The effect of resin type and strand thickness on applied properties of poplar parallel strand lumber made from underutilized species

Abstract

In this research, the effect of resin type and strand thickness on the applied properties of parallel strand lumber (PSL) made from poplar (Populus deltoides L.) was investigated. The laboratory PSL boards with strand thickness of 1 and 2 mm were manufactured using urea formaldehyde (UF), UF modified with nanocrystalline cellulose (NCC), melamine formaldehyde (MF), melamine formaldehyde-urea formaldehyde (MFUF), phenol formaldehyde (PF) and polymeric isocyanate (pMDI) as binders. Some technical properties including modulus of rupture (MOR), compression strength parallel to the grain (CS|), impact strength (IS), water absorption (WA) and thickness swelling (TS) were determined. Besides, shear strength (SS) in dry and wet conditions was compared for a better understanding of the glue performance. In general, the results showed that the mechanical properties of panels made with 2 mm thick strands employing PF and pMDI resin were better. Furthermore, SS values of the resulting boards in dry condition and after cold and hot water immersion showed the crucial influence of glue and strand thickness on the performance and applicability of PSL. In addition, the physical and mechanical properties of PSL panels improved by adding nanocrystalline cellulose to urea formaldehyde adhesive.