Monitoring electrical properties of thermally modified wood as a possible tool for quality assessment

Abstract

Abstract The electrical properties of thermally modified wood (TMW) of southern pine (Pinus spp.) have been investigated, while the samples were modified at 150°C, 175°C, 200°C, and 225°C for 4 h. After conditioning the samples at five relative humidities, the constants for electrical resistance (kR) and dielectricity (kP) were measured and calculated according to the model “electrical properties vs. moisture content”. The correlations between kR and kP and mass loss (ML), CIEL*a*b* color and bending properties in terms of modulus of rupture and modulus of elasticity were established. The coefficients of determination (R2) between these parameters were found to be between 0.926 and 0.999. TM influenced both kR and kP via changing the concentration and mobility of ions inside the wood and decreasing amount of polar groups of wood polymers. The conclusion is that the severity of TM such as the mechanical properties of TMW is in a close relation to the electrical properties.