Production of Plant Polymers and Biodegradable Plastics

Plastics are important materials in everyday use. They are polymers that can be moulded using heat and pressure. However, they present serious problems of disposal, persistence and environmental pollution and it would be preferable if biodegradable plastics could be generated from agricultural products, which could be degraded biologically to carbon dioxide and water.Potential sources of biological polymers include starch, cellulose, pectins, proteins and PHB. Various native starches from wheat, rice, maize and potato have been used to make plastics and a range of shaped products have been manufactured.However, production of PHB or related polyhydroxyalkanoates in plants provides the most attractive sources of biodegradable plastics at low cost. These crops will enhance the value of production and benefit land use and waste disposal.
A combination of microbiology, polymer chemistry and plant biotechnology is likely to provide new crops providing valuable non-food products. For example, there is the prospect of growing ‘easy-care’ polyester cotton, in which PHB is deposited in the hollow central lumen of the cotton fibre. Less than 1% of PHBs can improve the insulating property of the cotton fibre by 8–9%.