Microstructure-Crystallization Correlation with Surface Migration of Additives in High-Crystallinity Polypropylene Composites

This study aims to describe the crystallization structure and surface migration in polypropylene (PP) composites containing lubricants and talc during 0-72 h at 70 ℃ of accelerated thermal aging. The particles exposed on the surfaces of PP composites after accelerated aging are caused by lubricant components and certain types of talc migrating to the surface. This additive-migration phenomenon is found to be correlated to the surface migration of additives with the occurrence of secondary crystallization in PP composites owing to accelerated aging, which increases the heat of fusion, crystallinity, and nanocrystalline size. The accelerated aging evaluation method for PP composites adopted in this study reveals that the microstructure, crystallinity, crystal size, and heat of fusion are correlated. The findings of this study can be applied for improving the appearance and quality of composite products