化工学报 ›› 2023, Vol. 74 ›› Issue (3): 1092-1101.DOI: 10.11949/0438-1157.20221460

• 催化、动力学与反应器 • 上一篇    下一篇

孔道结构修饰的Ziegler-Natta催化剂设计与高抗冲低缠结UHMWPE的制备

刘倩1,2,3(), 曹禹1, 周琦2(), 穆景山1(), 历伟3,4   

  1. 1.宁波大学材料科学与化学工程学院,浙江 宁波 315211
    2.宁波工程学院材料与化学工程学院,浙江 宁波 315211
    3.浙江大学宁波科创中心,浙江 宁波 315100
    4.浙江大学化学工程与生物工程学院,浙江 杭州 310030
  • 收稿日期:2022-11-08 修回日期:2023-01-18 出版日期:2023-03-05 发布日期:2023-04-19
  • 通讯作者: 周琦,穆景山
  • 作者简介:刘倩(1998—),女,硕士研究生,1042646737@qq.com
  • 基金资助:
    国家自然科学基金优秀青年基金项目(22222810);浙江省自然科学基金面上项目(LY20B060003);宁波市自然科学基金重点项目(202003N4014)

Design of Ziegler-Natta catalyst modified with pore structure and preparation of UHMWPE with high impact resistance and low entanglement

Qian LIU1,2,3(), Yu CAO1, Qi ZHOU2(), Jingshan MU1(), Wei LI3,4   

  1. 1.School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, Zhejiang, China
    2.School of Materials and Chemical Engineering, Ningbo University of Technology, Ningbo 315211, Zhejiang, China
    3.Ningbo Science and Innovation Center of Zhejiang University, Ningbo 315100, Zhejiang, China
    4.School of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310030, Zhejiang, China
  • Received:2022-11-08 Revised:2023-01-18 Online:2023-03-05 Published:2023-04-19
  • Contact: Qi ZHOU, Jingshan MU

摘要:

从SiO2载体孔道修饰的角度出发,向多级孔道中同时引入聚苯乙烯(PS)和聚倍半硅氧烷(POSS),形成功能化复合载体,并用于负载TiCl4,制备SiO2/PS/POSS/TiCl4负载型催化剂。采用热重分析、N2等温吸附脱附、扫描电镜、漫反射红外光谱等手段对修饰前后催化剂的结构进行表征,发现利用苯乙烯的原位聚合能够向SiO2多级孔道,尤其是微孔中引入PS,孔道内 PS链段的溶胀行为导致聚合时乙烯传质阻力增大,聚合活性降低。向SiO2多级孔道中引入POSS,由于POSS分子的空间位阻,其只能进入SiO2大孔中,初生态聚乙烯分子链缠结程度降低有限。而将PS与POSS共同引入催化剂各级孔道中,PS与POSS能够产生良性协同作用,能够以高活性制备低缠结的超高分子量聚乙烯,显著提升了产品的抗冲击强度。最后通过降低孔道内TiCl4的负载量,进一步稀释催化剂活性中心,实现聚乙烯活性链解缠结的过程强化。当钛含量降至2.65%时,聚合活性、抗冲击强度和链缠结程度均达到最佳。

关键词: Ziegler-Natta催化剂, 聚乙烯, 冲击性能, 链缠结, 过程强化

Abstract:

From the perspective of SiO2 carrier channel modification, polystyrene (PS) and polysilsesquioxane (POSS) were simultaneously introduced into the multi-level channel to form a functional composite carrier, which was used to load TiCl4 to prepare SiO2/PS/POSS/TiCl4 supported catalyst. Thermal gravimetric analysis, N2 isothermal adsorption and desorption, scanning electron microscopy, and diffuse reflectance infrared spectroscopy were used to characterize the structures of the catalysts before and after the modification. It was found that it was possible to use in-situ polymerization of styrene to introduce PS into SiO2 multistage pores, especially into the micropores, and that the swelling behavior of PS chain segments within the pores led to an increase in ethylene mass transfer resistance and a decrease in polymerization activity during polymerization. After introducing POSS into the SiO2 multistage pore channel, it could only enter the SiO2 macropores due to the sterichindrance of POSS molecules, where the reduction effect to the entanglenets of nascent of polyethylene was limited. A benign synergy for reducing the chain entanglements of nascent polyethylene was generated owing to the successive introduction of PS and POSS into the catalyst pores. The impact strength of the synthesized polyethylene was greatly enhanced. Finally, the catalyst active center was further diluted through reducing the loading of TiCl4 in the pore channel, where the untwining process of the propagated polyethylene chain was further strengthened. The optimum polymerization activity, the highest impact strength of the synthesized polyethylene were achieved when the titanium content was reduced to 2.65%.

Key words: Ziegler-Natta catalyst, polyethylene, impact properties, chain entanglement, process intensification

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