Artificial Weathering Effects on the Physical and Chemical Properties of Paulownia tomentosa and Pinus koraiensis Woods Heat-Treated in Oil and Air

Abstract

This study evaluated the effect of artificial weathering on the surface characteristics, physical properties, and chemical compositions of oil heat-treated (OHT) and air heat-treated (AHT) Paulownia tomentosa and Pinus koraiensis woods. The untreated and heat-treated samples at 180, 200, and 220 °C for 2 h were exposed to ultraviolet (UV) and water for artificial weathering for 168 and 336 h, respectively, according to ASTM G53-96. The weathering experiment comprised 2 h of UV-light irradiation followed by 2 h of condensation cycles. Color change, volumetric swelling, and chemical components of weathered samples were determined. In both species, heat-treated woods showed a significantly lower total color change and volumetric swelling than the untreated woods. The total color change and VS of OHT woods were significantly lower than those of AHT. Fourier transform infrared spectra indicated that the lignin peaks in untreated and AHT woods decreased after weathering exposure, whereas the peaks were stable in OHT woods. Oil heat treatment is an effective method to stabilize dimensional change and color quality during weathering.