Chemical and physical changes required for producing dimensionally stable wood-based composites

Effect of Steaming on Some Properties of Compressed Oil Palm Trunk Lumber

“…Compressed OPT is subject to reversible and irreversible swelling phenomena. The reversible swelling is due to the hygroscopic nature of wood, while irreversible swelling is due to the springback of compressed (densified) wood and the breakage of adhesive bonds between the wood particles (Hsu et al 1988).…”

“…The internal stresses will result in excessive thickness swelling when samples are exposed to moisture. Steaming is believed to reduce the spring back due to the hydrolysis of hemicelluloses and consequently will increase the compressibility of wood (Hsu et al 1988). The recovery ratios of the steamed compressed OPT and the compressed OPT were 1.75% and 2.41%, respectively.…”

“…This is because steamed compressed OPT underwent steaming before being compressed. During the steaming process, the hemicelluloses could be hydrolyzed which would subsequently increase the compressibility and reduce the amount of stored stress due to the viscous flow of wood substances (Hsu et al 1988). …”

“…The cellulose functioned as a component to maintain the mechanical strength of the wood while the lignin provided rigidity and stiffness; therefore, these two components should be kept intact as much as possible. Certain degrees of breakdown of the hemicellulose components, however, should not cause any serious reduction in wood strength but may markedly increase the compressibility of the wood (Hsu et al 1988). According to Horn (1979), steam pretreatment facilitates the flow of hemicelluloses on the fiber surface and softens them in the cell wall to promote fiber flexibility.…”

“…Although many studies have reported on the use of oil palm trunks for laminated veneer (LVL), pulp and paper, and different types of composites (Dahlan 2000), very limited information is available on the use of oil palm for compressed lumber (Salim et al 2012) The concept of wood densification dates back to the early 1400s (Seborg et al 1962) and is used for strength enhancement. Properties of compressed lumber from different species have been investigated in past studies (Hsu et al 1988;Inoue et al 1993aInoue et al , 1996Kawai et al 1992). A study showed that the adhesives consumption in plywood produced from compressed veneer was reduced significantly (Bekhta et al 2009).…”