China Petroleum Processing & Petrochemical Technology ›› 2021, Vol. 23 ›› Issue (3): 12-22.

• Scientific Research • Previous Articles     Next Articles

Xia Xiaoqi1; Li Hongming2; Li Chunman3; Miao Qing3; Li Jing4; Zhu Feng3; Huang Qigu1; Yi Jianjun2; Zhao Zhong1   

  1. 1. State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and
    Functional Polymers, Ministry of Education, the College of Material Science and Engineering,
    Beijing University of Chemical Technology, Beijing 100029;
    2. Petrochemical Research Institute, PetroChina, Beijing 102206;
    3. CNPC Key Laboratory of Oil & Gas Storage and Transportation, PetroChina Pipeline R & D Center
  • Received:2021-02-27 Revised:2021-07-04 Online:2021-09-30 Published:2021-09-27
  • Contact: Huang Qigu
  • Supported by:
    supported by the People’s Republic of China Ministry of Industry and Information Technology (No. gxgh2019-795), and the National Natural Science Foundation of China (No. U1462102). The authors also appreciate the support provided by the Key Laboratory of Carbon Fiber and Functional Polymers.

Abstract: Due to the development of the new energy industry, polypropylene with ultra-high molecular weight plays a crucial role for battery isolation membrane. This work investigated the effect of internal electron donor of Ziegler-Natta catalyst system on the molecular weight of the obtained polypropylene. The scanning electron microscope (SEM) and Canon camera were used to characterize the surface morphologies of catalyst particles and polymer particles, respectively. Compared with the polypropylene particles featuring a spherical shape, these study results confirmed that the morphology duplication theory from the catalyst particle to the morphology of polymer particle was exhibited. The gel permeation chromatography (GPC) results revealed that the obtained polypropylene has a much higher average molecular weight than those prepared by conventional method. The Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectroscopy (XPS) revealed that the carbonyl oxygen atom on ester group was preferentially bound to Mg and Ti, as compared to the ether oxygen atom. The XPS results showed that the ratio of Ti3+/Ti4+ could be changed by internal electron donors. When Ti3+content was nearly 99% in the Ziegler-Natta catalyst system, isotactic polypropylene with an ultra-high molecular weight of up to 1.42×106 g/mol was obtained by Cat. 3. This result  implied that internal electron donor ID3 could reduce the β-hydride elimination reaction to further increase the molecular weight of the obtained polymer.

Key words: Internal electron donor, Ziegler-Natta catalyst, Ultra-high molecular weight, Isotactic polypropylene