Synthesis of citric acid crosslinked PVA/tapioca starch bioplastic reinforced with grafted cellulose

Abstract

Cellulose was grafted by palmitic acid with a yield of 61 ± 14 %. The crystallinity of cellulose decreased after grafting. PVA/starch bioplastic films were synthesized from PVA crosslinked with tapioca starch by the addition of activated citric acid as a crosslinker and then reinforced with the addition of cellulose and grafted cellulose. Activated citric acid was produced by converting the acid into a more reactive anhydrous state through heating. Characterization was carried out by FTIR. In addition, tensile test, swelling test, and solubility test were also carried out. Transparency of the plastics increased after the addition of starch, and further increased after the addition of cellulose. PVA films was very soluble in water because of the OH groups on its backbone structure. Crosslinking with starch and the strengthening with cellulose were able to reduce the swelling and solubility. However, the addition of grafted cellulose was unable to improve swelling and solubility because of the palmitic acid disturbing the plastic network. The addition of starch, cellulose, and grafted cellulose, respectively decreased the tensile strength of the original PVA films. Strength wise, PVA and crosslinked PVA/starch films were similar to that of HDPE and LDPE, respectively, yet elasticity wise they are much weaker.