Abstract:

The effect of projectile diameter (9—12mm) on glass fiber orientation, residual wall thickness size and uniformity, and pressure resistance of water-projectile assisted co-injection molded (W-PACIM) fittings with short glass fiber reinforced polypropylene (SGFRP) as the outer layer and polypropylene (PP) as the inner layer was investigated by experimental means. The experimental results showed that the glass fibers in the outer layers presented various orientations in different layers, the glass fibers in the outer near-interface layer were highly oriented along the flow direction, and those in the middle layers were less oriented, while in the near-mold-wall layers, they were haphazardly distributed, mostly at an acute or perpendicular angle with the flow direction. With the increase of projectile diameter, the glass fibers in the near-mold-wall layers were severely fractured, and the orientation of glass fibers in each layer was getting worse. Besides, the total wall thickness of the W-PACIM fittings gradually decreased with the inner wall thickness, while the outer wall thickness decreased in a small range. The pressure resistance of W-PACIM fittings decreased progressively with increasing projectile diameter. The combined quality of the W-PACIM fittings was the best when the projectile diameter was 10mm.

Key words: water projectile assisted co-injection molding, projectile diameter, composites, polymer processing, wall thickness, rheology

摘要：

针对短玻纤增强聚丙烯为外层、聚丙烯为内层的水驱动弹头辅助共注塑（W-PACIM）管件，通过实验手段探究弹头直径（9~12mm）对管件玻纤取向、残余壁厚大小及均匀性和耐压性能的影响。实验结果表明：外层玻纤在不同层取向度呈现差异，外侧近界面层玻纤沿流动方向取向度高，中间层玻纤取向度次之，近模壁层玻纤分布杂乱无章，大多与流动方向呈锐角或垂直分布；随着弹头直径的增大，靠近模具壁面层玻纤断裂严重，各层玻纤取向度也逐渐变低；随着弹头直径的增大，W-PACIM管件总壁厚与内层壁厚逐渐减小，而外层壁厚小范围下降；W-PACIM管件的耐压性能随着弹头直径的增大逐渐降低。当弹头直径为10mm时，W-PACIM管件综合质量最佳。

关键词: 水驱动弹头辅助共注塑, 弹头直径, 复合材料, 聚合物加工, 壁厚, 流变学