FIBER ORIENTATION MORPHOLOGICAL LAYERS IN INJECTION-MOLDED LONG-FIBERREINFORCED THERMOPLASTICS

Flow-induced fiber orientation can vary significantly across the thick ness of injection molded parts and is usually present in the form of t hrough-thickness layers. In this work, fiber orientation was examined both on the flow plane and through the thickness. The thickness of a s hell layer with fiber orientation in the flow direction and a core lay er with a fiber orientation mainly transverse to the flow were measure d via microscopy. The effect of filling speed and mold thickness on th e molded plaque morphology was identified. Mold-filling simulations vc ;ere undertaken in order to provide the characteristic shell and core layer fiber orientations as well as the frozen layer thickness at the end of filling and the gap-wise shear rate gradients. The combined fro zen and high shear rate regions were correlated with the experimental shell layer thicknesses.