Study On Thermal Degradation And Blending Modification Of Polyesters

Polyesters such as [poly (lactic acid), PLA],[poly lactic acid, PLA] are one of the most promising plastics. PLA is of good biodegradation and incomparable advantages. Due to internal and external factors (including light, heat, humidity, mechanical pressure), in the process of processing, storaging and using, the performance of polymer material will gradually declining, resulting in lossing of function Ultimately. Through the studies of polymer aging process, we can take appropriate measures to modificatting and delaying the aging of the material. Not only achieving the purpose of extending the service life, this is also one of the ways to solve white pollution.In this study, we set the temperature above glass translate temperature and expected to make clear the thermal degradation mechanism of Polyesters without oxygen. By testing the mass loss, tensile strength, strucuure,crystallinity and TG of specimens before and after aging, we try to deduce the rule of the aging. Furthermore we make study on improving the capability of the material.By the experiment,PC was aged above glass translate temperaturewithout Oxygen. It shows that the performance of specimens descended. The weight loss of the specimens is less than 5%; the capability of mechanicsdescend, behaved by the break elongation and stated burthen elongation descend. The FTIR result shows that the transformation of configuration unconspicuous;The result of the the X-Ray shows that crystallinity changeg from 2.25% to 24.25%.The rise of the crystallinity approved that the intensity, rigidity and hard of the material rised. The elasticity,break elongation and stated burthen elongation descended. The result of TG and DSC showed that the change of the thermal stability is unconspicuous. In conclusion, PC was a sort of material with excellent stability.By the experiment to PLA, It shows that the performance of specimens descended. PLA was sensitive to the high temperature. The weight loss of the specimens is larger than that of PC. The capability of mechanics descend, behaved by the break elongation and stated burthen elongation descend. The FTIR result shows that the transformation of configuration unconspicuous; The result of the the X-Ray shows that crystallinity changeg from 0.70%to 25.84%,there are spiculate apexs in the location of 16°,19° and 35°. The change of the crystallinity approved that the intensity, rigidity and hard of the material rised. The elasticity, break elongation and stated burthen elongation descended. It shows that the thermal stability of PLA ws not as good as PC. The thermal stability of PLA need improving.In the experiment we blend PLA and PC by different mass rate. It showed that the rate of PLA: PC=80: 20 was comparatively excellent. Through the experiment of thermal degradation, it shows that the weight loss of the specimens is less than 10%,lower than that of PLA. The capability of mechanics descend, behaved by the break elongation and stated burthen elongation descend. The FTIR result shows that the transformation of configuration unconspicuous. The result of TG and DSC showed that the thermal stability of the blend is better than that of pure PLA. In conclusion,it proved that the blend of PLA and PC manifest much more excellent than that of the pure PLA.In conclusion, PC showd the excellent thermal stability, all the capabilities of PC were better than that of PLA. It was proved that the capabilities of the blend of PLA and PC by the ratio of 4:1 was better thanthat of pure PLA, especially the mechanics capability and thermal capability. It was achived to improve the capability of PLA.