Study on thermal behavior and contact angle of furfurylated poplar wood-polymer

Different wood polymers have different properties compared to solid wood. Research has further investigated the physical and mechanical changes of these products. Therefore, this study was conducted to investigate the thermal behavior and drop contact angle of furfurylated poplar wood polymer.

Wood polymer samples were performed by saturation under pressure and polymerization of furfuryl alcohol monomer with heat catalyst. Wood samples were prepared in two levels of low and high level of furfurylation by increasing the weight percentage gain by 25.08% and 58.83%, respectively. Dimensional stability was assessed by long-term immersion according to ASTM D-4442 standard, drop contact angle by deionized water drip method and thermal behavior of samples by TGA (Thermogravimetric Analysis) and DTG (Derivative Thermogravimetry) techniques.

The results showed that volumetric swelling and water uptake of saturated samples decreased compared to control sample. Furfuryl alcohol is a polar monomer that enters the cell wall after penetrating the wood and swells the walls after polymerization, thus reducing the water absorption capacity of the wall and leaving less room for swelling. The drop contact angle was increased compared to the control samples and the highest drop angle was obtained at high level furfurylation. By reducing the spaces of moisture absorption and less water penetration inside the pores of the wood, the drop contact angle and the wettability of the wood-polymer will be reduced. The results of thermal analysis showed that with furfurylation and increasing its level, changes in TGA and DTG diagrams occur. DTG results showed that in the first phase, the amount of energy released is lower due to the high burning temperature of cellulose and the stability of the furfurylated specimens. In the second phase, the furfurylated wood-polymer showed greater thermal stability than the control and this stability increased with increasing the level of furfurylation. In the third phase, the samples of furfurylated wood-polymer at low and high levels had less energy released than the control samples. At this stage, the compounds resulting from the thermal degradation of cellulose are reduced and the flammable material is reduced compared to the control samples, resulting in a reduced energy release. In the third phase, the necessary energy is provided to break the bonds and is spent on igniting gases and tar.

According to the findings, furfurylated poplar wood-polymer has less water absorption and volumetric swelling than the control samples and undergoes less physical changes due to less water absorption and volumetric swelling. It can be expected that in the manufacture of wood products and urban furniture, the joints will be less affected by changes in weather conditions. This product also has a higher thermal stability than solid wood, which makes its use safer in cases exposed to higher temperatures.