Polyvinyl alcohol (PVA) molecular weight and extrusion temperature in starch/PVA biodegradable sheets

Abstract The aim of this work was to study the relationship of chain size of partially hydrolyzed PVA blended with starch in properties of biodegradable sheets produced by thermoplastic extrusion. It was also studied the effect of extrusion temperature profile to determine the better PVA chain size and temperature profile to produce biodegradable sheets through a factorial design. The processability and the mechanical, thermal, optical, and microstructural properties of the biodegradable sheets were adequate, indicating that PVA/cassava starch blends have potential to replace conventional non-biodegradable polymers. Tensile strength and Young’s modulus ranges from 1.0 to 2.6 and 3.0 to 6.9 MPa respectively, the elongation at break ranges from 42 to 421%. It was not possible to state a conclusive relationship between PVA molecular weight and the materials properties, but in general, PVA with medium molecular weight and high extrusion temperature profile promote an increase of mechanical properties of the sheets.

摘要 本研究旨在探究部分水解聚乙烯醇（Polyvinyl Alcohol, PVA）与淀粉共混体系中，PVA链段尺寸对热塑性挤出制备可生物降解片材性能的影响。本研究同时通过析因实验设计考察挤出温度曲线的影响，以确定最优的PVA链段尺寸与挤出温度参数，实现高性能可生物降解片材的制备。对所得可生物降解片材的加工性能、力学性能、热学性能、光学性能及微观结构性能进行表征后发现，其各项性能均满足应用要求，表明PVA/木薯淀粉共混体系具备替代传统非可生物降解聚合物的应用潜力。该类片材的拉伸强度与杨氏模量分别介于1.0~2.6 MPa与3.0~6.9 MPa之间，断裂伸长率则处于42%~421%的范围内。尽管无法明确PVA分子量与材料性能之间的确定性关联，但总体而言，采用中等分子量PVA并配合较高的挤出温度曲线，可有效提升片材的力学性能。