Wheat straw particleboard bonding improvements by enzyme pretreatment

Abstract

Three kinds of enzyme were used to treat wheat straw. Particleboards bonded with a UF resin were made with the treated wheat straw as a raw material. The results obtained show that the enzyme action is not affected under certain conditions when separated from the living cell producing it. The free-radical content of wheat straw was observed by electron spin resonance (ESR) to clearly increase after it is treated with cellulases from Trichoderma sp. and Aspergillus niger. The wheat straw benzene-ethanol or ether extracts content decreases after wheat straw treatment with lipases from Candida rugosa. This indirectly indicates that the surface wax of wheat straw is reduced if wheat straw is treated with lipases. The pH-values of wheat straw are somewhat changed by the enzyme treatment indicating that its buffering capacity is decreased. Wheat straw's surface wax is one of the main adhesion inhibitors in its use as a raw material for particleboard. The better properties of UF-bonded particleboard made using enzyme treated wheat straw can be explained on this basis. In this regard the effect of cellulases from Aspergillus niger yields the best result.