Change in mechanical interaction between cellulose microfibril and matrix substance in wood cell wall induced by hygrothermal treatment

To investigate in detail the mechanical interactions and associations between cellulose microfibrils (CMFs) and the matrix substance, we measured the dimensional changes in cellulose crystals in wood cell walls after different treatments. The transverse expansion of CMFs observed after hygrothermal treatment and subsequent drying suggests that the matrix substance compresses the CMFs transversely under green conditions. However, as heat treatment breaks or weakens the association of the CMFs and the matrix substance, under hygrothermal treatment and drying at high temperature the matrix substance cannot compress the CMFs in the direction of the chain.