Oxygen barrier properties of PET copolymers containing bis(2‐hydroxyethyl)hydroquinones

A series of poly[ethylene‐ co ‐bis(2‐ethoxy)hydroquinone terephthalate], PET‐ co ‐BEHQ copolymers were prepared by polymerization of various substituted bis(2‐hydroxyethyl)hydroquinones (BEHQs), dimethyl terephthalate (DMT), and ethylene glycol (EG). In addition to copolymers containing 6–16.5 mol % BEHQ, the homopolymer of BEHQ with dimethyl terephthalate, p(BEHQ‐T), was also prepared. The thermal and barrier properties of amorphous materials were studied. As the amount of comonomer was increased, the T g and T m of the materials decreased relative to those of PET. Oxygen permeability also decreased with increasing comonomer content. This improvement in barrier‐to‐oxygen permeability was primarily due to a decrease in solubility of oxygen in the polymer. All of the copolymers tested displayed similar oxygen diffusion coefficients. The decrease in solubility correlates with the decrease in T g . © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 934–942, 2003