Abstract
High-contrast X-ray computerized tomography (CT) observation reveals that the cavitation is commonly found in the glass fiber (GF) / polymer composites prepared by injection molding. Generally, the cavities in materials often lead to the poor mechanical properties, so that the reduction of the cavities is a serious issue in the mass-production of the plastic products. In this study, the cavitation is found to be localized in the middle of the test piece by X-ray CT observations, which is strongly related to the skin / core layer structure commonly known in the field of the injection molding. This fact strongly suggest that the cavitation is caused by the volume shrinkage during the cooling process after stopping the plastic flow, and that the phenomenon is coupled with the sink-mark. The analysis of the volume of cavities and sink-mark suggest not-simple cooling process.
