Two level factorial and optimization studies of Silicon Rubber surface resistivity for high voltage insulation — effects of raw materials and internal mixer processing parameters

Silicone Rubber (SIR) are steadily gaining acceptance in the high voltage insulation application due to a greater insulation properties and light weight attribute, which are suitable in substituting the conventional glass and ceramic insulator. There are still large research efforts conducted all around the world in order to improve the insulating behavior and sustainability of SIR. However, the investigation on the effects of materials formulation and processing parameters towards the insulation performances of SIR are still scarce. In this work, materials and processing parameters of Alumina Trihydrate (ATH) (10-50pphr), Dicumyl Peroxide (0.5-1.5pphr), speed of mixer (40-70 rpm) and mixing period (5-10 mins) were varied accordingly as to evaluates their effects towards dependent response of surface resistivity. The inter-correlation and contribution between all four parameters with response studied and optimization of it were established by using the statistical Design of Experiment (DOE) of two level full factorial at 2⁴ level using Design Expert v10 software. The model analysis is finalized with R² value of 88.72% together with a suggested optimized solution of A: ATH=50 pphr, B: DCP = 0.50 pphr, C: Mixing Speed = 70 rpm and D: Mixing Time = 10 mins with overall 0.959 of desirability value. In overall, this study emphasizes that the materials and processing factor had a major impact in influencing the surface resistivity of SIR for high voltage insulation purposes.