The effect of modification technologies on the triboelectric activation of wood surfaces

Abstract During brushing, friction between the brush and solid wood causes surfaces to become electrically charged through triboelectric effects. Wood, being a semi-conductive material, has its electrical conductivity influenced by factors such as moisture content, density, and anatomical structure. This study investigates the extent of triboelectric activation on wood surfaces using a wood brushing machine, with continuous detection of triboelectric surface field strengths. The effects of various wood modification technologies were assessed by comparing untreated control samples of two wood species, beech and poplar, to samples subjected to (1) densification, (2) steaming, and (3) thermal treatment at 120 °C and 180 °C. Positive triboelectric field strengths were recorded across all samples, with both nylon and steel wire brushes. The highest mean field strengths, 29.33 kV/m with the nylon brush and 7.86 kV/m with the steel brush, were observed in thermally treated at 180 °C and steamed poplar wood. Although surface field strength could not be directly correlated to density, a dependency on moisture content was established. These findings suggest that tailoring surface charges by controlling triboelectric effects could offer new opportunities for technical applications, such as chemistry-free primer modifications prior to wood coating.