Effect of Dimethyl Terephthalate and Dimethyl Isophthalate on the Free Volume and Barrier Properties of Poly(ethylene terephthalate) (PET): Amorphous PET

• DOI: 10.1021/acs.macromol.7b02230
• Publication Date: 2018-01-05T21:44:31Z
• Authors: S. Zekriardehani; A. S. Joshi; S. A. Jabarin; D. W. Gidley; M. R. Coleman
• Keywords: Dimethyl terephthalate

The effect of blending two low molecular weight diluents (LMWD), dimethyl terephthalate (DMT) and isophthalate (DMI), on the microstructure, free volume, barrier properties poly(ethylene terephthalate) (PET) was investigated. Incorporation additives at loadings up to 3 wt % led a substantial improvement in PET oxygen, carbon dioxide, helium. Although have similar structures, DMI showed enhanced compared PET/DMT samples. Positron annihilation lifetime spectroscopy as well density measurements indicated that there reduction fractional volume polymer upon incorporation LMWDs. Dynamic mechanical analysis disclosed activation energy for relaxation due decrease chain motion presence DMT or DMI. There permeability increase LMWDs primarily diffusivity which is consistent with mobility.