Description of second flow field via the deformation of polystyrene phase in high‐density polyethylene matrix

Real flow field has been critical in all kinds of injection molding, not only for understanding morphological evolution, but also for tailoring polymer physical property. Since the relaxation of PS phase in the HDPE matrix is successfully retarded by introduction of additional gas cooling, here, the second flow field in gas‐assisted injection molding is first calculated with the classical models for predicting the shapes of dispersed droplets in immiscible blend. The results indicate high gas penetration pressure facilitates strong second flow field. Gas penetration time is inversely proportional to the triggered flow intensity, which can be used for the qualitative comparison of the flow fields under various conditions. Importantly, the flow field can be designed by tailoring melt advancing rate, such as the penetration power and/or the penetration resistance of second fluid, which contributes to realizing the optimum coupling between external fields and chain architectures. Besides, this work opens a window for the understanding of real flow field under various processing conditions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43374.