Evaluation of bimodal polyethylene from chromium oxide/metallocene hybrid catalysts for high resistance applications

Abstract

An interesting alternative to the industrial two-stage cascade process for the production of bimodal polyethylene, used for high resistance applications such as pressure pipes, has been developed. The key point is a binary catalytic system with chromium and metallocene sites incorporated together on AlSBA-15 mesostructured material. This hybrid catalyst is able to produce bimodal polyethylene in a single reactor. In the present work, it is shown that, in the presence of hydrogen and comonomer (1-butene or 1-hexene) in the reaction medium, the obtained polyethylenes exhibit appropriate mechanical properties for pipes manufacture, such as resistance to rapid crack propagation (RCP) and low crack growth (SCG), reaching standards for PE100 and even for PE100RC grades.