Wood-inorganic composites prepared by the sol-gel process .6. Effects of a property-enhancer on fire-resistance in SiO2-P2O5 and SiO2-B2O3 wood-inorganic composites

A binary system to prepare wood-inorganic composites was studied in a previous work by adding trimethylphosphite (TMP) or trimethylborate (TMB) to a reaction system of TEOS (tetraethoxysilane silane)/EtOH/acetic acid (1:1:0.01 in molar ratio). The obtained SiO2-P2O5 and SiO2-B2O3 wood-inorganic composites were then evaluated on their enhanced thermal properties of the wood. These binary composites were tested on the stability of the gels against weathering, and P2O5 and B2O3 gels were found to have leached out from the composites. A property-enhancer added binary reaction system was, therefore, evaluated against water leaching of the gels. The results clearly indicated that, even after severe leaching test, the property-enhancers, such as 2-heptadecafluoro-octylethyltrimethoxysilane (HFOETMOS) and decyltrimethoxysilane (DTMOS) could maintain the fire-resisting properties, particularly in the SiO2-P2O5 composites due to their water-repellent properties. Additionally, the property-enhancer containing fluorine, as in HFOETMOS could even improve the fire-resisting properties of the binary composites.