Effect of the Propionylation Method on the Deformability under Thermal Pressure of Block-Shaped Wood

Abstract

Converting wood waste into thermoplastic materials is an attractive means of increasing its utilization because complex three-dimensional molded products can easily be obtained by press molding wood with thermoplasticity. Chemical modification, especially esterification, is a promising method for imparting thermoplasticity to wood. In this study, we produced multiple propionylated wood specimens using several propionylation methods and elucidated the factors affecting the deformability of the wood. Regardless of the method, all of the propionylated wood samples showed deformability in the tangential direction. However, in the longitudinal direction, not only the degree of propionylation but also the propionylation method had a significant influence on the deformability. The flow in the tangential direction occurred under a relatively low pressure, whereas the flow in the longitudinal direction occurred under higher pressure. The chemical composition and motility of each sample were evaluated using solid-state NMR measurements. With some propionylation methods, decomposition of the cellulose main chain occurred during the reaction, which had a dominant effect on the deformability of the wood in the longitudinal direction. These results indicate that the deformability of wood can be controlled by the appropriate selection of a propionylation method and its treatment conditions.

Deep Container Fabrication by Forging with High- and Low-Density Wood

“…For example, Miki et al formed a container by back-extrusion of Japanese cypress impregnated with resin [17]. Abe et al investigated the application of esterification methods such as propionylation to block-shaped wood to give it thermal plasticity [18] and successfully molded it into a cup shape in molding tests [19]. Seki et al studied treatments for wood components and delignified wood to improve flowability [20].…”

Influence of Lignin On Plastic Flow Deformation of Wood

“…However, to improve the deformability of wood during the forming process and the durability of the products, it is necessary to modify the wood by pretreatment before forming. The cell wall and compound middle lamella (CML) are modi ed by impregnating the wood with resin monomers (Miki et al 2014-2;Seki et al 2016) and/or chemical modi cation (Abe et al 2020; Abe et al 2021). WFF has great potential for various applications; however, it requires high temperatures (< 100°C) and pressures (< 50 MPa), making it energy-intensive and less productive.…”