Chem. J. Chinese Universities ›› 2022, Vol. 43 ›› Issue (10): 20220290.doi: 10.7503/cjcu20220290

• Polymer Chemistry • Previous Articles     Next Articles

Regulation of Silanes as External Electron Donors on Propylene/butene Sequential Polymerization

ZHOU Chengsi1, ZHAO Yuanjin1, HAN Meichen1, YANG Xia2, LIU Chenguang1, HE Aihua1()   

  1. 1.Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization,Key Laboratory of Rubber?Plastics (Ministry of Education),School of Polymer Science and Engineering,University of Science and Technology,Qingdao 266042,China
    2.Research Center for Computer and Chemical Engineering,College of Chemical Engineering,Qingdao University of Science and Technology,Qingdao 266042,China
  • Received:2022-04-29 Online:2022-10-10 Published:2022-05-24
  • Contact: HE Aihua E-mail:ahhe@qust.edu.cn
  • Supported by:
    the Major Scientific and Technological Innovation Project of Shandong Province, China(2019JZZY010352);the Natural Science Foundation of Shandong Province, China(ZR2020ME079);the Taishan Scholar Program, China

Abstract:

The influences of four kinds of silanes as external electron donor(ED) with different structure and electron density[dimethyl dimethoxysilane(D1), dibutyl dimethoxysilane(D2), diphenyl dimethoxysilane(D3), dicyclopentyl dimethoxysilane(D4)] on propylene homopolymerization and propylene(first stage)-butene(second stage) sequential polymerization were investigated. The results showed that ED had significant effects on the catalytic activity, number of active centers{[C*]/[Ti]} and the stereoregularity of active centers in olefin polymerization. Density functional theory(DFT) simulations showed that with the increase in steric hindrance and electron density of ED, the adsorption energy of ED on the surface of MgCl2 decreased, so the adsorption stability decreased. The increase in steric hindrance and electron density of ED was conducive improving the stereoregularity of the active centers. When n(D4)/n(Ti)=20, the content of isotactic polypropylene(iPP) fractions in polypropoylene(PP) reached as high as 92.8%. When n(ED)/n(Ti)=15, the rate constant for chain propagation of propylene polymerization reached the maximum value. The ED with greater steric hindrance and electron density enabled the active center of the sequential polymerization of propylene-butene with greater stereoregularity, ED had more significant effect on the polymerization activity of butene(second stage) and the melting point of the isotactic polybutene(iPB) fractions in polypropylene/polybutene alloys(PBA).

Key words: Ziegler-Natta catalyst, External electron donor, Density functional theory, Simulation and calculation, Polypropylene, Alloy

CLC Number: 

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