Crystallization and melting behaviors of polypropylene admixed by graphene and β-phase nucleating agent

In this work, the crystallization and melting behaviors of different polypropylene (PP) materials containing a certain amount of graphene, beta-phase nucleating agent (beta-NA), and their mixture, respectively, were comparatively investigated. The results showed that graphene exhibited the typical sheet structure in the PP matrix, and the presence of beta-NA did not change the dispersion of graphene apparently. Both graphene and beta-NA exhibited great nucleating effect for the crystallization of PP. However, the nucleation efficiency of beta-NA was much larger than that of graphene. With the simultaneous presence of graphene and beta-NA, the crystallization ability of PP matrix was greatly improved, which indicated that there was a synergistic effect between graphene and beta-NA in accelerating crystallization of PP matrix. Furthermore, it was proved that the synergistic effect was greatly dependent upon the crystallization conditions. The higher the isothermal crystallization temperature or the bigger the cooling rate, the more apparent the synergistic effect was.