Investigation on the Surface Condition of Gamma Irradiated Silicone Rubber Micro-Nanocomposites

Silicone rubber (SR) micro nanocomposites formed with micro-ATH and nano-alumina particles have been subjected to different levels of gamma-ray irradiation to understand the characteristic variation in the surface condition of the material through contact angle measurement, Atomic Force Microscopy (AFM) studies, water droplet-initiated corona inception voltage (CIV) measurement and by laser-induced breakdown spectroscopy (LIBS) analysis. It is realized that the recovery rate of silicone rubber micro nanocomposites is less compared with the base SR material. It is observed that, irrespective of the level of irradiation, the contact angle and water droplet initiated CIV of the specimen have shown direct correlation. FTIR analysis clearly indicates variation in methyl group formation on irradiation is less with S2 specimen. It is also observed that fractal dimension calculated by three different techniques for the surface profile data obtained using AFM is in directly in proportion with average surface roughness. In addition, the lacunarity values of the irradiated samples followed the same pattern as that of the average surface roughness. The variation in thermal degradation temperature has been analyzed by adopting thermogravimetric analysis (TGA). The calculated plasma temperature values from laser-induced breakdown spectroscopy and the crater depth formed due to laser ablation have shown inverse relationship. Artificial neural network (ANN) has been employed successfully using LIBS data, to understand the level of irradiation of the SR samples. Overall, the silicone rubber micro-nanocomposite sample S2 filled with micro-ATH and nano Alumina has reflected relatively lesser degradation after being exposed to gamma irradiation, over other test specimens.