Poly(epsilon-caprolactone) grafting into Scots pine wood: improvement on the dimensional stability, weathering and decay resistance

Wood modification treatments by substitution or blocking of wood hydroxyl groups with hydrophobic molecules are some of the novel approaches that may improve dimensional stability, weathering and decay resistance of wood. In this study, the Scots pine (Pinus sylvestris L.) wood was modified by ring opening polymerization of epsilon-caprolactone to investigate the artificial weathering and decay resistance. In total, 672 h of artificial weathering was applied on modified wood by exposure of UV-light and water cycles. Additionally, decay test was carried out by using Coniophora puteana and Trametes versicolor fungi on the samples after leaching procedure. After weathering, the color change and contact angle measurements, as well as macroscopic observations revealed that the modified wood had significantly better surface properties than reference wood. FT-IR and SEM analysis proved that there was still polycaprolactone on the weathered surface with some minor crack formations of wood structure. The polycaprolactone modification effectively protected wood against decay even after leaching. This study also demonstrates that the polycaprolactone modification can provide a significant improvement on dimensional stability, as well as water repellence of Scot pine wood.