Physicochemical properties of thermally treated poplar wood in silicone and rapeseed oils: A comparative study

The use of poplar as a nondurable wood in exterior applications exposed to harsh environments is limited and can impose a high maintenance cost. The heat treatment in silicone oil (SOHT) and rapeseed oil (ROHT) at 190 °C for 4 h was carried out on the poplar wood to impart long-lasting protection to the wood. The water-related properties of treated wood before and after the leaching test were determined. The chemical composition and thermal behavior of samples were also studied by FTIR and DSC analyses. The SOHT resulted in a darker color wood showing its higher effectiveness compared with the ROHT in terms of modifying wood properties. The SOHT changed the chemical composition of wood more drastically than ROHT. The SOHT samples showed good hydrophobic stability even after the leaching. Strong relations between surface wettability and FTIR signal, related to the changes of wood biopolymers, were also determined. The smallest spreading area of water drop was observed in SOHT samples. The SOHT resulted in the lower water absorption and the volumetric swelling of wood samples which were less affected by the time of soaking in water. The DSC analysis confirmed the lower capacity of moisture uptake and the higher thermal stability of SOHT samples. This study suggests that SOHT has a higher potential for improving the water-related properties of poplar wood than ROHT. •The heat treatment in oil media was carried out on poplar wood to impart long-lasting protection.•Surface wettability of treated wood in relation to chemical changes were explored.•The heat treatment in silicone oil showed a higher potential to improve moisture-related properties of wood.