聚丙烯(PP)冷压变形行为研究

Study on Deformation Behavior of PP under Cold Compression

采用镦粗变形对结晶型PP进行3种变形速度和4种变形程度的冷压变形实验,实验结果表明,镦粗变形的几何变形模式及其极限伸长率的几何性质与单向拉伸完全不同,但PP的屈服应力随变形速度增大而提高的现象与许多材料单向拉伸屈服应力相似。与此同时,冷压镦粗PP的延性大变形属于"类塑性"性质,其性质和数值与聚合物及其结构和变形回弹相关。虽然PP冷压镦粗后的回弹率很大,但回弹随变形速度提高而减小,因此为了研发聚合物锻造技术,需要提高变形速度或采用加热措施,或改用闭式锻造变形模式。

Based on cold compression experiments for crystalline PP with upsetting deformation using three kinds of deformation rates and four kinds of deformation degree, it analyzes the geometric deformaton man- ner, proposes different limit elongation ratio of upsetting with tensile test. The result is similar with yielding behavior of many materials. And the large ductile deformation of PP is of ＂plasticity- like behavior＂, whose character and value are related to deformation recovery, polymer and its structure. Although the deformation recovery of PP is very large after cold compressiing, but it becomes smaller with increase of deformation rate. The result indicates that it is necessary to increse deformation rate,or apply hot compression, and or change open forging to close forging.