相对分子质量对iPP薄膜结晶行为和力学性能的影响

Influence of Molecular Weight on Crystallization Behavior and Mechanical Properties of iPP Films

通过挤出-拉伸法制备了2种不同相对分子质量的等规聚丙烯(iPP-L和iPP-H)薄膜,研究了相对分子质量对薄膜结晶行为和力学性能的影响。采用X射线衍射(XRD)、差示扫描量热法(DSC)以及拉伸试验分别对2种薄膜的结晶行为和力学性能进行了表征。结果表明:iPP-H薄膜的结晶度、晶粒尺寸均比iPP-L薄膜的稍大,前者的结晶速率较慢;iPP-H薄膜在应变约为200%时表现出应变硬化现象,而iPP-L薄膜约在500%时才出现;iPP-H薄膜的拉伸强度和杨氏模量比iPP-L薄膜的大;与iPP-L薄膜相比,iPP-H薄膜的断裂伸长率和韧性较小。

iPP（inchuding iPP-L and iPP-H） films with different molecular weight were fabricated by extrusion-stretching method. The influence of molecular weight on the crystallization behavior and mechanical properties of the films was studied. The crystallization behavior and mechanical properties of these films were characterized by XRD, DSC and the tensile test. The results show that the crystallinity and crystallite size of iPP-H film are larger than those of iPP-L film. The crystallization rate of iPP- L film is lower, iPP-H film exhibits obvious strain-hardening behaviors when the strain is 200%, while iPP-L film is 500%. The tensile strength and modulus of iPP-H film are higher than those of IPP-H film. Compared to IPP-L film, the elongation at break and toughness of iPP-H film is lower.