Eco-friendly biodegradable foam composite from natural rubber and cassava starch

Abstract

We thoroughly investigated eco-friendly biodegradable foam from natural rubber (NR) and cassava starch (CS); NR/CS foams. NR, CS, polyethylene glycol (PEG) as a plasticizer, dicumyl peroxide (DCP) as a crosslinker, and azodicarbonamide (ADC) as a blowing agent were compounded in an internal mixer and subsequently cooled down using a two-roll mill. The effect of CS and PEG content on the properties of NR/CS foams was investigated. As evidenced by Mooney viscosity measurement, the viscosity of NR/CS compounds increased with higher CS contents, whereas the viscosity decreased with increasing PEG contents. The rise in viscosity in the NR/CS compounds resulted in increased pore size of NR/CS foams, with pore dimension expanding from 42 to 144 µm as viscosity increased from 17 to 50 ML 1 + 4 at 100°C. The increase in the CS contents in NR/CS foams resulted in an overall decrease in tensile strength, elongation at break, and rebound resilience but provided greater biodegradability. The foam containing 250 phr of CS exhibited a weight retention of only 32% after 1 month of soil burial. On the contrary, with increasing PEG contents, the tensile strength and elongation at break of the NR/CS foams showed an increasing trend. However, rebound resilience and biodegradability decreased. The pore size of the NR/CS foams is a key factor in the water and vegetable oil swelling behavior. The water and vegetable oil swelling increased with an increasing pore size of NR/CS foams. These findings indicated that NR/CS foam has significant potential for various applications, including shockproof and food packaging, while also contributing to the reduction of environmental problems.