Large deformability derived from a cell–cell slip mechanism in intercellular regions of solid wood

Abstract

A uniaxial compression experiment with solid wood under various saturated vapor temperature conditions revealed that remarkable deformation occurred in the tangential direction at higher temperatures of up to 180°C, with minimal longitudinal deformation. The maximum deformation ratio in the tangential direction exceeded 200% of the initial specimen diameter although a decrease in thickness became less than the tenth part of the initial one. Microscopic observations indicated that the large deformation behavior resulted from an accumulation of changing original position in mutual wood cells, which led to slip at the intercellular layer. Scanning probe microscopy indicated that this phenomenon was a result of the hierarchical structure of the wood cell and that the intercellular layer becomes selectively softened under specific hygrothermal conditions.