Composites Design and Manufacture (Plymouth University teaching support materials)
Bio-based and biodegradable resins.

CAUTION: For the purpose of the Sustainable Composites pages, the materials described are those from natural sources, without prejudice to the results of any future Quantitative Life Cycle Analysis (QLCA) which may (or may not) make the case for these materials being more environmentally-friendly than equivalent systems manufactured from man-made fibres and synthetic resins.  The inclusion of any specific system here is not an endorsement of that product: potential users will need to fully consider each system in the context of their specific technical requirements.

The value of Eco-System Services

Reddy et al [1] have presented a series of definitions pertinent to "bio-plastics", as follows:

InnProBio (the Forum for Bio-Based Innovation in Public Procurement) have published a series of factsheets:

  1. What are bio-based products?
  2. Sustainability of bio-based products
  3. Biodegradability - exposing some of the myths and facts
  4. Bio-based Products and Services in the Circular Economy
  5. Life Cycle Assessment (LCA) and Life Cycle Costing (LCC)

The Bio-Based Industries Joint Undertaking has a website with summaries of relevant funded projects.


CPLA (polylactide aliphatic copolymer) [3] is a biodegradable mixture of lactide and aliphatic polyesters. It can be either a hard plastic (similar to PS) or a soft flexible one (similar to PP) depending on the amount of aliphatic polyester present in the mixture.  It is easy to process with stability up to 200 °C. Possible applications will include compost bags, cushioning materials, food wrapping materials, fishing nets, etc.

PCL (polycaprolactone) [4, 5] is a biodegradable thermoplastic polymer made by polymerizing ε-caprolactone and hence derived from the chemical synthesis of crude oil. Although not produced from renewable raw materials, it is fully biodegradable.  It has good water, oil, solvent and chlorine resistance, a low melting-point (58-60 °C), low viscosity and it is easy to process.  It is used mainly in thermoplastic polyurethanes, resins for surface coatings, adhesives and synthetic leather and fabrics. It also serves to make stiffeners for shoes and orthopaedic splints, and fully biodegradable compostable bags, sutures, and fibres.  It is used as an additive for other resins to improve their processing characteristics and end use properties, and acts as a polymeric plasticizer with PVC.  PCL is compatible with most thermosetting and thermoplastic resins and elastomers. It increases impact resistance and aids mould release of thermosets.

PGA (polyglycolicacid) is a synthetic polymer of glycolic acid (HOCH2COOH).  As the monomer is terminated by a hydroxyl group at one end and a carboxyl group at the other, it can be polymerised by a condensation reaction to yield a polyester.  The polymer degrades to natural metabolic waste products and finds use in biomedical applications.

PHA (polyhydroxyalkanoate) [6, 7] is a class of linear polyesters produced in nature by bacterial fermentation of sugar or lipids.  More than 100 different monomers can be combined within this family to give materials with extremely different properties.  They can be either thermoplastic or elastomeric materials, with melting-points ranging from 40 to 180°C.  The most common type of PHA is PHB (poly-beta-hydroxybutyrate).  PHB has properties similar to those of PP, however it is stiffer and more brittle. More detail can be found on the AZoM site [8].  A PHB copolymer called PHBV (polyhydroxybutyrate-valerate) [6] is less stiff and tougher and finds use as packaging material.  More detail can be found on the AZoM site [9].

PLA (polylactide) [10, 11] is a biodegradable thermoplastic derived from lactic acid.  It resembles clear polystyrene, provides good aesthetics (gloss and clarity), but it is stiff and brittle and needs modifications for most practical applications (i.e. plasticizers increase its flexibility).  It can be processed like most thermoplastics into fibres, films, thermoformed or injection moulded. It is most commonly used for compost bags, plant pots, diapers and packaging.  Cargill Dow’s NatureWorks PLA [12, 13] is derived from corn.  Gupta et al [14] have reviewed the use of PLA as a fibre and identified the following key data: Tg ~60-70ºC, Tm ~150-170ºC, E(fibre) = 1.2-9.3 GPa, σt'(fibre) = 42-870 MPa and εt'(fibre) = 4-440% dependent on the processing route used.  Clark and Hardy [15] have compared and contrasted the sustainability implications of the life cycle of PLA with that for conventional polymers.  Life Cycle Assessments exist for PLA [16, 17].

DuPontTM Sorona® [18] is one member of a family of polymers based on Bio-PDO™ corn-derived chemical/1,3-propanediol: poly (trimethylene terephthalate), i.e. bio-based PTT.

There is some interest in the use of starch-based polymers as "sustainable" materials for extrusion or injection moulding.  However, processing these materials is more complex than using conventional polymers and involves multiple chemical and physical reactions, including water diffusion, granule expansion, gelatinisation, decomposition, melting and crystallization.  The thermal processing of these materials has been reviewed by Hongsheng Liu et al [19].   Starch-based resins can be made from corn, wheat, tapioca and potato (e.g. Cereplast Compostables® [20] and Potatopak [21]).

The UK government has run a series of projects under the LINK collaborative research scheme in Competitive Industrial Materials from Non-Food Crops (CIMNFC).  Of particular relevance to natural resins is StarPlast (lead by the IRC in Polymer Science & Technology at the University of Leeds):


  1. MM Reddy, S Vivekanandhan, M Misra, SK Bhatia and AK Mohanty, Biobased plastics and bionanocomposites: current status and future opportunities, Progress in Polymer Science, October–November 2013, 38(10–11), 1653-1689.
  2. Silvia Forni, EU policy framework on biobased and biodegradable plastics, Biodegradable plastics: how do we engage with consumers and society? webinar, streamed live on 21 May 2021.
  3. Torben Lenau, CPLA - polylactide aliphatic copolymer,, accessed Saturday 27 November 2004 12:04.
  4. Torben Lenau, PCL - polycaprolactone,, accessed Saturday 27 November 2004 12:07.
  5. Polycaprolactone,, accessed Saturday 27 November 2004 12:26.
  6. Torben Lenau, PHAs - polyhydroxyalkanoates,, accessed Saturday 27 November 2004 12:11.
  7. E Bugnicourt, P Cinelli, A Lazzeri and V Alvarez.[92 references]: Polyhydroxyalkanoate (PHA): review of synthesis, characteristics, processing and potential applications in packaging, Express Polymer Letters, 2014, 8(11), 791-808.
  8. Supplier data - polyhydroxybutyrate (PHB) Biopolymer,, accessed Saturday 27 November 2004 12:16.
  9. Supplier data - polyhydroxybutyrate/polyhydroxyvalerate 8% ( PHB92/PHV8 ) Biopolymer,, accessed Saturday 27 November 2004 12:19.
  10. Torben Lenau, PLA- polylactide,, accessed Saturday 27 November 2004 12:00.
  11. L-T Lim, R Auras and M Rubino, Processing technologies for poly(lactic acid), Progress in Polymer Science, August 2008, 33(8), 820-852.
  12. Plastics Produced from Renewable Sources Such as Corn Gaining in Popularity,, accessed Saturday 27 November 2004 12:21.
  13. Natureworks LLC,, accessed 15:20 on Monday 26 June 2006.
  14. Bhuvanesh Gupta, Nilesh Revagade and Jöns Hilborn, Poly(lactic acid) fiber: an overview, Progress in Polymer Science, April 2007, 32(4), 455-482.
  15. JH Clark and JJE Hardy, Towards sustainable chemical manufacturing: polylactic acid - a sustainable polymer?, Chapter 7 in A Azapagic, S Perdan and R Clift (editors), Sustainable Development in Practice - Case Studies for Engineers and Scientists, John Wiley & Sons, May 2004.  ISBN 0-470-85609-2.  Second edition: ISBN 978-0-470-71872-8.  PU CSH Library.
  16. AM Curran, Environmental life-cycle assessment, McGraw Hill, New Yourk, 1996. ISBN 0-07-015063-x.
  17. V Piemonte, Bioplastic wastes: the best final disposition for energy saving, Journal of Polymers and the Environment, December 2011, 19(4), 988-994.
  18. DuPontTM Sorona® Technology Platform,, accessed 15:16 Friday 11 February 2005.
  19. Hongsheng Liu, Fengwei Xie, Long Yu, Ling Chen, Lin Li, Thermal processing of starch-based polymers, Progress in Polymer Science, December 2009, 34(12), 1348-1368.
  20. Cereplast Incorporated, The renewable plastic, 2006, accessed 09:55 on 31 October 2009.
  21. Potatopak Limited,, accessed 10:00 on 31 October 2009.


For review papers on bio-based resins, follow this link.

Further reading

  1. Li Shen, J Haufe and MK Patel, Product overview and market projection of emerging bio-based plastics, Utrecht University report PRO-BIP 2009 for European Polysaccharide Network of Excellence and European Bioplastics, June 2009.
  2. JH Clark and JJE Hardy, Towards sustainable chemical manufacturing: polylactic acid - a sustainable polymer?, Chapter 7 in A Azapagic, S Perdan and R Clift (editors), Sustainable Development in Practice - Case Studies for Engineers and Scientists, John Wiley & Sons, May 2004.  ISBN 0-470-85609-2.  Second edition: ISBN 978-0-470-71872-8.  PU CSH Library.
  3. F Seniha Güner, Yusuf Yagci and A Tuncer Erciyes - Polymers from triglyceride oils, Progress in Polymer Science, 2006, 31(7) 633–670.
  4. Long Yu, Katherine Dean and Lin Li, Polymer blends and composites from renewable resources, Progress in Polymer Science, June 2006, 31(6), 576–602.
  5. Anders Södergård and Mikael Stolt - Properties of lactic acid based polymers and their correlation with composition, Progress in Polymer Science, 2002, 27(6), 1123-1163.
  6. R Chandra and R Rustgi, Biodegradable polymers, Progress in Polymer Science, 1998, 23(7), 1273-1335.

Suppliers of bio-based thermosetting resins.

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Updated by John Summerscales on 03-Jun-2021 22:15. Terms and conditions. Errors and omissions. Corrections.