接枝聚乳酸/塑化淀粉共混物的制备与性能研究

为提高聚乳酸(PLA)/淀粉共混物界面作用和降低成本,引入甲基丙烯酸缩水甘油酯(GMA)接枝聚乳酸和塑化淀粉(TPS),通过挤出和注射成型制备接枝聚乳酸/塑化淀粉共混物(PLA-g-GMA/TPS)。红外光谱分析证实,GMA成功接枝到PLA分子链上。对共混物的力学性能、热机械性能、微观形貌、热性能及亲水性等进行了系统研究,结果表明,选择GMA用量为6%(接枝率为1.51%)和TPS用量为10%时的拉伸强度、断裂伸长率及弹性模量最佳,分别为42.6MPa、8.9%及260MPa。FE-SEM观察结果表明,低含量TPS中颗粒被基体包覆或嵌入,界面平整,界面结合力强。DMA和DSC结果显示,不同质量配比的PLA-g-6%GMA/TPS共混物的Tg、储存模量、结晶度、结晶温度及熔融温度仅在小范围内发生变化。吸水率和接触角结果表明,低含量TPS的共混物吸水率和接触角变化幅度均小于高含量TPS体系。

The Preparation and Property Measurements of the Grafted Poly(lactic acid) and Plastified Starch Blends

The grafted poly(lactic acid)/thermoplastic starch blends with glycidyl methacrylate and thermoplastic starch addition were prepared by extrusion and injection molding technologies to improve the interfacial adhension of PLA/starch and lower the cost.Infrared spectrum analysis confirms that GMA has been successfully grafted onto the PLA.The mechanical properties,the thermal properties,the morphology of fractured composite surfaces and hydrophilic properties above were well-analyzed.The optimum results of tensile strength,elongation at break and elasticity modulus are 42.6MPa,8.9％ and 260MPa respectively,which is explored at the mass of 6％ GMA and 10％ TPS (the grafting ratio is 1.51％).Compared with higher thermoplastic starch content in the blends,the FE-SEM observations show that the starch particles on the tensile fracture surface of lower thermoplastic starch content are better embedded in the matrix,resulting in the partial starch granules and a strong interfacial adhension obviously.DMA and DSC results show that Tg,storage modulus,crystallinity,crystalline temperature and melting temperature just change on a small scale with different mass ratio of PLA-g-6 ％ GMA/TPS blends.The results of water absorption and contact angle values indicate that the blends of lower thermoplastic starch change less than those of higher thermoplastic starch.