复合应力场双向自增强聚丙烯管材的研究

Study of Biaxially Self-reinforced Polypropylene Pipes under Complex Stress Field

采用自制的剪切拉伸双向复合应力场挤管装置,在常规的生产工艺条件下生产出了双向自增强聚丙烯(PP)管材。当剪切套转速为10r/min时,剪切旋转段的温度为190℃,PP的周向和轴向拉伸强度较常规管材分别提高了21.4%和21.1%。通过电子显微镜、多晶X射线衍射仪和差示扫描量热仪等手段对PP管材试样进行了微观结构分析,结果发现,经过复合应力场后,管材内部已不再是明显的球晶结构,晶体规整性增强,熔融峰升高,结晶度增大。同时管材周、轴两向的衍射强度均增强,分子取向有所增强。

Polypropylene pipes were extruded using a home-made shearing/drawing biaxial complex stress field die. Compared to regularly extruded pipes, the circumferential and axial tensile strengths of the pipes were 21.4 % and 21.1% higher, respectively, when the shear casing rotational speed was 10 r/min and the shear casing temperature was 190℃. The pipe samples were characterized by SEM, WAXD and DSC. It was found that the spherulites of the pipe was not obvious and arranged more regularly. The melting points drift to higher temperature and the degree of crystallinity increased. XRD showed the orientation in both directions of the pipes was higher than regular ones.