Properties of hybrid strand board composed of virgin and recycled wood strands

Abstract

This study was to evaluate the feasibility of producing long strands of conventional sizes from post-consumer wood and to assess the impact on the properties of strand boards containing a fraction of such recycled strands. Randomly oriented strand boards were made using varying proportions of recycled wood (0%, 10%, 30%, 50% and 100%) mixed with virgin wood strands. To determine the influence of recycled wood on board properties, we analysed the fractional composition of strands, their wettability, sorption kinetics and cellulose crystallinity for both virgin and recycled wood, and tested various physical and mechanical properties of the resulting strand boards. We then compared the performance of these boards with the requirements of the European standard EN 300 and data from other studies. Boards containing recycled wood exhibited slightly lower but not statistically significant average values for modulus of rupture (MOR) and modulus of elasticity (MOE) compared with the control made from virgin wood. However, the results for internal bond (IB) strength indicated strong adhesion of the recycled strands, attributed to their favourable wetting behaviour. A key benefit of incorporating recycled wood was a significant improvement in the dimensional stability of the boards. In particular, boards made entirely of recycled strands demonstrated a 49.6% reduction in thickness swelling after 24 h of water immersion compared to those made exclusively from virgin wood. The findings indicate that substituting virgin strands with recycled counterparts enables the production of OSB/3 panels using shorter, narrower and thicker strands than standard virgin wood strands.