Functional properties of polylactic acid starch-based loose-fill packagingfoams

In this study, attempts were made to improve the characteristics of starch- based plastic foams by blending starch with polylactic acid (PLA), a biodeg radable polymer made from renewable sources. Formulations of the foams (typ es of starch, ratio of starch to polymer, and moisture content) were optimi zed. Physical and mechanical properties of the foams, including expansion, unit density, bulk density, water solubility index (WSI), spring index, and compressibility on both single piece and bulk samples were determined. The addition of the PLA polymer to regular (25% amylose) and waxy corn starche s significantly improved the physical and mechanical properties of the extr uded foams. Foams made from waxy starch had better radial expansions, highe r WSI, higher compressibilities, and lower spring indices than those of reg ular starch foams. Both regular and waxy starches produced foams with simil ar unit and bulk densities, bulk compressibilities, and bulk spring indices . Increasing PLA polymer contents increased the radial expansions and sprin g indices and significantly reduced the unit and bulk densities and bulk co mpressibilities. Changing the PLA content had no significant effect on WSI, compressibilities, and bulk spring indices. Increasing the moisture conten t adversely affected foam characteristics. The formulation containing waxy starch, 40% PLA, and 19% moisture produced a loose fill foam with the best physical characteristics and mechanical properties.