Historically, various processes have been used for wood densification. The problem with most processes was the unstable deformation that occurred if the densified wood was exposed to high humidity. This led to the development of viscoelastic thermal compression (VTC) of wood with improved mechanical properties. Later on, a modified VTC process was developed, which produces densified wood that remains stable even after being soaked in water. Our research compared the adhesive bonding properties of two types of wood with different densification levels. We had to examine the impact of densification on the adhesive bonding of VTC wood. The research was conducted with modified viscoelastic thermally compressed specimens of spruce and beech wood. The specimens were bonded with an adhesive based on liquefied wood and their adhesive bonding properties were compared with the ones of specimens bonded with a phenol-formaldehyde adhesive. The shear test and bending test were used to test the specimens. The mechanical tests showed that adhesive bonding of VTC wood is entirely comparable with that of non-densified wood.
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