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Preparation of multimodal high and ultra-high molecular weight polyethylene
International Journal of Polymer Analysis and Characterization ( IF 1.9 ) Pub Date : 2021-08-04 , DOI: 10.1080/1023666x.2021.1959867
Sara Pereira de Agrela 1 , Luiz Rogério Pinho de Andrade Lima 1 , Rosemário Cerqueira Souza 1
Affiliation  

Abstract

The multimodal molecular weight distribution of high molecular weight polyethylene combines enhanced mechanical properties and good processing properties. The conventional slurry process produces a high-density polyethylene with mono or bimodal molecular weight distribution, using the classical Ziegler type catalysts supported on inorganic materials. The production of multimodal molecular weight distribution high molecular weight polyethylene is very intricate and requires parallel reactor cascades with different residence times or the use of a supported catalyst with different active sites. This study shows that ethylene polymerization reactions using an unsupported Ziegler type catalyst, in a batch reactor, can produce polymers with a density higher than 0.93 g mL−1, a melting temperature of about 140 °C, and a degree of crystallization of about 79%. The molecular weight distributions of the produced polymer have a broad dispersion of molecular weight (log M) 2 to 7.2 and there are four peaks, showing multimodal distribution and large molar weight. The polyethylene produced using this single-step method is a blend of high and very high molecular weight polyethylene.



中文翻译:

多峰高、超高分子量聚乙烯的制备

摘要

高分子量聚乙烯的多峰分子量分布结合了增强的机械性能和良好的加工性能。传统的淤浆工艺使用负载在无机材料上的经典齐格勒型催化剂生产具有单峰或双峰分子量分布的高密度聚乙烯。多峰分子量分布高分子量聚乙烯的生产非常复杂,需要具有不同停留时间的平行反应器级联或使用具有不同活性位点的负载型催化剂。该研究表明,在间歇式反应器中使用无载体齐格勒型催化剂的乙烯聚合反应可以生产密度高于 0.93 g mL -1 的聚合物,熔点约140°C,结晶度约79%。所得聚合物的分子量分布具有较宽的分子量分布(log M)2~7.2,有4个峰,呈现多峰分布,分子量大。使用这种一步法生产的聚乙烯是高分子量聚乙烯和超高分子量聚乙烯的混合物。

更新日期:2021-09-10
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