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In this research, a linear low density polyethylene (LLDPE) was first melt blended with a series of high density polyethylenes (HDPE) with different molecular weights at a fixed ratio of LLDPE/HDPE=90/10 (w/w). The prepared HDPE/LLDPE blends were then injection-molded into specimen bars through a dynamic packing injection molding (DPIM) technique, in which an oscillating shear field was imposed on the melt by two pistons that move reversibly with the same frequency during the packing stage. The crystal morphology, orientation and tensile properties were characterized by scanning electron microscopy, two-dimensional wide-angle X-ray scattering and Instron, respectively. Compared with conventional injection molding, DPIM caused an obvious increase in tensile strength in the injection-molded bars. Interestingly, LLDPE blended with low molecular weight HDPE (LMW-PE) was found to possess much …