The effect mechanism and properties of poplar wood cross-linking modified with polyols and polycarboxylic acid

Although cross-linking modification by polycarboxylic acid greatly improves dimensional stability and decay resistance, it causes severe brittleness and rigidity in wood. Introducing polyols into the cross-linking network could improve the flexibility of the modified wood, however, the related research is limited, especially the relationship between the strength and the reaction. In this study, poplar wood was modified by cross-linking with 1,2,3,4-butanetetracarboxylic acid (BTCA). D-sorbitol (SO) and sucrose (SU) used as the polyols were introduced to the modification system to esterify with BTCA. The physical and mechanical properties of the resulting wood were investigated. The effect mechanism and microstructure of the wood were also examined. The findings demonstrated that a cross-linked structure was formed in wood with increased ester bonds and ample polymer filling in the lumens. SU has lower leachability than SO. Although the incorporation of polyols has lowered anti-swelling efficiency, the reduction of modulus of rupture caused by BTCA treatment could be redeemed by reducing the degree of cross-linking between BTCA and wood components, especially SO-BTCA treatment. The addition of polyols has slight impact on the modulus of elasticity of BTCA treated wood.

Automated summary

Cross-linking modification using polycarboxylic acid improves dimensional stability and decay resistance, but increases brittleness and rigidity in wood. Introducing polyols into the cross-linking network enhances flexibility, but the relationship between strength and reaction is limited in research. This study modified poplar wood by cross-linking with BTCA and esterifying with polyols (SO and SU). The physical and mechanical properties, effect mechanism, and microstructure were investigated. The findings showed a cross-linked structure with increased ester bonds and ample polymer filling in the lumens, and SU had lower leachability. The reduction in modulus of rupture caused by BTCA treatment could be compensated by reducing the degree of cross-linking, especially with SO-BTCA treatment. The modulus of elasticity of BTCA treated wood was slightly affected by the addition of polyols.