PEX synthesized via peroxide for oil pipes, starting from different commercial polyethylenes: Influence of comonomer and catalyst type

Abstract

In the present work, crosslinked polyethylene (PEX) was obtained by adding dicumyl peroxide (DCP) to polyethylene. High-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) were used as starting polymers, synthesized by Ziegler-Natta or metallocene catalysts. Also, the effect of the comonomer type (butene or hexane) in the LLDPE was investigated. Materials were processed with increasing amounts of dicumyl peroxide (DCP). Samples were pressed with suitable amounts of these components. The efficiency of the crosslinking reaction was evaluated by gel content and thermal properties, and the melting temperature and degree of crystallinity were evaluated using differential scanning calorimetry (DSC). The microstructure of the starting polyethylene was correlated with the effectiveness of crosslinking and the resultant thermal and mechanical properties of the PEX. A new crosslinking coagent was also evaluated, along with the resistance of PEX samples in oil. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.