聚碳酸亚丙酯/聚乳酸共混物光照条件下的降解行为研究

Degradation Properties of Poly(propylene carbonate)/Poly(lactic acid) Blends Under Natural Light Irradiation

研究了聚碳酸亚丙酯(PPC)/聚乳酸(PLA)共混物在光照条件下的降解性能,通过力学实验、质量变化、扫描电子显微镜等分别研究了共混物的力学性能、质量损失、表面微观形貌等的变化规律。结果表明,100/0、70/30、50/50、30/70、0/100(质量比,下同)的PPC/PLA共混物光照56d时质量损失率分别为34.89%、40.50%、39.38%、29.6%、6.24%;共混物在14d时几乎损失所有的力学性能;光照56d后PPC和50/50的PPC/PLA共混物表面有明显的裂纹和孔洞,而PLA表面没有变化;光照时间越长,共混物表面越粗糙,降解程度越大;共混物的羟基指数和羰基指数在前21d不断增大,其中前14d比较明显;共混物在光照56d后相对分子质量降低,多分散性指数减小,相对分子质量分布变窄;共混物失重5%的热分解温度和最大速率失重温度提高,而PPC的最大速率失重温度却降低。

The degradation properties of poly(propylene carbonate)(PPC)/poly(lactic acid)(PLA)blends were studied under natural light irradiation,andthevariations in mechanical properties,weight loss,surface microstructure of the blends were investigated.The results indicated that the weight-loss rate of the blends were 34.89 wt%,40.50 wt%,39.38 wt%,29.6 wt%and 6.24 wt%at the PPC/PLA mass ratios of 100/0,70/30,50/50,30/70 and 0/100,respectively,after irradiation for 56 days.The blends lost almost all of their mechanical properties after irradiation for 14 days.There were obvious cracks and holes found on the surface of pure PPC and PPC/PLA blends at a mass ratio of 50/50 after irradiation for 56 days,and however there was no change found on the surface of pure PLA.It was also observed that the longer the irradiation time,the coarser the surface of blends,and the greater was the degree of degradation.The hydroxyl index and carbonyl index of the blends were found to increase continuously at the first 21 days,especially within the first 14 days.The relative molecular weight and polydispersityindex of the blends decreased,which made the molecular weight distribution narrowed after irradiated for 56 days accordingly.Moreover,the blends presented an increase in thermal decomposition temperature and weight loss temperature(T p)at a maximum rate,whereaspure PPC showed a decrease in T P after irradiation.