Effects of -nucleating agent and graphene oxide on the crystallization and polymorphic composition of isotactic polypropylene / graphene oxide composites for bridge pavement

To control the polymorphic and crystallization behavior of -nucleated isotactic polypropylene / graphene oxide (-iPP/GO) composites for bridge pavement, the roles of -nucleating agent (-NA) concentration and GO content in the polymorphic crystallization behavior, morphology and crystallization kinetics were studied by means of differential scanning calorimentry (DSC), wide-angle X-ray diffraction (WAXD), scanning electronic microscopy (SEM). Results revealed that with the increase of -NA concentration, the crystallization temperature, the percentage of -phase (c) and relative degree of crystallinity X-c increased evidently. Moreover, the crystallite sizes decreased, and the crystallization activation energy oE decreased, reflecting the strong nucleation effect of the -NA to the composites; On the other hand, as the GO content increased, the crystallization temperatures and relative degree of crystallinity X-c also increased slightly. Interestingly, GO exhibited strong -nucleation effect, which was not favorable for formation of -phase. When the GO content was 2.0wt%, unusual small banding patterned crystals were observed. In general, to control the polymorphic behavior and morphology of the -iPP/GO composites, both -NA concentration and GO content were very important factors.