PP三元共混合金的力学性能及结晶行为研究

THE BEHAVIOR OF MECHANICS AND CRYSTALLIZATION OF PP TRINARY BLENDING ALLOYS

研究了不同乙烯含量的 EPDM对 PP/UHMWPE(超高分子量聚乙烯 )合金的增容作用 ,并讨论了共混体系结晶行为的变化情况。发现 EPDM中乙烯含量的增加可提高增容效果 ;在 PP/UHMWPE/EPDM为 1 0 0 /1 0 /6时 ,共混物缺口冲击强度可达 91 .1 k J/m2 ,为 PP的 3.5倍 ,此时拉伸强度仍比纯 PP高 4.3MPa。 DSC分析表明 ,UHMWPE与 PP中的乙烯嵌段晶相相容 ;在较快的降温速率下 ,UHMWPE会先于 PP结晶并成为 PP的晶核 ,促使两组分同时结晶。EPDM的混入能显著地提高合金的结晶度 ,并使结晶速度大大加快。结晶形态观察进一步证实了 PP与 UHMWPE所形成的复合共晶的存在 ,并发现 EPDM对复合共晶具有明显地插入、分割和细化作用 ,从而使结晶的完善程度显著降低。

EPDM was studied as compatibilizer of PP and UHMWPE, and the variation of crystal behaviors of the alloy was also discussed. The results show that the rising of ethylene content in EPDM can improve the compatibility. When the ratio of PP/UHMWPE/EPDM is 100/10/6, the impact strength of notch can reach to 91.1 kJ/m 2, which is 3.5 times of PP and the tensile strength is 4.3 MPa higher.The DSC analysis demonstrates that UHMWPE and ethylene diblock of PP have crystal phase compatibility, at higher decreasing temperature rate UHMWPE crystallizes ahead of PP and become its crystal nucleus making the two composites crystallize simultaneously, and the crystallinity and cryatllization rate of the alloy are both remarkably enhanced by adding EPDM into it. The crystalline patterns prove further the present of the complex cocrystal and show that EPDM has the functions of inserting, deviding and fining to alloy spherocrystal, thus deeply destroyed the perfectibility of crystallization.