Biopolymers

601 Pages·2014·11.633 MB·English

by  Michael Niaounakis

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Recent titles in the series
Biopolymers: Processing and Products, Michael Niaounakis (ISBN: 9780323266987)
Biopolymers: Reuse, Recycling, and Disposal, Michael Niaounakis (ISBN: 9781455731459)
Carbon Nanotube Reinforced Composites, Marcio Loos (ISBN: 9781455731954)
Extrusion, 2e, John Wagner & Eldridge Mount (ISBN: 9781437734812)
Fluoroplastics, Volume 1, 2e, Sina Ebnesajjad (ISBN: 9781455731992)
Handbook of Biopolymers and Biodegradable Plastics, Sina Ebnesajjad (ISBN: 9781455728343)
Handbook of Molded Part Shrinkage and Warpage, Jerry Fischer (ISBN: 9781455725977)
Handbook of Polymer Applications in Medicine and Medical Devices, Kayvon Modjarrad & Sina Ebnesajjad
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Handbook of Thermoplastic Elastomers, Jiri G Drobny (ISBN: 9780323221368)
Handbook of Thermoset Plastics, 2e, Hanna Dodiuk & Sidney Goodman (ISBN: 9781455731077)
High Performance Polymers, 2e, Johannes Karl Fink (ISBN: 9780323312226)
Introduction to Fluoropolymers, Sina Ebnesajjad (ISBN: 9781455774425)
Ionizing Radiation and Polymers, Jiri G Drobny (ISBN: 9781455778812)
Manufacturing Flexible Packaging, Thomas Dunn (ISBN: 9780323264365)
Plastic Films in Food Packaging, Sina Ebnesajjad (ISBN: 9781455731121)
Plastics in Medical Devices, 2e, Vinny Sastri (ISBN: 9781455732012)
Polylactic Acid, Rahmat et al. (ISBN: 9781437744590)
Polyvinyl Fluoride, Sina Ebnesajjad (ISBN: 9781455778850)
Reactive Polymers, 2e, Johannes Karl Fink (ISBN: 9781455731497)
The Effect of Creep and Other Time Related Factors on Plastics and Elastomers, 3e, Laurence McKeen
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The Effect of Long Term Thermal Exposure on Plastics and Elastomers, Laurence McKeen
(ISBN: 9780323221085)
The Effect of Sterilization on Plastics and Elastomers, 3e, Laurence McKeen
(ISBN: 9781455725984)
The Effect of Temperature and Other Factors on Plastics and Elastomers, 3e, Laurence McKeen
(ISBN: 9780323310161)
The Effect of UV Light and Weather on Plastics and Elastomers, 3e, Laurence McKeen
(ISBN: 9781455728510)
Thermoforming of Single and Multilayer Laminates, Ali Ashter (ISBN: 9781455731725)
Thermoplastics and Thermoplastic Composites, 2e, Michel Biron (ISBN: 9781455778980)
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Biopolymers: Processing
and Products
Michael Niaounakis
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Foreword
The present book forms the second part of a trilogy dedi- Reuse and Recycling,” Elsevier, 2006, albeit in an extended
cated to biopolymers. The book “Biopolymers: Reuse, and updated form.
Recycling and Disposal” formed the first part, and the book Chapter 1, introduction, constitutes of three parts. The
“Applications and Trends”—to appear in spring 2015—will first part presents and compares the various terms used to
form the third part. All three books cover every aspect of describe biopolymers, namely “degradable,” “biodegrad-
biopolymers, from feedstocks for the production of bio- able,” “bio-based,” “compostable,” and “biopolymer,”
polymers to the disposal and/or recycling. which appear to have multiple and overlapping meanings.
In the present study the term “biopolymers” is inter- The second part gives an extensive introduction to most
preted as including both polymers derived from renewable of the existing and newly developed biopolymers and pro-
resources (bio-based), which are either biodegradable or vides updated lists of their commercial products and current
nonbiodegradable, and polymers derived from fossil fuel applications. The third part investigates the possible sources
resources, which are biodegradable. Biopolymers can be of biopolymers, including first, second, and third generation
produced by biological systems such as microorganisms, feedstocks.
plants, or animals, or obtained by chemical synthesis. Chapter 2 presents the main properties of biopolymers
Emphasis is given to patents, which despite their indus- and constitutes of three parts. The first part relates to intrin-
trial and economical importance are still underrepresented sic properties, which refer to the polymer itself. The sec-
in scientific literature. Although a substantial number of pat- ond part relates to processing properties, which refer to
ents has been cited and critically commented, the book does the behavior of the polymer during forming. The third part
not pretend to cover the whole range of available patents. relates to product properties, which refer to the properties of
Undoubtedly, important patents were left out, but taken into the polymer as an entity. Among the intrinsic properties are:
account the extent of the coverage, this was unavoidable. density, transition temperatures and crystallinity, solubility,
In any case, a genuine effort was made to cover the most gas barrier properties, transparency, and electromagnetic
represented patents in each technical field. properties. Among the product properties are: mechanical
The patents were retrieved from the patent server behavior, heat resistance, water resistance, antistatic prop-
“espacenet” (www.espacenet.com) of the European Patent erties, aesthetic properties, and environmental behavior
Office (EPO). EPO’s worldwide collection of published of biopolymers. The chapter contains several comparative
patent applications contains not only patents from the major tables, tables of selected properties, and schemes of (bio)
patent offices (EPO, WIPO, USA, JPO), but also patents degradation mechanisms.
from over 90 national offices. This server has certain advan- Chapter 3 relates to blending of biopolymers with other
tages compared to other free patent servers, as it covers not polymers, and constitutes mainly of two parts. The first part
only patents in English, but also patents in German and examines blends of biopolymers with other biopolymers.
French. In addition, espacenet contains bibliographic data The second part examines blends of biopolymers with syn-
and abstracts of all Japanese, Korean, Chinese and Russian thetic nonbiodegradable polymers, where the biopolymers
patents, as well as patents in several other languages, and are either in majority or minority. The chapter is accom-
provides machine translations of most of these patents. It is panied by several tables that summarize a large number of
firmly believed that the appeal of the book will increase by blend formulations of biopolymers and their miscibilities
the retrieval and analysis of patent information in so many with other (bio)polymers.
languages. Chapter 4 relates to emulsions, dispersions, solu-
The book consists of 16 chapters. The first 2 c hapters tions, and gels of biopolymers made by other methods
provide basic information on biopolymers, while the remain- than by emulsion, suspension, or solution polymerization.
ing 14 chapters are focusing on processing and products. The various techniques described in the prior art for the
Few parts of the present book, and especially Chapter 1: preparation of polymer emulsions, dispersions and lat-
Introduction, and Chapter 16: Recycling, are coming inevi- tices are divided roughly into three main groups: solvent-
tably from the previous book, “Biopolymers: Disposal, based, thermomechanical, and solvent-free destructuring
ix
x Foreword
methods. The solvent-based methods in turn include the coating with inorganic or low molecular weight organic
emulsification–evaporation, (nano)precipitation, salting, compounds, and coating with polymer(s).
and emulsification-diffusion techniques. Chapter 9 relates to foams and constitutes of five parts.
Chapter 5 investigates the various techniques employed The first part examines foams made of various types of bio-
for the compounding of biopolymers with additives catego- polymers, namely polyesters and starch. The second part
rized in two main groups: (1) compounding by shear and examines physical and chemical foaming agents, as well as
heat, and (2) compounding in liquid or solution. In both compounding ingredients. The third part examines expand-
groups the additives are added to the biopolymer as pow- able particles. The fourth part examines composite foams
ders, dispersions, solutions or masterbatches. A separate and crosslinking; and the fifth part examines the after treat-
section reviews the various types of additives and modifiers ment of foams including heat treatment and coating.
which are used to protect the biopolymers during process- Chapter 10 relates to films and constitutes of two parts.
ing and/or service life, including also some other additives The first part examines free standing films made of vari-
which can accelerate the degradation of the biopolymer ous types of biopolymers. Two special types of films are
after disposal. The chapter is accompanied by several tables the shrinkable films and the porous films. The second part
summarizing representative compounding techniques and examines laminates that are multilayered structures com-
formulations of biopolymers, as well as lists of selected posed at least in part of biopolymers.
additives in biopolymer systems. Chapter 11 relates to fibers made of biopolymers
Chapter 6 relates to methods of preparing particles and constitutes of three parts. The first part examines
from preformed biopolymers and constitutes of six parts: fibers made of various types of biopolymers. The sec-
(1) pelletization (e.g., by melt kneading), (2) pulverization ond part examines fiber structures, namely nonwoven
(e.g., by mechanical crushing, grinding, or shredding), (3) webs including carpets and woven/knitted fabrics. The
dissolution–deposition, (4) emulsion-precipitation, (5) third part examines selected properties of fibers made of
coagulation and (6) supercritical fluid technology. biopolymers including wearing resistance and antistatic
Chapter 7 relates to chemical treatment or chemical properties. A separate section is dedicated to nanofibers.
modification of biopolymers, and constitutes of four parts. Chapter 12 relates to biocomposites and constitutes
The first part examines the various techniques of introduc- of two parts. The first part examines the various types of
ing functional groups in a polymer chain and includes the biocomposites including biopolymers reinforced with inor-
cases of: (1) incorporation of functional monomers during ganic or organic fillers in the form of loose or coherent par-
the polymerization process; (2) modification of the terminal ticles or fibers. A special category of biocomposites is the
groups; and (3) grafting/block copolymerization. The sec- nanobiocomposites that are biopolymers reinforced with
ond part examines the techniques for modifying the molecu- nanofillers and/or nanofibers. Another category is the pre-
lar weight of a biopolymer by either controlled degradation pregs that are fiber structures that have been impregnated
or increase of the molecular weight through coupling. The with resins prior to curing the composition. The second part
third part relates to radiation treatment of biopolymers in examines the various techniques of bonding a preformed
the bulk, which is distinguished from the radiation on the biopolymer to the same or other solid material by means of
surface of biopolymers of Chapter 8. The fourth part relates adhesives, heat and surface treatment.
to the various techniques of crosslinking including the Chapter 13 relates to coating compositions based on
special case of interpenetrating network (IPN). biopolymers applied to any type of substrates. The chapter
Chapter 8 examines the various techniques of altering is distinguished from the coating compositions of Chap-
the surface nature of biopolymers categorized into three ter 8: Surface treatment, wherein any type of material,
groups: (1) physical treatment, (2) chemical treatment, and including biopolymers, is applied to a biopolymer sub-
(3) coating or printing, which can include a pretreatment strate. The chapter constitutes of two parts. The first part
step by any of the techniques of (1) and (2). The physical examines coating compositions made of various types of
methods (1) include (a) treatment with solvents/swelling biopolymers. The second part examines powder coatings
agents, (b) roughening (e.g., mechanical abrasion) and (c) and temporary or strippable coatings. The various types of
heat treatment (e.g., annealing). The chemical methods (2) biopolymer-based coating compositions are summarized in
used to modify the surface properties of biopolymers are a comprehensive table.
divided in the following subgroups: (a) hydrolysis/aminoly- Chapter 14 relates to inks made of biopolymers. Various
sis/solvolysis; (b) incorporation of functional groups by types of inks are examined including jet printing inks such
chemical means, flame treatment, radiation, plasma, corona as hot melt inks, flexographic inks, gravure inks, screen
treatment, or any method that can introduce functional inks, electrophotographic toners, color changing inks, and
groups to the surface of the biopolymer; and (c) grafting of writing inks.
polymerizable monomers or preformed polymers. C oating Chapter 15 relates to adhesives made of biopolymers and
or printing (3) includes single coating and multiple coatings, constitutes of two parts. The first part examines nonreactive
Foreword xi
adhesives including drying adhesives, water-based adhe- recycling. The third part examines the various methods for
sives, solvent-based adhesives, pressure-sensitive adhe- the chemical recycling of biopolymers including hydrolysis/
sives, and hot melt adhesives. The second part relates to alcoholysis, dry heat depolymerization, hydrothermal depo-
reactive adhesives including one-component reactive adhe- lymerization, and enzymatic depolymerization.
sives and multicomponent reactive adhesives. I wish to thank Dr Sina Ebnesajjad, Series Editor of
Chapter 16 relates to the recycling of biopolymers and Plastics Design Library (PDL), published by Elsevier, for
constitutes of three parts. The first part examines all the pos- giving me the opportunity to author this book. I am also
sible ways of reusing discarded biopolymers. The second part greatly indebted to David Jackson, Acquisitions Editor
examines the various methods for the physical or mechanical at Elsevier, and Peter Gane, Editorial Project Manager at
recycling of biopolymers including techniques for identify- Elsevier, for their continuous guidance and support during
ing and sorting materials by polymer type. A separate sec- the writing of this book.
tion reviews the various marker systems including the Resin
Identification Codes (RIC) and fluorescent additives. A dis- Michael Niaounakis
tinction is made between reuse and physical or mechanical May 2014, Rijswijk
Abbreviations of Biopolymers
γ-PGA poly(γ-glutamic acid) PCL poly(ε-caprolactone)
ε-PL poly(ε-lysine) PDLA poly(d-lactide), poly(d-lactic acid)
CA c ellulose acetate PDLLA poly(d-lactic-co-l-lactic acid) or poly(d,l-lactide)
CAB cellulose acetate butyrate or poly(d,l-lactic acid)
CAP cellulose acetate propionate PDLGA p oly(d,l-lactide-co-glycolide), poly(d,l-lactic-co-
CMC carboxymethylcellulose glycolic acid)
CN c ellulose nitrate PDO polydioxanone (or PDS)
HEC hydroxyethylcellulose PE polyethylene (bio-based)
P2HB p oly(2-hydroxybutyrate) PEA poly(ethylene adipate)
P3DD poly(3-hydroxydodecanoate) PEAM poly(ester amide)
P3HB p oly(3-hydroxybutyrate) (or PHB or β-PHB) PEAz poly(ethylene azelate)
P3HB4HB poly(3-hydroxybutyrate-co-4-hydroxybutyrate) PEC poly(ethylene carbonate)
P3HBHHx poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or PEDe poly(ethylene decamethylate)
poly(hydroxybutyrate-co-hydroxyhexanoate) PEF poly(ethylene furanoate)
P3HD poly(3-hydroxydecanoate) (or PHD) PEOx poly(ethylene oxalate)
P3HN poly(3-hydroxynonanoate) (or PHN) PES poly(ethylene succinate)
P3HO poly(3-hydroxyoctanoate) PESA poly(ethylene succinate-co-adipate)
P3HP poly(3-hydroxypropionate) PESE poly(ethylene sebacate)
P3HV poly(3-hydroxyvalerate) PEST poly(ethylene succinate-co-terephthalate)
P3UD poly(3-hydroxyundecanoate) PESu poly(ethylene suberate)
P4HB p oly(4-hydroxybutyrate) PET poly(ethylene terephthalate) (bio-based)
P4HB2HB poly(4-hydroxybutyrate-co-2-hydroxybutyrate) PEUU poly(ester urethane urea) (biodegradable)
P4HP poly(4-hydroxypropionate) PGA polyglycolide, poly(glycolic acid)
P4HV poly(4-hydroxyvalerate) PGCL poly(glycolide-co-caprolactone)
P5HB p oly(5-hydroxybutyrate) PHA polyhydroxyalkanoate
P5HV poly(5-hydroxyvalerate) PHBHD poly(3-hydroxybutryrate-co-3-hydroxydecanoate)
P6HH poly(6-hydroxyhexanoate) PHBHP poly(3-hydroxybutyrate-co-3-hydroxypropionate)
PA 1010 polyamide 1010 PHBO poly(3-hydroxybutyrate-co-3-hydroxyoctanoate)
PA 1012 polyamide 1012 PHBHV poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
PA 11 polyamide 11 PHD polyhydroxydecanoate (or P3HD)
PA 410 polyamide 410 PHHp poly(3-hydroxyheptanoate)
PA 610 polyamide 610 PHHx poly(3-hydroxyhexanoate) or poly(3-hydroxycap-
PAA poly(alkylene alkanoate) roate)
PADC poly(alkylene dicarboxylate) PHN polyhydroxynonanoate (or P3HN)
PBA poly(butylene adipate) PHP poly(3-hydroxypropionate) (or P3HP)
PBAT poly(butylene adipate-co-terephthalate) PHSE poly(hexamethylene sebacate)
PBT poly(butylene carbonate) PLA polylactide, poly(lactic acid)
PBP poly(butylene pimelate) PLCL poly(lactide-co-caprolactone)
PBS poly(butylene succinate); see also poly(tetramethylene PLGA poly(lactide-co-glycolide)
succinate) (PTMS); (different CAS) PLLA poly(l-lactide), poly(l-lactic acid)
PBSA poly(butylene succinate-co-adipate) PLLCL poly(l-lactide-co-ε-caprolactone)
PBSC poly(butylene succinate-co-carbonate) PLLGA poly(l-lactide-co-glycolide)
PBSE poly(butylene sebacate) PM polymandelide
PBSeT poly(butylene sebacate-co-terephthalate) PMLA Poly(β-malic acid)
PBSL poly(butylene succinate-co-lactate) POE I poly(ortho ester) I
PBST poly(butylene succinate-co-terephthalate) POE II p oly(ortho ester) II
PCHC poly(cyclohexene carbonate) POE III poly(ortho ester) IIII
xiii
xiv Abbreviations of Biopolymers
POE IV poly(ortho ester) IV PTMA poly(trimethylene adipate)
PPA polyphthalamide PTMAT p oly(methylene adipate-co-terephthalate)
PPHOS polyphosphazene PTeMA poly(tetramethylene adipate)
PPF poly(propylene fumarate) PTMG poly(tetramethyl glycolide)
PPL poly(β-propiolactone) (or β-PPL) PTeMS poly(tetramethylene succinate); see also
PPS poly(propylene succinate) poly(butylene succinate) (PBS) (different CAS)
PPT poly(propylene terephthalate) (bio-based); see also PTT poly(trimethylene terephthalate) (bio-based); see also
PTT PPT
PTeMAT poly(tetramethylene adipate-co-terephthalate) PU polyurethane (bio-based)
PTeMC poly(tetramethylene carbonate) PVOH poly(vinyl alcohol)
PTMC poly(trimethylene carbonate) scPLA stereocomplex PLA
PTMS/PTeMC poly[(tetramethylene succinate)-co-(tetramethylene TPS thermoplastic starch
carbonate)]
Chapter 1
Introduction
1.1 DEFINITION OF TERMS determined by the International Organization for Standard-
ization (ISO) methods and evaluated based upon the prees-
In recent years, interest in protecting the environment by not
tablished criteria. Only biodegradable plastics that meet the
only using products made from natural renewable resources
rigorous criteria such as contents of heavy metals and safe
but also products that decompose into environmentally
intermediate reaction products may be classified as Green-
friendly constituents has been steadily and rapidly increas-
Pla® [1].
ing. Green movements, initiatives, and regulations have
Biodegradable polymers are certified according to any
sprung up in almost every developed country to reduce the
of the following legally binding international standards [2]:
volume of solid polymers waste generated by consumers
ISO 17088:2012
each year. Consumers have also expressed their desire for
EN 13432:2000, EN 14995:2006
products that are environmentally friendly while providing
ASTM D6400-12
the same results with products made from synthetic mate-
Bio-based is a term focused on the raw materials basis,
rials. However, consumer preferences for environmentally
and it is applied to polymers derived from renewable
friendly products can be hindered by the higher cost and
resources. Raw materials are defined as renewable if they
inferior properties of these products as compared to syn-
are replenished by natural procedures at rates comparable
thetically derived products.
or faster than their rate of consumption [3].
In literature and patents there is no consensus over the
Bio-based products as defined by the Farm Security
exact definition of the generic terms degradable, biode-
and Rural Investment Act of 2002 (FSRIA) [4] are prod-
gradable, bio-based, compostable, and biopolymer, which
ucts determined by the U.S. Secretary of Agriculture to
appear to have multiple and overlapping meanings.
be “commercial or industrial goods—other than food or
Degradable is a broad term applied to polymers or plas-
feed—composed in whole or in significant part of bio-
tics that disintegrate by a number of processes, including
logical products, forestry materials or renewable domestic
physical disintegration, chemical degradation, and biodeg-
agricultural materials, including plant, animal or marine
radation by biological mechanisms. As a result of this defi-
materials” [5]. ASTM defines a bio-based material as “an
nition, a polymer may be degradable but not biodegradable.
organic material in which carbon is derived from a renew-
Biodegradable is a term focused on the functional-
able resource via biological processes. Bio-based materi-
ity of a polymer, “biodegradability,” and it is applied to
als include all plant and animal mass derived from carbon
polymers that will degrade under the action of microor-
dioxide (CO ) recently fixed via photosynthesis, per defi-
2
ganisms such as molds, fungi, and bacteria within a spe-
nition of a renewable resource.” In practical terms, a bio-
cific period of time and environment. On its own, the term
based polymer is not per se a sustainable polymer; this
biodegradable has no clear meaning and creates confu-
depends on a variety of issues, including the source mate-
sion. According to the withdrawn standard ASTM D5488-
rial, production process, and how the material is managed
94de1, biodegradable polymers refer to polymers that are
at the end of its useful life. Not every bio-based polymer
“capable of undergoing decomposition into carbon diox-
is biodegradable, e.g., bio-based polyethylene or polyam-
ide, methane, water, inorganic compounds, or biomass in
ide 11; and not every biodegradable polymer is bio-based,
which the predominant mechanism is the enzymatic action
e.g., poly(ε-caprolactone) or poly(glycolic acid); although
of microorganisms that can be measured by standard tests,
some fall into both categories, such as polyhydroxyal-
over a specific period of time, reflecting available disposal
kanoates (PHA)s.
conditions.”
Currently, there are no standards on what can be called
The Japan Bioplastics Association (JBPA) defines the
“bio-based product.” However, there are objective ways to
term biodegradability as the characteristics of material that
quantify the bio-based content of a product. The ASTM and
can be microbiologically degraded to the final products of
ISO have developed standards for measuring the bio-based
carbon dioxide and water, which, in turn, are recycled in
content of materials via carbon isotope analysis. Relevant
nature. Biodegradation should be distinguished from disin-
standards include:
tegration, which simply means the material is broken into
ASTM D6866-12
small and separate pieces. Biodegradability of plastics is
ASTM D7026-04
Biopolymers: Processing and Products. http://dx.doi.org/10.1016/B978-0-323-26698-7.00001-5
Copyright © 2015 Elsevier Inc. All rights reserved. 1
2 Biopolymers: Processing and Products
The bio-based content of a biopolymer can be deter- synthesized from biological starting materials (e.g., corn,
mined by calculating the number of carbon atoms that come sugar, starch, etc.). Biodegradable bio-based biopolymers
from the short CO cycle, that is, from biomass as raw mate- include: (1) synthetic polymers from renewable resources
2
rial. It is known in the art that carbon-14 (14C), which has a such as poly(lactic acid) (PLA); (2) biopolymers produced
half-life of about 5700 years, is found in bio-based materi- by microorganisms, such as PHAs; (3) natural occurring bio-
als but not in fossil fuels. Thus, “bio-based materials” refer polymers, such as starch or proteins—natural polymers are by
to organic materials in which the carbon comes from non- definition those that are biosynthesized by various routes in
fossil biological sources. The detection of 14C is indicative the biosphere. The most used bio-based biodegradable poly-
of a bio-based material. 14C levels can be determined by mers are starch and PHAs.
measuring its decay process (disintegrations per minute per The biopolymers of (B) can be produced from biomass
gram carbon or dpm/gC) through liquid scintillation count- or renewable resources and are nonbiodegradable. Nonbio-
ing. A bio-based PET comprises at least about 0.1 dpm/gC degradable bio-based biopolymers include: (1) synthetic
(disintegrations per minute per gram carbon) of 14C [6]. polymers from renewable resources such as specific poly-
“Compostable” polymer was defined by ASTM D6002 amides from castor oil (polyamide 11), specific polyesters
as “a plastic which is capable of undergoing biological based on biopropanediol, biopolyethylene (bio-LDPE,
decomposition in a compost site as part of an available pro- bio-HDPE), biopolypropylene (bio-PP) or biopoly (vinyl
gram, such that the plastic is not visually distinguishable and chloride) (bio-PVC) based on bio-ethanol (e.g., from sugar
breaks down to carbon dioxide, water, inorganic compounds, cane), etc.; (2) natural occurring biopolymers such as
and biomass at a rate consistent with known compostable natural rubber or amber.
materials (e.g., cellulose) and leave no toxic residue.” How- The biopolymers of (C) are produced from fossil fuel,
ever, this definition drew much criticism, and in January such as synthetic aliphatic polyesters made from crude oil
2011, the ASTM withdrew standard ASTM D6002 [7]. or natural gas, and are certified biodegradable and com-
In order for a polymer to be called compostable, it postable. Poly(ε-caprolactone) (PCL), poly(butylene succi-
should meet any of the following international standards: nate) (PBS), and certain “aliphatic-aromatic” copolyesters
ASTM Standard D6400 (for compostable plastics) or are at least partly fossil fuel–based polymers, but they can
D6868 (for compostable packaging) be degraded by microorganisms.
CEN standard EN 14995:2006 (for compostable plas- According to European Bioplastics a plastic material
tics) or EN 13432:2000 (for compostable packaging) is defined as a bioplastic if it is either bio-based, biode-
ISO 17088:2012 gradable, or features both properties [8]. On the basis of
The standards ISO 17088:2012 and ASTM D6400 describe this definition, biopolymers or bioplastics consist of either
the same check scheme as EN 13432:2000. The ISO-Standard biodegradable polymers (e.g., polymers of type A or C) or
not only refers to plastic packaging but to plastics in general. bio-based polymers (e.g., polymers of type A or B). There-
A polymer that meets the requirements of any of the fore, a biopolyethylene derived from sugarcane, nicknamed
above standards: (1) disintegrate rapidly during the com- “green polyethylene,” is nonbiodegradable, but emits less
posting; (2) biodegrade quickly under the composting con- greenhouse gases when compared to fossil-based polyeth-
ditions; (3) not reduce the value or utility of the finished ylene, and is classified as biopolymer. The interrelationship
compost and the compost can support plant life; (4) not con- between biodegradable polymers and bio-based polymers is
tain high amounts of regulated metals or any toxic materials. shown in Table 1.1. To summarize:
The difference between biodegradable polymers and “Biopolymers are defined as polymers that are derived
compostable polymers is determined by the rate of biodeg- from renewable resources, as well as biological and fossil-
radation, disintegration, and toxicity. All compostable poly- based biodegradable polymers.”
mers are by default biodegradable but not vice versa.
Two different criteria underline the definition of a “bio-
1.2 C LASSIFICATION OF BIOPOLYMERS
polymer” (or “bioplastic”): (1) the source of the raw mate-
rials, and (2) the biodegradability of the polymer. Here, a Biopolymers can be divided also into two broad groups,
differentiation is made between: namely biodegradable and nonbiodegradable biopolymers.
Alternatively, biopolymers can be classified on their origin
A. b iopolymers made from renewable raw materials
as being either bio-based or fossil fuel-based. The bio-based
(bio-based), and being biodegradable;
biopolymers can be produced from plants, animals, or
B. biopolymers made from renewable raw materials
microorganisms. There are many more nondegradable bio-
(bio-based), and not being biodegradable;
based biopolymers than there are biodegradable bio-based
C. b iopolymers made from fossil fuels, and being
biopolymers [3].
biodegradable.
Table 1.2 presents the main categories for distinguish-
The biopolymers of (A) can be produced by biological ing between the different types of biopolymers. This is not
systems (microorganisms, plants, and animals), or chemically meant to be a comprehensive and all-inclusive list. Several