This work explores the fiber migration during injection molding of long glass fiber-reinforced polypropylene. It was found that the simplified assumption of uniform fiber concentration distribution is inaccurate, and the process causes substantial variations in the fiber concentration along the flow path and through the thickness of injection molded parts. This was tested for a simple plate geometry molded at varying nominal fiber concentrations. The fiber concentration was measured by pyrolysis to obtain a global concentration, and using micro computed-tomography for a through-thickness analysis. Additionally, the fiber concentration at the melt front of partially filled moldings was investigated. A new measurement protocol using micro computed-tomography and digital image processing is proposed to calculate the through-thickness fiber concentration. The results of this study show substantial heterogeneity of the fiber concentration throughout the molded plates. Fibers agglomerated in the core layer with volume fractions up to 1.5 times the nominal fiber concentration.

这项工作探讨了长玻璃纤维增​​强聚丙烯注射成型过程中的纤维迁移。发现均匀纤维浓度分布的简化假设是不准确的，并且该过程导致沿流动路径和整个注射成型部件厚度的纤维浓度发生实质性变化。测试了在不同标称纤维浓度下模制的简单板的几何形状。通过热解测量纤维浓度以获得总浓度，并使用显微计算机断层摄影术进行厚度全程分析。此外，还研究了部分填充成型品在熔体前沿的纤维浓度。提出了一种使用微计算机断层扫描和数字图像处理的新测量协议，以计算通过厚度的纤维浓度。这项研究的结果表明，整个模塑板中纤维的浓度存在很大的异质性。纤维聚集在芯层中，其体积分数高达标称纤维浓度的1.5倍。