In-situ investigation of fiber orientation and behavior in flowing polymer melts

Fiber-reinforced composites enable a wide range of applications due to their high mechanical properties while being light-weight. However, the full potential of these mechanical properties can only be reached by designing the respective part in such a way, that the fiber orientations are tailored to the load path. Therefore, the quality assurance by means of non-destructive testing, such as X-ray computed tomography (CT), is of utmost importance. In addition to defect detection after production, it is also necessary to fully control the manufacturing process. Slight variations in the process, for example during injection moulding (temperature, polymer viscosity etc.) could potentially lead to fiber misalignments and ultimately critical part failure. To predict the fiber orientation in fiber-reinforced plastic parts, multiple approaches are available. Fistly, fiber orientation can be simulated based on existing models or past experiences and comparing these results with the manufactured part via X-ray CT or microscopy. However, these approaches require the manufacturing of costly tools to begin with and only represent a static state of the material. To investigate how the polymer melt influences fiber orientation and behavior under application-oriented conditions, a method based on X-ray particle tracking velocimetry (XPTV) was introduced in prior work to analyze particle-laden polymer melts. Building on this previous work, the present study demonstrates the application of XPTV to investigate the behavior of alkaliresistant (AR) glass fibers with a significant ZrO2 content suspended in a polymer melt flowing through a heated melt channel.