The use of the polymeric materials in high voltage applications is considered especially interesting in the electrical and industrial materials sectors. In this context, the purpose of this paper is to improve the electrical properties of Tree Retardant Cross-linked Polyethylene (TR-XLPE) with respect to mechanical characteristics by adding Kaolin filler with 15%, 30%, 40% and 50% concentration percentages. The dielectric strength of the composites was tested under several conditions such as (dry, wet and salty wet at (20000µS/cm, 30000µS/cm and 50000µS/cm)). Tensile strength test was applied to investigate the mechanical properties of TRXLPE after adding Kaolin filler with 15%, 30%, 40% and 50% concentration percentages. Soft program (Curve fitting) is used to select the most proper equation between dielectric strength values under each condition and different percentages of Kaolin filler also between tensile strength and the same percentages of Kaolin filler. Grey Wolf Optimizer (GWO) was applied to find the best suitable percentages of Kaolin filler to obtain the best optimal values of dielectric strength and tensile strength.

Keywords : TR-XLPE; Kaolin; Dielectric strength; Tensile strength; GWO.