A New Method Of Separating HDPE And PP With An Improved Barrier Screw

A new method of plastic separation is presented in this thesis. With an improved barrier screw and accessory device, the plastics of different melting points were separated in the extruder. The new screw and affiliated device was designed, and the orthogonal experiment was conducted to separate HDPE/PP mixtures, the purity of the separated material and the separative efficiency were taken as the evaluation indexes to evaluate the separating capacity of the device; The melting model of mixed materials in the barrier screw was established by the inspection and analysis of the separated material which was obtained through the screw ejector method. Based on the analysis and experiments, the main conclusions are made as follows:(1) The designed new experiment device can realize the separation of plastics with different melting points. For EVA and PP mixture, the pure EVA can be obtained from the die of the extruder; For HDPE and PP mixture, HDPE with high purity also can be obtained.(2) Orthogonal experiment results showed that the first section temperature of the barrel, the second section temperature of the barrel, the screw speed and the compression ratio of the solid screw channel are the main factors influencing the separation effect. And with the rise of the first and second section temperature of the barrel, the separation effect is reduced; there exists an optimal value for the rotational speed of the screw, no mater the rotational speed is greater or less than the optimal value, the separation effect will decline.(3) Increasing the compression ratio of the solid screw channel can improve the separation efficiency, and meanwhile to keep the purity of the separated material.