High Permeability of Boron along the Transverse Direction of Wood under High-Voltage Electrostatic Field (HVEF) Treatment

Permeability of wood preservative is one of the most significant factors for protection of wood construction. Anisotropic flow permeability was involved in different directions of wood with higher flow resistance in the transverse and lower longitudinal directions. In this study, boron acid solution was brushed onto the tangential section of air-dried wood cubes and boron penetration along wood transverse direction was investigated under free diffusion, vacuum and HVEF treatments. Multi-scale boron distribution, FTIR measurement, leaching property, mechanical properties and fungistatic characteristic were investigated for free diffusion, vacuum and HVEF treated samples respectively. The results revealed that boron exhibited high permeability along the transverse direction with the penetration depth of approximate to 35 mm for HVEF treated samples and approximate to 1 mm for free diffusion and vacuum treated samples. For HVEF treated samples, no significant decrease of hardness, compression modulus of elasticity and strength were found in the treated samples. Better fungistatic characteristic was showcased in HVEF treated samples exposed to white rot fungi. Thus, HVEF treatment has a positive effect on boron permeability and the improvement of penetration depth of preservatives hence playing a significant role in wood protection and prolonging the service life of wood construction.