两种聚丙烯工程管材的性能及微观结构比较

Microstructure and Properties of Two Isotactic Polypropylene Engineering Mandrel Pipes

测定了两种聚丙烯工程管材(PP-A,PP-B)的物理力学性能,同时用熔体流动指数法、凝胶渗透色谱、碳核磁共振谱、差示扫描量热法和X射线衍射法分析了两种管材聚合物的微观结构。流动指数法与凝胶渗透色谱试验结果得出,PP-A熔指小、分子量大和分布相对较窄,而PP-B熔指大、分子量小和分布相对较宽。与PP-B相比,PP-A等规度相对较低,且立构缺陷相对集中。PP-A在再结晶时易形成β结晶,PP-B较易形成γ结晶。PP-A是Z-N催化等规聚丙烯(ZNIPP),而PP-B是茂金属催化等规聚丙烯(MIPP),工程应用过程中出现问题主要由其微观结构所决定。

The physical and mechanical properties of two polypropylene （PP） engineering mandrel pipes were measured, and the microstructures of the two PPs were characterized with the melt flow index（MFI） tester, gel permeation chromatography, nuclear magnetic resonance, differential scanning calorimetry, and X-ray diffraction. The results show that, PP-A has a smaller MFI value, a larger molar mass and a narrower molar mass distribution than those of PP-B, and PP-A gives slightly low degree of isotacticity and concentrates stereo-irregular defects along the polymer chains compared with those of PP-B, and PP-A indicates the tendency to form beta crystallite while PP-B easily produces the gamma crystallite at their respective favorable conditions. Therefore, PP-A would be the product of Zieglar-Natta PP whereas PP-B the product of metallocene PP, their advantage and disadvantage during the service period will mainly stem from their origins.