Facile high-temperature synthesis of weakly entangled polyethylene using a highly activated Ziegler-Natta catalyst
作者：Wei Li, Lei Hui, Bing Xue, Chuanding Dong, Yuming Chen, Linxi Hou, Binbo Jiang, Jingdai Wang
關鍵字：Heterogenous catalysts, Chain entanglements, Density functional theory, Ziegler-Natta catalyst
論文來源：期刊
發表時間：2018年
A Polyhedral oligomeric silsesquioxane (POSS) modified Ziegler-Natta catalyst is reported to synthesize the weakly entangled ultra-high molecular weight polyethylene at a high temperature and with a high activity. Incorporation of POSS can form numbers of aggregates with a mean size of 48 nm adsorbing on the surface of SiO2. The structure of nanoaggregates is evidenced by the experiments and theoretical calculations where one POSS can coordinate with multiple MgCl2 molecules serving as an electric donor to the further immobilized TiCl4. The catalyst is thus featured by two distinct active regions positioned in the POSS/MgCl2 nanoaggregates and d-MgCl2, respectively. The former regions present extremely low activity on ethylene polymerization, which function as horizontal separators for isolating the active TiCl4 sites and the growing chains. This catalyst exhibits an exceptional activity (i.e. 1.3 106 gPE molTi 1 h1 bar1) for the synthesis of weakly entangled polyethylene at 60 C.