An electromagnetic dynamic plasticating extruder, invented by the authors, was used to prepare isotactic polypropylene (PP) sheets. Tensile and impact tests show that the extruded samples can simultaneously be reinforced and toughened along the flow and transverse directions in a moderate frequency and amplitude range. The microstructures of the obtained samples were characterized by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and scanning electron microcopy (SEM).The results indicate that the vibration plasticating extrusion affected the morphology of the PP extrudate, it especially resulted in finer spherulites, and move tie molecules, which account for the enhancement of the tensile strength and impact toughness of PP sheets in both extrusion and transversal directions. INTRODUCTIONMany efforts were made using vibration reinforced extrusion by several researchers [1][2][3][4] , such as Fridman, Isayev, Ibar, Shen, and Li et al., who introduced mechanical or ultrasonic vibrations into the die during solidifying of the extrudate to enhanced properties. Some investigations showed that superimposing vibrations at the exit of an extruder can improve the mechanical properties of final products and reduce the die pressure. For examples, Cao and Li [5] used an ultrasonic vibration extrusion system to obtain greatly improved surface appearance of polystyrene (PS) extrudate and increase the productivity of PS extrudate through decreasing the melt flow activation energy in the presence of vibration; Ibar [3] found that the ultrasonic vibrations in the melt can result in a large increase of the number of small crystals leading to better clarity

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