Utilization of Wheat Straw in Manufacture of Particleboard

Wheat straw is one of the most abundant and cheap agricultural wastes, and it is estimated that about 250 million tons are produced annually in China. Wheat straw is predominantly disposed of by direct burning in open field due to lack of effective utilization, which also causes serious environmental pollution. It is an important issue to deal with the agricultural waste both for the comprehensive utilization of lignocellulosic resources and for the prevention of environmental pollution. The aim of the present work was to investigate the suitability of wheat straw as a raw material for particleboard. In this study, phenol–formaldehyde resin was modified with polyisocyanate as an adhesive for wheat straw particleboard preparation. Orthogonal experiment design was used to study the effects of hot-press temperature, hot-press time, resin application ratio, and wax application ratio on mechanical and water soaking properties of the wheat straw particleboard. Results showed that hot-press temperature was the dominant influencing factor. Mechanical and soaking properties improved as hot-press temperature increased and reached their highest point at 160°C. Hot-press time, resin application ratio, and wax application ratio also had a significant effect on mechanical and water soaking properties of the board. The optimum manufacture condition was 160°C for hot-press temperature, 6 min for hot-press time, 20% for resin application ratio, 0.7% for wax application ratio. Under the optimum condition, 11.9 Mpa of the modulus of rupture, 0.30 Mpa of the internal bond and 4.8% of the thickness swell were obtained, higher than the requirement of JIS A 5908.