Preparation and characterization of low density polyethylene/modified chitosan/papain composite

Abstract

The objective of this research was to impart biodegradability to a polyethylene blend using Chitosan as the main additive which was extracted from fishery waste. Papain, a natural enzyme derived from papaya plant, was also used to enhance the biodegradability. The biodegradability of this Polyethylene blend was studied using low molecular weight chitosan both in the presence and absence of papain. The influence of concentration and type of alkali on the chitin yield and chitosan obtained from deacetylation process were investigated. Low molecular weight chitosan was prepared by different depolymerization methods. This study investigated the time dependent weight loss using soil burial test, stress – strain properties and water absorption properties of the developed polymer, to evaluate the degree of biodegradability. The Fourier transform infrared spectroscopy (FTIR), Differential thermal analysis (DTA), Thermogravimetric analysis (TGA) and optical and Scanning electron microscopic investigation (SEM) were used to determine the properties of LDPE – Chitosan – Papain composite. The optimum composition for the industrial trial production was selected by considering the tensile strength, elongation, optimum degradability as well as good processability. Industrial trial production was done using composition containing of LDPE with 5% chitosan and 3% papain by weight. Soil burial test results showed that specimens degraded by 60% in a six month period, while complete degradation occurred after one year. Since experimental analysis did not indicate formation of new bonds, it could be concluded that Chitosan, LDPE and Papain are present in the final product as a physical mixture without any detectable chemical reactions among different constitutes. Products manufactured in industrial scale also showed appreciable biodegradable properties. The biodegradation mechanism proposed for LDPE – Chitosan – Papain composite is based on the hydrolysis followed by actions of microorganisms.