Title: Effect of nucleating agent supported on zeolite via the impregnation on the crystallization ability of isotactic polypropylene and its mechanism

Biography:

Chao Li is now a graduate student mainly engaged in the field of modified polypropylene properties in East China University of Science and Technology, China. She had completed his Bachelor's degree from Wuhan University of Technology when she was 22 years old.

Abstract

Addition of an alpha-nucleating agent is the simple and effective method to increase nucleation efficiency of isotactic polypropylene (iPP). However, severe agglomeration and poor dispersibility of sodium 2, 2’-methylene-bis (4,6-di-tertbutylphenyl) phosphate (NA11), decrease the nucleation efficiency in the iPP, and much more nucleating agent is needed to maintain the nucleating property. As a result, it becomes the key how to decrease the size of NA11 and increase the nucleating property. In this paper, zeolite 4A (Z4A) was firstly supported by NA11 through solution impregnation, and NA11 was dispersed by Z4A depending on the dispersion of zeolite as carrier for the second component. Then the dispersed NA11 system (NA11-Z4A) exhibited a superior nucleation behaviour during the crystallization of the iPP matrix when it was used with iPP together. The isothermal and non-isothermal crystallization kinetics indicated that the NA11-Z4A /iPP system had the best crystallization effect. Polarized optical microscopy (POM) and scanning electron microscopy (SEM) analyses showed that the size of NA11 was decrease obviously when it was adsorbed on the surface of Z4A, which leads a better dispersibility of the nucleating agent and thus an accelerated nucleation process in the iPP matrix. In the end, the mechanism for the excellent dispersibility of NA11-Z4A, which was based on hydrogen bonding between NA11 and Z4A, was confirmed by Fourier transform infrared spectroscopy (FT-IR). Based on the research work, the solution impregnation strategy can potentially be applied to other systems to inhibit the agglomeration and improve the dispersibility of additives in iPP.