Preparation of Ultra High Molecular Weight Polyethylene with MgCl2/TiCl4 Catalysts: Effect of Temperature and Pressure
writer：Young-jun Shin1, He-xin Zhang, Keun-Byoung Yoon*, and Dong-ho Lee*
keywords：Ziegler-Natta catalyst, UHMWPE, molecular weight distribution.
source：期刊
specific source：Macromolecular Research, Vol. 18, No. 10, pp 951-955 (2010)
Issue time：2010年
The polymerization of ethylene (E) was carried out using a MgCl2-supported TiCl4 catalyst in conjunction with triethylaluminium as a cocatalyst. The effects of the polymerization temperature (Tp) and E pressure (PE) on E polymerization were studied. The maximum catalyst activity was obtained at 40 oC. The melting temperature (Tm) and crystallinity (Xc) were less affected by the Tp. The molecular weight decreased with increasing Tp but the polydispersity index (PDI) increased. In addition, the effect of two stepwise Tp on E polymerization was investigated and the bimodal gel permeation chromatography (GPC) curve was obtained. The catalyst activity increased drastically with increasing PE. The higher PE in the range of 1-12 kgf/cm2 showed a higher Mv of the ultra high molecular weight polyethylene (UHMWPE) obtained, whereas increasing PE decreased the PDI. Because it was very difficult to obtain the molecular weight distribution of UHMWPE through GPC analysis, the molecular weight distribution was analyzed from rheometry measurements of the UHMWPE melt.