Treatment of Chemically Modified Wood with VTC Process to Improve Dimensional Stability (Viscoelastic Thermal Compression‪)‬

Abstract To produce a highly stable wood-based product with increased mechanical properties, various types of chemical modifications were combined with the viscoelastic thermal compression (VTC) process. Dimensional stability and bending stiffness were evaluated. Three chemical impregnation processes were studied: phenol-formaldehyde (PF), tung oil (TO), and acetylation with acetic anhydride (AA). After 24-hour room temperature water soak from the ovendry condition, PF and AA treated samples showed high levels of dimensional stability while TO treated samples showed no increase in stability compared to unmodified VTC processed controls. Two PF resins with weight average molecular weights of 172 and 780 were studied. The higher molecular weight PF provided greater stability with an average thickness swell value of 12 percent compared to 20 percent and 37 percent for the lower molecular weight PF resin treatment and control, respectively. Thickness swell for the AA and TO treatments were 19 percent and 43 percent, respectively.