Biodegradable flexible foam: Novel material based on cassava TPS obtained by extrusion

Abstract

Thermoplastic foams made from petrochemical polymers are commonly commercialized in the market, which, due to their chemical nature, require hundreds of years to degrade and therefore end up accumulating and polluting the environment. Therefore, the present research sought to develop a biodegradable foam from thermoplastic cassava starch, biodegradable polyester, and wheat gluten. Initially, an extreme vertex blend design was run, which comprised 60 to 70% thermoplastic starch (TPS), 30 to 40% biodegradable polyester, and 0 to 5% wheat gluten, the foam was obtained by extrusion and evaluated for expansion rate, bulk density, damping index, and morphology. A thin layer of rubber latex was applied to the foamed material with the most outstanding properties in order to reduce moisture adsorption, and its biodegradability was also evaluated. The results indicated that with the addition of 70% TPS, 30% polyester, and 0% wheat gluten, it was possible to obtain by extrusion a flexible thermoplastic foam with high radial expansion rate and low bulk density. Impregnation of the foam with natural rubber latex created an impermeable layer that helped to decrease moisture adsorption; however, there was an increase in compressibility. Also, it was found that this foam met the biodegradability condition since it presented a percentage of mineralization in relative terms of 97.59% in less than 180 days.