Enhancement of Fire Retardancy Using Surface-Modified Silica Spheres with Aluminum Hydroxide

Large surface area and fire-inert property of sub-micrometer silica spheres were employed to improve the fire retardant performance by attaching large number of Si-O-Al(OH) groups. Various amounts of AlCl were attached to the surface of silica spheres and the residual -AlCl was hydrolyzed by adding excess amount of KOH. Although the FESEM image of pure silica spheres showed smooth surface, the surface-modified silica spheres exhibited nanoparticles on the surface of silica spheres. The characteristic absorption peaks of Al-OH and Si-O-Al were detected by FTIR spectra. Silica spheres attached with Si-O-Al(OH) were uniformly distributed on the surface of cellulose acetate films. The performance of the fire retardant was greatly enhanced by increasing the amount of aluminum hydroxide.