Recycling rice husk ash as a filler on biodegradable cassava starch-based foams.

Starch-based foams can be used in packaging development to replace nonbiodegradable petrochemical plastics. However, starch-based materials possess poor mechanical properties and low water resistance. These properties can be improved by adding plasticizers and fillers to the bulk composition. In the present work, the effect of rice husk ash content on physical, morphological, and mechanical properties of cassava starch-based foams produced by thermal expansion was investigated. The composites were formed by mixing cassava starch, rice husk ash (content varying from 0 to 60%), water, and glycerol. The obtained dough was placed in a metallic mold and then expanded in a thermohydraulic press machine. The addition of 20-50% of ash content improved thermal stability, density, and biodegradation of starch-based foams and decreased water absorption capacity. Filled starch-based foams also exhibited smaller pores in internal structure. Compared to foams without ash filler, the addition of 20-40% ash increased the flexural tensile strength and the addition of more than 50% dropped the mechanical resistance. Hence, based on the results obtained, rice husk ash can be a great filler in biodegradable starch-based foams.