PROCESSING AND CHARACTERIZATION OF BIODEGRADABLE PRODUCTS BASED ON STARCH

Different types of starch were processed in blend systems with natural plasticizers and commercial fibres by conventional extrusion and inje ction moulding techniques. Processing conditions and product qualities differed widely according to the kind of starches and additives used. Starch polymer characteristics, i.e. amylose/amylopectin ratio and mo lecular mass distribution, were studied in native and extruded samples in order to reveal structural effects on product quality. As a result it could be shown that thermomechanical treatments of starch caused s ignificant depolymerization, especially of the amylopectin fraction, w hile the amylose fraction remained stable. Considerable improvements i n product properties were achieved by adding small amounts of fibres t o the starch samples. Blend systems with 2-7% fibres resulted in an in crease of tensile strength and water resistance of these products. (C) 1998 Elsevier Science Limited. All rights reserved.