Effect of Some Chemicals on Thermal Conductivity of Impregnated Laminated Veneer Lumbers Bonded with Poly(vinyl acetate) and Melamine–Formaldehyde Adhesives

Abstract

Thermal conductivity is a very important parameter in determining heat transfer rate and is required for the development of drying models and for the industrial operations such as adhesive cure rate. The objective of this research was to investigate the effects of impregnation on the thermal conductivity of six-layered laminated veneer lumber (LVL) made of beech and pine. Boric acid, zinc chloride, and ammonium sulfate were used as impregnation chemicals and poly(vinyl acetate) (PVAc) and melamine-formaldehyde (MF) adhesives as bonding agent were used to produce LVLs. The veneers were impregnated by using the vacuum-pressure method. The thermal conductivity test was performed based on ASTM C 1113-99 hot-wire method. Results showed that the impregnation chemicals increase the thermal conductivity. As impregnation chemicals the highest values were obtained with boric acid and zinc chloride. In addition, the thermal conductivity of LVL made of beech was higher than that of LVL made of pine. The thermal conductivity of LVL bonded with PVAc was absolutely higher than LVL bonded with MF in both wood species.

Keywords:

• Ammonium sulfate
• Boric acid
• Impregnation
• Laminated veneer lumber
• Thermal conductivity
• Zinc chloride

Notes

B.I.: before impregnation; A.I.: after impregnation.

∗Same letters denotes insignificant statistical differences (p = 0.05).