Phytic acid for dual wood protection against fungi and fire
Abstract
Phytic acid (PA) is a natural compound derived from plant seeds and cereals with excellent antifungal properties and fire resistance. However, the potential of PA for dual wood protection is yet to be reported. This study investigated the antifungal properties and fire performance of PA for wood protection. The antifungal properties of PA against common wood-decaying fungi, including two white-rot fungi, Trametes versicolor (T.v.) and Irpex lacteus (I.l.), and two brown-rot fungi, Gloeophyllum trabeum (G.t.) and Rhodonia placenta (R.p.), were studied for both in vitro and in vivo tests. The thermal stability (pine and polar) and fire resistance (pine) of wood samples treated with different concentrations of PA by vacuum impregnation were also evaluated. For the in vitro test, PA almost fully inhibited the growth of three of the four fungi tested at a PA concentration of 0.25 wt% except for fungus R.p., which was less sensitive to PA and could still grow at 4 wt% PA. The in vivo durability test results showed that PA significantly improved the fungal resistance of both pine and poplar wood blocks for the brown-rot and white-rot fungi, respectively, as shown by lower mass losses of 5-25% compared with the control group’s 25-45%. The results from thermogravimetric analysis under both air and nitrogen indicated that PA increased the thermal stability of both pine and poplar samples, which was further confirmed by the results from the mass loss calorimeter. The peak heat release rate and the total heat release rate of 10 wt% PA-treated samples were decreased by 39% and 48%, respectively, at 148 kW/m2 and 34.6 MJ/m2 compared with the control, whereas the residual mass increased by 137% at 48.4%. Overall, this research demonstrates the potential of using PA to improve both fungal resistance and fire performance of wood products.
