Synthesis of polyaluminum hydroxide on silica spheres for effective fire retardant

Until recent years, the majority of flame retardants have been halogen-containing compounds. Although halogen compounds slow down the flame spread and reduce the fire growth, they increase the release of toxic gases, such as CO and HX (hydrogen halide), are carcinogenic and toxic chemicals, and accumulate environment. The authors carried out the synthesis of polyaluminum hydroxide on silica spheres for effective fire retardant. Large surface area of nanosilica spheres was utilized for improve the fire retardancy. The surface of silica spheres was modified with 3-mercaptopropyltrimethoxysilane (MPTMS) and polyaluminum hydroxide. The field emission scanning electron microscope images showed that the amount of aluminum hydroxide increased with increasing the amount of AlCl3. The characteristic absorption peaks of Al-OH, Si-OH, Si-O-Si, Si-O, -CH, Si-O-C, and Si-O-Al were observed. The existence of sulfur indicated the surface of silica spheres were modified with MPTMS. The small amount of Cl implied that most of the Al-Cl-3 were hydrolyzed.