Several SiO2 wood-inorganic composites and their fire-resisting properties

In a study on the SiO2 wood-inorganic composites prepared by the sol-gel process with tetraethoxysilane (TEOS), it is more appropriate to use safer agents than TEOS, considering the operational and processing environments. In this study, therefore, methyltrimethoxysilane (MTMOS) was used to prepare the SiO2 wood-inorganic composites, and comparative studies were made with TEOS. Resultingly, SiO2 wood-inorganic composites could be successfully prepared from MTMOS reaction system, as in TEOS system, with its lower concentration, and both composites had SiO2 gels specifically formed within the cell walls from moisture-conditioned wood specimens. On this SiO2 composites, the water-repellent properties were added most effectively with a molar ratio of 2-heptadecafluorooctylethyltrimethoxysilane (HFOETMOS) to alcohol being 1/250 and 1/180 for TEOS and MTMOS reaction systems, respectively. On the other hand, fire-resisting properties were tried to add to SiO2 composites with several fire-resisting agents. The fire-resisting agents in the obtained composites are not, however, stable and leached out readily. Therefore, a small addition of HFOETMOS was tested to the MTMOS and TEOS reaction systems with fire-resisting agents. The obtained results clearly indicated that HFOETMOS could restrain the fire-resisting agents to be leached from the composites, and that composites from MTMOS system were superior to TEOS system on the antileachability. Therefore, MTMOS can be appropriate for displacement of TEOS as a chemical agent to prepare SiO2 wood-inorganic composites.