Influence of dispersing aids on nano alumina/micro aluminum tri hydrate filled silicone rubber composites for outdoor high voltage insulators

Abstract Nano alumina and micro aluminum tri hydrate filled high‐temperature vulcanizing silicone rubber composites were prepared with dispersing aids of surfactant Triton™‐X‐100 (TX‐100) and silane coupling agent 3‐methacryloxypropyltrimethoxysilane (KH‐570), through an in situ modification technique. Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) analysis were carried out to understand the effects of dispersing aids on the structural and crystallographic properties of composites. Scanning electron microscopy images of TX‐100 dispersed composites revealed the presence of several localized regions of agglomeration, whereas KH‐570 dispersed composites showed moderate dispersion. Measurements of volume resistivity demonstrated an increment of four decades for KH‐570 dispersed nanocomposite over TX‐100. Better compatibility between fillers and base matrix through KH‐570 was evident from the low loss factor values. Inclined plane tracking and erosion results were discussed in detail with leakage current analysis. The binary composite prepared with KH‐570 was observed to resist the detrimental dry band arcing and subsequent erosion by 2 h and 20 min over TX‐100 dispersed composite. Dry arc resistance and the formation of thermal pathways connecting micro and nanofillers were discussed in detail. FTIR analysis of ash generated after inclined plane tracking and erosion test confirmed the surfacing of added fillers. KH‐570 dispersed composites showed superior properties as compared to composites prepared with TX‐100.