Two types of β nucleating agents (β-NAs), aryl dicarboxylic acid amide (TMB-5) and diphenyl phthalate diamine (NT-C), were adopted to modify the polypropylene (PP)/ethylene propylene diene monomer (EPDM) blends, which were prepared by dynamic-vulcanization technology. Wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) were used to study the crystallization kinetics of PP. Our results showed that the addition of β-NAs can considerably increase the crystallization temperature, and significantly decrease the spherulite size of β-PP (L300). The Jeziorny analysis showed there were ~82% and ~89% of relative crystallinity generated from the primary crystallization in the composites containing TMB-5 and NT-C, respectively. The crystallization half time (t0.5) showed that NT-C improved the overall crystallization rate more effectively than TMB-5. In addition, the peaks of the relative crystallization rate curves were shifted towards higher temperature by 14 and 9 ℃ with the addition of TMB-5 and NT-C, respectively.

Keywords: β nucleating agent; PP/EPDM; crystallization kinetics; toughening; dynamic-vulcanization