透明聚丙烯结构与性能研究

The Structure and Property Studies of Transparent Polypropylenes

通过升温淋洗分级仪(TREF),核磁共振波谱仪(NMR)、凝胶渗透色谱仪(GPC)、差示扫描量热仪(DSC)等多种仪器分析设备对市场主导的茂金属共聚透明聚丙烯试样和普通齐格勒-纳塔(Z-N)催化剂生产的透明聚丙烯产品进行了剖析,从微观结构到聚集态结构的分析结果均表明,催化剂分子结构对聚合物分子链结构的影响颇为显著:单活性中心的茂金属催化剂生产的共聚产品具有相当窄的分子量分布,高刚性、低雾度。共聚少量乙烯单体就可以获得透明聚丙烯优异产品。TREF不同级份组成随温度的升高而呈现结构规整性提高的趋势。文章将茂金属催化剂和Z-N催化剂生产的透明聚丙烯产品进行了物理性能对比,采用茂金属催化剂合成的无规共聚聚丙烯产品其光学性能明显优于由Z-N催化剂合成的产品。

In this article,the market predominant metallocene transparent PPs(mTPPs)and Ziegler-Natta PP random copolymers(RCP)are analyzed with several analytical techniques,such as temperature rising elusion fractionation(TREF),nuclear magnetic resonance(NMR),gel permeation chromatography(GPC),and differential scanning calorimetry(DSC)etc.The analytical results indicate that,from molecular to aggregation state,catalyst structure has a significant influence to the microstructures of the polymer chain;i.e.the products made from single-site metallocene catalyst have narrow molecular distribution,higher stiffness and low haze.With small amount of ethylene comonomer incorporation into the PP chain,the mTPPs exhibit excellent properties such as very narrow molecular weight distribution,high rigidity,and low haze.For different fractions of TREF,the PP microstructural regularity increases with the increasing elusion temperature.The physical properties between the PP products made from different catalysts are compared,it is clear that the TPPs made from metallocene catalyst exhibit better optical properties than the TPPs made from Z-N catalyst.