Influence of Press Pressure on the Properties of Parallel Strand Lumber Glued with Urea Formaldehyde Adhesive

Abstract

The effects of press pressure on laboratory-made parallel strand lumbers (PSLs) that were manufactured from fast-growing rotary-peeled I-77/51 (Populus deltoides) hybrid poplar clones' veneer strands with a urea formaldehyde (UF) adhesive using press pressures ranging from 7.5 to 15 kg cm−2 in increments of 2.5 kg cm−2 were investigated. The physical and mechanical properties of PSL were affected by the press pressures. However, press pressures did not affect the combustion properties. Results indicated that higher press pressures lead to higher densification or compaction rates and specific gravities (SGs). For improved physical and mechanical properties, higher press pressures were found to be necessary. A press pressure of 12.5 kg cm−2 was found to be the optimum press pressure in relation to PSL properties. There are positive correlations among SG and mechanical properties as well as press pressures. The results may provide valuable information to assess the behavior of structural composite lumbers, including PSLs, that are manufactured using low and high press pressures. Utilization of fast-growing tree species is possible because their strength properties are improved through pressing.