Utilization of Pine and Birch Juvenile Wood for Low-Density Particleboard Production.

This study investigated the effect of using juvenile pine and birch wood for the production of particleboards with lowered density, glued with urea-formaldehyde (UF) resin. The wood used was characterized by a number of annual rings ranging from 5 to 13, which ensured that only juvenile wood was used in the study. In addition to the basic characteristics of the wood particles obtained from this type of raw material, the density profiles of the manufactured particleboards, the internal bond, bending strength, modulus of elasticity, swelling, and water absorption after short-term water exposure (2 h) were also investigated. The results were compared to particleboards made from industrial wood particles from mature wood. It was found that particleboards made from juvenile pine wood exhibited higher internal bond than those made from juvenile birch wood. The bending strength of boards made from both types of juvenile wood was comparable to that of industrial particleboards; however, the modulus of elasticity of the particleboards made from juvenile pine was lower, which indicates reduced stiffness. These particleboards also showed higher swelling and water absorption, which may limit their durability under humid conditions. In contrast, birch boards exhibited lower internal bond, but their bending strength and modulus of elasticity were similar to those of industrial particles-based particleboards. Birch boards also showed slightly better water resistance than pine particleboards made from juvenile wood. However, their swelling remained higher than that of industrial particleboards. Overall, particleboards made from juvenile wood, especially birch, show good potential for further research.