The shape change of microprofile in extrusion was investigated using a capillary rheometer. The shapes of die orifice were trilobal and elliptical respectively, and the material was fiber-grade polypropylene. The research result showed that during the extrusion of microprofile, the shape of extrudate deviated greatly from the die orifice. The size of extrudate was increased with the increasing of extruding speed and temperature, while it was decreased with the increasing of drawing speed. Water-cooling was benefit for reducing shape change. Shape change of trilobal leaf in direction of width was much larger than that in the direction of length, and the shape change in the direction of minor diameter was larger than in the direction of major diameter.%在毛细管流变仪上对微轮廓的挤出成型过程中的形变进行了实验研究,所采用的微轮廓口模孔分别为三叶形和椭圆形,试验原材料为纤维级聚丙烯.结果表明,在微轮廓的挤出成型中,挤出物轮廓形状发生了明显的变化,微轮廓尺寸随挤出速度的增加而增大,随挤出温度的升高而增大,随拉伸速度的增加而减小;采用水冷却有利于减小形变;三叶形轮廓的叶片在宽度方向的形变要远大于长度方向,椭圆形轮廓的形变在短轴方向大于长轴方向.
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