MECHANICAL PROPERTIES OF STARCH-BASED FOAMS AS AFFECTED BY INGREDIENT FORMULATIONS AND FOAM PHYSICAL CHARACTERISTICS

摘要

Mechanical properties of foams extruded with starch and biodegradable polymers were correlated with ingredient formulations and physical characteristics of the extrudates. The type of polymer had a significant effect on foam compressibility and Young’s modulus. The PLA-starch and EBC-starch foams were softer than the Mater-Bi ® -starch foam. Both regular and waxy corn starch-based foams had similar mechanical properties. Spring indices were not affected by the types of polymers and starches. A 25% polymer content resulted in the softest foams. Foams containing 10% polymers possessed the highest spring indices. Higher moisture contents increased the compressibilities and spring indices. A moisture content of 22% resulted in the lowest Young’s modulus. The relationships between the compressibilities, Young’s moduli and the physical characteristics were described by power law equations. Compressibilities and Young’s moduli decreased as radial expansion increased, and increased as the unit densities increased. Unit density had little effect on spring index. Increasing bulk density significantly increased compressibility and Young’s modulus. The correlations between spring indices and physical characteristics were low.