The processing of starch as a thermoplastic

The thermoplastics processing of native starch in the presence of water is a recent development with very wide possible applications. Eventually, oil-based polymer materials have to be replaced in many applications by sustainable, inexpensive, natural materials from renewable resources. As with conventional thermoplastics, starch-water melts may be processed by injection moulding and extrusion. The present contribution focuses on injection moulding. The bases of the processing and the thermal and molecular changes occurring are described. In addition, the rheological behaviour of the starch-water melts during processing is analysed quantitatively to give apparent melt viscosities. The dimensional, thermal and mechanical properties of moulded thermoplastic starch polymer (TSP) materials and the products presently being produced from them are discussed.