Effect of Impact Modifier Type on Water Absorption and Thickness Swelling Parameters of Wood Flour- Recycled Polypropylene Composites

In this research، the effect of impact modifier type on water diffusion coefficient، maximum water absorption and thickness swelling parameters of wood flour- recycled polypropylene composites were evaluated. For this purpose، a virgin PP was thermo-mechanically degraded by two times extrusion under controlled conditions in a twin-screw extruder at a rotor speed of 100 rpm and a temperature of 1900C. The virgin and recycled PP in 2nd stage، compatibilizer (0، 2 % w/w) and wood flour were compounded at 50% weight sawdust loading in a counter-rotating twin-screw extruder in presence different type of impact modifiers (0، 6 % w/w). Ethylene vinyl acetate (EVA)، ethylene-propylene-diene monomer (EPDM) and acrylonitrile-butadiene-styrene (ABS) were used as impact modifiers. The analysis of diffusion mechanism and thickness swelling rate were done based on Fick’s theory and swelling model for wood flour- recycled polypropylene composites. The composites containing two times recycled PP exhibited lower moisture diffusion coefficients، swelling rate parameter، maximum water absorption، thickness swelling. Also results showed that moisture diffusion coefficients and thickness swelling parameters of composites containing EVA are lower than composites containing EPDM and ABS. The use of compatibilizer decreased the moisture diffusion coefficients and thickness swelling parameters of the wood flour- recycled polypropylene composites