Biodegradable plastic from cross-linked rice flour: Effect of cross-linking agent and plasticizer

Abstract

Plastics made from petroleum have long been used in packaging. However, most plastics end up in landfills and bodies of water. Moreover, plastic does not degrade for hundreds of years, creating an issue for the ecosystem. One of the solutions is to use biodegradable plastic instead of petroleum-based plastic. Numerous studies have been conducted on manufacturing biodegradable plastic from renewable resources like starch. Rice flour, which contains up to 93.3% starch, is a potential material for biodegradable plastic. The flour was modified by cross-linking with sodium trimetaphosphate (STMP) before producing biodegradable plastic. This work aimed to study the effect of the amount of STMP (1%, 2% and 3%), the type of plasticizer (glycerol and sorbitol), and the amount of the plasticizer (40%, 50% and 60%) on the properties of the plastic. The amount of STMP decreases the swelling index and increases the tensile strength, but it does not significantly affect the biodegradability of the plastic. Although the plasticizer enhances biodegradability and reduces the tensile strength, it has little effect on the swelling index. The glycerol-plasticized plastic has a higher swelling index and biodegradability but lower tensile strength than the sorbitol-plasticized plastic. Plastic with 40% sorbitol and 3% STMP has the highest tensile strength (4.3 MPa).