柠檬酸对挤压吹塑淀粉/聚乙烯醇复合膜性能的影响

摘要

为了提高淀粉基复合膜的阻水性和疏水性,选取羟丙基二淀粉磷酸酯与聚乙烯醇(PVA)为成膜基材,添加柠檬酸为交联剂,采用挤压吹塑法制备了淀粉/PVA复合膜,并对其流变性能、阻水性能、疏水性能和交联程度等进行表征.结果表明,随着柠檬酸添加量的增加,高聚物流体的表观黏度升高,淀粉/PVA复合膜的交联和酯化程度随之增加,淀粉膜的抗拉强度和拉伸模量呈降低趋势,而断裂伸长率先升高后降低;添加2％的柠檬酸,淀粉/PVA复合膜的阻水性最佳,疏水性最强,具有最小的溶胀度、最大的凝胶质量和最高的交联密度.%To improve the moisture barrier properties and hydrophobicity of starch-based composite films,hydroxypropyl distarch phosphate and polyvinyl alcohol (PVA)were selected as film forming substrate,adding citric acid as crosslinking agent.The starch/PVA composite films were prepared by extrusion film blowing in this study.Besides,the rheological properties,moisture barrier properties,hydrophobic properties and the degree of crosslinking were characterized.The results showed that both the apparent viscosity of the polymer fluid and the crosslinking and esterification degree of starch/PVA composite films increased accompanied with the increase of citric acid content.At the same time,the tensile strength and tensile modulus decreased and the elongation at break increased first and then decreased.The starch/PVA composite film with 2％ citric acid had the best moisture barrier property,the strongest hydrophobic property as well as the smallest swelling degree,the largest gel mass and the highest crosslinking density.