Surface properties of poplar wood after heat treatment, resin impregnation, or both modifications

To investigate the surface properties of different modified poplar (Populus tomentosa Carr.) wood samples, the color, surface roughness, and wettability of untreated poplar wood (control) and poplar modified via heat treatment, resin impregnation, and impregnation combined heat treatment were analyzed and compared in this study. The impregnant used in the test was a modified urea-formaldehyde resin with a low molecular weight and low viscosity. The results showed that the lightness of the samples was sorted in order as follows: the control was lighter than the resin impregnated sample, which was lighter than the impregnation combined heat treatment sample, which was lighter than the heat treatment sample. The surface of the control samples was relatively smooth, while after the impregnation, heat, and impregnation combined heat treatments, the Ra and Rz values increased, which indicated increased surface roughness due to the modifications. Among them, the heat-treated samples had the roughest surface, and the surface roughness of the impregnation combined heat treated samples at 160 °C had no major difference from the resin impregnated sample. The wettability of the samples decreased after heat treatment and increased after impregnation combined heat treatment. It was concluded that after the modification treatments, the color of the wood became darker, and the surface roughness and hydrophobicity increased.