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首页> 外文期刊>Macromolecular rapid communications: Publishing the newsletters of the European Polymer Federation >A Hemi-metallocene Chromium Catalyst with Trimethylaluminum-Free Methylaluminoxane for the Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene
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A Hemi-metallocene Chromium Catalyst with Trimethylaluminum-Free Methylaluminoxane for the Synthesis of Disentangled Ultra-High Molecular Weight Polyethylene

机译:不含三甲基铝的甲基铝氧烷的半金属茂铬催化剂,用于合成纠缠的超高分子量聚乙烯

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摘要

Recently, it has been shown that by using a single-site catalytic system having titanium as a metallic center, it is possible to tailor the entanglement density in the amorphous region of a semi-crystalline ultra-high molecular weight polyethylene (UHMWPE). This route provides the possibility to make high-modulus, high-strength uniaxially and biaxially drawn tapes and films, without using any solvent during processing. In this publication, it is shown that a single-site catalyst having chromium as metallic center, proposed by Enders and co-workers, can also be tuned to provide control on the entanglement density during synthesis of the UHMWPE. However, to achieve the goal some modifications during the synthesis are required. The synthesized polymers can be processed in the solid state below the equilibrium melting temperature, resulting in uniaxially drawn tapes having tensile strength and modulus greater than 3.5 N/tex and 200 N/tex, respectively. Rheological studies have been performed to follow the increase in entanglement density in melt state with time.
机译:最近,已经显示出通过使用具有钛作为金属中心的单点催化体系,可以调整半结晶超高分子量聚乙烯(UHMWPE)的非晶区中的缠结密度。这种途径提供了在加工过程中不使用任何溶剂的情况下制造高模量,高强度的单轴和双轴拉伸带和膜的可能性。在该出版物中,显示了恩德斯和同事提出的以铬为金属中心的单中心催化剂也可以进行调节,以控制UHMWPE合成过程中的缠结密度。但是,为了实现该目标,需要在合成过程中进行一些修改。可以在低于平衡熔融温度的固态下处理合成的聚合物,从而得到拉伸强度和模量分别大于3.5 N / tex和200 N / tex的单轴拉伸带。已经进行了流变学研究,以追踪熔融态纠缠密度随时间的增加。

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