Cross-linked Polyethylene (XLPE) has emerged as an outstanding insulator for high-voltage direct current power transmission cables due to its favorable dielectric properties, low water permeability, structural integrity at high temperature and chemical resistance. Dicumyl peroxide (DCP) is the most commonly used peroxide agent for the crosslinking of polyethylene for high voltage power cables. However, DCP-initiated crosslinking leads to the formation of different byproducts which remain in the final product and may have adverse effects on cable function and its long-term properties. Currently, our knowledge of the effects of the byproducts and chemical reactions involved during the crosslinking procedure on the properties of the final XLPE product is limited. By understanding how the crosslinking byproducts change the XLPE properties, improvements may be formulated relative to conventional XLPE cables. In order to design and optimize XLPE cables, it is crucial to obtain detailed, atomistic-scale insight of XLPE chemistry since every byproduct in XLPE affects differently the electrical properties of the polymer and thus the effect of each of the byproducts should be investigated. Quantum mechanic (QC) methods are considered the most accurate technique among atomistic simulation methods, however, these methods are prohibitively expensive, making them impractical for larger systems. The ReaxFF reactive force field method can model chemical reactions based on the bond order concept without the full expense of QC methods, and it has been successfully applied to a wide range of systems such as covalent and metal oxide/hydride/carbide materials. In this study, we developed a ReaxFF force field validated against DFT data obtained for XLPE chemistry. Using this force field, we studied the effects of different parameters such as temperature, density, type of peroxide, and the ratio of peroxides to polyethylene on the formation of byproducts, distribution of functional groups, and cross-linking.

Computational study on the peroxide crosslinking of polyethylene using ReaxFF reactive force field

2019 Spring National Meeting

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