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Thermoplastic starches for industrial non-food uses

Thermoplastics based on petrochemical resources are widely used for production of films, coatings and food packaging. There are opportunities to replace these with biodegradable products based on starch. However, there is a need to match quality and performance of such novel products with those of the established plastics, at a competitive price. The project obtains more background information concerning factors of relevance to production and use of thermoplastic starches. In particular, the project focuses on phase transitions and time-dependent changes in properties in relation to biodegradability, raw material composition and chemical structure, as well as mechanical and thermal history during manufacture.

Wet and dry separation technology has resulted in starches and starchy fractions of wheat, smooth and wrinkled pea, maize and rye, providing well characterized materials to the participants. The melting of starch has been studied and the effects of low molecular weight solutes have been investigated. Two methods for quantitative analysis of starch crystallinity have been developed and initial experiments investigating the changes in starch structure during extrusion have been performed, showing that during extrusion crystallinity and helicity decrease steadily but other structures appear to be formed that have a significant effect on the mechanical properties. A test device has been developed for compression moulding of starch below and above plasticization temperature. It was demonstrated that the amount of water present during processing influences the mechanical properties of thermoplastic starch, while various chemical modifications of starch have been carried out to increase hydrophobicity, with both high and low degrees of substitution. The potential for controlling enzymatic activity in extruders was identified in a two stage extruder. Main variables and operating conditions have been analysed. Kinetic analysis of retrogradation processes have been carried out and a model for this process was developed. Influence of the composition has been studied.

Contact

Huibert TOURNOIS
Tel.: +31-8370-75015
Fax: +31-8370-12260
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