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Reduced Entanglement Density of Ultrahigh-Molecular-Weight Polyethylene Favored by the Isolated Immobilization on the MgCl2 (110) Plane
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2020-02-17 , DOI: 10.1021/acs.iecr.9b06780 Zhen Yue 1 , Ning Wang 1 , Yu Cao 1 , Wei Li 1 , Chuan-ding Dong 2
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2020-02-17 , DOI: 10.1021/acs.iecr.9b06780 Zhen Yue 1 , Ning Wang 1 , Yu Cao 1 , Wei Li 1 , Chuan-ding Dong 2
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The polyhedral oligomeric silsesquioxane (POSS)-modified Ziegler–Natta catalysts with judicious immobilization of TiCl4 were synthesized for ethylene polymerization. The structure of active sites in this heterogeneous catalyst was investigated by X-ray photoelectron spectroscopy, CO low-temperature adsorption diffusion reflectance infrared Fourier transform (DRIFT) spectra, and density functional theory calculations. The incorporated POSS molecules contribute to the formation of the MgCl2 (110) plane, creating more positions for hosting the active sites. Simultaneously, POSS induced the crystallization of MgCl2 molecules, and the latter capture the deactivated TiCl4 molecules and consume part of the loaded TiCl4. This combination dilutes the active sites on the catalytic surface and gives rise to more isolated active species and results in enhanced catalytic activity and decrement of the chain overlap. As a result, the ultrahigh-molecular-weight polyethylene (UHMWPE) with a less entangled state was successfully synthesized at 80 °C, with exceptional activity (6.18 × 105 g PE molTi–1 h–1 bar–1). The synthesized UHMWPE presents less morphological defects after the fusion, thanks to the weakly entangled state, and shows a pronounced improvement of the impact property.
中文翻译：
MgCl 2（110）平面上的单独固定化有利于降低超高分子量聚乙烯的缠结密度
合成了明智地固定TiCl 4的多面体低聚倍半硅氧烷（POSS）改性的Ziegler-Natta催化剂用于乙烯聚合。通过X射线光电子能谱，CO低温吸附扩散反射红外傅里叶变换（DRIFT）光谱和密度泛函理论计算，研究了该非均相催化剂中活性位的结构。并入的POSS分子有助于MgCl 2（110）平面的形成，从而为容纳活性位点创造了更多位置。同时，POSS诱导了MgCl 2分子的结晶，后者捕获了失活的TiCl 4分子并消耗了一部分负载的TiCl 4。这种组合稀释了催化表面上的活性位点，并产生了更多的分离出的活性物种，并导致增强了催化活性并减少了链重叠。结果，在80°C下成功地合成了缠结程度较小的超高分子量聚乙烯（UHMWPE），并具有出色的活性（6.18×10 5 g PE mol Ti –1 h –1 bar –1）。归因于弱缠结态，合成的UHMWPE在融合后呈现出较少的形态缺陷，并显着改善了冲击性能。
更新日期：2020-02-17
中文翻译：
MgCl 2（110）平面上的单独固定化有利于降低超高分子量聚乙烯的缠结密度
合成了明智地固定TiCl 4的多面体低聚倍半硅氧烷（POSS）改性的Ziegler-Natta催化剂用于乙烯聚合。通过X射线光电子能谱，CO低温吸附扩散反射红外傅里叶变换（DRIFT）光谱和密度泛函理论计算，研究了该非均相催化剂中活性位的结构。并入的POSS分子有助于MgCl 2（110）平面的形成，从而为容纳活性位点创造了更多位置。同时，POSS诱导了MgCl 2分子的结晶，后者捕获了失活的TiCl 4分子并消耗了一部分负载的TiCl 4。这种组合稀释了催化表面上的活性位点，并产生了更多的分离出的活性物种，并导致增强了催化活性并减少了链重叠。结果，在80°C下成功地合成了缠结程度较小的超高分子量聚乙烯（UHMWPE），并具有出色的活性（6.18×10 5 g PE mol Ti –1 h –1 bar –1）。归因于弱缠结态，合成的UHMWPE在融合后呈现出较少的形态缺陷，并显着改善了冲击性能。
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