A novel self-dispersed β nucleating agent for isotactic polypropylene and its unique nucleation behavior and mechanism

Adding beta nucleating agent (beta-NA) is the most effective way to induce beta-form in isotactic polypropylene (iPP). However, the problem of agglomeration and poor dispersion result in the low nucleation efficiency of beta-NA. We reported herein a novel self-dispersed beta nucleating agent of iPP, zinc salt of bicycle [2.2.1] hept-5-ene-2-dodecanamide-3-carboxylate (NBDA30), which exhibited a unique nucleation behavior during the crystallization of iPP. The results showed that the content of beta crystal of iPP nucleated with 0.2 wt% NBDA30 can reach 0.82 (k(beta) value), implying that NBDA30 is an effective beta nucleating agent of iPP. Polarized optical microscopy (POM) analyses showed that the NBDA30 gradually melted upon increasing temperature and then the melt induced the crystallization of iPP. The unique nucleation behavior was first reported in this study and the nucleation mechanism of iPP induced by NBDA30 was revealed by POM, fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM) and scanning electron Microscope (SEM). The results indicated that the NBDA30 was converted into ZnO nanoparticles and the group of ROO chemically adsorbed on the surface of ZnO nanoparticles (NPs). The problem of agglomeration of ZnO nanoparticles was well solved by in situ thermal decomposition of NBDA30 and the compatibility of ZnO and iPP matrix was greatly improved by chemical adsorption of organic carboxylic acid on the surface of ZnO NPs. Therefore, the nucleation efficiency of ZnO NPs was greatly increased. The preparation method of self-dispersed nucleating agent can potentially be extended to other nucleating agent or additives to prevent them from aggregating. (C) 2017 Elsevier Ltd. All rights reserved.