Effect of temperature on the dynamic wettability of Chinese fir wood: integrative consideration of surface spreading, penetration and evaporation

Wood wettability, the process of liquid interaction with wood surfaces, is influenced by wood surface chemistry, structure, ambient conditions, and temperature. Understanding how temperature impacts wood wettability is crucial for high-temperature manufacturing processes. In this study, the sessile drop method was employed to explore the dynamic wettability of Chinese fir wood using three different liquids (water, glycerol and polyvinyl acetate (PVAc)) across a range of temperatures (25, 40, 60 and 80 °C). By considering spreading, penetration and evaporation, we revealed that the dynamic wettability of Chinese fir was strongly dependent on temperature and the type of liquid. Temperature elevation enhances wettability, leading to reduced contact angles and increased penetration ratios. Water exhibited the highest wettability, followed by glycerol, with PVAc being the least wetting agent. Notably, after 180 s of wetting at 80 °C, the measured contact angles were 0° for water, 45° for glycerol, and 120° for PVAc. When accounting for evaporation, the penetration of water decreased from 57 % to 47 % (25 °C) and 100 % to 62 % (80 °C). The activation energies for the penetration of water and PVAc into Chinese fir exhibited variations, with values of 35.3 and 158.3 kJ/mol, respectively. These comprehensive wetting results, covering spreading, penetration and evaporation, provide valuable insights into wood–water and wood–adhesive interactions, particularly when exposed to high-temperature conditions.