流延用茂金属聚乙烯树脂的结构与加工性能评价

Structure and processing performance analysis of metallocene polyethylene resin for casting

利用高温凝胶渗透色谱仪、差式扫描量热分析仪、核磁共振谱仪、高压毛细流变仪等分析手段,对牌号分别为HPR 3518 CB和3518 PA的流延用茂金属聚乙烯进行了结构及加工性能评价。结果表明:2种样品的熔体流动速率和密度相当,HPR 3518 CB的拉伸性能略低于3518 PA;与3518 PA相比,HPR 3518 CB共聚单体摩尔分数低,晶片厚且分布较宽,熔融、结晶温度较高,剪切黏度对温度的敏感性更强;在相同薄膜加工条件下,2种样品加工成型过程平稳,未发生熔体流动不稳定的现象;与3518 PA薄膜相比,HPR 3518 CB薄膜的拉伸力学性能和落镖冲击质量均略低,热封温度略高,光学性能基本相近。

The structure and processing performance analysis of metallocene polyethylene HPR 3518 CB and 3518 PA were carried out by means of high temperature gel penetration chromatograph,differential scanning calorimetry,nuclear magnetic resonance spectrometer and high pressure capillary fluidiometer.The results showed that the melt flow rates and densities of the two samples were similar,and the tensile properties of HPR 3518 CB were slightly lower than that of 3518 PA.Compared with 3518 PA,HPR 3518 CB had lower comonomer mole fraction,thicker wafer and wider distribution,higher melting and crystallization temperature,and its shear viscosity was more sensitive to temperature.Under the same processing conditions,the processing of the two samples were both stable,and there was no melt flow instability phenomenon.Compared with the 3518 PA film,the tensile mechanical properties and the impact mass of falling darts of HPR 3518 CB film were slightly lower,the heat sealing temperature was slightly higher,and the optical properties were the same.