This article investigates the self-reinforcement of general grade polypropylene(PP) in oscillating stress field. The Young's modulus and yield strength of self-reinforced polypropylene have been enhanced sighficantly from original 1.4GPa

31MPa to 3.0GPa

58MPa in oscillating stress field under low pressure. Its morphology has been investigated by differential scanning calorimetry (DSC) and X-ray diffraction. It has been found that the improvement in mechanical properties of PP should boe ascertained to the production of shishkebab crystals and the orientaion of molecular chains along the flow direction.High working pressure is unnecessary for the self-reinforcement of PP in oscillating stress field.