【摘要】 采用球形TiCl4/MgCl2·内酯型高效催化剂,通过加氢与非加氢气相聚合间多段切换的方法合成了宽相对分子质量分布的聚丙烯(PP)。研究了加氢/非加氢切换频率和加氢量对PP相对分子质量及其分布和结晶形貌的影响。总聚合时间相同时,增加加氢/非加氢切换频率对聚合活性的影响较小,对相对分子质量及其分布的影响也不明显,但使PP球晶尺寸减小,球晶形貌不规整程度增大。增大加氢量使相对分子质量分布增至11．0以上,球晶尺寸减小。更多还原

【Abstract】 Polypropylene (PP) with broad relative molecular weight distribution (MWD) was synthesized by a spherical TiCl4/MgCl2 phthalate type high efficiency Ziegler-Natta catalyst in gas phase process involving two-stage polymerizations. The monomer reactant stream was switched over for several times between the first-stage in which only propylene monomers reacted and the second-stage in which propylene monomers polymerized in the presence of H2 specially added. Influences of the switchover frequency and the H2 partial pressure on the molecular weight, MWD and crystalline morphology of the PP specimen were studied. Under the condition of remaining the total polymerization time unchanged, increasing switchover frequency caused a little influence on the polymerization activity and MWD, but maked the spherulites of PP smaller and the irregularity in morphology of the spherulites more obvious. Raising the partial pressure of H2 resulted in broadening of MWD and decreasing of spherulite dimension.更多还原