The Research On The Toughness Of Wood-flour-recycled Polystyrene Composites

In this paper, the modification of Wood flour-recycled polystyrene composites prepared by extruding process was studied to improve its toughness. By adding thermoplastic elastomers and coupling agent to the formulation, the toughness of the composites was increased significantly. The mechanical properties of the composites were evaluated by tension, bending and impact test. The viscoelastic properties and the interface structure of the composites were characterized by dynamic mechanical thermal analysis and scanning electron microscopy. The main results were showed as follows:By using a double screw extruder/single screw extruder/profiling system, three kinds of thermoplastic elastomers were blended with recycled polystyrene in certain proportion respectively. The mechanical properties of the different polymer blends were studied. TPR, a copolymer of styrene and butadiene, was found to be more effective as impact modifier than other thermoplastic elastomers. Compared to recycled polystyrene, the elongation at break and unnotched strength of the polymer blended with TPR were dramatically increased by 58.6%and 350% and the stiffness was slightly decreased.The mechanical properties of wood powder-recycled polystyrene composites with different contents of coupling agent were compared, and it was found that composites with coupling agent had higher tensile and bending strength by 5% whereas elongation at break and unnotched impact strength decreased. Coupling agent (5% by weight) and TPR (5% by weight) were blended together with wood powder and recycled polystyrene. The results showed that proper proportion with coupling agent together with TPR improved considerably the toughness and strength of the composites, much better than the addition of TPR by itself.Dynamic mechanical thermal analysis showed that the addition of TPR improved the damping of the composite, but decreased the storage modulus and the glass transition temperature of the composite. It was discovered that coupling agent and TPR together, not only improved the storage modulus and the glass transition temperature, but also improved the damping of composite. Impact fracture surface morphology analysis by Scanning electron microscopy showed that coupling agent improved the interface compatibility and adhesion between wood and polymer compared to composite without coupling agent. TPR elastomers domains were homogeneously dispersed in the polymer matrix and the size of the elastomer distributed in the polymer were between 0.1 to 0.5 urn for composites with by 5% coupling agents and by 5% TPR. And "the craze chalazas" were alsofound.