Effect of agar and walnut (Juglans regia.L) shell fibre addition on thermal stability, water barrier, biodegradability and mechanical properties of corn starch composites

ABSTRACT Starch-based films plasticised with sorbitol and citric acids as cross-linking agents were synthesised by the solvent casting method with varying concentrations of agar. The films were characterised in terms of TGA, water barrier, tensile data and soil burial degradability testing. The increasing concentration of agar enhanced the thermal stability and degradability of the composites. At an optimum level of agar, the film showed the maximum tensile strength (17.84 ± 0.23) MPa which was further chosen to analyse the additional effect of walnut shell fibre (WSF). The film containing WSF showed a remarkable improvement in tensile strength (TS) up to 15% (29.43 ± 0.75) MPa. The analysis of variance (ANOVA) of the tensile data confirmed the significant differences in the mean tensile strength from one kind of polymer blend to another (p < 0.05). TGA results showed that there was a regular increase in onset degradation temperature (To) and a decrease in weight loss percentage (at To) of starch/agar composites with the addition of fibre. The blends were more resistive towards water absorption in comparison to virgin. GRAPHICAL ABSTRACT