SEBS-g-MAH对LLDPE结晶行为的影响

利用差示扫描量热法结合Avrami方程研究了线性低密度聚乙烯(LLDPE)、LLDPE与苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)共混体系及LLDPE与不同接枝率的SEBS共聚物接枝马来酸酐(SEBS-g-MAH)共混体系的非等温结晶动力学,探讨了SEBS-g-MAH对LLDPE结晶行为的影响.通过偏光显微镜(POM)观察了各体系的结晶形态.通过Gupta法、Jeziorny法和莫志深法分别对非等温结晶过程进行表征,结果显示:热塑性弹性体SEBS及其接枝物SEBS-g-MAH的加入阻碍了LLDPE分子链的规则排列,影响了链段在结晶扩散迁移过程中的规整排列速率,使得结晶速率变慢,对LLDPE晶体生长起了抑制作用.样品的Avrami指数均为1.1～1.5,说明LLDPE的结晶成核机理和生长方式没有改变.

Influence of SEBS-g-MAH on Crystallization Behavior of LLDPE

The non-isothermal crystallization behavior and kinetics of LLDPE,LLDPE/SEBS,LLDPE/SEBS-g-MAH were studied by differential scanning calorimetry combined with the Avrami equation.The influences of SEBS-g-MAH on crystallization behavior of LLDPE were discussed.The crystalline morphology was examined using polarized optical microscope(POM).The methods of Gupta,Jeziorny and Mo Zhi-shen for non-isothermal crystallization kinetics were used to analyze the crystallization characteristics.The results demonstrated that due to partial destruction of crystal region,the crystallization rate of LLDPE decreased with adding SEBS and its grafts.Addition of elastomer played an inhibition for crystal growth of LLDPE.The fact that all samples had Avrami exponents in a range of 1.1～1.5 implied the nucleation mechanism and geometry of crystal growth of LLDPE was not changed.