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Dundar Yilmaz1 Dooman Akbarian1 Adri Duin1

1, The Pennsylvania State University, State College, Pennsylvania, United States

Polyethylene (PE) is one of the widely used commercial polymers. Cross linking improve many properties of PE such as high dielectric strength, mechanical strength, low water permeability.
Cross-linked PE (XLPE) has emerged as the insulator of choice for high-voltage direct current (HVDC) power transmission cables due to its favorable dielectric properties, low water permeability, structural integrity at high temperature and chemical resistance.
Dicumyl Peroxide (DCP) has been used as an accelerating agent in cross linking PE. We investigated cross linking mechanisms and mechanical and electrical properties of XLPE systems using large scale molecular dynamics simulations. We first started with a non-reactive force field to understand diffusion of DCP molecules into the PE matrix with and without the influence of external electric field. Second, we employed eReaxFF to investigate cross linking mechanisms. ReaxFF reactive force fields first developed for hydrocarbons and later ported to different systems such as ceramics, metals and their oxides and provided precise results for those systems. eReaxFF is an extension to ReaxFF in which electrons are treated explicitly in a pseudo classical manner. We adopted a previous ReaxFF reactive force field and developed eReaxFF reactive force field to capture DCP-PE interactions, and investigated reaction mechanisms of crosslinking of PE via DCP under the external electric field using large scale molecular dynamics simulations. We investigated the effects of different parameters such as temperature, density, pressure and the ratio of peroxides to polyethylene on the formation of byproducts, distribution of functional groups and cross-linking. Furthermore we investigatedmechanical ( tensile strength, bulk modulus) and electrical properties ( dielectric strength ) of the cross linked PE.

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