Effect of formulation and process on the extrudability of starch-based foam cushions

Abstract

Solid foams produced from petroleum sources have a number of environmental and sustainability issues. Using renewable resources to produce foams has great perspectives but those kinds of foams are technically difficult to process. Starch foams from wheat, pea and potato starches were prepared using reactive extrusion with different concentrations of starch/glycerol/gluten/sodium bicarbonate. The density, the expansion ratio, the elasticity and the dynamic damping properties of such foams were determined. Foams made from wheat starch exhibited the best mechanical properties, especially during ageing. Using the ratios of wheat starch/glycerol/gluten/sodium bicarbonate that gave the best results (100/46/25/1), extrusion parameters were adjusted and higher and more stable expansion (Expansion ratio = 9.1) was obtained when the screw speed was as low (300 rpm) as the highest input rate could afford (21 kg/h).