Elastic properties of hot-pressed aspen strands

The in-situ elastic constants of a wood strand are affected by the physical changes that it experiences during the manufacturing process of a wood-strand composite. The hot-pressing conditions and the location in the mat govern the environmental conditions surrounding each strand, which in turn influence the adhesive cure and final strand density. Few studies have examined systematically the changes in strand elastic constants as influenced by strand density, location, and/or resin content. Understanding these interactions is important to determine the role of pressing variables on altering strand properties and to accurately model structure-property relationships in wood-strand composites. The following presentation will discuss the results of a study conducted to investigate the influence of strand location and resin content on changes in strand density and elastic properties within a pressed panel. In-situ properties of the strands were evaluated after isolating the strands from resinated hot-pressed oriented strandboards. Response models based on mixture design, considering the hot-pressing effects, were developed to predict the in-situ elastic constants of strands. Addition of resin positively influenced the strand stiffness and decreased strand's Poisson's ratio. Strand stiffness greatly increased with increasing resin content in regions of higher densification.