聚丙烯等通道转角挤压加工中挤压载荷变化规律的实验研究

Experimental Study on the Extrusion Load of Polypropylene during Equal Channel Angular Extrusion

对聚丙烯(PP)进行等通道转角挤压(ECAE)加工,利用电子万能试验机获得PP在不同挤压工艺参数下的挤压载荷-行程曲线,根据其宏观剪切变形情况,分析了在ECAE加工过程中挤压载荷的变化规律;并分析了挤压工艺参数对PP屈服载荷的影响。结果表明:在ECAE加工中挤压载荷分为压缩弹性变形引起的载荷增加,形成塑性剪切带引起的载荷快速增加,持续的剪切塑性变形引起的载荷基本稳定3个阶段;在挤压工艺参数中挤压温度对挤压载荷-行程曲线影响显著,在同一挤压速度下,屈服载荷随着挤压温度的升高而显著降低。

Experiments were conducted to achieve the load-ram displacement curves when polypropylene （PP） were processed by equal channel angular extrusion （ECAE） under different extrusion conditions. According to the shear plastic deformation behavior of PP,the variation law of the extrusion load during ECAE processing was analyzed during ECAE processing. The following conclusion was reached that the PP ECAE processing could be classified into three phases：the increasing phase of load caused by the compress elastic deformation, the fast increasing phase of the load caused by the shear plastic deformation, the stable phase of the load because of the shear plastic flow. The influence of extrusion conditions on the yield load was investigated, the result showed that the shear yield load was deeply influenced by extrusion temperature compared with the extrusion rate, and under the same extrusion rate the yield load of PP declined distinctly with extrusion temperature increasing.