分散相含量对乙烯-醋酸乙烯酯共聚物/聚丙烯原位微纤复合材料微纤形态、结晶行为及流变和力学性能的影响

Dispersed Phase Content of Ethylene-vinyl Acetate Copolymer/Polypropylene(EVA/PP)In-situ Microfibrillar Composites(MFCs):Influences to Microfiber Morphology,Crystallization Behavior,Rheological and Mechanical Properties

利用微纳层叠共挤出装置成功制得EVA/PP原位微纤复合材料(MFCs),并对其微纤形态、力学性能、结晶性能和流变行为进行了研究。结果表明:PP在EVA中能够形成微纤,且随PP含量增加,直径较大的微纤数量显著增多,MFCs的储能模量(G′)和损耗模量(G″)都相应增大。且当PP含量低于10%(质量分数,下同)时,复合材料体系是部分相容的,但当PP含量超过10%时,体系发生相分离现象。PP微纤能够有效提高EVA的拉伸强度。当PP含量为20%时,拉伸强度最大,为16.71MPa,比纯EVA树脂提高了42.9%。差示扫描量热法(DSC)测试显示PP微纤会阻碍EVA的结晶行为,使MFCs的结晶度降低。

A series of ethylene-vinyl acetate copolymer/polypropylene（EVA/PP）in-situ microfibrillar composites（MFCs）differed in dispersed phase（i.e.PP）content were prepared using a multistage stretching extruder with an assembly of laminatingmultiplying elements（LMEs）,and the products＇ microfibers morphology,crystallization behaviors,mechanical and dynamic rheological performances were studied.The results showed that PP could form microfibers in situ in EVA,and more PP content would lead to obviously more large-diameter microfibers and higher storage modulus（G′）and loss modulus（G″）of the MFCs.The systems with PP contents below 10 wt% were partially compatible,while the phase separation occurred in systems with PP contents over10 wt%.PP microfibers could enhance the tensile performance of EVA effectively,as the EVA/20 wt%PP MFCs owned the maximum tensile strength of 16.71 MPa,which was 42.9% higher than that of pure EVA.We also observed an obstructive effect of PP microfibers on the crystallization behavior of EVA,which consequently attenuates the crystallinity of the MFCs.