串联催化体系制备长链支化聚乙烯

doi:10.19894/j.issn.1000-0518.200170

摘要/Abstract

摘要： 利用两种串联催化体系,Cat.I/Cat.II和Cat.I/Cat.III{Cat.I:[ArNCH-C₈H₃(CH₂)₂(C₆H₅)O]₂ZrBn₂;Cat.II:(η⁵-C₅Me₄)Si(Me)₂N^tBuTiCl₂;Cat.III:tans-Et(Ind)₂ZrCl₂)},催化了乙烯聚合,一步法制备出了长链支化聚乙烯(LCBPEs)。聚合过程中,在Cat.I作用下,乙烯转化为分子链末端带有双键的齐聚物;然后Cat.II和Cat.III催化乙烯与乙烯齐聚物共聚,制得LCBPEs。通过改变n(Cat.I)/n(Cat.II)和n(Cat.I)/n(Cat.III),所制得的LCBPEs的支化度可在物质的量分数0.84%~3.95%范围内进行调控。另外,所得聚合物的结构也利用核磁共振和凝胶渗透色谱进行了进一步的证明。与线性聚乙烯相比,本文所制得的LCBPEs的结晶度较低,拉伸强度也较低。不过,由于长链支化结构的影响,LCBPEs的剪切变稀现象不如线性聚乙烯明显,且断裂伸长率高于线性聚乙烯。

关键词: 串联催化体系, 烯烃聚合, 乙烯聚合, 长链支化聚乙烯

Abstract: Two tandem catalytic systems, Cat.I/Cat.II {Cat.I:[ArNCH-C₈H₃(CH₂)₂(C₆H₅)O]₂ZrBn₂; Cat.II:(η⁵-C₅Me₄)Si(Me)₂N^tBuTiCl₂} and Cat.I/Cat.III (Cat.III:tans-Et(Ind)₂ZrCl₂), were employed respectively to prepare long chain branched polyethylene (LCBPE) by using ethylene as the sole monomer. Ethylene is initially acted upon by Cat.I to give ethylene oligomers with terminal vinyl groups. Subsequently, the copolymerization of the resultant oligomers with ethylene is promoted by Cat.II and Cat.III respectively and affords long chain branched polyethylene (LCBPE). By varying the molar ratio of Cat.I/Cat.II as well as Cat.I/Cat.III, a series of LCBPEs with controllable branching molar fraction (0.84%~3.95%) was prepared successfully. All of these obtained polymers exhibits a unimodal distribution, indicating that all of the obtained polymers are pure LCBPEs rather than the blends of ethylene oligomers and linear PE. The LCBPEs show lower crystallinity than the linear PE. Because of the entanglement of the long chain branches, the resultant LCBPEs show more obvious shear-thinning phenomenon and higher elongation. However, the lower crystallinity of the LCBPEs results in lower tensile strength.

Key words: Tandem catalytic system, Olefin polymerization, Polymerization of ethylene, Long chain branched polyethylene

中图分类号:

O632

卢令攀, 吴佳骏, 王凯悌. 串联催化体系制备长链支化聚乙烯[J]. 应用化学, 2021, 38(1): 69-76.

LU Ling-Pan, WU Jia-Jun, WANG Kai-Ti. Preparation of Long-Chain Branched Polyethylene Catalyzed by Tandem Catalytic System[J]. Chinese Journal of Applied Chemistry, 2021, 38(1): 69-76.

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