maincomponent of PET is terephthalic acid, which couldbe replaced by bio-based FDCA. According toAvantium, PEF exceeds PET in terms of oxygenbarrier and temperature performance.

Even though the PEF production process is stillunder development, it has been estimated that thecomplete substitution of PET by PEF is likely to offersavings of between 43 and 51% of fossil fuel, anda reduction of between 46 and 54% of CO2 emissionsfor the system cradle-to-grave [37].

Poly(trimethylene terephthalate) (PTT) (bio-based)Poly(trimethylene terephthalate) or poly(propylene

terephthalate) (PPT) belongs to the group of lineararomatic polyesters next to poly(ethylene terephtha-late) and poly(butylene terephthalate) (PBT)with threemethylene groups in the glycol repeating units (see

Scheme 1.22 Poly(ethylene furanoate) (PEF).Scheme 1.23). The odd number of methylene unitsaffects the physical and chemical structure of PTT,

OCH2

CH2CH2

O C

O

Scheme 1.23 Poly(trimethylene terephthalate) (PTT).PONT) and US6428767 B1 (2002, DU PONT;GENENCOR INT), bio-based 1,3-propanediol andpolymers derived therefrom can be distinguishedfrom their petrochemical-derived counterparts onthe basis of 14C and dual carbon-isotopic finger-printing.

Bio-based PTT is marketed by DuPont Companyas Sorona fibers, and the polymer is additionallyused in many other end-use applications for films,filaments, and engineering plastics. DuPontsSorona EP thermoplastic polymers contain between20 and 37% renewably sourced material (by weight)derived from corn sugar 1,3-propanediol. The newmaterial exhibits performance and molding charac-teristics similar to high-performance PBT.

DuPont Packaging & Industrial Polymers intro-duced Biomax PTT, which contains up to 35%renewably sourced content for packaging applica-tions, where chemical resistance and durability areessential features. Biomax PTT 1100 is an unfilledresin especially suitable for use in injection-moldedcontainers, cosmetic packaging, and other partswhere polyesters are used.

1.4 Poly(ether-ester)s

Poly(ether-ester)s are generally prepared by a two-stage melt transesterification process from readilyavailable starting materials such as dimethyl tere-phthalate, an alkane diol, and a poly(alkylene glycol

C

O

nthe fields of sportswear and active wear [38,39].PTT is made by polycondensation of 1,3-pro-

panediol and either terephthalic acid or dimethylterephthalate. This polymer has attracted attention inrecent years after the development of productionof 1,3-propanediol from starch-derived glucose,a renewable resource (WO0112833 A2, 2001, DU

ether). The resulting poly(ether-ester)s consist ofsequences of crystallizable alkylene terephthalatesequences (hard segments) and elastomeric poly-(alkylene oxide) sequences (soft segments). Thesematerials show a wide range of properties depending

are known, such as Hytrel RS (DuPont) andArnitel Eco (DSM). These materials combine many

synthesized using zinc carboxylate catalysts tocopolymerize propylene oxide and carbon dioxide.

O O

O

n

O O

CH3

O

n

INTRODUCTION TO BIOPOLYMERS 23interesting properties, including a high temperatureTm, a low Tg, high yield stress, elongation at break,and elasticity. They are also easy to process [42].According to DuPont, Hytrel RS thermoplasticelastomers have many applications, including hosesand tubing for automotive and industrial uses, bootsfor CV joints, air bag doors, and energy dampers.According to DSM, Arnitel Eco is suitable forapplications in consumer electronics, sports andleisure, automotive interiors and exteriors, furniture,alternative energy, and specialty packaging. Thematerial is designed for a long service lifetime underextreme conditions.

Polydioxanone (PDO or PDS)Referred to as poly(oxyethylene glycoate) and

poly(ether-ester), the ring-opening polymerization ofp-dioxanone results in a synthetic suture knownasPDSor polydioxanone (US4490326 A, 1984, ETHICONINC) (see Scheme 1.24). The polymer is processed atthe lowest possible temperature to prevent depoly-merization back to monomer. The monofilament loses50% of its initial breaking strength after three weeksand is absorbed within six months, providing anadvantage over other products for slow-healingwounds. A commercial product of poly(p-dioxanone)is PDS Plus Antibacterial Suture from Ethicon, Inc.,which is a monofilament synthetic absorbable suture.

1.5 Aliphatic Polycarbonates

The synthesis of high molecular weight poly-(alkylene carbonate)s was first reported by Inoue

OO

O nupon the content of alkylene terephthalate segmentsand the length of poly(alkylene oxide) [40e42].Several commercially available block poly(ether-ester)s based on PBT and poly(tetramethylene oxide)

Scheme 1.24 Polydioxanone (PDO).et al. in the late 1960s [43]. These rather new poly-mers are derived from carbon dioxide and areproduced through the copolymerization of CO2 withone or more epoxy compounds (ethylene oxide orpropylene oxide). They can contain up to 50% CO2or CO by mass and sequester this harmful greenhousegas permanently from the environment.

Poly(ethylene carbonate) (PEC)Poly(ethylene carbonate) (PEC) is the product of

alternating copolymerization of ethylene oxide andcarbon dioxide (see Scheme 1.25). PEC is a biode-gradable amorphous polymer with a Tg of 15e25

C,and it exhibits elastomeric characteristics at ambienttemperature. Extruded films of PEC have highoxygen barrier properties that make it useful asa barrier layer for food packaging applications. PEChas also been found to decompose cleanly at lowertemperatures, both in nitrogen and in air, than mostother commercial polymers.

Empower Materials Inc. commercializesQPAC25, a PEC, which is used as binder or sacri-ficial material.

Novomer also commercializes PEC in two appli-cation markets: as a traditional polymer for pack-aging, and as a clean-burning sacrificial material forhigh-end processing, including ceramic and elec-tronic processing.

Poly(propylene carbonate) (PPC)Poly(propylene carbonate) (PPC) is the product of

alternating copolymerization of ethylene oxide andcarbon dioxide (see Scheme 1.26). Until recently,high molecular weight PPC has been predominantly

Scheme 1.25 Poly(ethylene carbonate) (PEC).Scheme 1.26 Poly(propylene carbonate) (PPC).

a PPC composition in combination with one or more

Polyamides are polymers with amide groups (R-CO-NH-R0) as integral parts of the main polymerchain. Bio-polyamides are basically formed frompolycondensation of the following: (1) diamines anddicarboxylic acids; (2)u-amino carboxylic acids as bi-functional monomers; and (3) a-amino carboxylic

24 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALThe resulting material was the focus of intenseinvestigation, and several companies have exploredapplications for the material as a commodity ther-moplastic. To date, PPC has been commercializedonly as a sacrificial polymer in applications wherethe clean thermal decomposition of PPC is advanta-geous. Commercialization of the material for ther-moplastic applications has been complicated by poorthermal and processing properties. Recently, transi-tion metal complexes have been developed for thecopolymerization of carbon dioxide and epoxides,but such complexes have not been fully exploitedand/or optimized in the preparation of improved PPCmaterials. PPC has good properties such as compat-ibility and impact resistance. Its thermal stability andbiodegradation need to be improved. A classical wayto do this is to blend it with other polymers [44].

Empower Materials Inc. commercializesQPAC40, a PPC, which like QPAC25 is used inbinder and sacrificial structure applications.

In addition toPECandPPC,EmpowerMaterials Inc.synthesized multiple other QPAC polymers on a pilotscale including: QPAC60 (polybutylene carbonate,PBC), QPAC100 (polypropylene carbonate/polycy-clohexene carbonate, PBC/PCHC), and QPAC130(polycyclohexene carbonate, PCHC).

Novomer (USA) and SK Energy Co., Ltd. (SK) arealso commercializing PPC. SK is creating its 44%CO2-based Greenpol

PPC using a proprietary cata-lyst and a continuous polymerization process. PPC haspotential uses for packaging materials, competingwith commodity polymers such as polyolefins.

Novomer is working with Eastman Kodak todevelop PPC for packaging applications. Novomerplans on making enough PPC resins and films thatpotential customers can test them in packagingapplications. Novomer targets its first PPC product,NB-180, as a temporary binder for electronics.Because it breaks down into carbon dioxide andwater when exposed to high temperatures, it can beburned off without a trace. Both NB-180 and the newPPC polymer are made by polymerizing propyleneoxide with carbon dioxide using a proprietary cata-lyst. As a packaging polymer, PPC is touted asoffering unique impact resistance, stiffness, andoxygen barrier properties.

WO2011005664 A2 (2011, NOVOMER INC)discloses PPC films as parts of a multilayer film. Incertain embodiments, PPC acts as a tie layer ina laminate film. In some embodiments, a PPC

composition provides a structural layer in a multilayerother degradable polymers such as PLA, PHB, poly(3-hydroxypropionate (P3HP or PHP), starch, or modi-fied cellulose. In still other embodiments, the layercontaining the PPC composition acts as a barrier layerto retard the transmission of oxygen, water vapor,carbon dioxide, or organic molecules.

Poly(trimethylene carbonate) (PTMC)Poly(trimethylene carbonate) (PTMC) is a biode-

gradable polycarbonate with rubber-like properties.PTMC is obtained by ring-opening polymerization oftrimethylene carbonate (TMC) and catalyzed withdiethyl zinc [1] (see Scheme 1.27). A high molecularweight flexible polymer was prepared, but displayspoor mechanical performance [45]. Due to thisproperty, its applications are limited and copolymersare more often used. Copolymers with glycolide anddioxanone have also been prepared [9].

Mitsubishi Gas Chemical Co. has marketed a co-polyester carbonate, namelypoly[oligo(tetramethylenesuccinate)-co-(tetramethylene carbonate)] (PTeMS/PTeMC). The copolyester carbonate is composed ofa polyester part and a polycarbonate part. The car-bonate content inside the copolymer is variable. Themelting point of the copolymer is about 100e110C.Introducing poly(tetramethylene carbonate) (PTeMC)into poly(tetramethylene succinate) (PTMS) probablycauses disorder in the crystal structure, thus loweringits melting point and increasing its susceptibility toenzymatic and microbial attacks [1]. The microbialdegradability of the copolyester carbonate wasconfirmed to be higher than that of both of its con-stituents [46].

1.6 Polyamidesfilm. In certain other embodiments, the films comprise

O O

O

n

Scheme 1.27 Poly(trimethylene carbonate) (PTMC).acids as bi-functional monomers [47]. Bio-polyamides

INTRODUCTION TO BIOPOLYMERS 25include both bio-based polyamides and biodegradablefossil fuel-based polyamides. The commerciallyavailable bio-polyamides are shown in Table 1.9.

1.6.1 Polycondensation ofDiamines and Dicarboxylic Acids

Dicarboxylic acids can be derived from renew-able resources such as castor oil. Diamines aremainly derived from fossil fuel [47]. Commercialbio-polyamides produced by the polycondensationof diamines and dicarboxylic acids include poly-amide 1010 (PA 1010), polyamide 410 (PA 410),polyamide 610 (PA 610), and polyphthalamides(PPA).

1.6.2 Polycondensation ofu-Amino Carboxylic Acidsor Lactams

An example of a bio-polyamide produced by thering-opening polymerization of e-caprolactam ispolyamide 11 (PA 11).

1.6.3 Poly(a-amino acid)s

Synthetic polymers of a-amino acids containpeptide bonds in the main chain and can be composedof the same structural units (a-amino acids) as poly-(amino acids) of natural origin, such as polypeptidesand proteins. In this regard they may be consideredas being protein analogues. Two amino acid homo-polymers comprising a single type of amino acidare known in nature [48]: poly(g-glutamic acid)(g-PGA) and e-poly(L-lysine) (e-PL).

Poly(a-amino acids) are mainly used to createhigh-purity materials needed for biomedical appli-cations. To date, commercial applications of pro-tein polymers, such as poly(D-lysine) and poly(L-lysine), are limited to use as adhesives/substratesfor cell culture. Copolymers of a-amino acids (suchas serine) with other biodegradable polymers (such asPLA) are synthesized as drug delivery systems(WO9828357 A1, 1998, CONNAUGHT LAB). Inaddition to drug delivery and targeting, poly(aminoacids) are being investigated for applications such asbiodegradable sutures and artificial skins.

Three kinds of poly(amino acids) e poly(g-glutamic acid), poly(a-aspartic acid) and e-poly(L-lysine) e have attracted more attention because of

their unique properties and various applications.Poly(g-glutamic acid) (g-PGA)Poly(g-glutamic acid) (also known as poly-

glutamate and g-PGA) is a water-soluble, anionic,biodegradable polyamide consisting of D- andL-glutamic acid monomers connected by amidelinkages between a-amino and g-carboxyl groups(see Scheme 1.28). g-PGA is synthesized by severalbacteria and its molecular weight can vary anywherefrom 20,000 to over 2 million Da depending on themethod of production. A major advantage of usingg-PGA is its low cost and relative abundance [49,50].g-PGA has several environmental/industrial, agri-cultural, food, and pharmaceutical applications. Oneenvironmental application of g-PGA is its use asa flocculent. Another newer environmental applica-tion of g-PGA is in removing heavy metal contami-nants, such as those used by the plating industry.g-PGA has a very large anionic charge density.Contaminants such as copper, lead, mercury andother positively charged metal ions associate verystrongly with g-PGA, and can then be concentratedand removed from the waste stream.

Since g-PGA is comprised of an amino acid, it is anexcellent source of nitrogen. This suggests an appli-cation in agriculture as a fertilizer. For analogousreasons it is good for drug delivery. A polymermixture can be packed with nutrients for a particularcrop. Once the fertilizer is applied, it has a longerresidence time in the soil since the fertilizer nutrientsare protected from the natural environment by theg-PGA.

In the food industry, work has been done thatshows PGA functions as a cryoprotectant. g-PGA hasbeen shown to have antifreeze activity significantlyhigher than glucose, a common cryoprotectant. In themedical field, PGA is being studied as a biologicaladhesive and a drug delivery system (US2005095679A1, 2005, CRESCENT INNOVATIONS INC).

PGA is degraded by a class of extracellularenzymes called g-glutamyl hydrolases, and asa polyamide is more resistant than synthetic poly-esters to random chain hydrolysis. In biologicalsystems g-PGA undergoes enzymatic degradationfrom the surface, rather than bulk hydrolysis. Thus,g-PGA provides benefits for use as a scaffold mate-rial because it prevents rapid deterioration in scaffoldstrength. In addition, due to the presence of thecarboxyl group (eCOOH) on the side chain, g-PGAexhibits unique advantages over other materials interms of scaffold applications (WO2012004402 A1,

2012, IMP INNOVATIONS LTD).

Table 1.9 Commercially available bio-polyamides

Biopolymer Commercial name Manufacturer Applications

PA 11 Rilsan Arkema (FR) Electrical cables, automotive,pneumatic and hydraulic hose

PA Rilsan Clear G830Rnew

Arkema (FR) Molding applications, ideally suitedfor optics as high end eyewearframes

Co-PA Platamid Rnew Arkema (FR) Hot melt adhesive

PA 1010 Grilamid 1S EMS-GRIVORY (DE) Reinforced Grilamid 1S:manufacture of stiff covers;Non-reinforced, amorphous grades:injection-molding processes forovermolding metal sheets

PA 1010 VESTAMID Terra DS Evonik (DE) Injection molding, fibers, powder,extrusion, and films

PA 1010 Zytel RS LC1000BK385Zytel RS LC1200BK385Zytel RS LC1600BK385

DuPont (USA) Multiple extrusion applications

PA 1010 Hiprolon 200 series Suzhou Hipro Polymers(CN)

Gear, electronics housing parts,rigid technical tubing, technical film,powder coating

PA 1012 VESTAMID Terra DD Evonik (DE) Injection molding, fibers, powder,extrusion, and films

PA 1012 Hiprolon 400 series Suzhou Hipro Polymers(CN)

Automotive tubing systems, oil andgas pipe, technical decorative films

PA 410 EcoPaXX DSM (NL) Automotive and electricalapplications: engine cover, coolingcircuit components, sensors

PA 610 VESTAMID Terra HS Evonik (DE) Injection molding, fibers, powder,extrusion, and films

PA 610 Grilamid 2S EMS-GRIVORY (DE) Injection molding, extrusion(tubes for automotive industry)

PA (amorphous) Grilamid BTR EMS-GRIVORY (DE) Used to make windows

PA 610 Ultramid S Balance BASF (DE) Overmolding metal and electroniccomponents, plug-in connectors,pipes and reservoirs in coolingcircuits

PA 610 Zytel RS LS3030NC010Zytel RS LC3060NC010Zytel RS LC3090NC010

DuPont (USA) Zytel RS LS3030 NC010: injectionapplications;Zytel RS LC3060 NC010: injectionand extrusion applications;Zytel RS LC3090 NC010:extrusion applications

(Continued )

26 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSAL

ntinu

ctur

Hipr

Hipr

Hipr

Hipr

INTRODUCTION TO BIOPOLYMERS 27Table 1.9 Commercially available bio-polyamides (Co

Biopolymer Commercial name Manufa

PA 610 Hiprolon 70 series Suzhou(CN)

PA 612 Hiprolon 90 series Suzhou(CN)

Longchain PA Hiprolon 11 Suzhou(CN)

Long-chain PA Hiprolon 211 SuzhouUS2005095679 A1 (2005, CRESCENT INNO-VATIONS INC) discloses a method for producinghigh molecular weight g-PGAvia the fermentation ofa nonpathogenic organism, which may includeBacillus subtilis, or recombinant E. coli, thoughBacillus licheniformisATCC 9945a is preferred. ThisPGA may be isolated and purified via a series ofmembrane filtration steps and/or pH adjustment andcentrifugation. Inclusion of all steps results ina medical grade product capable of being used in vivowithout any immune response from the body. If lowerlevels of purity are required, they may be achieved byselectively eliminating various purification steps.Purification is accomplished by buffer exchange via

(CN)

PPA Rilsan HT Arkema (FR

PPA Grivory HT3 EMS-GRIVO

PPA VESTAMID HT plus Evonik (DE)

PA 1010: Polyamide 1010; produced from 1,10-decamethylene diamine (c

PA 11: Polyamide 11; produced from 11-aminodecanoic acid (derived from

PA 1012: Polyamide 1012; produced from 1,10-decamethylene diamine a

kernel oil).

PA 410: Polyamide 410; produced from tetramethylene diamine and seba

PA 610: Polyamide 610; produced from hexamethylene diamine and seba

PPA: Polyphthalamide; produced from decamethylene diamine, terephtha

HN

O

OHO n

Scheme 1.28 Poly(g-glutamic acid).ed )

er Applications

o Polymers Monofilament, industrial parts withhigh heat resistance and extrusiontubing product

o Polymers Monofilament and other industrialparts with different compoundingprocess

o Polymers Auto fuel lines, air brake tubing,cable sheathing

o Polymers Auto fuel lines, air brake tubing,cable sheathing

) Flexible tubing, injection molding

RY (DE) Electronic connector applications

Material for housings of pumps andfilter systems or for use in vehicles inthe vicinity of the engine, as in thecharge air duct

astor oil derivative) and sebacic acid (both derived from castor oil).diafiltration using a filter with a molecular weightcutoff of less than about 100 kDa, and preferably atleast about 30 kDa. Typically, in order to produceagricultural-grade PGA, viable cells are removed byfiltration at about 0.22 mm. For a food-grade product,this would be followed by filtration at about 0.1 mm,which clarifies the product. Any medical use requiresthe diafiltration steps.

US4450150 A (1984, LITTLE INC A) andFR2786098 A1 (2000, FLAMELTECH SA) disclosecopolymers of polyglutamic acid and polyglutamatethat are pharmaceutically acceptable matrices fordrugs or other active substances wherein the copol-ymer controls the rate of drug release.

Poly(a-aspartic acid)Poly(a-aspartic acid) (also called polyaspartate)

is a biodegradable polyamide synthesized fromL-aspartic acid, a natural amino acid (see Scheme1.29). Poly(a-aspartic acid) has similar properties tothe polyacrylate, and so it is used as an antifoulingagent, dispersant, antiscalant, or superabsorber.

US5315010 A (1994, DONLAR CORP) disclosesa method for producing poly(a-aspartic acid) by

castor oil).

nd 1,12-dodecanedioic acid (both derived from plant oil, e.g., palm

cic acid (derived from castor oil).

cic acid (derived from castor oil).

lic acid and amino acid.

n28 BIOPOLYMERS: REUSE, RECYCLING, AND DISPOSALhydrolysis of polysuccinimide (anhydropolyasparticacid). The polysuccinimide is produced by thermalcondensation polymerization of L-aspartic acidcomprising the following steps:

(1) Heat powdered L-aspartic acid to at least188C (350F) to initiate the condensationreaction and produce a reaction mixture.

(2) Raise the reaction mixture temperature to atleast 232C (450F).

(3) Maintain at least the 232C (450F) tempera-ture for the reaction mixture until at least 80%conversion has occurred.

NanoChem, which bought the Donlar assets,produces polyaspartates for industrial and consumerapplications. NanoChem polyaspartates have a widerange of molecular weights:

Low molecular weight polyaspartates A-2C,A-3C, and A-5D have applications as general-purpose antiscalants in hard water environments,corrosion inhibitors, dispersants for mineral slur-ries, and for control of redeposition of soil inlaundry and hard surface cleaners.

High molecular weight polyaspartates C-5D andC-10D have applications as general-purposedispersants, for clay-soil removal, for inorganic

O

NH

O

OH

OO

NH

OH

nm

Scheme 1.29 Thermal poly(a,b-D,L-aspartate).scale removal, as antiscalants in hard water envi-ronments, as mineral slurry dispersants, and forcontrol of redeposition of soil in laundry andhard surface cleaner applications.

Low color polyaspartates C-LC, C-LC/SD andC-LC/GC have applications as general-purposeantiscalants in hard water environments, disper-sants for mineral slurries, and for control of rede-position of soil in laundry and hard surfacecleaners. Because of their low color, these poly-mers are specifically designed for applicationswhere color affects the end use.e-Poly(L-lysine) (e-PL)e-Poly(L-lysine) (e-PL) is a biodegradable, water-

soluble, natural homopolymer of the essential aminoacid L-lysine that is produced by bacterial fermen-tation (see Scheme 1.30). e-PL consists of 25 to 35L-lysine residues with linkages between a-carboxylgroups and e-amino groups produced by Strepto-myces albulus; they have highly selective antimi-crobial activity. This biopolymer is widely used asa food additive. It has also been used for preparationof biodegradable hydrogels by g-irradiation ofmicrobial e-poly(L-lysine) aqueous solutions [51].

Ajinomoto and Toray have entered into an agree-ment to begin joint research for manufacturing thenylon raw material 1,5-pentanediamine (1,5-PD)from the amino acid lysine produced from plantmaterials by Ajinomoto using fermentation tech-nology. The goal is to commercialize a bio-basednylon made from this substance. The bio-based nylonthat Ajinomoto and Toray will research and developis produced from plant materials by decarbonatingthe amino acid lysine through an enzyme reaction tomake 1,5-PD, which Toray then polymerizes withdicarboxylic acid. This bio-based nylon fiber madefrom 1,5-PD is not only sustainable because it isplant-based, but also shows promise for developmentinto highly comfortable clothing. For example, PA 56(nylon 56) fiber manufactured using 1,5-PD ispleasing to the touch, yet has the same strength andheat resistance as conventional nylon fiber madefrom the petrochemical derivative hexamethylenedi-amine. It also absorbs and desorbs moisture nearly as

Scheme 1.30 e-Poly(L-lysine) (e-PL).HN C

NH2

Owell as cotton [52].

1.7 Poly(ester amide)s

Poly(ester amide)s constitute a promising familyof biodegradable materials since they combinea degradable character, afforded by the easilyhydrolyzable ester groups (eCOOe), with relativelygood thermal and mechanical properties given by the

and are also completely biodegradable are known

monomers (b) are based on polyamide 6,6 and named

INTRODUCTION TO BIOPOLYMERS 29BAK 402 and BAK 2195 [54] (DE19754418 A1,1999, BAYER AG).

Hyperbranched poly(ester amide)s are producedon an industrial scale and commercialized by DSM(Hybrane). These poly(ester amide)s are intrinsi-cally biodegradable and synthesized from cyclicanhydride (e.g., succinic anhydride) and a diisopro-panol amine. Hyperbranched poly(ester amide)s areused as performance additives in m