-
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