Abstract: Thermo-hydro-mechanical (THM) treatment is a
combined action of temperature, moisture, and mechanical
force, which leads to modified wood (THMW). Various
types of eco-friendly THM processes have been developed
to enhance wood properties and generate new materials,
such as welding, densification, molding, bending, profiling,
artificial aging, panel manufacture, and surface
densification. The various transformation processes in
the course of THM bring about positive effects in terms of
the mechanical and physical properties as well as the biological
durability. To the negative effects belong the loss
in strength and fracture toughness, and one of the challenges
is to minimize these negative aspects. The present
paper reviews the chemical transformations processes
during THM treatment in a closed processing system and
presents the relationship between processing parameters
and THMW properties. The discussion includes the
problems associated with eliminating the set recovery of
densified wood by THM posttreatments and the chemical
origin of the relaxation of internal stresses induced by
densification.
Keywords: chemical-mechanical, chemistry, densification,
fixation of compression set, moisture content (MC),
temperature, woo
