Accelerated ultraviolet weathering investigation on micro-/nano-SiO2 filled silicone rubber composites

Abstract

This study attempts to elucidate whether the addition of micro and/or nano-silica (SiO2) particles can enhance the resistance of pure polydimethylsiloxane against synergistic effects of UV, temperature and high-voltage stress. Four types of composites (U-SR, M-SR, MN-SR and N-SR) are fabricated by adding micro and/or nano-silica particles and then subjected to multi-stress degradation in a test chamber. Results show that there is an apparent surface discoloration in the form of yellowish pale tint and a significant resistance to hydrophobicity reduction is offered by N-SR and MN-SR followed by M-SR and U-SR. Scanning electron microscopy and surface roughness findings proclaimed that N-SR and MN-SR offer excellent resistance against filler exposure and an increase in surface roughness. There is a minor reduction in absorbance level of Si (CH3)2 and Si-O-Si functional groups of composites but interestingly, hydrophilic hydroxyl group absorbance level is found higher in the USR comparatively. Furthermore, dielectric response measurements indicate considerable sensitivity to weathering with N-SR and MN-SR giving the lowest dielectric loss. Results indicate that the addition of nano-silica to pure and micro-silica filled SR can enhance its UV weathering resistance considerably by building an effective UV shielding layer.