Incorporation of oxidized paraffin into a composite with modified polyethylene wax improves the surface coating and interfacial properties of hot-waxed wood

Modified polyethylene wax (MPEW) has an excellent performance in wood hot-waxing. However, MPEW hot-waxed wood still has deficiencies in terms of hydrophobicity, wax coating adhesion, and thermal stability. Here we prepared a composite wax by combining the oxidized paraffin wax (OPW) with MPEW in the hot-waxing treatment of wood to enhance the performance of MPEW hot-waxed wood. The impact of the amount of OPW on the surface/interface properties of the hot-waxed wood was investigated and compared with those of wood treated with MPEW alone during hot waxing. Our results demonstrate that the inclusion of OPW endows the wax coating with higher surface roughness and lower surface energy. It also enhances the penetration of MPEW into the wood and promotes the wax filling in the lumen of wood cells, resulting in a more uniform distribution of wax deposited in the cell lumina and an increased surface water contact angle of the hot-waxed wood. Additionally, this inclusion slows down the water absorption. On the other hand, there is the inhibitory effect of OPW on the thermal decomposition of MPEW, thereby enhancing the thermal stability of hot-waxed wood. By introducing more active groups, it improves the reaction probability between MPEW and the hydroxyl groups in the wood, which further strengthens the bond at the wax-wood interface, leading to a reduction in the amorphous wood components. At a mass ratio of 70/30 for MPEW to OPW, composite wax hot-waxed wood with better hydrophobicity, adhesion, and thermal stability can be obtained.