Push-pull-processing (PPP) is a live in-mold manipulation method of co-injection molding used for enhancing the orientation of the polymer molecules and reinforcing fillers. This technique implements an alternating shear field induced by a coordinated action of two injection units to create multiple oriented layers across the thickness of molding during the packing phase. In this investigation, the PPP is employed to enhance the weldline strength of short-glass-fiber reinforced polycarbonate (SFRPC) with respect to the fiber orientation in the weldline areas. The effects of glass-fiber concentration and processing parameters including the number of push-pull strokes and the holding pressure differences between both of the injection units have been studied. In addition the degradation of the fiber length caused by the oscillation is also investigated.
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