Structural effects of ionomers on the morphology, isothermal crystallization kinetics and melting behaviors of PET/ionomers

Morphology, isothermal crystallization kinetics and melting behaviors of PET modified by low molecular weight of ionomers with different structures, ethylene–sodium acrylate (AClyn) and styrene–sodium acrylate (SAA–Na), have been investigated by scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and polarizing optical microscopy (POM). At both high and low temperature regions, AClyn and SAA–Na act as heterogeneous nucleating agent to induce the formation of PET nuclei. The presence of benzene side group in SAA–Na increased the interactions between PET and SAA–Na, leading better compatibility of PET/SAA–Na than that of PET/AClyn. Although SAA–Na had less sodium ions than AClyn at the same content, SAA–Na exhibited similar efficiency to enhance the crystallization rate of PET with AClyn. Isothermal kinetic analysis showed that the same growth dimension was obtained for PET/ionomers regardless of the structural difference between AClyn and SAA–Na. After isothermal melt-crystallization, the second peak of multiple melting endotherms of PET/SAA–Na had almost the same value with PET/AClyn.