A combination of poly(diphenylmethane diisocyanate) and stearic anhydride as a novel compatibilizer for wood–polyethylene composites

Abstract

A combination of poly(diphenylmethane diisocyanate) (PMDI) and stearic anhydride was investigated as a new compatibilizer system for improving the interfacial adhesion between wood and polyethylene (PE). The treatment of wood flour with PMDI increased both the modulus-of-rupture (MOR) and the modulus-of-elasticity (MOE) of the resulting wood–PE composites. The combination of stearic anhydride and PMDI further increased both MOR and MOE of the resulting composites. Compared with the commercially used compatibilizer maleic-anhydride-grafted polyethylene (MAPE), the PMDI-stearic anhydride compatibilizer system resulted in significantly higher MOR and MOE. The moisture content of wood flour affected the compatibilization of both the PMDI-stearic anhydride compatibilizer system and MAPE. The compatibilization mechanisms of PMDI-stearic anhydride system were investigated in detail. Water-resistance tests indicated that the composites with the PMDI-stearic anhydride system were statistically more water-resistant than those with MAPE.