Preparation and characterisation of wood flour/polystyrene composites by subcritical fluid-assisted reactive extrusion

In this work, subcritical fluids are applied to twin-screw extruders as a novel design for the preparation of wood flour/polystyrene composites. Subcritical fluids have suitable process conditions, excellent swellability and diffusibility. Therefore, the subcritical fluids in the extruder system can alleviate the thermal degradation of wood floor, reduce the viscosity of the resin and strengthen the mass transfer rate. Wood flour evenly distributed in the polystyrene matrix in the presence of subcritical n-propanol. The best adhesion between wood flour and PS is shown when 10 wt-% MAPS is added. MAPS was confirmed to be grafted onto wood flour. In addition, the thermal stability and crystallinity of wood flour and the composites are studied. Mechanical tests proved the effectiveness of subcritical fluids, particularly subcritical n-propanol, in improving the mechanical properties of the composites. The extrusion temperature and content of MAPS show optimum values at 190°C and 10%, respectively.