相容剂对PP/POE共混体系脆韧转变行为的影响

采用熔融挤出法制备了不同相容剂含量的PP/POE共混体系,测试了不同体系的脆韧转变温度、热性能和力学性能.结果表明,乙烯-丙烯多嵌段共聚物相容剂的加入降低了PP/POE共混物的脆韧转变温度,提高了共混物的韧性.AFM和STEM照片显示相容剂的加入减小了橡胶分散相的临界粒子间距,PP和POE在两相界面结合处相互扩散或渗透,实现了POE弹性体在PP树脂中合适的尺度分布以及良好的形态分散.当相容剂含量达到10％时,POE分散相尺寸细小均匀,分散相粒子粒径为0.54μm,粒子间距为0.1 μm,PP结晶链段更多地插入到弹性体内部,弹性体POE分散相形成明显的“硬核-软壳”结构.DSC曲线中结晶峰和熔融峰的变化说明适量的相容剂对于材料结晶度的提高具有一定的促进作用.力学性能测试结果可以看出相容剂的加入在提高材料韧性,降低其脆韧转变温度的同时也保持了材料的刚性性能.

EFFECT OF COMPATIBILIZER ON THE BRITTLE-DUCTILE TRANSITION BEHAVIOR OF PP/POE BLENDS

The PP/POE blends with different contents of compatibilizer were prepared by melt mixing process,and the brittle-ductile transition behavior,thermal property and mechanical performance of the PP/POE blends were examined.The results showed that the addition of ethylene-propylene block copolymer based compatibilizer decreased the brittle-ductile transition temperature of PP/ POE blends accordingly.AFM results suggested that proper contents of compatibilizer induced the well dispersion and phase morphologies of POE particles in PP matrix.STEM results showed that the compatibilizer decreased the critical interparticle distance(IDc) of POE domains,leading to their homogeneous distribution.The dispersed POE particles and PP matrix diffused and interpenetrated into each other near the edge of their interfaces,indicating the improvement of the blend systems' compatibility.When the content of compatibilizer reached 10%,the small and well homogenous POE domains were obtained and the obvious hard core-tough shell structures of POE domains were formed.The average diameter of POE domains was 0.54 μm and the interparticle distance was 0.1 μm.The DSC curves during the cooling and the second heating runs demonstrated that the incorporation of proper content of compatibilizer could enhance the crystallization degree of PP/POE blends.Mechanical testing data illustrated that the addition of compatibilizer not only enhanced the toughness of PP/POE blends and decreased their brittle-ductile transition temperature,but also maintained the materials' stiffness,so the stiffness-toughess balance of the PP/POE blends was well kept.