Biopolymers

Softcover  158 pp  ISBN 9781859573792      £85.00

The earth has finite resources in terms of fossil origin fuel and a finite capacity for disposal of waste. Biopolymers may offer a solution to both these issues in the long-term. The ideal biopolymer is both of renewable biological origin and biodegradable at the end of its life. In some cases material may be of a biological origin and not readily biodegradable, such as thermosets made from cashew nut shell liquid. On the other hand, polyvinyl alcohol is an example of a polymer of a synthetic origin and biodegradable.

Environmental degradation can involve enzymatic pathways and microorganisms such as bacteria and fungi, or chemical pathways such as hydrolysis. It is important that biopolymers have an adequate life span for applications - their biodegradability makes them ideal for use in resorbable medical products such as sutures, in short-term packaging applications for fast foods and fresh groceries, and for sanitary uses.

This review sets out to examine the current trends in biopolymer science. The different types of biological polymers are discussed. The chemistry and synthesis of some key biopolymers is described, including cellulose, hemicellulose, starch, polyhydroxyalkanoates (of bacterial origin), tannins (polyphenolic plant products), cashew nut shell liquid, rosins (from tree sap), lignin (from wood), and man made polylactides. Many other biopolymers are also being investigated, for example, alginates from seaweed and algae, and proteins such as casein and soybean. The abstracts at the end of this report cover an extensive range of materials and are fully indexed.

Commercially, bioplastics have proven to be relatively expensive and available only in small quantities. This has lead to limitations on applications to date. However, there are signs that this is changing, with increasing environmental awareness and more stringent legislation regarding recyclability and restrictions on waste disposal. Cargill Dow has a polylactic acid polymer in production (Natureworks). Metabolix has been working on polyhydroxyalkanoates (Biopol). Several companies have been developing starch products such as Avebe, Biop, Earthshell and Midwest Grain Products Inc. Polyols for polyurethane have been obtained from vegetable oils, etc.

Certification of compostability is now available from DIN CERTCO. The requirements for this standard are discussed in the report. Additives can compromise the environmentally-friendly status of a polymer and must be chosen with care. Thus natural fibre reinforcements are also discussed briefly here. Biocomposites have been developed comprising natural origin polymer matrices and natural fibres, such as sugar cane bagasse and jute.

This review is accompanied by over 400 abstracts compiled from the Polymer Library, to facilitate further reading on this subject. A subject index and a company index are included.

Contents

• Introduction
• Synthesis of Biopolymers
• Commercially Available Biopolymers
• Uses of Biopolymers
• Fillers and Reinforcement for Biopolymers
• The Markets and Economics for Biopolymers
• Compostability Certification
• The Chemistry and Biology of Polymer Degradation
• Conclusions

Additional References
Abbreviations and Acronyms