High temperature and fire behavior of hydrothermally modified wood impregnated with carbon nanomaterials

Wood is one of the most widely used construction materials but it is thermally degradable and combustible, which poses serious safety concerns. In this research, the high temperature and fire behavior of hydrothermally modified western hemlock, impregnated with carbon nanomaterials pre-adsorbed with alkali lignin, was examined by cone calorimetry, scanning electron microscopy, thermal gravimetric analysis, and Fourier transform infrared spectroscopy. The hydrothermal treatment made the wood less hydrophilic, allowing the formation of a dense protective layer of carbon-rich additives on the external wood surface at low loading (5 wt%) after aqueous-phase vacuum impregnation. Results revealed that the unique combination of these two processes reduced the total heat release by up to 32%, diminished flame spread by 31%, decreased the average carbon dioxide yield by 12%, lowered the total mass loss by 10%, and significantly slowed the pyrolytic reactions of wood. This research has important implications for the development of valued-added wood products with superior fire safety from relatively low cost timbers, such as western hemlock.