Effect of Re-Compounding on the Properties of Polypropylene / Wood Flour Composites

Abstract

Two different mixers were used for re-compounding of wood fl our / polypropylene composites (WPC): internal Banbury mixer and co-rotating twin-screw extruder. Five cycles in an internal mixer and twelve cycles in an extruder were performed on WPC in order to compare the properties of composites. After 3 cycles in an internal mixer, an increase of the WPC mechanical properties (tensile, fl exural and impact strength) and a decrease of water uptake was observed. Further increase of the number of cycles in an internal mixer leads to a signifi cant decrease of WPC properties, as long as the properties remain unchanged, if reprocessing was done in extruder. More signifi cant degradation of WPC occurred in an internal mixer compared to the extruder, therefore only 10% of the recyclate prepared in the Banbury mixer and 30% of the recyclate prepared in the extruder can be added to virgin WPC without a decrease of its properties.

Rheological and mechanical characterization of polypropylene-based wood plastic composites

“…Aesthetics and mechanical properties are not as good as natural wood, but if compared to other engineered wood products, such as medium‐density fiberboard or particleboard, WPC performs better. Finally, WPC is recyclable like all thermoplastics: although it may be difficult to reprocess, Viksne and Rence and Shahi et al have found that the mechanical properties do not decay too much with the number of reprocessing cycles.…”