Synthesis and characterization of PVA/Starch/CMC composite films reinforced with walnut (Juglans regia L.) shell flour

Polyvinyl alcohol/Starch/Carboxymethyl cellulose (PSC) composite films were synthesized by solvent casting method using glycerol as plasticizer and citric acid as cross linking agent. The effect of different loadings of carboxymethyl cellulose (CMC) on thermal and tensile properties of PVA/Starch (PS) composites was investigated. The increasing concentration of CMC enhanced the thermal stability of PS composite films. PSC film at an optimum level of CMC showed the maximum tensile strength (36.56 +/- 1.54 MPa) and was further chosen to analyze the effect of walnut shell flour (WSF) addition. PSC films reinforced with different amounts of WSF were analyzed by thermogravimetric analysis, UV absorption spectra, tensile testing, water absorption study and soil burial degradability test. The reinforcement of WSF showed a remarkable improvement in thermal stability and water resistant property of the films. Addition of WSF in PSC films reduced the degradability of films, with maximum percentage of weight loss obtained with 2% loading. Further, the tensile strength was found to be improved up to 6% level (41.09 +/- 0.71 MPa). ANOVA of the tensile data recognized the considerable differences between the mean tensile strength from one composition to another (p < 0.05).