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首页> 外文期刊>Journal of Applied Polymer Science >Low dielectric loss polyethylene polymerized with chromocene catalyst
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Low dielectric loss polyethylene polymerized with chromocene catalyst

机译：二茂铬催化剂聚合的低介电损耗聚乙烯

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We studied the polymerization of ethylene monomers with chromocene catalyst to produce polyethylene with low dielectric loss in the microwave region. Chromocene (bis-cyclopentadienyl chromium) is very active for a long period during ethylene polymerization, and it also has a very low dipole moment because of its symmetrical molecular structure. Polyethylene polymerized by using chromocene has a low dielectric loss in the 500 MHz region caused by gamma relaxation. We were able to calculate the loss in this wavelength region from a summation of each individual contribution. The contributors included catalyst residue, and polar groups, i.e., methyl groups and double bonds such as vinyl, internal trans-vinylene, and vinylidene groups at a certain crystallinity. In order to make low dielectric loss polyethylene with a chromocene catalyst, we first tried to improve both the process of ethylene polymerization with a chromocene catalyst and the dielectric loss (tan delta) of polyethylene at 500 MHz. We measured the number of polar groups and the residual catalyst in polyethylene with the IR method. Our results revealed that both the hydrogenation reaction that occurs during ethylene polymerization with the chromocene catalyst and the crystallization of polyethylene after polymerization were very effective in reducing the dielectric loss of polyethylene. (C) 1998 John Wiley & Sons, Inc. [References: 6]
机译：我们研究了二茂铬催化剂与乙烯单体的聚合反应，以生产在微波区域具有低介电损耗的聚乙烯。铬茂（双环戊二烯铬）在乙烯聚合过程中具有很长的活性，并且由于其对称的分子结构，偶极矩也很低。通过使用二茂铬聚合的聚乙烯在500 MHz范围内由于伽马弛豫引起的介电损耗低。我们能够通过每个贡献的总和来计算该波长区域的损耗。贡献者包括催化剂残基和极性基团，即在一定结晶度下的甲基和双键，例如乙烯基，内部反式亚乙烯基和亚乙烯基。为了用二茂铬催化剂制备低介电损耗的聚乙烯，我们首先尝试同时改进二茂铬催化剂进行乙烯聚合的过程和聚乙烯在500 MHz时的介电损耗（tanδ）。我们用IR方法测量了聚乙烯中的极性基团数和残留的催化剂。我们的结果表明，在用二茂铬催化剂进行乙烯聚合过程中发生的氢化反应和聚合后聚乙烯的结晶都对减少聚乙烯的介电损耗非常有效。 （C）1998 John Wiley＆Sons，Inc. [参考：6]

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