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Physical and Mechanical Properties of Laminated Veneer Lumber Manufactured by Poplar Veneer



Author(s)

M. Nazerian and M. Dahmardeh Ghalehno

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DOI:10.17265/2161-6256/2011.11A.013

Department of Wood and Paper Science and Technology, University of Zabol, Zabol 98615-538, Iran

Efficient usage of laminated veneer lumber (LVL) in the construction industry requires an understanding the effects of the heat treatment process on the physical and mechanical properties of LVL. It is well known that the heat treatment is often used to improve the dimensional stability of solid wood, but it cases to decrease mechanical properties of solid wood. However, this study aimed testing the physical and mechanical properties of LVL manufactured from heat-treated and untreated poplar veneers. The LVL samples were produced from poplar heat treated veneers (Populus nigra) in the seven ply form (3 mm each) by using urea-formaldehyde (UF) adhesive. Before manufacturing LVL, veneers were subjected to heat treatment at varying temperatures and for varying durations of heating. Significant differences were determined (P ≤ 0.05) in the physical and mechanical properties of the LVLs. The results were recorded the lowest density increment as 29%, the lowest radial swelling as 48%, the lowest tangential swelling as 45% and the lowest longitudinal swelling as 33% for LVL manufactured from heat treated veneers at 180 °C for 5 h as compared to the control sample. The highest flat-wise and edge-wise modulus of rupture (MOR) (107.67 MPa and 102.1 MPa) and modulus of elasticity (MOE) (6,190 MPa and 6,017 MPa) were obtained in the control sample manufactured from untreated veneers. It was determined that modulus of elasticity was less sensitive than modulus of rupture of composite lumber to change due to increase in temperature and heat durations. According to the statistical analyses of variance, the mechanical and physical properties of LVL were more sensitive to temperature than duration of exposure.

Heat treatment, laminated veneer lumber (LVL), mechanical and physical properties, Populus nigra, poplar, urea-formaldehyde (UF) adhesive.