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首页> 外文期刊>Journal of Applied Polymer Science >Residual metal content in ethylene-propylene-diene monomers synthesized using vanadium- and zirconocene-based catalysts
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Residual metal content in ethylene-propylene-diene monomers synthesized using vanadium- and zirconocene-based catalysts

机译：使用基于钒和锆茂的催化剂合成的乙烯-丙烯-二烯单体中的残留金属含量

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摘要

Ethylene-propylene-diene monomer (EPDM) terpolymers were prepared using either vanadium (VOCl_3/Al_2Et_3Cl_3) or zirconocene (Et(Ind)_2ZrCl_2/MAO) catalyst systems. Residual metal contents in EPDM films were determined by Rutherford backscattering spectrometry. Metallocene catalyst systems exhibited a higher activity, producing EPDM with lower molecular weight and narrower molecular weight distribution. The highest activity guaranteed lower residual metal content (Zr/C = 10~(-5)) than in the case of EPDM produced by VOCl_3/Al_2Et_3Cl_3 (V/C = 10~(-4)). Subsequent steps of dissolution of the polymer and its reprecipitation were seen to reduce the metal contents in both metal systems. Concerning the cocatalyst retention, despite initial use of a very high amount of methylaluminoxane/metallocene (Al/Zr = 3000) in the reactor, only about 4% of this initial concentration remained in the polymer. On the other hand, in the case of vanadium-based catalyst, almost all Al present in the initial conditions ( congruent 8.3) remained in the polymer. In both cases, the residual Al/M ratio was close to the value generally proposed for the generation/stabilization of the active species. In the case of vanadium systems, a test in the synthesis of ethylene propylene rubbers indicated that the absence of diene in the polymer structure leads to a reduction in the residual vanadium content, indicating that the diene double bond might be responsible for partially vanadium coordination.
机译：使用钒（VOCl_3 / Al_2Et_3Cl_3）或锆茂（Et（Ind）_2ZrCl_2 / MAO）催化剂体系制备乙烯-丙烯-二烯单体（EPDM）三元共聚物。 EPDM膜中的残留金属含量通过卢瑟福反向散射光谱法测定。茂金属催化剂体系表现出较高的活性，产生具有较低分子量和较窄分子量分布的EPDM。与VOCl_3 / Al_2Et_3Cl_3（V / C = 10〜（-4））制得的EPDM相比，最高活性可确保更低的残留金属含量（Zr / C = 10〜（-5））。可以看到，随后的聚合物溶解步骤及其再沉淀降低了两种金属体系中的金属含量。关于助催化剂的保留，尽管在反应器中最初使用了非常大量的甲基铝氧烷/茂金属（Al / Zr = 3000），但聚合物中仅保留了约4％的初始浓度。另一方面，在钒基催化剂的情况下，几乎所有初始条件下存在的Al（同等8.3）都保留在聚合物中。在这两种情况下，残留的Al / M比率都接近于为活性物质的产生/稳定化通常提出的值。对于钒系统，乙烯丙烯橡胶合成中的一项测试表明，聚合物结构中不存在二烯会导致残留钒含量降低，这表明二烯双键可能是部分钒配位的原因。

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