Improving anti-weathering performance of thermally modified wood by TiO2 sol or/and paraffin emulsion

The poor anti-weathering performance of thermally modified wood is always an issue that influences its appearance as well as its service life after exposure in outdoor circumstance. In this study, titania (TiO2) sol, paraffin emulsion, and their combination were used to impregnate thermally modified Scots pine (Pinus sylvestris L.) sapwood, modified at 212 °C, and then the samples were subjected to an accelerated weathering test for up to 1176 h. The time-dependent changes on surface color, gloss and water contact angle (WCA) of control and post-treated samples were investigated during the weathering process. Moreover, the chemical and morphological alterations were analyzed by attenuated total reflected Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The results showed that TiO2 was not resistant to water but addition of paraffin emulsion improved the adherence of TiO2 on wood surface. After post-treatment with TiO2 sol and paraffin emulsion, the anti-weathering performance of thermally modified wood improves due to the controlling of negative effects from ultraviolet and water on wood surface, respectively. The degradation of wood components decreased significantly in TiO2/paraffin treated samples, which was confirmed by the FTIR and SEM results.