A novel combination of sandwich and co‐continuous structure based on polypropylene and styrene‐butadiene‐styrene block copolymer formed with wide range of polypropylene content

The styrene–butadiene–styrene block copolymer (SBS)/polypropylene (PP) blends with a unique sandwich layered co‐continuous structure were prepared by melt compounding. Differing from single conventional co‐continuous and sandwich structure, this structure was formed, where pure PP and co‐continuous SBS/PP phase acting as the face sheets and core. Even though the volume content was 20 or 10 vol %, PP always amazingly formed a continuous phase in SBS/PP blends, whereas the morphology of SBS phase relatively changed from dispersed particles to continuous network as its content increased to 50 vol %. For immiscible SBS/PP blends, due to the huge difference of complex viscosity and surface tension between SBS and PP, a pure PP layer existed on the surface of blends which can be ascribed to the PP enrichment. Herein, the structure of blends with more than 50 vol % SBS was presented as sandwich layered co‐continuous structure by combining the pure PP layer and co‐continuous structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46580.