Effects of hexamethylenediisocyanate coupling agent on physical, mechanical, and thermal properties of wood plastic composites

Abstract

In this study, we investigated the physical, mechanical, and thermal properties of polypropylene/old corrugated container fibers and polypropylene/poplar fiber composites, which were treated with 1, 2, 3, and 4 wt% of hexamethylenediisocyanate coupling agent. Compounding was conducted by a counter-rotating twin-screw extruder, and samples for measurements of tensile, flexural, and impact properties were prepared by an injection molding machine. Thermal properties of composite samples were studied by thermogravimetric analysis and differential scanning calorimetry techniques. Thermal stability and crystallinity content of the prepared composites were determined, as well. The obtained results showed that the addition of coupling agent increased the thermal properties of the composites. Mechanical resulting indicated that by the addition of coupling agent, there was improvement in the tensile and flexural properties but there was declination in impact properties. Scanning electron micrographs taken from failed surfaces of the composite samples showed that the addition of coupling agents resulted in the improvement of bonding between wood fibers and polymer matrix at their interface.