多元环氧扩链剂对聚乳酸等温结晶行为及力学性能的影响

Effects of Multiple Epoxy Chain Extender on Isothermal Crystallization Behavior and Mechanical Performances of PLA

采用多元环氧扩链剂(ADR)对聚乳酸(PLA)进行熔融扩链改性,得到PLA/ADR共混物。采用差示扫描量热仪(DSC)对共混物的熔体等温结晶行为进行表征和分析。结果表明:在110~120℃温度范围内,ADR的加入提高了PLA熔体的结晶速率;随着ADR用量的增加,PLA等温结晶速率明显提高,半结晶时间缩短。结合熔体流动速率和偏光显微镜分析,从分子运动能力和熔体黏度的角度解释了ADR对PLA等温结晶行为的影响机理。此外,研究了结晶度变化对PLA/ADR共混物拉伸性能和维卡软化温度(VST)的影响。当PLA/ADR(100/1.0)共混物的结晶度由1.7%提高到32.2%时,其拉伸强度由55.6 MPa提高到63.2 MPa,VST由61.9℃提高到156.9℃。结晶度的增大有利于PLA/ADR共混物力学性能和耐热性能的进一步提高。

Poly（lactic acid）（PLA） was modified with a multiple epoxy chain extender（ADR） by meltmixing method.Isothermal melt-crystallization behaviors of PLA/ADR blends were investigated using a differential scanning calorimeter（DSC）.The isothermal crystallization kinetics analysis indicates that the isothermal crystallization rate of PLA enhances with the introduction of ADR while crystallized at the temperature range of 110~120℃.With the increasing of ADR loading,the isothermal crystallization rate of PLA increases significantly,as well as the crystallization halftime reduces.The effect of ADR on the isothermal crystallization behavior of PLA was explained from the point of view of molecular motion and melt viscosity based on melt flow rate（MFR） and polarizing optical microscope（POM） measurements.In addition,the impact of crystallinity on tensile performance and vicat softening temperature（VST） of PLA/ADR blends were investigated.While the crystallinity of PLA/ADR（100/1.0） blend increases from 1.7% to 32.2%,its tensile strength increases from 55.6 MPa to 63.2 MPa.Meanwhile,the VST increases from 61.9℃ to 156.9℃.The results show that the increase of crystallinity can further enhance the mechanical performances and heat resistance of PLA/ADR blends.