Combined effect of fluorocarbon resin impregnation and heat treatment: a dual approach for improving properties of paulownia wood

Paulownia wood has a significant economic value as it is a fast-growing tree species. Fluorocarbon (FC) resin impregnation with heat treatment (HT) at different levels (15% FC and 25% FC treatments at 150 and 160 degrees C) was used to minimise the adverse effect of the treatment on the properties of paulownia wood, particularly mechanical properties. Water contact-angle measurements showed a significant increase in hydrophobicity with the HT and FC treatments. Surface roughness analysis showed a decrease in roughness with the heat treatment and FC addition. FC treatment improved surface hydrophobicity and colour properties of the heat-treated wood. The control specimen had the highest modulus of rupture (MOR) of 42 MPa and modulus of elasticity (MOE) of 1935 MPa, but had lower compressive strength than the 15% FC/150 degrees C treated specimens. Specimens with 15% FC at 150 degrees C had better mechanical properties (MOR 38 MPa, MOE 1900 MPa; compressive strength: 32.3 MPa) than those treated with HT-150 alone. Increasing FC resin content in both heat treatments decreased the mechanical properties. Overall, treating paulownia wood with 15% FC resin and heat treatment at 150 degrees C produced better MOE, MOE, and compressive strength than heat treatment alone.