Synergistic effect of silica sol and K2CO3 on flame-retardant and thermal properties of wood

Abstract

In this study, silica sol (SiO2 sol) and K2CO3 were used as flame retardants for wood. The synergistic effect of SiO2 sol and K2CO3 on the flame retardancy, leaching resistance, and thermal properties of wood was investigated. The limiting oxygen index results revealed a significant improvement in the flame retardancy and leaching resistance of the wood sample treated with K2CO3 and SiO2 sol using the double bath technique. The thermal analysis results showed that the synergistic effect of K2CO3 and the SiO2 sol effectively prolonged the degradation of the wood sample during the charring stage and improved the stability of the char residue. The thermogravimetry–mass spectrometry analysis and scanning electron microscopy results showed that K2CO3 catalyzed the degradation reaction of the wood sample at lower temperatures resulting in an increase in the water and carbon dioxide output, and the SiO2 sol formed a compact and melted barrier on the surface of the char residue, which hindered the transfer of heat and combustible gases in the condensed phase. Thus, the combination of K2CO3 and SiO2 sol proves to be a promising flame-retardant system for wood.