The influences of α/β compound nucleating agents based on octamethylenedicarboxylic dibenzoylhydrazide on crystallization and melting behavior of isotactic polypropylene

The influences of alpha/beta compound nucleating agents based on octamethylenedicarboxylic dibenzoylhydrazide on crystallization and melting behavior of isotactic polypropylene (iPP) were analyzed. It is found that the crystallization temperatures of nucleated iPP were increased by above 11.0 degrees C and the relative contents of beta-crystals (K-beta) in iPP reached above 0.40 after addition of compound nucleating agents. The K-beta values depend on cooling rate, crystallization temperature in isothermal crystallization, and the difference between the crystallization temperatures of iPP nucleated by two individual nucleating agents. The nonisothermal crystallization kinetics were studied by Caze method and Mo method, respectively. The effective activation energy was calculated by the Friedman's method. The results illustrate that the half crystallization time was shortened and the crystallization rate was increased obviously after addition of nucleating agents, and the effective activation energy was increased with the relative crystallinity.