The Effect of Impact Modifier on Impact Strength of Recycled Polypropylene- Wood Flour Composites

In this study، the influence of two types of impact modifier on impact strength of recycled polypropylene (PP) - wood flour composites was evaluated. For this purpose، a virgin PP was thermo-mechanically degraded by five extrusion cycles under controlled conditions in a twin-screw extruder at the rotor speed of 100 rpm and temperature of 190°C. The PP (virgin and recycled polypropylene after 2nd and 5th cycles) and wood flour were compounded at 50% (w/w) wood flour loading in a counter-rotating twin-screw extruder in the presence of different impact modifiers to produce wood flour-PP composites. Ethylene vinyl acetate (EVA) and ethylene-propylene-diene monomer (EPDM) were used as impact modifiers. The results showed that composites containing recycled PP exhibited significantly lower impact strengths. Both impact modifiers increased the impact strength of the PP/WF composites but the addition of EVA resulted in the greatest improvements in impact strength. The composites containing virgin PP exhibited higher impact strengths than those containing recycled PP and EVA.