BIODEGRADABLE POLYMERS AND
PLASTICS IN LANDFILL SITES

Introduction

Today, landfill may be regarded as a last resort for the waste management of
plastics. Recycle through the reuse of plastic waste in fabrication, incineration
for energy generation, and recycle through the natural cycle of biodegradation in
compost or soil are much preferred disposal methods. However, considerable quan-
tities of plastics (millions of tons annually), particularly packaging plastics, are
still being dumped into landfills, where they occupy large volumes and contribute
to capacity shortages.

Modern landfills are generally classified in several ways. One classification

is by the types of waste that they receive, such as hazardous waste or municipal
waste. In practice, these are not exclusive classifications since inevitably there is
always some crossover because of source separation problems. An alternative clas-
sification is based on the functional mode of the landfill. Total containment land-
fills are designed to prevent any exchange with the surrounding environment and
are particularly desirable for hazardous waste disposal. Leachate recycle landfills
are designed to capture and recycle aqueous leachate to prevent or reduce environ-
mental leakage of potentially harmful waste or degradation residues. Controlled
contaminant release landfills allow for gradual migration of leachate into the en-
vironment under closely monitored conditions to ensure that no harmful events
happen. Unrestricted contaminant release landfills, which are older waste dumps,
are particularly prevalent in poorer nations, and have no controls of leachate or
environmental contamination.

Plastics entering any of these landfill types may or may not degrade

and/or biodegrade depending on their composition and the particular landfill
environmental conditions to which they are exposed. By their nature, landfill

40

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POLYMERS AND PLASTICS IN LANDFILL SITES

41

environments are initially aerobic and undergo transition into anaerobic environ-
ments at a rate dependent on the utilization of oxygen by the microorganisms
present to degrade waste and on the depth of the landfill. This article reviews
what is known regarding the fate of common plastics placed into landfill sites for
disposal or for a specific application such as a landfill daily cover. Degradations in
both aerobic and anaerobic environments are discussed for a variety of packaging
plastics and other polymers commonly found in landfill sites.

Polyolefins, particularly polyethylene, have been studied extensively in the

real-world environment of landfills, where evidence of degradation and some po-
tential for biodegradation is becoming apparent, though not yet conclusive. For
most other plastics, anaerobic testing in laboratory simulation of landfills has
been the focus with mixed results. Some polymers, such as the naturally pro-
duced polyhydroxyalkanoates, are biodegradable in aerobic and anaerobic envi-
ronments, whereas most others are not at all biodegradable in anaerobic envi-
ronments. Clearly, much work remains to be done to understand degradation and
biodegradation in landfills, both in the laboratory and in the real world. The re-
sults will be important and will have great impact on the future directions for
polymer and plastics waste management.

Composition of Trash in Landfill Sites

William L. Rathje, Professor of Archeology at the University of Arizona, is one
of the most experienced and articulate “garbage pickers” in the world today. As
the founder of the Garbage Project, he, his colleagues, and his students have been
investigating the contents of landfills for about 30 years. His published analyses
include landfills in and around Chicago, the San Francisco Bay area, Tuscon,
Phoenix, Toronto, and New York City (1). As well as providing an historical context
[garbage through the ages, as it were (2)], Prof. Rathje relates differences in social
patterns and life styles to what he finds in landfills, sanitary, or otherwise. He
has also noted that there are common misperceptions about what materials are
actually discarded, collected, and deposited in landfills.

In 1991, Rathje estimated that every person in the continental United States

generated an average of 1.8 kg (4 lb) of trash per day. The Fresh Kills Landfill (on
Staten Island, now closed) received 15,500 t of garbage daily from New York City,
6 days a week. Prof. Rathje’s assessment of the content by wt% is as follows: paper
50%, plastic 10%, metal 6%, glass 1%, and organic 13% (including yard waste, food
waste, wood). The remaining 20% is a mixture that includes construction debris,
disposable diapers, rubber, textiles, and tires. Rather more detail is available (3)
about the composition of refuse from the Mallard North Landfill site (Chicago).
Mean weight percent values are as follows: paper 32.7%, ash 22.2%, wood 12.3%,
fines 8.6%, ferrous metal 7.4%, plastic 5.6%, glass 4.5%, textiles 3.8%, garden
waste 1.9%, and rubber 1.0%; food, nonferrous metals, foamed polystyrene and
cigarettes were each less than 1%. The waste, dated by means of discarded news-
papers, was excavated in 1988, when it was about 20 years old.

The data derived from Prof. Rathje’s excavations during October 1991 in the

metropolitan Toronto area (4) are consistent with those obtained by his team
of “garbologists” from analogous investigations throughout the United States.

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POLYMERS AND PLASTICS IN LANDFILL SITES

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Omitting the construction and demolition debris from the calculations, the compo-
sition (by volume this time) is as follows: paper and paperboard 50%, plastics 14%,
metals 12%, glass 4%, organics 6%, and miscellaneous 14%. All plastic packaging
(post-consumer, industrial, commercial, and institutional) represented about 8%
of the overall refuse. It is a reasonable assumption that the composition of plastics
discarded in landfills is a reflection of the quantities produced for packaging ap-
plications; the commodity plastics polyethylene, polypropylene, polystyrene, and
poly(vinyl chloride) should be well represented (see E

THYLENE

P

OLYMERS

; P

ROPY

-

LENE

P

OLYMERS

(PP); S

TYRENE

P

OLYMERS

; V

INYL

C

HLORIDE

P

OLYMERS

).

Degradation Processes in Landfills

The fate of polymers and plastics in landfill can be represented schematically as
shown below:

They may remain unchanged, or they may degrade by some biotic or abiotic

process to fragments that either remain or biodegrade to gaseous products and
water. The gaseous products are carbon dioxide in an aerobic environment and a
mixture of carbon dioxide and methane in an anaerobic environment. The path-
ways obviously play a strong role in the subsequent stability and volume usage
of the landfill, and there needs to be a thorough understanding of the chemistries
involved with the particular polymer or plastic.

Biodegradation of organic materials is the result of activities of microorgan-

isms, such microflora as fungi, yeasts, actinomycetes, and bacteria. Focusing on
the first and last of these, the two main groups represent an enormous array of
possibilities. Fungi operate primarily under aerobic, moist conditions, and prolif-
erate by sporulation. Their spores and hyphal fragments are found universally
and will generate new colonies whenever and wherever favorable conditions exist
or arise. The environment “selects” which of the 80,000 or so species will germinate
and grow. Bacteria, like fungi, are distributed universally throughout the surface
of the earth and in the atmosphere. Around 2000 species of bacteria are known,
but there are almost certainly many more species that are not known. Bacteria
proliferate by cell division and require the presence of liquid water.

Biodegradation is nature’s way of returning nonliving organic ma-

terial to the carbon cycle. Commonly, microorganisms generate and se-
crete aqueous solutions of enzymes that chemically degrade and dissolve

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POLYMERS AND PLASTICS IN LANDFILL SITES

43

supporting material (the substrate), which is then absorbed back into the organ-
ism through the cell walls, as food for growth and energy generation. Moisture is
essential and the organic substrates should be hydrophilic and easily “wettable”
to provide sites for enzyme activity. Under the right conditions, the proliferation
of microorganisms can occur to a phenomenal extent. It has been calculated, for
example, that the weight of microorganisms in arable land is 3 to 5 ton in an area
of 4.05

× 10

3

m

2

(1 acre) to a depth of 30 cm (1 foot), and that 1 g of microorgan-

isms may contain 10

10

individuals. In soil, bacteria are found at greater depths

than are fungi since many of them, the anaerobes, are able to survive without
free oxygen in the reducing conditions that kill all other forms of life. This fact is
relevant to microbial activity at the lower levels in landfills.

There is much evidence of extensive microbial activity in landfills, which is

not surprising in view of the large organic content of waste, and the ubiquitous
occurrence of fungi and bacteria, The heat generated by the microbes as they
convert carbon into usable intermediates is significant, even at only moderate
depths below the active face of the landfill. For some time (months, a year, or
even longer) following the dumping of waste at the active face of a landfill, there
will be enough oxygen present to allow for vigorous aerobic biodegradation of the
susceptible refuse by fungi, bacteria, and the like. At some later stage, after a
time period that will vary with conditions and operating procedures, a shortage
of oxygen is likely to develop, and at the deeper levels of the landfill, anaerobic
biodegradation largely by bacteria will begin and eventually dominate. It may
be argued that it is entirely preferable to encourage as much biodegradation as
possible during the aerobic period, for these reasons:

(1) The ultimate conversion product of the organic carbon in the waste from

aerobic biodegradation is carbon dioxide, CO

2

, whereas the major product

from anaerobic biodegradation is methane, CH

4

. The latter gas is 24.5 times

more potent than carbon dioxide (5) as a greenhouse gas.

(2) The commodity of value in the operation of a landfill is space, and the more

rapidly abiotic degradation and biodegradation occur, the longer the space
will last before a new site is required.

(3) The more rapidly the biodegradation occurs, the shorter and less expensive

will be the after-care period, and the sooner the site can be used safely for
another purpose.

The Resource Conservation and Recovery Act, the US Federal Government,

defines the criteria for the operation of Municipal Solid Waste Landfills (MSWLF),
effective October 1993. Daily and alternative daily cover (ADC) requirements are
described under Subtitle D, as follows:

(1) the owner or operator of all MSWLF must cover disposed solid waste with

150 mm (6 in.) of earthen material at the end of each operating day, or
at more frequent intervals if necessary, in order to control disease vectors,
fires, odor, blowing litter, and scavenging;

(2) alternative materials of a thickness other than 150 mm earthen mate-

rial may be approved

. . .if the owner or operator demonstrates that the

alternative material performs the same functions as the 150 mm of soil.

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POLYMERS AND PLASTICS IN LANDFILL SITES

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In addition this ADC must not present a threat to human health and the
environment.

A comprehensive investigation carried out (6) at the District of Chilliwack’s

Bailey Sanitary Landfill (approximately 60 km east of Vancouver, B.C.) based on
the merits of ADC material evaluated technology developed by EPI Environmen-
tal Products Inc. as a landfill cover. This 76-

µm (3 mil) polyethylene film contained

an additive formulation (totally degradable plastic additives or TDPA) that results
in a much higher than normal rate of oxidation. The heat generated by the activity
of microorganisms in the landfill initiated the thermal oxidation of the polyethy-
lene film, and the prodegradant in the additive dramatically increased the rate of
oxidative degradation of the plastic. After burial for 98 days (December 18, 1995 to
March 21, 1996) at a mean monthly air temperature between 1 and 5

◦

C and a cu-

mulative rainfall of about 700 mm, the film no longer existed as an intact layer but
was punctured by numerous holes, and mixed up with the waste. The melt index
of the plastic had increased, and the tensile breaking strength and elongation to
break had decreased significantly. Fourier transform infrared (FTIR) spectroscopy
of the recovered material indicated extensive film oxidation and degradation, as a
result of thermal initiation. Similar observations were made (6) on the oxidation
of a polyethylene ADC film used at the Shenzehu Xiapin landfill in China during
the period October to December 1998. In this case, analysis of a sample exposed
on the surface indicated that the EPI film, prepared using a TDPA formulation,
is also susceptible to photochemically induced oxidation. Analogous results were
obtained (7) in a study conducted by M. J. Carter Associates at the Edwin Richards
Quarry landfill site located near Birmingham, England. A controlled trial showed
that polyethylene containing a TDPA formulation undergoes significant chemi-
cal and mechanical degradation over a period of several months (2001–2002) in
a landfill environment. Heavy rainfall and low ambient temperatures kept the
average temperature in the waste below 30

◦

C for the first seven months after

the film samples were placed. After a further seven months, however, molar mass
reduction of the polyethylene film that incorporated EPI’s TDPA prodegradant for-
mulation was from M

w

115,000 to 4250, well below the threshold for significant

biodegradability. In contrast, the control film (containing no TDPA) had a final
M

w

of 107,000. The report by M. J. Carter Associates reached the conclusion that

the results of this trial “confirm the benefits of using degradable plastic materials
in a landfill environment.” Simply stated these are as follows.

(1) “Refuse sacks that degrade will expose the enclosed refuse to water and

micro-organisms and accelerate biodegradation of the waste.”

(2) “Using degradable plastic sheets as cover for landfills will reduce the need

for conventional imported cover materials and maximize void in the site for
waste.”

Degradation of Plastics

Standard laboratory testing methods have been developed by ASTM and others
to measure degradation and biodegradation in landfill sites in both the initial

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POLYMERS AND PLASTICS IN LANDFILL SITES

45

aerobic or oxygen-containing phase and in the later anaerobic or oxygen-deficient
phase of this environment.

These laboratory simulation tests generally are used for estimating the

degradation of condensation polymers, which hydrolytically degrade and then
biodegrade in aerobic environments. In anaerobic environments, degradation and
biodegradation are generally very slow. Poly(3-hydroxyalkanoates) (qv) produced
naturally by bacteria, are an exception to this anaerobic rule as they are readily
biodegradable in such environments.

Addition polymers, such as polyolefins, on the other hand, have had limited

testing in the laboratory and extensive testing in the real world in working landfill
sites. They degrade initially by oxidation and subsequently by biodegradation.

Degradation of Addition Polymers.

Conventional Polyolefins.

Among the most versatile of all plastics, the

polyolefins (all varieties of polyethylene, and polypropylene) are widely used in a
very large number of applications. A partial list of their properties provides the
explanation: inexpensive, light, strong, tough, stretchy, low glass-transition tem-
peratures, easy to fabricate, excellent barrier properties and wet strength, and
biologically inert. The last three items in particular contribute to the usefulness
in food packaging applications, which are characterized by a relatively short use
life followed by disposal in a landfill.

It has been recognized for many years that polyolefins are susceptible to ox-

idative degradation, and a great deal of research has been done to determine why
and how, and what to do about it. The reader is encouraged to consult monographs
and review articles (8–13) in order to acquire some of the details and complexities
of polyolefin oxidation (see also D

EGRADATION

; S

TABILIZATION

). In essence, oxidative

degradation can be summarized as follows.

Even in the presence of a processing antioxidant, the heat and mechani-

cal shear stress of extrusion will give rise to low levels of hydroperoxide group
formation, by reactions 1, 2, and 3 where RH is a polyolefin. There is always a
trace of oxygen present in extrusion equipment. It is the inevitable presence of
hydroperoxide groups that renders polyolefins susceptible to oxidative degrada-
tion (frequently called peroxidation). Indeed polyolefins, if pure, would not absorb
any radiation from terrestrial sunlight and would be inherently photostable. Such
is not the case, however. The major difference between the oxidative degradation
of polyolefins initiated by heat (thermal oxidation) and by near-UV light (photo-
oxidation) is that ketone groups are stable to heat but are unstable to UV light,
and this adds to the rate of photodegradation.

Oxidative Degradation

(1)

R

•

+ O

2

⇒ ROO

•

(2)

ROO

•

+ RH ⇒ ROOH +

•

R

(3)

46

POLYMERS AND PLASTICS IN LANDFILL SITES

Vol. 9

(4)

(5)

or

RO

•

⇒ Alcohols (by hydrogen abstraction)

(6)

It should be noted that reaction 6 does not lead to polymer chain scission;

ie, there is no molar mass reduction here, in contrast to reaction 5 where there is
a molar mass reduction. It should also be noted that the formation and reaction
of hydroperoxide groups attached to polymer molecules (reactions 3 and 4) are
much slower, ie, rate determining, than the other processes shown. It will be
apparent from the free-radical products formed in reactions 1 through 4 that this
whole peroxidation procedure is a branching chain reaction. Additive chemistry
is required to provide polyolefins with any sort of prolonged service life, and such
chemistry is well known and entirely effective.

Polyolefins are semicrystalline materials in which oxidation is initially fo-

cused in the less-ordered (amorphous) zones. These zones are where impurities,
oxygen, stabilizers, and virtually all other additives (if present) are located. In
the absence of stabilizing additives, or after the depletion of them, chain scission
will occur, tensile elongation values will decrease markedly, and the polyolefin will
become brittle. It is generally accepted that at values of elongation at break below
10%, the material breaks into fragments very readily.

Differences in the rates at which various polyolefins undergo oxidative degra-

dation are related primarily (but not entirely) to their molecular structures. There
is a significant correlation, for example, between relatively high levels of suscep-
tibility to oxidation and number of tertiary C H bonds since these bonds have
lower bond-dissociation energies than secondary C H bonds. If this were the only
relevant criterion, then the order of increasing susceptibility to oxidation would
be HDPE

< LDPE < LLDPE < PP. The actual situation is not that simple, but

the important point is that there are differences.

As noted above, the primary products of the oxidative degradation (the per-

oxidation chain reaction) of polyolefins are hydroperoxides, which are unstable
and undergo thermolysis or photolysis with chain scission. The products are lower
molar mass materials including carboxylic acids, alcohols, aldehydes, and ketones
(14,15). Depending on the amounts of antioxidant and other stabilizers that are
present, and on the nature of the environment in which they are discarded, it
may take a few years or even decades before conventional polyolefins undergo
sufficient oxidative degradation to become brittle and disintegrate.

Activated Polyolefins. There are a number of ways of rendering polyolefins

unusually photosensitive, the more effective of which involve copolymerizing

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POLYMERS AND PLASTICS IN LANDFILL SITES

47

ethylene, for example, with other monomers such that ketone groups are intro-
duced into the polymer chains. Such plastics photodegrade readily, but this is
not a particularly useful characteristic for materials that will be disposed of in
landfill sites. In this context, an activated polyolefin is one which incorporates an
additive that will significantly increase the rate of oxidative degradation of the
plastic that occurs in warm environments. The mechanism and products of the
oxidation that is initiated thermally will normally be the same as for conventional
polyolefins not containing the additive. In other words, this is the same situation
that was described in the previous section for conventional polyolefins. The same
chemistry occurs for activated polyolefins (only it all happens very much faster)
at a rate controlled by the level of prodegradant additive. As was indicated above,
the slowest part of the oxidation chain reaction is the decomposition of the hy-
droperoxide groups attached to the polyolefin molecules, and it is the thermolysis
of these groups that will lead (much of the time, as shown) to molar mass reduc-
tion of polyolefins that are buried in landfills. It has been known for many years
that traces of transition metals accelerate the thermal oxidation of polyethylene
(and other hydrocarbons) by inducing hydroperoxide decomposition. The relevant
mechanism is usually a redox reaction that is genuinely catalytic.

M

n

+ ROOH ⇒ M

n

+1

+ RO

•

+ OH

−

(7)

M

n

+1

+ ROOH ⇒ M

n

+ ROO

•

+ H

+

(8)

Hydroperoxide decomposition by this pair of processes is essentially equiv-

alent to the lowering of the activation energy of the bimolecular peroxide decom-
position reaction. It is a major factor in both heat- and light-induced oxidation of
activated polyolefins. In view of the mandatory requirement for a shelf life and a
use life, even when these total only months rather than years, it is important to
note that prodegradant additives for polyolefins that are based on transition met-
als are not oxidizing agents. In other words, the presence of these prodegradants
does not render the plastic instantly unstable. They simply increase, typically by
two or three orders of magnitude, the rate of polyolefin oxidation after it has been
initiated by heat, UV light, mechanical stress, or some combination of these.

An early manifestation of the use of metal-containing prodegradants to con-

vert polyolefin film products to oxo-biodegradable materials was the Scott/Gilead
system (16,17, and references therein). In its simplest form, the additive here
contains a metal ion complexed to sulfur (for example, a ferric dithiocarbamate)
such that the metal complex is an antioxidant until exposed outdoors where it
undergoes photolysis. The metal ion then acts as a prodegradant, as indicated
in reactions 7 and 8. Products based on this and related clever chemistries have
been used for many years with great success as agricultural mulch films, and the
like. The relevance of that technology here is that Scott/Gilead systems can act as
thermal pro-oxidants as well.

The prodegradant systems for polyolefins and polystyrene developed by EPI

Environmental Products Inc. involve additives that also impart sensitivity to heat
and/or UV light. The composition and quantity of their TDPA formulations added
to conventional polyolefin resins provide performance that features a controlled

48

POLYMERS AND PLASTICS IN LANDFILL SITES

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lifetime (storage, use) followed by rates of oxidation/biodegradation commensu-
rate with the disposal environment. This combination of controlled but adjustable
service life and a variety of degradation rates has been demonstrated (18–22) for a
number of applications, such as agricultural mulch films, litter control, and com-
post bags. It should be noted, however, that the emphasis in the landfill disposal
environment for the polyolefin products incorporating TDPA is for packaging plas-
tics, shopping bags, ADC materials, and numerous other plastics that are disposed
of in landfill. In this case, the activated materials become brittle and disintegrate
in a matter of 6 to 18 months, much more rapidly than the corresponding products
made from ordinary polyolefins.

Other Addition Polymers. There are few studies on other reported polymer

and plastic components of landfills. Poly(vinyl chloride) seems to be inert in land-
fill showing no degradation in real-world tests (23,24) and laboratory simula-
tions (25). In the latter study, plasticizer migration occurred with its subsequent
biodegradation.

In an evaluation of cross-linked poly(acrylate) superabsorbents (26), little or

no changes were seen and migration was not observed.

Condensation Polymers.

The degradation pathways for condensation

polymers are shown schematically below for both aerobic and anaerobic
environments.

Testing for degradation in aerobic landfill environments is typified by an

ASTM standard method for soil burial (27), by changing the environment, where
measurements of carbon dioxide are related to rate and degree of biodegradation.

Notwithstanding the difficulties of testing in anaerobic environments, sev-

eral laboratory methods, as indicated earlier, have been developed. These measure
carbon dioxide and methane evolution. The ASTM standard was developed on the
basis of work from Europe (28) and is widely used for these polymers (29). Several
variants on this method reported for example by Barlaz and co-workers (30) for
a variety of polymers including polyesters, acrylates, cellulosics, and others are
used. Similarly, the earlier pioneering work of McCarthy and co-workers is also
useful (31).

Polyhydroxyalkanoates, which are produced by bacterial synthesis, are well

known to biodegrade (32) under anaerobic conditions, and several studies have
been reported and compared with synthetic polyesters such as polycaprolactone
(33). Radiolabeled C

14

polyesters give credence to biodegradation by allowing

methane and carbon dioxide to be readily quantified. R.-J. Mueller and co-workers
(34) reported similar results in a comparative laboratory test with synthetic and
natural polyesters. Work in Asia is also consistent with the anaerobic biodegrada-
tion of polyhydroxyalkanoates (35) in contrast with other condensation polymers
including poly(lactic acid), and aromatic and aliphatic polyesters, which, appar-
ently, do not biodegrade in the absence of oxygen.

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POLYMERS AND PLASTICS IN LANDFILL SITES

49

Summary

Discarded plastics, especially packaging plastics, represent a significant part of
the solid waste that is disposed of in landfills. They can persist for many years
in this environment and thereby contribute to the premature filling of the sites.
Activated polyolefins, such as those containing EPI’s TDPA prodegradants, de-
grade and disintegrate as a result of the heat generated by microorganisms in
landfills, and this permits much more rapid aerobic biodegradation of the other
organic waste, thus prolonging the useful life of landfills. Little evidence has been
acquired to date about the biodegradation of addition polymers in landfills. A
number of hydrolyzable condensation polymers will biodegrade aerobically, but
only the polyhydroxyalkanoates have been shown to biodegrade under anaerobic
conditions.

BIBLIOGRAPHY

“Microbiological Degradation” in EPST 1st ed., Vol. 4, pp. 716–725, by Walter M. Be-
juki, BioSciences Information Service of Biological Abstracts; “Biodegradable Polymers”
in EPSE 2nd ed., Vol. 2, pp. 220–243, by Samuel J. Huang, The University of Connecticut;
“Disposal and Reuse of Plastics” in EPSE 2nd ed., Vol. 5, pp. 103–128, by Harvey Alter,
U.S. Chamber of Commerce.”

1. W. L. Rathje, Natl. Geogr. 179, 116 (1991).
2. W. L. Rathje, Atlantic Monthly 264, 99 (1989).
3. R. V. Kinman, D. L. Nutini, and W. L. Rathje, Paper presented at the 44th Annual

Purdue Industrial Waste Conference, May 9, 1989.

4. News and Views for the Environment and Plastics Institute of Canada (Spring

1992).

5. G. Scott, Polymers and the Environment, The Royal Society of Chemistry, Cambridge,

1999.

6. G. Scott and D. M. Wiles, in G. Scott, ed., Degradable Polymers: Principles and Ap-

plications, 2nd ed., Kluwer Academic Publishers, Dordrecht, The Netherlands, 2002,
pp. 456–457.

7. Joseph G. Gho, personal communication, Dec. 2002.
8. G. Scott, Atmospheric Oxidation and Antioxidants, Elsevier, Amsterdam, 1965.
9. G. Geuskens, ed., Degradation and Stabilisation of Polymers, Applied Science, London,

1975.

10. N. S. Allen, ed., Degradation and Stabilisation of Polyolefins, Applied Science, London,

1983.

11. N. Grassie and G. Scott, Polymer Degradation and Stabilisation, Cambridge University

Press, Cambridge, 1985.

12. D. J. Carlsson and D. M. Wiles, Encyclopedia of Polymer Science and Engineering, 2nd

ed., Vol. 4, John Wiley & Sons, Inc., New York, 1986, pp. 631–696.

13. G. Scott, ed., Atmospheric Oxidation and Antioxidants, Vol. II, Elsevier, Amsterdam,

1993.

14. A.-C. Albertsson, C. Barenstadt, S. Karlsson, and T. Lindberg, Polymer 36, 3075 (1995).
15. S. Karlsson and A.-C. Albertsson, Polym. Eng. Sci. 38, 1251 (1998).
16. G. Scott, Polym. News 14, 168 (1989).
17. G. Scott, Polym. Deg. Stab. 29, 135 (1990).
18. D. M. Wiles, B. E. Cermak, J. G. Gho, and C. W. J. Hare, Environews 8, 6 (1998).

50

POLYMERS AND PLASTICS IN LANDFILL SITES

Vol. 9

19. J.-F. Tung, D. M. Wiles, B. E. Cermak, J. G. Gho, and C. W. J. Hare, in Proceedings of the

Fifth International Plastics Additives and Modifiers Conference, Prague, Oct. 27–28,
1999, Paper 17.

20. D. M. Wiles, J.-F. Tung, B. E. Cermak, C. W. J. Hare, and J. G. Gho, in Proceedings of

the Biodegradable Plastics 2000 Conference, Frankfurt, June 6–7, 2000.

21. B. Raninger, G. Steiner, D. M. Wiles, and C. W. J. Hare, in H. Insam, S. Klammer,

and N. Riddich, eds., Microbiology of Composting, Springer-Verlag, Berlin, 2002,
pp. 299–308.

22. N. C. Billingham, M. Bonora, and D. De Corte, in Proceedings of the 7th World Confer-

ence on Biodegradable Polymers and Plastics, Pisa, Italy, June 4–8, 2002.

23. I. Mersiowsky and R. Stegmann, in 6th International Landfill Conference, October

13–17, 1997, Vol. 1, Monograph, pp. 220–235.

24. I. Mersiowsky, J. Ejlertsson, and M. Weller, ACS Abstr. 222 (Aug. 2001).
25. I. Mersiowsky, M. Weller, and J. Ejlertsson, Water Res. 35, 13, 3063–3070, (2001).
26. R. Stegmann, S. Lotter, L. King, and W. D. Hopping, Waste Manage Res. 11, 2, 155–170,

(1993).

27. ASTM D5988-96, Standard Method for Determining the Aerobic Biodegradation of

Plastic Materials in Soil Burial.

28. ASTM D5526-94, Standard Test Method for Determining the Anaerobic Biodegradation

of Plastic Materials under Accelerated Landfill Conditions.

29. Mededelingen van de Faculteit Landbouwwetenschappen 58(4a), 1621–1628 (1993).
30. M. A. Barlaz, B. B. Rees, P. P. Calvert, and C. A. Pettigrew, Environ. Sci. Technol. 32,

6, 821–827 (1998).

31. D. S. McCarthy, D. Kaplan, J. Mayer, D. Eberiel, R. Gross, and co-workers, Polym.

Prepr. Am. Chem. Soc., Div. Polym. Chem. 31, 1, 439–440, 443 (1990).

32. B. Schink, P. H. Janssen, and J. Frings, FEMS Microbiol. Rev. 103, 2–4, 311–316 (1992).
33. T. W. Federle, Biomarcomolecules 3(4), 813–822 (2002).
34. R.-J. Mueller, D.-M. Abou-Zeid, and W.-D. Deckwer, J. Biotechnol. 86, 2, 113–126 (2001).
35. K. S. Pyong, H. K. Myung, M. K. Jong, P. K. Shin, M. H. Kim, and J. M. Kim, J. Environ.

Polym. Degrad. 5, 33–39, 1997.

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RAHAM

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WIFT

GS Polymer Consultants
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AVID

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ILES

Plastichem Consulting

BIODEGRADABLE POLYMERS, MEDICAL APPLICATIONS.

See Volume 5.

BIOMOLECULES AT INTERFACES.

See Volume 5.

BIOTECHNOLOGY APPLICATIONS.

See Volume 1.

BLOCK COPOLYMERS.

See Volume 1.

BLOCK COPOLYMERS, TERNARY TRIBLOCK.

See Volume 1.

Vol. 9

POLYMERS AND PLASTICS IN LANDFILL SITES

51

BLOWING AGENTS.

See C

ELLULAR

M

ATERIALS

.

BLOW MOLDING.

See Volume 1.

BULK AND SOLUTION POLYMERIZATIONS REACTORS.

See Volume 5.

BUTADIENE POLYMERS.

See Volume 5.

BUTYL RUBBER.

See Volume 5.