Composite Contains Large Content of In Situ Microfibril, Prepared Directly by Injection Molding: Morphology and Property

During vibration injection molding (VIM), the in situ microfibril composite (MFC) based on high‐density polyethylene (HDPE)/polystyrene (PS) is molded. A large content of uniform microfibrils with an average diameter about 0.55 µm can be found from the surface to the center region. This phenomenon shows a big difference from the skin‐core structure of CIM samples as a result of shear flow. Apart from the PS phase going through a big deformation, the molecular chains of HDPE are also stretched along the flow direction. And finally, some super crystalline, like shish‐kebab, hybrid shish‐kebab structures exist in the strong shear region. Both the microfibril and super crystalline structure make a contribution to the mechanical improvement of the composite according to the mechanical testing results. This work can simplify the traditional MFC process, achieve the goal of direct fibrillation and provide a new idea of utilizing the properties of immiscible polymer systems.