| This paper introduces recent investigation on the auxetic phenomenon in the polyolefin blends. The blends in which PE as the matrix and PP as the inclusion with the contention 5%,10%,15%,20% were chosen in our experiment. The V was tested by YJY stress transducer with MVAD card by the methods of recording the deformation in the wideness and thickness direction of the specimens during the tensile test. A stable auxetic polyolefin blend with the minimal value -1.4 was observed after repeated test. In addition to , the effects such as process pressure , the consistence and modulus relationship on the V of the auxetic polyolefin blends were discussed respectively. It was observed that the minimal V of auxetic polyolefin blends reached -1.6 under low pressure from the contrast result of different specimens processed under 20%,40%,60% of atoms. Increasing consistence in a limited range could decrease the V when EPDM was chosen to be the compatible. Although no regular relationship between the modulus and V existed, it still could be shown that the good auxetic properties did exist in the polyolefin blends whose modulus differential was in the range from 800 to 1000 MPa between two phases. Rotation- cavitation mechanism was outlined based on the experiment results and the essential conditions for the occurrence of auxetic properties in polyolefin blends were concluded as followed: firstly there must be at least two phases, the matrix can be soft materials which were able to be networks when being stretched, as well as suitable consistence must be provided between twophases. Fracture stress work measurement was optioned to characterize the force between two phases. Finally, the auxtic property repeatability of the blends was measured and the fact that the auxetic property could only occur in the elastic range was certificated by the result that only the specimens which were stretched for 5s, 10s had repeatability after being retained for 1 months.
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