Fatigue Performance of Wet and Dry Pulverized Wood Flour Reinforced PP Composites

In this paper, we exclusively studied the effects of dry and wet pulverization of different wood flours on the fatigue performance of polypropylene (PP)/wood flour (WF) composites. Wood flours obtained from cypress and Scots pine trees were pulverized in both dry and wet conditions at two different mill-plate gaps, 200 µm and 350 µm, and were used as reinforcement in PP matrices. Master batches of PP with different types of pulverized WF were compounded before processing in an extruder. The PP/WF composites of initial WF were also prepared for comparison. The prepared composites were analyzed by tensile and fatigue tests. It was found that the tensile properties of wood/polypropylene composites were affected by the pulverization of WF. Fatigue test results displayed that wet pulverization of short cypress flour had a negative effect on the fatigue life of PP/WF composites, while wet pulverization of long cypress flour and pine flour had a positive effect on the fatigue life of PP/WF composites.