Oleothermal modification of fir wood with a combination of soybean oil and maleic anhydride and its effects on physico-mechanical properties of treated wood

This research work aimed at studying the effects of oleothermal modification of fir wood by using combined soybean oil with maleic anhydride (OHT–MA) to achieve lower treatment temperatures and enhance physico-mechanical properties. Wood blocks were oleothermally treated with soybean oil and OHT–MA at five different treatment temperatures (100, 120, 140, 160 and 180 °C) for three different holding times (30, 60 and 180 min). Afterward, physical and mechanical properties of the treated samples were determined, i.e., density, water absorption and volumetric swelling as the physical properties and bending strength, compression parallel to grain and impact load resistance as the mechanical properties. Results revealed increases in densities and reduction in water absorption as well as volumetric swelling of all treated samples. The mechanical properties were affected by OHT–MA treatment at different temperatures. Bending modulus of elasticity as well as compression parallel to grain was increased due to OHT–MA treatment. In addition, there was less reduction in impact load resistance of the treated samples. It was revealed that the OHT–MA enhanced wood properties at low treatment temperatures as well as shorter holding times.