The morphology control and mechanical properties of high density polyethylene and polypropylene blend under oscillating shear stress field

The improvement of mechanical properties of high-density polyethylene (HDPE ) and polypropylene (PP) blend was studied by controlling the phase miscibi lity vs. phase separation. Because the phase morphology and crystal morphol ogy compete with each other, it is difficult to control the degree of the m icro phase separation in an ordinary way, but with the special method of os cillating packing injection molding at a low pressure, the fine structure c ombined with micro-phase separation and phase morphology which was studied with SEM method can be controlled to a certain extent. The high tensile str ength and high toughness of HDPE/PP blends were got within the PP content i n the range from 5% to 20%, The key properties of the blend were as follows : tensile strength and notched impact strength of HDPE/PP (92/8) blend spec imens in the oscillating packing are 97.1 MPa and 45.5 kJ/m(2), 4.3 times a nd 9.5 times of the static packing specimens respectively.