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Internal Structure of Sandwich Injection Moldings
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Hamada, Hiroyuki / Semba, Takeshi
Sandwich injection moldings having different structures in the skin and core layers are produced by injecting different resins from two injection cylinders sequentially.
In this study, the internal structure of the sandwich injection moldings was quantitatively investigated. The materials used were polycarbonate (PC), acryronitryl-butadiene-styrene terpolymer (ABS) and PC/ABS blend. The sandwich injection moldings were subjected to chemical treatment in a chromic acid mixture, which etched the ABS component. In this way, the internal structure of sandwich injection moldings could be observed. From these observations, the degree of deformation in ABS parts was quantitatively evaluated. Ordinary injection moldings with a single injection unit and compressive moldings were also investigated to compare with sandwich injection moldings. These evaluation showed that the internal structure of moldings depend on processing methods. The most interesting observation is that the melt flow of the core layer in sandwich injection moldings is "the plug flow".
Key words: Sandwich injection molding / Polycarbonate / ABS / Internal structure