Isocyanate Modification of Wood Fiber in Enhancing the Performance of its Composites with High Density Polyethylene

Abstract

This study is focused on the modification of wood fiber by using a reactive diisocyanate (toluene diisocyanate, TDI) linker to couple wood fiber with cetyl alcohol and the investigation of its effects on mechanical properties of wood fiber–HDPE composites. The reaction of TDI with wood fiber and then cetyl alcohol resulted in the formation of new urethane bonds assessed by FTIR analysis. Therefore, TDI ended cetyl alcohol was used as a coupling agent in the preparation of wood fiber/ HDPE composite. The outcomes showed that the addition of such coupling agents resulted in greater reinforcement of composites, as indicated by the improvement in mechanical properties. Tensile strength of prepared composites increased by almost 64%, whereas 47% increase in flexural strength and 113% increase in impact properties was observed. However, the moisture absorption of the composites decreased by about 43%. All chemically treated composites showed lower moisture uptake than the untreated composites. This may be due to chemical treatment of wood fiber which reduces its hydrophilicity. These chemical treatments promote interfacial adhesion of fiber and HDPE matrix. Furthermore, scanning electron microscopy (SEM) revealed the improved morphology of the fractured surfaces of composites.