Effects of Hydrolytic Aging on the Behaviour of Nano Silica (SiO2)-Treated Spruce Wood

Wood is a viscoelastic composite material that has been historically prominent in the construction of buildings and continues to see widespread use. When used for exterior applications, wood is exposed to dynamic environmental conditions and can degrade if left untreated. Previous research has proven that vacuum impregnation of the lignin matrix with a silica (SiO2) nanoparticle colloid can enhance the viscoelastic properties, increase the density, and reduce the water uptake of wood. However, the behaviour of SiO2-treated wood under different environmental conditions over time has yet to be fully explored. This research aims to examine the durability and performance of SiO2-treated spruce wood samples subjected to accelerated hydrolytic aging conditions. Spruce wood samples treated with 40% SiO2 nanoparticle colloid under a −90 kPa vacuum were placed in an environmental chamber at 90 ºC and 80% RH. The samples were removed at regular intervals and thermogravimetric analysis, dynamic mechanical analysis, and tensiometry tests were performed. When compared to the results obtained from a set of non-treated samples, it was found that the SiO2-treated samples exhibited lower water uptake values as well as a lower rate of decrease in peak cellulose degradation temperatures when subjected to hydrolytic aging. The effects of the aging conditions on the viscoelastic properties of the samples were also found to be insignificant. These results indicate that the durability and properties of wood can be improved through nano-SiO2 impregnation as the material remains relatively stable when subjected to high temperature and humidity conditions over time.