Processamento de compósitos de polipropileno/pó de madeira em extrusora de dupla rosca.

Abstract

In this work, compounds of heterophasic polypropylene (PP) with 10%, 20% and 30% of wood flour were processed in a modular corrotational twin-screw extruder operated with different screw speeds and feed rates. Process parameters recorded by the equipment (temperature and discharge pressure, flow and specific energy, etc.) were studied and the process simulated using WinTXS™, a commercial process simulation software. Virtual processing allowed to experimentally obtain difficult accesse process variables (residence time, chamber filling, axial pressure and temperature profiles, etc.). The compounds were characterized by differential scanning calorimetry, optical microscopy and melt flow rate. Tensile, flexural and impact properties were determined, and the effect of loading content and processing conditions on these properties were evaluated. The same compositions were prepared in an internal mixer and analyzed to determine the effect of the filler on incipient degradation during processing. The results were satisfactory. The feasibility of processing PP and PP/wood flour compounds was demonstrated and it was possible to adjust the simulation software at the operating conditions of the actual extruder. Characterization tests showed good filler distribution, significant improvements in mechanical properties and increased crystallinity with filler content. The sample with 10% of wood flour showed some exceptional characteristics: greater elongation at break and impact strength on the extruded compounds, higher rate of degradation in the product processed in the internal mixer.