Extruded Starch/PVA Composites: Water Resistance, Thermal Properties, and Morphology

Abstract

Poor processability and strong hydrophilicity are the main disadvantages of starch/PVA (SP) composites. Thermoplastic SP composites are prepared by a single-screw extruder in this study. The influence of the formulation on the hydrophilicity of SP composites is studied by an orthogonal array and the analysis of variance (ANOVA). The results of ANOVA show that the water absorption (WA) of the SP composites with increasing amount of starch, but glycerol and citric acid (CA) are useful in decreasing the WA of the SP composites. Some interactions between the factors occur, the most important one being the interaction between WCA and WB. When the content of PVA is <30%, it shows good compatibility with starch, but the starch granules coalesce significantly according to the thermal analysis and SEM analysis. Increasing the amount of CA and borax can improve the mechanical properties of SP composites and decrease the WA of SP composites by cross-linking starch and PVA.