Thermal and Mechanical Properties of Wood Flour-Polystyrene Blends from Postconsumer Plastic Waste

Polystyrene (PS) from packing materials and plastic cups was reinforced with 30 and 50% wood flour through a blending process with and without a commercial compatibilizing agent. The processability of the pure recycled polystyrene (rPS) and wood-rPS composites was studied in terms of the torque of the mixing process; this was then compared with that of a commercial virgin multipurpose PS. The physical and mechanical properties were compared with those of the virgin PS reinforced with 30 and 50% wood flour. The results show that the mechanical properties of the pure and reinforced rPS did not decrease with respect to the virgin PS, and in terms of the impact strength, the rPS was superior to the virgin plastic. The mechanical properties were not affected by the commercial compatibilizing agent, but the torque of the blends was significantly lower with the compatibilizer. Differential scanning calorimetry (DSC) and dynamic mechanical analysis were used to study the glass-transition temperature (T-g) of both the pure virgin PS and pure rPS and the wood flour-PS composites. The T-g values of the rPS and wood-rPS composites were higher than those of the virgin PS and wood-virgin PS composites. The use of rPS increased the stiffness and flexural modulus of the composites. Thermogravimetric analysis revealed that the thermal stability of rPS and its composites was slightly greater than that of the virgin PS and its composites. These results suggest that postconsumer PS can be used to obtain composite materials with good mechanical and thermal properties. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 443-451, 2011