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Bimodal/Broad Polyethylene Prepared in a Disentangled State

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journal contribution
posted on 22.01.2014, 00:00 by Wei Li, Chao Guan, Jie Xu, Zhong-ren Chen, Binbo Jiang, Jingdai Wang, Yongrong Yang
Disentangled broad/bimodal polyethylene with an inverted distribution of short chain branches (SCBs) was synthesized with a supported hybrid catalyst. Poly­[styrene-co-(acrylic acid)]- (PSA-) coated SiO2 particles were used to support the hybrid catalysts. The PSA was coated on SiO2-supported VCl3 catalyst. Then, Fe­(acac)3/2,6-bis­[1-(2-isopropylanilinoethyl)]­pyridine was immobilized onto the PSA layer. It was demonstrated that the Fe­(acac)3/2,6-bis­[1-(2-isopropylanilinoethyl)]­pyridine catalyst prepared linear polyethylene with a low molecular weight (MW) and C4–C22 α-olefin. Meanwhile, this α-olefin could be used as the comonomer for VCl3 to prepare high-MW polyethylene with SCBs. Hence, broad-MW-distribution polyethylene (MWD = 120) with an inverted distribution of SCBs was obtained from only one monomer (ethylene). Interestingly, this is the first time that the synthesized polyethylene was reported to exhibit a disentangled state. The isothermal kinetics of crystallization based on the Avrami and Tobin methods was studied to obtain details about the evolution of the disentangled state during the polymerization process.