Hollow silica sphere as filler for RTV-1 silicone rubber

Abstract

Hollow silica spheres were synthesised and used as filler for room-temperature vulcanised (RTV-1) silicone rubber. The template-assisted method was chosen to prepare this special kind of filler. Polyvinyl acetate spheres were obtained by dispersion polymerisation. Spheres with diameters of 100–500 nm were selected as a sacrificial template to synthesise hollow silica spheres. Tetraethoxysilane was chosen as the silicone source. A silica shell formed synchronously with template core dissolution by coating the silicone source on the template by the sol–gel method. The diameter of the hollow silica sphere was determined by the template size. The shell thickness was controlled by adjusting the amount of the silicone resource. The morphologies of the template and filler were characterised by transmission electron microscopy. The silicone rubber was strengthened with the filler prepared in this method. The swelling rate of RTV-1 silicone rubber was also tested to explain the reinforcing effect further. The possible mechanism for this behaviour is brought forward in this paper.