Fabrication of silicone rubber nanocomposites and quantitative evaluation of dispersion state of nanofillers

Silicone rubber nanocomposites were newly fabricated for outdoor insulation in a laboratory scale. Two kinds of mixing devices, namely a triple roll mill and a high pressure-type mixer, were used to compare the dispersibility of nanofillers. Nano-sized silica (SiO₂) and boehmite alumina (AlOOH) particles were used as nanofillers. Microsized aluminum trihydrate (Al(OH)₃) particle was used as a microfiller for comparison. The dispersion state of nanofillers in specimens was observed by scanning electron microscopy and then evaluated quantitatively by an image processing technique. Consequently, it was found that the high pressure-type mixer perform best for the nano-sized silica dispersion between them, and the nano-sized silica particles could be dispersed in 100 nm or less. It was also shown that uniformly dispersed nanofillers in silicone rubber have little influence on the hydrophobicity of the specimen surfaces.