In this study, an injection molding machine with a low-fracture-fiber mechanism was designed with three stages: a plasticizing stage, an injection stage, and a packing stage. The fiber-fracture behavior is observed under the screw (plasticizing stage) of low-compression/shear ratio for the ultra-long fiber during the molding process. The molding material employed in this study was 25-mm-ultra-long-glass-fiber-reinforced polypropylene (PP/U-LGF). In addition, a thickness of 3 mm and a width of 12 mm spiral-flow-mold were constructed for studying the melt flow length and flow-length ratio through an experiment. The experimental results showed that the use of an injection molding machine with a three-stage mechanism decreased the fiber length when the screw speed was increased. On average, each fiber was shortened by 50% (>15 mm on average) from its original length of 25 mm. Longer glass fibers were more resistant to melt filling, and as the fiber length was reduced, the mixing between the melt and glass fibers was improved. Thus, the melt fluidity and fiber ratios were increased. In addition, the mixing/flow direction of the melt had an impact on the dispersion and arrangement of glass fibers, thus the tensile strength of PP/U-LGF increased.

中文翻译：

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低断裂纤维机理对超长玻璃纤维增​​强聚丙烯复合材料注射成型纤维/熔体流动行为和拉伸性能的影响

在这项研究中，设计了具有低断裂纤维机制的注塑机，该机分为三个阶段：塑化阶段，注射阶段和包装阶段。在成型过程中，对于超长纤维，在低压缩/剪切比的螺杆（塑化阶段）下观察到纤维断裂行为。本研究中使用的成型材料是25毫米超长玻璃纤维增​​强聚丙烯（PP / U-LGF）。另外，构造3mm的厚度和12mm的宽度的螺旋流动模具以通过实验研究熔体流动长度和流动长度比。实验结果表明，当螺杆速度提高时，使用具有三级机构的注射成型机可减少纤维长度。平均每根纤维缩短了50％（> 平均15毫米）。更长的玻璃纤维更耐熔体填充，并且随着纤维长度的减少，熔体与玻璃纤维之间的混合得到改善。因此，熔体流动性和纤维比率增加。另外，熔体的混合/流动方向对玻璃纤维的分散和排列有影响，因此PP / U-LGF的拉伸强度增加。