Incorporation of tyre rubber into wood plastic composites to develop novel multifunctional composites: Interface and bonding mechanisms

Abstract

This paper reports the novel formulation of rubber-wood-plastic composites (RubWPC) with the focus on their interfacial optimisation by using maleated and silane coupling agents. Spectroscopic techniques were used to examine the variation of chemical properties of RubWPC after coupling agent treatments. The unveiled chemical interactions between the coupling agents and substrates suggested the improvement of constituent compatibility and interfacial adhesion, promoting distribution and embedment of wood and rubber particles in polyethylene (PE) matrix, which were confirmed by Scanning Electron Microscope (SEM) analysis. Compared to untreated and single coupling agent treated composites, the composite treated with the combination of maleic anhydride grafted polyethylene (MAPE) and bis(triethoxysilylpropyl)tetrasulfide (Si69) coupling agents possessed superior tensile properties (i.e. tensile strength increased by 57.1% and tensile modulus increased by 20.7%) owing to the enhanced interfacial bonding and more efficient stress transfer. In addition, the nanomechanical property of MAPE&Si69 treated composite (i.e. elastic modulus increased from 15.93 GPa to 19.25 GPa) was also increased due to the penetration of matrix resin into wood cells as well as the reaction between wood cell walls and the coupling agents.