Surface modification of magnesium hydroxide by wet process and effect on the thermal stability of silicone rubber

This work reported the surface modification of magnesium hydroxide (MH) employing vinyltriethoxysilane (VTES) by wet process for the sake of improving the compatibility between magnesium hydroxide (MH) and silicone rubbers (SR). The morphology, surface property and dispersion stability in organic phase of VTES-modified MH (VTES-MH) were studied in detail. Fourier transform infrared (FT-IR) spectra and photoelectron spectra (XPS) proved that the VTES molecules were chemically bound to the surface of MH via the reaction between SiOC2H5 of VTES and hydroxyl group of MH. The contact angle tests implied that the surface of MH was transformed from hydrophilic to hydrophobic successfully with the interface energy of MH decreased from 63.35 to 25.13 mJ·m−2. Dispersion stability tests showed the dispersibility of MH nanoparticles in the organic phase was significantly improved after modification. Finally, the VTES-MH was applied as a flame retardant to enhance the thermal stability and reduce the flammability of SR. The VTES-MH showed good compatibility to SR even at high loading amount (5:5) and a high limit oxygen index (LOI) of 40.2% was obtained. The formation mechanism of SR/VTES-MH composites was also discussed.