Effect of a Combination of Moderate-Temperature Heat Treatment and Subsequent Wax Impregnation on Wood Hygroscopicity, Dimensional Stability, and Mechanical Properties

Abstract

Wood is an environmentally friendly material, but some natural properties limit its wide application. To study the effect of a combination of heat treatment (HT) and wax impregnation (WI) on wood hygroscopicity, dimensional stability, and mechanical properties, samples of Pterocarpus macrocarpus Kurz wood were subjected to HT at a moderate temperature of 120 °C and a high temperature of 180 °C, for a 4 h duration. Subsequently, half of the 120 °C HT samples were treated with WI at 90 °C. The results showed that 180 °C HT and WI decreased the capacity of adsorption and liquid water uptake and swelled the wood significantly, while WI had the biggest reduction. The effect of 120 °C HT was significant only on decreasing the capacity of adsorption and the swelling of liquid water uptake. The bending strength (MOR) of wood decreased only after 180 °C HT, and 120 °C/4h HT and WI had no significant influence on MOR. The bending stiffness (MOE) increased significantly after 180 °C HT and WI, while 120 °C/4h HT had no significant influence on MOE. Therefore, the combination of moderate-temperature HT can act synergistically in the improvement of certain aspects of wood properties such as capacity of water adsorption and liquid water uptake. WI effectively improved wood hygroscopicity, dimensional stability, and mechanical properties.

Effect of Thermal Modification on the Nano-Mechanical Properties of the Wood Cell Wall and Waterborne Polyacrylic Coating

“…This indicated that thermal modification of wood had a negative effect on the mechanical properties of the coating applied to TMWs and became worse with the increase in temperature of thermal modification. This was because wood extraction had a positive effect on the coating while the thermal modification reduced the content of wood extraction [49,50]. The components of the lower molecular weight of the coating embedded the CWs of TMWs after being coated, and the resin interacted with the extractions in the cell wall ultimately leading to the difference in mechanical properties.…”

“…In the process of thermal modification, the lignin condensation via cross-linking reactions with furfural set free from hemicelluloses, which may have contributed to the increase in the cellulose crystallinity index of the wood [51]. In addition, it is possible that the cross-linking reaction between CWs and the molecules of the coating also played an important role in improving the E r and H of CWs [49,50]. Figure 8 illustrates the Er of the coating and cell walls at different locations of the natural wood and on the cross-sections of TMW samples.…”

A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

“…At the same time, considering that wood contains cellulose, hemicellulose, lignin, starch, sugar, and other components, it is a hotbed for microbial growth [ 31 , 32 ]. When the temperature and humidity and other environmental conditions are appropriate, these microorganisms will attach to the wood for a large number of growth and reproduction, resulting in wood decay, discoloration, and moldy, which influence the strength, toughness, and permeability of wood [ 6 , 33 , 34 , 35 ]. It also poses a threat to the life and health of the users [ 36 , 37 , 38 ].…”

Characterizing Mode I Fracture Behaviors of Wood Using Compact Tension in Selected System Crack Propagation

“…Previous studies have conducted some valuable works on the effects of factors that influencing the fracture mechanical properties of wood materials, such as temperature [20,21], testing method [22], moisture content [23][24][25][26][27], wood species [26,28,29], fracture modes [30], cracking system [30], etc. These studies provided fundamental data for characterizing wood fracture behaviors.…”