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Biodegradable and Compostable Packaging:
A review of the South African landscape
Prepared by The Moss Group on behalf of
The South African Initiative to End Plastic Waste
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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Assessment of the biodegradable and compostable
packaging landscape in South Africa
Introduction
The South African Initiative to End Plastic Waste, through the Biodegradable and
Compostable Packaging Working Group, initiated a process to evaluate the landscape with
respect to the integration of biodegradable and compostable packaging in South Africa.
The objectives of this paper are two-fold:
● To provide a balanced perspective and consolidated view of the South African
context with regard to biodegradable and compostable packaging, based on sound
research and stakeholder inputs.
● To be used to inform players across the value chain, as well as other interested
stakeholders around the responsible manufacture, use, management and disposal of
biodegradable and compostable packaging.
This document focuses specifically on the country’s current capacity to responsibly integrate
these materials into the existing packaging economy and looks to provide direction on what
is required going forward.
The SA Initiative to End Plastic Waste acknowledges that there are material types and
applications of traditional plastics that are problematic and present specific challenges with
respect to collection and recycling. The intention of this paper is not to compare the merits
of traditional plastic relative to biodegradable and compostable alternatives.
Background
Plastic pollution, particularly in the marine environment [1], has become a focal point for
campaigns highlighting the negative impacts of increased consumerism [2]. Globally, major
players in the plastics value chain, brand owners, NGOs and governments have recognised
the need to work collaboratively to address this issue. This has led to the launch of the New
Plastics Economy [3], by the Ellen McArthur Foundation and the UN Environment
Programme, and the Global Alliance to End Plastic Waste. In South Africa, over 20 key
stakeholders have signed up as members of the recently launched SA Plastics Pact [4].
Consequently, there is an increasing drive toward reducing the amount of plastic packaging,
eliminating problematic packaging types, increasing post-consumer collection and recycling
and transitioning away from petrochemical-based materials to more sustainable
alternatives. The desire for alternatives that deliver lower environmental impact than
traditional plastics has created a growing market for biodegradable and compostable
packaging.
Globally, the cost of biodegradable and compostable materials is currently substantially
higher than traditional, petrochemical-based polymers in many cases, but this is expected to
decrease as volumes increase [5].
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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South African context
The South African consumer packaging waste landscape has several defining factors that
need to be considered when looking at integrating biodegradable and compostable
packaging.
Formal municipal waste collection is not effective in capturing all post-consumer waste, with
over 34% of households not having access to regular waste removal services [6]. Separation
at source is not legislated, so is not widely practiced. Where it is, it tends to be limited to
separation of paper and packaging for recycling (i.e. not separation of organic waste).
Material sorting is primarily done by hand or density separation. Hand sorting may be
beneficial as experienced sorters are able to separate a range of material types. Informal
waste pickers are responsible for collecting a significant proportion of recyclable material,
mostly from the environment, landfill and household refuse bins [7]. As a result,
contamination of recyclable materials is often high. Waste pickers are paid by buy-back
centres for the materials they collect, resulting in pickers mostly focussing their efforts on a
select few, high value materials. The country has high levels of visible litter in the
environment, much of which is lightweight packaging that has been irresponsibly disposed
of by consumers and has little to no value to informal collectors.
Organic waste is predominantly disposed of with general waste and therefore ends up in
landfill, where its degradation under anaerobic conditions leads to the undesirable release
of methane, a potent greenhouse gas. There is currently limited household collection
infrastructure, municipal or private, for organic waste. However, there is movement, led by
the Western Cape government, to eliminate organic waste from landfill [8]. Composting
facilities already exist around South Africa, with varying infrastructure and technologies in
place. Plastic contamination is a challenge for most composters. It is important to note
that, unlike recyclers, composters do not pay for waste entering their facilities and many
charge a gate fee based on the composition of the material. The financial sustainability of
composting at scale is under increasing pressure and several facilities have closed as a result.
There is currently very limited separation, collection and processing infrastructure to
support the responsible post-consumer management of packaging made from
biodegradable and compostable materials. Furthermore, informal pickers currently have no
economic incentive to collect biodegradable or compostable packaging for processing, so
they are likely to be overlooked, much like lightweight flexible and multi-layer products.
However, due to poor labelling and the absence of clear identification these products,
especially carrier bags, are being inadvertently collected with traditional plastics.
At present, there is very little legislation pertaining specifically to biodegradable and
compostable materials in South Africa, with the exception of SANS 1728:2019 that relates to
the requirements for the marking and identification of degradable plastics. In addition there
are sections of the Consumer Protection Act that refer broadly to false claims relating to the
performance of materials.
Most South African consumers have very limited awareness and understanding of what
biodegradability and compostability mean and therefore what is required for responsible
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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post-consumer management. The absence of effective education and awareness can create
the misconception that biodegradable materials decompose rapidly in the environment,
potentially exacerbating the littering culture.
At this stage the majority of the raw materials (resins) and some finished products are
imported, which has limited direct benefit for the South African economy.
Key terms and definitions
● Fossil fuel-based polymers are derived from petroleum, coal or natural gas products or
by-products. The majority of plastics in use today are fossil fuel based.
● Bio-based polymers are defined as plastics that are derived from renewable (plant-
based) sources. These may be identical to fossil fuel-based polymers (e.g. PET, PE, PP),
where the monomeric units (e.g. ethylene) are produced from plant-based materials
rather than fossil fuels, or may be so-called bioplastics (e.g. PLA, PHA, thermoplastic
starch). These can be first generation, derived from food crops such as corn, potatoes
and sugar cane, or second generation, derived from agricultural by-products, non-food
crops or organic waste. Bio-PET, Bio-PE and Bio-PP can be recycled with conventional
fossil fuel-based plastics.
● Biodegradable materials degrade by biological activity, resulting in a specific change in
the chemical structure of the material. Degradation can occur under aerobic or
anaerobic conditions. The end products are gas (carbon dioxide or methane), water,
biomass and mineral components. Plastics labelled “biodegradable” break down at a
faster rate than conventional plastics. The degradation of biodegradable materials does
not necessarily imply that the material can be converted into good quality compost or
that degradation will take place within a specified timeframe. Biodegradable materials
can be produced from renewable feedstocks (biomass) or fossil fuels. In the sections
that follow, the term “biodegradable” includes compostable, unless specifically stated.
● Compostable materials are a group of biodegradable materials that break down in an
aerobic composting process through the action of naturally occurring microorganisms
and do so to a high extent within a specified timeframe. The biological processes yield
carbon dioxide, water, inorganic compounds and biomass, leaving no visible
contaminants or toxic residues.
● Industrial composting refers to the breakdown of biodegradable materials under
controlled conditions (50-70˚C, forced aeration, managed humidity) in an industrial
composting facility. Internationally, standards specify the conditions, timeframe and
extent of degradation required for a material to be certified as “compostable”.
● Home composting refers to the breakdown of biodegradable material under conditions
(temperature and moisture) found in domestic compost piles. There are fewer
international standards for this.
● Prodegradent additives refer to materials that are added to traditional polymers to
initiate the accelerated degradation of the plastic structure. There are two groups of
additives, oxo-additives (e.g. d2w) which rely on oxygen, heat and UV light to accelerate
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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the initial fragmentation and bio-additives (e.g. Biosphere) which act as sites for
microbial attack to accelerate biological degradation.
A more detailed description of the range of available materials, their key properties,
application and research related to their environmental performance is available in the
Appendix to this document.
Working group assessment
Based on the analysis of the information available in the public domain and academic
literature, as well as the engagement with a range of stakeholders across the value chain,
the working group has prepared the following As-Is assessment of the landscape relating to
biodegradable and compostable materials. The document is structured using the value
chain as a guide, as illustrated below.
Raw material and packaging production
● The local market for biodegradable and compostable packaging is still too small to
justify significant investment in infrastructure to produce raw materials (e.g. resins).
However, the potential for developing local capacity for the production of bio-
based polymers and biodegradable materials should be continuously assessed and
considered as part of the South African Bio-economy Strategy [9]. The assessment
should consider socio-economic (job creation, food security, etc.) and
environmental implications. This will become increasingly relevant as the demand
for these materials grows.
● The current global market size for biodegradable plastics made from food crops is
too small to negatively impact food security (0.016% of global agricultural land in
2018, according to European Bioplastics [10]). This position is unlikely to change in
the medium term. However, it should remain a key consideration that is evaluated
regularly.
● There is currently no mandatory legislation specific to the material properties of
biodegradable and compostable plastics. A South African National Standard (SANS)
for Compostable Materials based on ISO 17088 is currently open for public
comment. The SANS standard 1728:2019 does specify that relevant raw material
technical data sheets should accompany these products, but SANS 1728:2019 is not
currently a compulsory standard. There are provisions within the Standards Act of
2008 that prohibit businesses from operating in a manner that is likely to create the
impression that products comply with a South African National Standard or other
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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publications of the SABS. In addition, sections of the Consumer Protection Act refer
broadly to false claims relating to the performance of materials.
● There are a number of products on the market that make claims relating to
biodegradability without any reference to appropriate international standards, as
required by SANS 1728:2019. Stakeholders from within and outside the
biodegradable materials value chain expressed concern that the importing of non-
certified products could have negative consequences for both the environment and
the biodegradables industry.
● Biodegradable and compostable plastics are currently marked with the number 7
resin code, which can lead to confusion as this code is used for traditional plastics
that fall outside the six major polymer types. The suggestion for the allocation of a
unique resin code for these materials was widely supported.
● Food contact materials need to be tested and certified to comply with the same
local and international food safety legislation, detailed in the Foodstuffs, Cosmetics
and Disinfectants Act, as traditional plastics to ensure that they have the necessary
barrier properties to ensure effective food protection, that they contain no
contaminants (including natural organic toxins) that may threaten food safety and
that material integrity is not compromised by extended shelf-life.
Marketing and sales
● The SANS 1728:2019 standard specifies the requirements for marking and
identification of degradable plastics. The requirements are applicable, but not
limited to, biodegradable, compostable, oxo-biodegradable and water-soluble
plastics. The requirements include:
o The product must carry the internationally recognised polymer code, as a
numeral inside the triangle, in conjunction with the description of the claim.
The acronym for the material (e.g. PET, PLA etc.) along with the appropriate
wording (i.e. biodegradable, compostable or oxo-biodegradable) must be
displayed below the resin code.
o If the product is made of multiple components and these are intended for
different waste streams, the information must be clearly displayed on the
package (e.g. closure – recyclable, PLA bottle – compostable).
o The product must conform to the appropriate international standards if it is
claimed to be biodegradable (DIN 38412:30 or ISO 14855-1), compostable
(ISO 17088, EN 13432 or ASTM D6400) or oxo-biodegradable (ASTM D6954-
04). Claims made by the manufacturer of the end product must be verified
by accredited laboratories and supported by raw material technical data
sheets, as per the appropriate standard.
o If the entire product is not biodegradable or compostable the claim needs to
identify the specific components that are. If separation of components is
required, clear instructions on how to do this must be included.
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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o Vague or non-specific claims that imply the product has environmental
benefits, such as “green”, “environment friendly”, “earth safe” etc. are not
permitted.
o At this stage there are no definitive methods for measuring sustainability or
confirming its accomplishment, so no claims of achieving sustainability
should be made.
o If self-declared environmental claims are likely to result in confusion, an
explanatory statement must accompany these.
● Very few products on the market comply fully with the requirements of SANS 1728.
● There is currently little in the way of effective consumer education around
biodegradable and compostable plastics. Brand owners, retailers and consumers
are typically unaware of the range of material types, their properties and the fact
that different materials may only be certified to degrade or compost under specific,
controlled conditions. The performance outside of these conditions is often poorly
understood, but evidence suggests degradation rates are likely to be significantly
slower.
● Several stakeholders raised the concern that inadequate or misleading marketing,
coupled with poor consumer education, could create incorrect expectations with
respect to biodegradability and therefore promote a “throw away” culture. This
contention was broadly disputed by manufactures and distributors of biodegradable
and compostable products.
● During the consultation process, producers and importers of biodegradable and
compostable materials highlighted the risk to their industry posed by the import
and distribution of products that carry false or unsubstantiated claims. The value
of self-regulation, by an industry association, in this regard was widely
acknowledged and discussions around the formation of an association have begun.
Waste collection
● There is currently no economic incentive for informal waste pickers to collect
biodegradable or compostable plastics from the environment, landfill or household
waste. Therefore, it is highly unlikely that these materials will be collected if they
are disposed of through conventional means.
● At this point, there are few systems in place for the separation and collection of
biodegradable and compostable waste to enable responsible post-consumer
management of this packaging.
● While materials certified as compostable will degrade within a defined timeframe
under controlled conditions, there is limited information on the degradation rates
of different biodegradable materials outside a controlled environment. Academic
literature suggests that biodegradation may be significantly slower in dry conditions
(low humidity) [11] at lower temperatures, in marine and aquatic environments and
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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where microbial concentrations are low [12-17]. Under these unfavourable
conditions most materials will persist for years to decades. Therefore,
biodegradable and compostable materials are unlikely to provide an immediate
solution to the problem of visible litter in the environment.
Waste processing
● South Africa has a well-established mechanical recycling industry that provides a
livelihood for a large number of people in the collection, transport and processing of
recyclable plastics. Collection and recycling rates for certain material types, such as
HDPE dairy packaging [18] (> 75%) and PET beverage bottles [6] (63%), are among
the highest in the world. The market for recycled polymer is dependent on
confidence in the technical integrity of the recycled material. Material sorting is
primarily by hand or density separation. Therefore, products made from
incompatible materials (e.g. PLA beverage bottles) that are difficult to distinguish
from traditional polymers (e.g. PET beverage bottles) risk contaminating recycling
streams, at least in the short to medium term.
● It is noted that composting is not necessarily the only end-of-life solution for
biodegradable plastics. The Department of Science and Innovation (DSI) is currently
funding research programmes under the broad title “End of life options for bio-
based plastics”.
● Bio-based, non-biodegradable polymers, such as bio-PET and bio-HDPE, are
essentially identical to the petrochemical-based materials. Therefore, they are
deemed acceptable within the current collection and recycling landscape in South
Africa.
● The effectiveness of prodegradant additives (oxo and bio) remains a matter of
contention. Notwithstanding claims by the manufacturers [19] regarding
biodegradability and supporting literature [20-22], there is a significant body of
academic literature that contests the claims that prodegradant additives accelerate
the fragmentation and subsequent biodegradation of the plastic in all
environments [23-27]. No independent research was found that conclusively proves
that prodegradant additives do not result in persistent microplastics.
● The prevailing position of the majority of recyclers in SA is that the presence of
these additives in recycled material is not desirable and widespread use could have
negative consequences for the industry. However, half of those consulted indicated
that they may reconsider this position in the face of compelling evidence.
Proponents of the additives refer to several reports [28,29] that indicate the
additives will not compromise the structural integrity of recycled products, although
other studies have come to a different conclusion [30].
● Prodegradent additives that require microbial activity to initiate fragmentation (i.e.
not oxos) pose less of a risk to the technical integrity of recycled products as most
are not designed for prolonged use in microbe-rich environments. The exception
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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would be applications where the recycled product is used in environments where
exposure to high concentrations of bacteria and fungi is likely, such as irrigation
piping.
Support
● There is currently no producer responsibility organisation (PRO) or similar structure
to provide oversight and promote the responsible sourcing, marketing and post-
consumer management of biodegradable and compostable materials.
● Several manufacturers, importers and brand owners of biodegradable and
compostable packaging have acknowledged the importance of Extended Producer
Responsibility (EPR). They recognise their role in the establishment of systems and
infrastructure to enable responsible post-consumer management.
Conclusion
Biodegradable and compostable materials have become a reality in South Africa, driven
largely by consumer demand for alternatives that have improved environmental
performance relative to traditional plastics. At this stage, the applications are primarily in
food and drink containers, utensils and carrier and barrier bags for niche markets. Despite
volumes being relatively low at this stage, post-consumer management of these products
needs to be proactively considered due to the potential growth of this sector.
It is therefore critical that key stakeholders from industry, civil society and government
collaborate to develop a coherent master plan for these materials that is appropriate and
relevant to South Africa. Six key principles need to underpin this plan:
1. Biodegradable and compostable plastics that are certified and verified and are part of
an effective collection and processing system can provide a responsible end-of-life
option that is in line with circular economy principles.
2. The industry master plan and resultant decisions should be based on robust research.
There is a substantial body of international research, but this should be critically
evaluated to build on information that is relevant to the South African context.
3. The industry strategy should strive towards strengthening the local economy,
supporting transformation and job creation.
4. Biodegradable and compostable plastics and the associated waste management systems
and processes need to be implemented in a way that enhances existing collection and
recycling systems and improves consumer behaviour.
5. All manufacturers, importers and brand owners need to actively participate in Extended
Producer Responsibility programmes, which should include inter alia aspects relating to
consumer education and awareness, certification and collection and processing
infrastructure set up and management.
6. The status quo should not be viewed as a barrier to entry for alternate materials.
However, the acceptance of alternative materials into the value chain is likely to be
accelerated if these target “fit for purpose” applications and those where traditional
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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plastics are most problematic, rather than high volume applications that currently
underpin the recycling sector, at least initially.
7. The plan should aim to foster collaboration between the biodegradables sector and the
traditional plastics industry to address the serious challenges facing the packaging
sector.
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
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References – As-Is Assessment
[1] Law, K.L. (2017) Plastics in the Marine Environment. Annu. Rev. Mar. Sci. 9: 205-229.
[2] Buranyi, S. (2018) The plastic backlash: What’s behind the sudden rage – and will it make
a difference. https://www.theguardian.com/environment/2018/nov/13/the-plastic-
backlash-whats-behind-our-sudden-rage-and-will-it-make-a-difference.
[3] Ellen McArthur Foundation – The new plastics economy.
https://www.newplasticseconomy.org
[4] https://www.saplasticspact.org.za
[5] van den Oever, M., Molenveld, K., van der Zen, M. And Bos, H. (2017) Bio-based and
biodegradable plastics – facts and figures. Wageningen Food and Bio-based Research,
Wageningen, The Netherlands. DOI http://dx.doi.org/10.18174/408350.
[6] Plastics SA (2019) National Plastics Recycling Survey 2018, Plastics SA
[7] Godfrey, L., Strydom, W. and Phukubye, R. (2016) Integrating the informal sector into
the South African waste and recycling economy in the context of extended producer
responsibility. Briefing Note February 2016. CSIR Policy Brief and Briefing Note Series.
[8] Western Cape Government (2019) A guide to separation of waste at source.
Environmental Affairs and Development Planning, Western Cape Government.
[9] Department of Science and Technology (2013) The Bio-economy Strategy.
https://www.gov.za/sites/default/files/gcis_document/201409/bioeconomy-strategya.pdf
[10] European Bioplastics. Land use estimates for bioplastics 2019 and 2024.
https://www.european-bioplastics.org/market/
[11] Ho, K-L.G., Pometto III, A.L. and Hinz, P.N. (1999) Effects of temperature and relative
humidity on polylactic acid plastic degradation. J. Environ. Polym. Degrad. 7: 83-92.
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and Treude, T. (2016) Microbial colonization and degradation of polyethylene and
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[14] Pischedda, A., Tosin, M. and Degli-Innocenti, F. (2019) Biodegradation of plastics in soil:
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[16] Karamanlioglu, M., Preziosi, R. and Robson, G.D. (2017) Abiotic and biotic
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[18] The Moss Group (2019) Quantification of the recycling rate for HDPE dairy packaging.
[19] Symphony Environmental (2019) d2w a scientifically proven biodegradable technology.
Special Report, July 2019. Symphony Environmental.
[20] Chiellini, E., Corti, A., D’Antone, S.D. and Baciu, R. (2006) Oxo-biodegradable carbon
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M.H., Moreno, A., Martinez, L. and Yanez, J.M. (2016) Biodegradation and ecotoxicity of
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[22] Rose, R-S., Richardson, K.H., Latveanen, E.J., Hanson, C.A., Resmini, M. and Sanders, I.A.
(2020) Microbial degradation of plastic in aqueous solutions demonstrated by CO2 evolution
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[24] Musiol, M., Rydz, J., Janeczek, H., Radecka, I., Jiang, G. and Kowalczuk, M. (2017)
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[27] Gomez, E.F. and Michel Jr, F.C. (2013) Biodegradability of conventional and bio-based
plastics and natural fiber composites during composting, anaerobic digestion and long-term
soil incubation. Pol. Degrad. Stab. 98: 2583-2591.
[28] Jakubowicz, I. and Enebro, J. (2012) Effects of reprocessing oxobiodegradable and non-
degradable polyethylene on the durability of recycled materials. Pol. Degrad. Stab. 97: 316-
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[30] Hann, S., Ettlinger, S., Gibbs, A. and Hogg, D. (2016) The impact of the use of “oxo-
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Acknowledgements
Working Group members
The following individuals are active members of the Biodegradable and Compostable
Working Group. We would like to thank them for their time and contributions in assisting
with the development of this paper.
Company
Name
Circular Vision
Sally-Anne Käsner
CSIR
Dr Suzan Oelofse
CSIR
Dr Sudhakar Muniyasamy
Encore
Devin Galtrey
Food Lovers Market
Siglinda Losch
Pick n Pay
Roan Snyman
Pick n Pay
Nicki Russell
Roundtable on Sustainable Biomaterials (RSB)
Arianna Baldo
South African Plastics Recycling Organisation (SAPRO)
Johann Conradie
SPAR Group
James Lonsdale
The Moss Group
Nicky van Hille (Working Group Chair)
The Moss Group
Dr Rob van Hille
Tiger Brands
Sinethemba Kameni
UNIDO
Nahomi Nishio
Woolworths
Don Macfarlane
WWF
Lorren de Kock
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
14
Other contributors to the paper
Thank you to the following people for their valuable contributions to the paper.
Industry sector
Company
Name
Composters
Master Organics
Odette Lourens
ORASA
Melanie Ludwig
Reliance
Eddie Redelinghuis
YWaste
Emile Fourie
Recyclers
Myplas
Johann Conradie
20 recyclers (various)
Anonymous – inputs via online
survey
Not for profit
GreenCape
Kirsten Barnes
GreenCape
Sam Smout
Scientific research
CSIR
Aubrey Muswema
University of Stellenbosch
Prof. Albert van Reenen
Polymer science
Roediger Associates
Dr Andy Roediger
Plastix 911
Annabe Pretorius
Brand owners and retailers
Tiger Brands
Stiaan Wandrag
Julie Ntseke
Meghan Draddy
8 brand owners and retailers
(various)
Anonymous – inputs via online
survey
Biodegradable & Compostable
packaging importers and
producers
BioFuture
Dean Lynch
BioSphere
Neil Smith
Bonnie Bio
George Schweitzer
Bonnie Bio
Lauren Vorster
Cape Cup
Jessica Sjouerman
Enviromall
John Fox
Green Home
Cassandra Gamble
Kompost-it
Emma Algotsson
Kompost-it
Pierre Pretorius
Biodegradable and Compostable Packaging: As-Is SA landscape (March 2020)
15
Lension SA
Raquel Paganini
Lension SA
Jacques Tredoux
Mater Bi
Andrew Smith
Mater Bi
Andrew Pollock
Mielie Mailer
Trent Pike
Mielie Mailer
Renato Marchesini
Mielie Mailer
Erik Bourlov
Oryx Polymers
Jaco du Plessis
Oryx Polymers
Gigi Mariani
Sychro Environmental
Michael Butz
Converter (traditional plastics)
Ferro Plastics
Theuns Steyn
Flexo Tuff
Bilal Hassim
Other
Private
Alan Booth
Biodegradable and compostable plastics: Material types and applications
i
Appendix: Biodegradable and compostable plastics:
Material types and applications
Table of contents: Material types and applications
Context ...................................................................................................................................... ii!
Glossary .................................................................................................................................... iii!
Summary of bio-based, additive containing and biodegradable plastics ................................. iv!
Material types and applications ................................................................................................ v!
Bio-based biodegradable plastics .......................................................................................... v!
Polylactic acid (PLA) ........................................................................................................... v!
Polyglycolic acid (PGA) ...................................................................................................... vi!
Thermoplastic starch (TPS) .............................................................................................. vii!
Polyhydroxyalkanoates (e.g. PHA, PHB, PHV) ................................................................. viii!
Polybutylene succinate (PBS) ............................................................................................ ix!
Biodegradable, fossil fuel-based plastics ............................................................................... x!
Polycaprolactone (PCL) ...................................................................................................... x!
Bio-based, non-biodegradable plastics ................................................................................. xi!
Bio-PET/PP/PE/PVC ........................................................................................................... xi!
Polyethylene furanoate (PEF) ........................................................................................... xi!
Plastics with prodegradant additives .................................................................................. xiii!
Oxo-degradable additives ............................................................................................... xiii!
Bio-additives ................................................................................................................... xiv!
Summary of commercially available biodegradable plastics ................................................... xv!
References .............................................................................................................................. xvi!
Biodegradable and compostable plastics: Material types and applications
ii
Context
This document has been prepared to support the position paper developed by the
Biodegradable and Compostable Materials Working Group, under the South African
Initiative to End Plastic Waste. The document is intended to provide more detailed
information on the wide range of materials that are being applied in biodegradable
packaging, highlighting the raw material sources, manufacturing process, properties of the
polymers, range of applications and end of life fate.
Polymer production, particularly at large scale, is a complex process and multiple steps are
required to get from raw feedstock (fossil fuel or biomass) to the purified polymer. In some
cases, the feedstock may be similar, but the production processes can be very different,
producing end products that have very different structures and properties, applications and
propensity to biodegrade. For example, polylactic acid (PLA) and polyhydroxybutyrate (PHB)
are both biodegradable polymers that can be produced by the microbial fermentation of
cornstarch. However, in the case of PLA the lactic acid monomers are secreted into the
fermentation medium, are purified and then polymerised into the final product over a
chemical catalyst. The PHB polymer is synthesised within the bacterial cells as a secondary
storage product and is purified from the growth media after the cells have been disrupted.
The polymer structures and properties are also very different.
There is a considerable amount of on-going research in the field of biodegradable and
compostable plastics, with new polymers and polymer blends being developed, particularly
from second generation (non-food crop) biomass sources. Many of these are showcased in
the popular press or on social media platforms, often with enthusiastic pronouncements
that this material can solve the plastics crisis. Fundamental research will continue to play a
critical role in the development of viable alternatives to traditional plastics, but an
appreciation of the complexity and challenges associate with bridging the gap between
laboratory research and commercial application will help to manage expectations.
Manufacturers of biodegradable materials and those who market them can make
exaggerated claims regarding the performance of their products. There is a tendency to
highlight research that supports the claims, while ignoring research that comes to less
convincing or contradictory conclusions. This document aims to present a balanced
overview of some of the pertinent research and provide useful information that retailers,
brand owners and converters can draw on when presented with new materials.
The document begins with a high-level overview of the different materials, then proceeds to
present more technical detail on the main classes of polymer.
Biodegradable and compostable plastics: Material types and applications
iii
Glossary
Carbonyl group: A functional group composed of a carbon atom double bonded to an oxygen atom
(C=O). The oxygen molecule is more electronegative than the carbon, so there is some polarity across
the bond, making it more reactive than a carbon-carbon (C-C) bond. The introduction of carbonyl
groups into plastics increases their potential for biodegradation. Carbonyl groups include aldehydes,
ketones, carboxylic acids and carboxylic esters.
Carbonyl index (CI): The CI is measured by infrared spectroscopy and is defined as the ratio between
carbonyl and methylene absorbances. An increase in CI represents an increase in the number of
carbonyl groups and is indicative of the degree of oxidative degradation of the polymer.
Enzyme: A specific class of protein that speeds up the rate of chemical reactions (building or
breaking).
Enzymatic hydrolysis: The cleaving of chemical bonds with the addition of elements of water (OH
and H), catalysed by a specific enzyme.
Glass transition temperature: Temperature range above which the properties of a plastic change
from a hard and relatively brittle state to a viscous or rubbery state.
Melt flow index (MFI): A measure of the ease of flow of a thermoplastic polymer. It is defined as the
mass (g) of polymer flowing through a capillary of specific diameter in 10 minutes at a specified
temperature and pressure. MFI is an indirect measure of molecular weight.
Polyester: A group of polymers that contain an ester (R-COO-R’) functional group in their main chain.
They are typically formed by the reaction of an alcohol with a carboxylic acid.
Retrogradation: A process by which gelatinous starch recrystallises upon cooling, usually with the
expulsion of water. The process is undesirable and reduces the plasticity, making the resulting
product brittle.
Thermoplastic: A polymer, typically with high molecular weight, that becomes mouldable above a
certain temperature and solidifies upon cooling. They are used in processing techniques such as
injection moulding, compression moulding, extrusion and calendaring.
Biodegradable and compostable plastics: Material types and applications
iv
Summary of bio-based, additive containing and biodegradable plastics
Name
Feedstock
Properties
Applications
Biodegradable
Industrial
composting
Home
composting
Mechanical
recycling
Bio-PET/PE/PP/PVC
Ethanol
Identical to fossil fuel-based
analogues
Wide range of rigid and flexible
packaging applications
X"
X!
X!
✔!
Plastics with oxo-
additives
Fossil fuels or ethanol
Similar to base polymer with
accelerated fragmentation when
exposed to UV and heat
Similar applications to base polymer
Contested
X!
X!
Uncertain
Plastics with bio-
additives
Fossil fuels or ethanol
Similar to base polymer, less
hydrophobic, accelerated
degradation due to microbial
attack (aerobic and anaerobic)
Similar applications to base polymer
Uncertain
X!
X!
Uncertain
PEF
Glucose from vegetables
and potentially from
lignocellulosic biomass
Similar to PET, with improved
thermal and barrier properties
for oxygen, CO2 and water
vapour
Similar to those for PET
X!
X!
X!
✔!
TPS
Food crops
Typically blended with other
materials to improve properties.
Can be glassy or rubbery
Rigid and flexible packaging, service
ware and agricultural products
✔!
✔!
✔!
X!
PGA
Fermentation of starch
or petrochemical
High melting point, high
crystallinty, relatively high glass
transition temperature
Biomedical applications and potential
as an interlayer in films to improve
barrier properties
✔!
✔!
X!
X!
PLA
Food crops, potentially
agricultural waste or
fossil fuels
Isomer blends allow variety of
properties, ranging from PS to
PET
Rigid and flexible packaging, service
ware and textiles
✔!
✔!
X!
X!
PHAs
Fermentation of
renewable feedstocks
Mechanical properties similar to
PP. Good UV stability and barrier
properties
Flexible packaging, films, carrier
bags, food trays and disposable
cutlery
✔!
✔!
✔!
X!
PBS/PBSA
Renewable feedstocks or
fossil fuel
Similar properties to PP
Flexible packaging and
agricultural/horticultural applications
✔!
✔!
X!
X!
PBAT
Fossil fuels
Low crystallinity, tough, flexible,
similar to LDPE
Flexible packaging (films and bags),
waterproof coatings, additives
✔!
✔!
✔!
X!
PCL
Fossil fuels
Semi-crystalline, resistant to
water, oil, solvents and chlorine
Biomedical applications or blended
with starch to improve properties
✔!
✔!
✔!
X!
Modified from The Green House - Decision Tree for Biodegradable Plastic
Biodegradable and compostable plastics: Material types and applications
v
Material types and applications
Bio-based biodegradable plastics
These plastics are derived from renewable biomass that may either be classified as first generation or
second generation. First generation feedstocks are agricultural crops such as corn, wheat or potatoes,
while second generation refers to non-food crops (switch grass, algae etc.) or the non-edible residues from
feed crops (bagasse, rice bran etc.). Biodegradable materials can be broken down to their constituents as a
result of microbial activity. Compostable materials biodegrade beyond a threshold level under specified
conditions within a defined time period.
Polylactic acid (PLA)
Raw material source and production
PLA is a polyester that can be synthesised from either lactic acid (by direct condensation) or lactide (by ring-
opening polymerisation) monomers. The monomers are produced by the fermentation of starch, typically
derived from agricultural crops such as corn, wheat, sugar beet, potatoes, sugar cane and tapioca.
The global market for PLA is currently around 220 000 tons. PLA resin sells for between $3500 and $4500
per ton.
Basic properties
PLA is a thermoplastic with a melting temperature of 150-170˚C and a density of 1.24. The monomers can
have different conformations (D- and L- isomers) and manipulating these during polymer formation allows
the production of different grades, with different properties (MFI from 6-50).
PLA has a glass transition temperature of between 55˚C and 65˚C, although heat resistant variants that can
tolerate up to 110˚C have been produced.
The basic mechanical properties are between those of polystyrene and PET.
Applications
A variety of grades are available that allow PLA to be used in a number of processes, including injection
moulding, thermoforming, extrusion and the production of fibre and films.
The majority of PLA is used in the production of rigid packaging (cups, trays etc), with significant amounts
also used in flexible packaging (bags), textiles and service ware (disposable cutlery, straws etc).
End of life
PLA has the potential to be mechanically or chemically recycled, although this is less likely for PLA
packaging. It is not currently recycled in South Africa.
The majority of PLA packaging products available in South Africa are marketed as compostable. The
material may be compostable under industrial composting conditions, but is not suitable for home
composting, unless it has been blended with other materials, such as polycaprolactone (PCL). A number of
Biodegradable and compostable plastics: Material types and applications
vi
microorganisms have been shown to produce enzymes that are capable of degrading PLA. PLA does not
degrade in the absence of oxygen (anaerobic), so is unlikely to break down in a landfill.
PLA can also degrade in the absence of bacteria, by hydrolysis and photodegradation (UV), but the rates are
very slow at ambient temperature.
Concerns/challenges
PLA is indistinguishable from PET (density 1.38) and can only be easily separated using expensive near-
infrared (NIR) technology. Both materials will sink. A small amount of PLA can contaminate a PET recycling
stream rendering the recyclate unusable.
The degradation rate of PLA outside of industrial composting facilities is very slow, particularly in
environments where the temperature is low, there is limited oxygen or low numbers of the appropriate
microbes, such as the ocean or aquatic sediments. There is limited information on the degradation rates in
the terrestrial environment.
PLA is typically produced from food crops. While this has little impact on land use and food security at
current volumes it may become a concern if demand increases substantially.
Polyglycolic acid (PGA)
Raw material source and production
PGA is the simplest linear polyester produced from glycolic acid monomers. Traditionally, the majority of
glycolic acid has been produced from petrochemical sources. More recently, microbial fermentation of
renewable biomass has been developed as an alternative.
The current market for PGA is small.
Basic properties
PGA is a thermoplastic with a melting temperature of 225-230˚C and a density of 1.53. The polymer has a
glass transition temperature of between 35˚C and 40˚C.
PGA typically exhibits a high degree of crystallinity (45-55%), which means it is insoluble in water.
However, the chemical structure means it is prone to hydrolysis (breakdown in water).
Applications
The hydrolytic instability of PGA has limited the range of applications, which have been dominated by
biomedical applications, such as absorbable sutures and other implants.
The high degree of crystallisation means the PGA has very good gas barrier properties. High molecular
weight PGA is finding applications in packaging, particularly as an interlayer between PET to improve shelf
life of perishable foods and carbonated drinks. This may become more important as packaging is further
light-weighted.
PGA is also being investigated as a replacement for foil layers to allow the production of fully biodegradable
films that still have good barrier properties.
Biodegradable and compostable plastics: Material types and applications
vii
End of life
Pure PGA will degrade relatively rapidly in water and this process is accelerated by microbial enzymes.
Concerns/challenges
There are currently relatively few applications for PGA in packaging and these are predominantly as a
component of other biodegradable materials, so this material is not a major concern.
Thermoplastic starch (TPS)
Raw material source and production
TPS is derived from starch, with is typically extracted from maize, wheat, potatoes and other starch-rich
agricultural crops, although second generation sources such as rice straw are being investigated.
Starch is composed of amylose (15-30%), a linear polymer of D-glucose, and amylopectin (70-85%), a highly
branched polymer of D-glucose. The higher the amylopectin fraction the greater the crystallinity and this
differs between crop types.
Thermoplastics are typically processed by heating to above their melting point to allow viscous flow.
Native starch degrades at temperatures below the melting points, so the addition of plasticisers is required
to produce thermoplastic starch. Water is the most common plasticiser, but is typically not used alone as it
results in undesirable mechanical properties and can lead to retrogradation. More commonly, glycerol or a
mixture of glycerol and water are used. Another method used to combat retrogradation involves blending
starch with other polymers. These may be biodegradable, such as PLA, PHB or PCL, to produce a fully
biodegradable product, or non-biodegradable (PE, PVA and polyesters). Blending is typically accomplished
by twin-screw extrusion at elevated temperatures.
Starch blends make up over 40% of the biodegradable plastics market, with current demand exceeding 385
000 tons. TPS pellets sell for between $3500 and $4500 per ton.
Basic properties
Native starch degrades at temperatures below the melting point, so needs to be treated with plasticisers or
blended with other polymers to produce a thermoplastic. Depending on the nature of the blend, the
thermal and mechanical properties of the product can vary significantly.
Native starch has a density of 1.5, so most thermoplastic blends will also have densities in excess of 1. The
glass transition temperature depends on the nature of the blend and can vary from below freezing to
above 100˚C. Therefore, blends can be produced that are either glassy (brittle, transparent, rigid) or
rubbery (tough, flexible, resistant to reagent attack) at ambient temperature.
Applications
The range of available blends means that TPS can be processed by a variety of mechanisms, including
kneading, compression moulding, injection moulding, blow moulding, thermoforming, extrusion and the
production of films.
Biodegradable and compostable plastics: Material types and applications
viii
Thermoplastic starch is predominantly used in the production of flexible packaging (bags), with significant
amounts also used in rigid packaging, service ware (disposable cutlery), agriculture, consumer goods and
coatings.
End of life
The biodegradability of TPS blends depends greatly on the formulation. Native starch is completely
biodegradable and fully degradable products can be produced by blending with other biopolymers (e.g.
cellulose) or biodegradable polymers (PCL, PVA).
The general mechanism of starch degradation by enzymatic hydrolysis involves the attachment of the
enzyme to the substrate surface, followed by cleaving of the bonds. Therefore, the rate is dependent on
the chemical structure of the polymer, surface area, pH, temperature, moisture content, type and
abundance of microorganism, wettability etc. Altering the chemical structure of starch by blending or
including additives will typically reduce the degradability. Similarly, blending starch with non-
biodegradable polymers will produce a material that is only partially biodegradable.
Concerns/challenges
Due to the versatility of starch blends it is possible to produce materials that appear physically similar to
traditional polymers that could have a negative impact on mechanical recycling streams.
Polyhydroxyalkanoates (e.g. PHA, PHB, PHV)
Raw material source and production
PHAs are a group of polyesters that are produced in nature by a wide range of bacteria, often via the
fermentation of sugars or lipids (oils). More than 150 different monomers can be combined to form this
group of polymers, giving a wide range of material types. They are typically accumulated as energy storage
molecules when there is a deficiency of a nutrient required for active growth (e.g. phosphorous, nitrogen of
trace elements), but an abundance of the carbon source. During production by industrial fermentation the
conditions initially favour rapid cell growth after which the medium is manipulated to promote PHA
accumulation. The simplest and most commonly produced PHA is poly-3-hydroxybutyrate (P3HB),
PHAs are deposited as granules within the cells and can make up as much as 80% of the cell mass. The cells
need to be disrupted in order to recover the granules, which increases the complexity and cost of
manufacture.
The market for PHAs is still relatively small, around 29 500 tons, but is expected to grow by over 80% in the
next five years. The majority of PHAs are used to manufacture flexible packaging. PHA pellets sell for
between $2 000 and $4 500 per ton.
Basic properties
PHA polymers are thermoplastics and can be processed using conventional machinery, most commonly by
extrusion and injection moulding. The properties differ according to their composition (homo- or co-
polymer) and which fatty acids are incorporated.
The PHAs are more UV stable than most bioplastics and has good aroma and water barrier properties.
Biodegradable and compostable plastics: Material types and applications
ix
The most common PHA (P3HB) has a density between 1.18 and 1.26, depending on the degree of
crystallinity, a melting point of 180˚C and a glass transition temperature of 4˚C. The mechanical properties
and tensile strength are similar to those of polypropylene, although the extension to break (5%) is
substantially lower than PP (400%), so P3HB appears stiffer and more brittle.
Increasing the amount of valeric acid in the polymer reduces the stiffness and increases the impact strength
and flexibility, making the material more attractive for flexible packaging.
Applications
By manipulating the co-polymer blends, PHAs can be produced with similar properties to PVC (flexible,
ductile and moisture and oxygen barrier) for films, LDPE (flexible, tough, ductile) for carrier bags, PP (tough,
high operating temperature) for food trays and high impact PS (strong, stiff, high softening temperature)
for disposable cutlery.
At present, the majority of PHA is used in flexible packaging applications.
End of life
PHAs are readily biodegradable in aerobic and anaerobic environments. A number of bacterial and fungal
species have been shown to produce extracellular PHA-degrading enzymes (PHA depolymerases), which
hydrolyse the polymer into water-soluble molecules that can be transported into the cells. The rate of PHA
degradation depends on the degree of crystallinity (slower for high crystallinity) as well as the
concentration and properties of the enzyme and reaction conditions.
Based on the relative ease of degradation most PHA-based products are compostable under industrial and
home composting conditions.
Concerns/challenges
The versatility of PHA co-polymer blends means that they can potentially be used for a range of
applications (e.g. water bottles) that are currently dominated by material types that have high collection
and recycling rates. PHAs are not compatible with PET or PP so there is a danger of contamination of
recycling streams if the products are indistinguishable.
Polybutylene succinate (PBS)
Raw material source and production
PBS is a linear polyester produced from succinic acid and butanediol monomers. Traditionally, the
monomers were produced by chemical synthesis, but genetically engineered strains of bacteria and yeast
have been developed to produce succinic acid by fermenting glucose.
The current market for PBS is around 100 000 tons per year. Virgin PBS resin sells for between $3000 and
$4000 per ton.
Basic properties
PBS is a thermoplastic with a melting temperature of 115˚C and a density of 1.26. It has similar properties
to polypropylene.
Applications
Biodegradable and compostable plastics: Material types and applications
x
The majority of PBS is currently used in flexible packaging and agricultural/horticultural applications.
End of life
PBS will degrade under industrial composting conditions within about 90 days. Under home composting
conditions degradation should occur within 12 months and under normal soil conditions in around two
years.
PBS and PBS blends do not readily degrade under anaerobic conditions.
As with most biodegradable polymers the rate of degradation is influenced by factors such as temperature
and the prevalence of bacteria and fungi. Therefore, in low-temperature marine environments, where
bacterial concentrations are low and fungi are often absent PBS-based materials can persist for extend
periods.
Concerns/challenges
Misleading labelling of fossil fuel-based PBS as bio-based.
Biodegradable, fossil fuel-based plastics
These materials are produced from monomers derived from fossil fuels but are still biodegradable and may
be compostable.
Polycaprolactone (PCL)
Raw material source and production
PCL is a biodegradable linear polyester that is produced from fossil fuel-based chemicals. The primary
method of production is the ring opening polymerisation of ε-caprolactone over a metal catalyst. ε-
caprolactone is synthesised via a series of chemical reactions, beginning with the conversion of benzene to
cyclohexane, the oxidation of cyclohexane to cyclohexanone and finally the oxidation of cyclohexanone
with peracetic acid.
The current market for PCL is estimated at around $500 million, with the majority of the demand for use in
the production of specialised polyurethanes. PCL resin sells for between $1000 and $3000 per ton.
Basic properties
Polycaprolactone is a thermoplastic with a melting temperature of 60˚C, a glass transition point of -60˚C
and a density of 1.145. PCL imparts good resistance to water, oil, solvents and chlorine. It is semi-
crystalline and the crystallinity decreases with increased molecular weight.
Applications
Native PCL degrades as a result of the hydrolysis of the ester linkages, so has been widely used in the
biomedical industry for implantable devices and controlled drug release devices. It is more crystalline than
PLA, so takes longer to degrade within the body.
For bioplastic applications PCL is typically blended with starch to reduce the cost, improve the barrier
properties and biodegradability.
Biodegradable and compostable plastics: Material types and applications
xi
End of life
Native PCL will degrade within 2-4 years by abiotic hydrolysis, but this is accelerated in enzyme-rich and
acidic environments. Starch-PCL blends are typically compostable under industrial and home composting
conditions.
Concerns/challenges
As PCL is fossil fuel-based it is subject to the several of the concerns raised about the sustainability of
traditional petrochemical-based polymers.
Bio-based, non-biodegradable plastics
These polymers are produced from monomers derived from renewable biomass that are identical to those
derived from fossil fuels, so have the same material properties and resistance to biodegradation.
Bio-PET/PP/PE/PVC
These bio-based polymers, also referred to as drop-ins, are produced from monomeric units derived from
bioethanol. They are structurally and functionally identical to the fossil fuel-based polymers and are
therefore not biodegradable or compostable, but can be recycled along with the traditional polymers using
the existing recycling infrastructure.
Polyethylene furanoate (PEF)
Polyethylene furanoate (Polyethylene 2,5-furandicarboxylate) is an aromatic polyester that can be
produced by polycondensation of 2,5-furandicarboxylic acid (FDCA) and ethylene glycol. PEF is an analogue
of PET that was first patented in 1951. It has become the subject of renewed interest since the US
Department of Energy identified the FDCA monomer as a potential bio-based alternative to purified
teraphthalic acid (PTA).
PEF offers superior thermal and gas barrier properties to PET, making it an attractive alternative,
particularly for small (250-330 ml) carbonate beverage bottles. In addition, a life cycle assessment by
Eerhart and co-workers in 2012 indicated that PEF significantly outperformed PET with respect to
greenhouse gas emissions and non-renewable energy use.
Recently, research in the field of advanced catalysis has demonstrated the potential of extracting glucose
from the lignocellulosic fraction of plant biomass and number of European companies intend scaling up the
conversion of the glucose to FDCA and then fully bio-based PEF.
PEF is not biodegradable, but can be mechanically recycled to rPEF in a similar way to the recycling of PET
to rPET. It has been reported that a small amount of PEF will can be processed with PET. PEF and PET can
be distinguished and separated using infra-red based automated separation, but this technology is not yet
widely available in South Africa.
Biodegradable and compostable plastics: Material types and applications
xii
At this stage, commercial production facilities for bio-based PEF are still being developed and are expected
to produce around 75 000 tons by 2023.
Biodegradable and compostable plastics: Material types and applications
xiii
Plastics with prodegradant additives
Prodegradant additives are added in small amounts to conventional polymers during processing and are
intended to accelerate the degradation of the polymer under oxidative conditions (oxo-additives) or due to
microbial degradation (bio-additives).
Oxo-degradable additives
These are a group of additives, often metal salts of carboxylic acids and dithiocarbamates, that are
marketed on the hypothesis that they accelerate the degradation of the polymer structure to produce
fragments with a molecular weight low enough that they can be broken down to carbon dioxide and water
by microorganisms. On this basis materials containing the additives are often referred to as oxo-
biodegradable.
The mechanism of action has been widely reported. Heat, oxygen, UV exposure and stress are responsible
for the generation of hydro-peroxide groups. The decomposition of these groups is catalysed by the metal
salts used in the additives and results in free radical formation. The radicals react with other polymer
chains to form carbonyl groups, including ketones. These can cause chain scission, which results in a loss of
mechanical properties and the polymer becomes brittle and prone to disintegration into small fragments.
There has been a substantial amount of industry-funded and independent research conducted on the
efficacy and potential environmental risks associated with oxo-degradable additives, with widely varying
results.
The most direct measurement of biodegradation under aerobic conditions is the conversion of polymer to
carbon dioxide. Proponents of oxo-degradable additives frequently cite research conducted by Chiellini
and co-workers. In these studies the additive containing films were first subjected to artificial weathering
conditions (UV light and/or heating at 50-70˚C) prior to the biodegradation studies. Results indicated a lag
phase of around 150 days, after which carbon dioxide evolution increased, achieving calculated
degradation rates between 45 and 60% after 600 days.
However, a number of other studies have presented conflicting results. A study by Portillo and co-workers
that applied the ASTM D-5208 protocol to PE films with and without oxo-additives, after initial treatment
under accelerated oxidation conditions (UV and elevated temperature). While the additive did induce
degradation under the accelerated oxidation conditions, including a reduction in molecular weight,
mechanical weakening and increase in carbonyl index (CI of 5.6 vs 0.59 for native PE) there was no
significant difference in subsequent biodegradation between native and additive containing material over
the 90 day test period. Other studies, which investigated the degradation of oxo-additive containing
materials in soil and aquatic (marine and freshwater) environments, without prior exposure to accelerated
oxidation conditions found very limited degradation.
A review of oxo-degradable plastics by Thomas and co-workers concluded that it is the low molecular
weight components of the oxidised oxo-degradable polymers that are capable of undergoing some
biodegradation. However, they note that it is difficult to extrapolate the accelerated oxidation conditions
to real world exposure, where UV, temperature and oxygen availability vary significantly. The review
concluded that under UK conditions oxo-degradable plastics in the environment would fragment in 2-5
Biodegradable and compostable plastics: Material types and applications
xiv
years and subsequent biodegradation of the fragments would proceed very slowly, many times slower than
compostable plastics. There is no data on degradation rates under South African environmental conditions.
The second major concern associated with oxo-degradable additives is the formation of microplastic
fragments that persist in the soil or aquatic environment, where they can be ingested by earthworms, birds
and fish. The potential for cross-linking of fragments, increasing their stability, has also been raised as a
concern. An associated concern is the potential of these fragments to concentrate pesticide residues in the
soil or the ocean, as has been shown for fragments of PP and PE. The tests typically performed to assess
biodegradability were not developed to investigate fragmentation, but the limited extent of biodegradation
observed in most studies strongly indicates the persistence of plastic fragments.
Producers of oxo-degradable additives claim that the additives do not negatively impact the mechanical
recyclability of the plastic. While this is strictly true, to the extent that even partially degraded plastic can
be re-melted and pelletised, recyclers have raised concerns around the mechanical integrity of the
recyclate. To date, oxo-additives have predominantly been used in films where there is limited post-
consumer collection and recycling, so potential impacts are limited. Application of the additives in PET or
HDPE bottles would substantially increase the potential for negative impacts. In South Africa, the previous
experimentation with oxo-additives in bread bags resulted in recyclers no longer accepting these products
and the recycling rate has not recovered over the last decade. Recent engagement with recyclers
confirmed that their attitude to oxo-additives has not changed.
Bio-additives
These are a group of propriety molecules (e.g. BioSphere) that are proposed to function by accelerating the
degradation of the polymer structure, followed by the microbial degradation of the small fragments.
Therefore, the overarching mechanism is similar to that for oxo-degradable materials, with the major
difference that the initial degradation is not induced by heat, UV and oxygen, but rather by microbial
action. The additives are said to reduce the hydrophobicity of the plastic, making it easier for microbes to
attach and initiate the degradation process.
Bio-additives have not been on the market for as long as oxo-additives and there have been no
independent scientific studies to verify the claims by the manufacturers. Internal and industry-
commissioned studies have shown slow degradation under anaerobic conditions, based on methane
production rates.
The manufacturers claim that the additives do not promote fragmentation in the same way oxo-additives,
but have not been able to provide definitive evidence to support this claim. In the absence of this, it can be
assumed that the plastic is likely to fragment and that the biodegradation of the fragments will proceed at
a similar rate to those induced by oxo-additives.
Biodegradable and compostable plastics: Material types and applications
xv
Summary of commercially available biodegradable plastics
Company
Product
Feedstock
Certification
Thermoplastic starch blends
Novamont
Materi-Bi
Starch-PCL/PVOH blends
Vegetable and/or fossil fuel raw material
Biodegradable
Industrial composting
Home composting
Rodenberg
Solanyl
Partially fermented starch
Second generation potato starch
Bio-based
Biodegradable
Industrial composting
Biotec
Bioplast
Starch polyester blend
Potato starch
Renewable feedstock
Biodegradable
Industrial composting
Home composting
Limagrain
Biolice
Starch polyester blend
Cereal and maize
Industrial composting
Plantic
Plantic HP
Corn starch
Bio-based
Biodegradable
Home compostable
BiologiQ
NuPlastiQ
Thermoplastic starch
Potato, corn and sugar beet
Bio-based
Industrial composting
Marine biodegradable
Polyhydroxyacids
Tianan Biologic
ENMAT (Y1000P)
Biodegradable
Industrial composting
Danimer Scientific
Noadx
Bio-based
Biodegradable
Industrial composting
Home composting
PLA
Total Corbion
Cane sugar and sugar beet
Bio-based
Industrial composting
Natureworks
Ingeo
Cassava, corn starch, sugar cane
Investigating 2nd generation feeds
Bio-based
Industrial composting
Untika
Terrmac
Bio-based
Biodegradable
Bonnie Bio
Corn starch
Biodegradable
Industrial composting
PBS/PBSA
Showa Highpolymer
Bionolle
Renewable starch/fossil fuels
Biodegradable
Industrial composting
IRe
Enpol
Biodegradable
Industrial composting
PCL
Perstorp
CAPA
Fossil fuels
Biodegradable
Industrial composting
PBAT
BASF
Ecoflex
Fossil fuel, partial biomass
Biodegradable
IRe
Enpol G8060
Fossil fuel
Biodegradable
Industrial compostable
Modified from The Green House - Decision Tree for Biodegradable Plastics
Biodegradable and compostable plastics: Material types and applications
xvi
References: Material types and applications
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Degradability of HDPE, LDPE, PE-BIO and PE-OXO Films Under UV-B Radiation. Journal of Spectroscopy
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2019 Edition.
Thomas, N.L., McLauchlin, A.R., Clarke, J., Patrick, S.G. (2012) Oxo-degradable plastics: degradation,
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Biodegradable and compostable plastics: Material types and applications
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