复配内给电子体催化剂催化丙烯聚合

对TiCl4/MgCl2/1,3-二醇酯(LLX)/邻苯二甲酸酯(DBP)复配内给电子体催化剂的丙烯聚合行为进行了研究。用表面能谱仪分析催化剂活性中心Ti2p3/2的电子状态表明,TiCl4/MgCl2/LLX/DBP复配内给电子体催化剂与TiCl4/MgCl2/DBP催化剂相比,Ti附近的电子云密度大;丙烯聚合动力学和本体聚合实验结果表明,采用TiCl4/MgCl2/LLX/DBP复配内给电子体催化剂,初始聚合速率快且衰减慢、活性高、氢调敏感性好。用凝胶渗透色谱、示差扫描量热仪、13C核磁共振等方法对TiCl4/MgCl2/LLX/DBP复配内给电子体催化剂制备的聚丙烯进行了表征,与TiCl4/MgCl2/DBP催化剂制备的聚丙烯相比,前者的相对分子质量分布变宽、熔点降低、熔融焓减小、分子链的规整度下降。

Propylene Polymerization Catalyzed by Internal Electron Donor Compound Catalyst

Propylene polymerization was studied with TiCl4/MgCl2/1,3-diol dibenzoate(LLX)/diisobutyl phthalate(DBP) as catalyst,in which LLX/DBP was used as internal electron donor compounds.Electronic state on active center of catalyst was analyzed by means of XPS.The results indicate the electron cloud density around Ti in this catalyst was higher than that around Ti in TiCl4/MgCl2/DBP catalyst. In bulk polymerization the TiCl4/MgCl2/LLX/DBP catalyst showed higher activity and better hydrogen response than TiCl4/MgCl2/DBP.Known from reaction kinetics the initial polymerization rate of TiCl4/MgCl2/LLX/DBP catalyst is faster and decaying rate is slower than that of TiCl4/MgCl2/DBP.Polypropylene obtained with TiCl4/MgCl2/LLX/DBP catalyst was characterized by means of DSC,GPC and 13C NMR.In aspects of wider relative molecular mass distribution,lower melting point,lower melting enthalpy and lower molecular chain regularity the polymer obtained by the new catalyst is more promising than that produced by TiCl4/MgCl2/DBP.