Poly(maleic acid-co-acrylic acid) ionomer as nucleating agent on the crystallization behavior and properties of poly(ethylene terephthalate)

Abstract

Polyethylene terephthalate (PET) generally suffers from low crystallization rate and long molding cycle, which limits its application in injection molding of engineering plastics. To overcome the specific shortcoming, polymaleic acid-co-acrylic acid (PMA-AA) ionomer used as a nucleating agent was added to PET by melt blending, and its effect on the crystallization behavior of PET was investigated in this paper. It is indicated that the modified PET samples (MPET) with the addition of nucleating agents exhibit much higher molecular order and faster crystallization rate. The nucleation mechanism of MPET induced by PMA-AA ionomer was analyzed by means of Avrami equation and Hoffman–Lauritzen theory, revealing that the addition of PMA-AA ionomer provides more nucleation sites and reduces the fold surface free energy of PET. The nucleation and dispersion behavior of PMA-AA ionomer were further observed by SEM and POM morphologies. The results demonstrated that ionomer was dispersed homogeneously in the PET matrix, thus leading to faster crystallization rate of MPET than neat PET. In addition, the thermal stability, mechanical properties, and gas barrier of PET and MPET were characterized.