Influence of β-nucleating agent dispersion on the crystallization behavior of isotactic polypropylene

In this article we report an in-situ catalytic strategy for homogeneous dispersion of beta-nucleating agent N,N'-dicyclohexyl-terephthalamide (DCTPA) into isotactic polypropylene (iPP) as well as morphology control of the DCTPA/iPP composites. This strategy is based on catalyst to polymer morphology replication approach, in which by embedding Ziegler-Natta catalyst species on DCTPA surface, the fresh iPP chains first grew on the DCTPA tiny crystals and then wrapped about them; thus the interaction between DCTPA crystals and iPP matrix was enhanced, and the thermodynamic barrier of dispersing DCTPA in the inert iPP was avoided. The dispersion morphology and the self-assembly/recrystallization morphology of DCTPA in iPP were investigated; the relationship between DCTPA/iPP composites micro-structures and their crystallization behaviors was compared with that of the melting-blended DCTPA/iPP systems. Due to the improvement of DCTPA dispersion and the enhancement of interaction between DCTPA and iPP melts, the synthesized samples presented characteristics of fast crystallization initiation and slow spherulites growth rate, which is different from the general melting-blended composites. (C) 2018 Elsevier Ltd. All rights reserved.