Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2006
Publication Date: June 14, 2006
Citation: Glenn, G.M., Klamczynski, A., Ludvik, C.N., Chiou, B., Imam, S.H., Orts, W.J., Wood, D.F. 2006. 13th Annual BEPS International Meeting, Chicago, IL, June 14-17, 2006, Paper No. 50. Technical Abstract: The present study describes a method of making starch-based pellets that can be expanded into a low density foam by heating at ambient pressures. Conventional methods of making starch foam products typically rely on a rapid drop in pressure to induce foaming thus making it difficult to form molded articles. The present method of making starch foams relies only on heat to induce expansion and is better suited to making molded foam products. Formulations containing starch (50-85%), sorbitol (5-15%), glycerol (4-12%) talc (0-4%) ethylene vinyl alcohol (EVAL, 5-15%) and water (10-20%) were studied. The starch formulations were extruded into solid rods and pelletized into pellets 2 mm in diameter. The pellets were expanded with hot air (190°C) and evaluated for moisture resistance and bulk density. Bulk density was negatively correlated to sorbitol, glycerol and water content. The EVAL content increased bulk density, especially at concentrations higher than 15%. Wheat and potato starch formulations had a lower bulk density compared to formulations made with Dent corn starch. The expansion temperature for the starch pellets decreased more than 20°C as moisture content increased over the range of 10-25%. The addition of EVAL in the formulations decreased the equilibrium moisture content of the foam and reduced water absorption during a 1 hr soaking period. Pre-expanded pellets of starch were heated in a mold to form a molded article. The adhesion of the pre-expanded pellets was dependent on moisture content.