Synergistically Improved Oxygen Barrier Properties of Polyethylene Terephthalate by Combining “Active” and “Passive” Barrier Techniques

The relatively poor oxygen barrier properties of polyethylene terephthalate (PET) limit its high-end use in flexible electronic substrates. In this work, the oxygen barrier properties of PET films are highly improved by biaxially stretching PET films containing oxygen scavengers. The “active” oxygen scavengers result in a higher crystallinity of biaxially stretched PET films, improving the “passive” barrier properties. Biaxial stretching processing increases the surface area of oxygen scavengers’ domain, which consumes the oxygen molecules more effectively, thus improving the “active” barrier properties. More importantly, the enhanced “passive” barrier path prolongs the residence time of oxygen molecules in the films, allowing the oxygen scavenges to have enough time to sufficiently react with oxygen molecules. As a result, the oxygen permeability coefficient of biaxially stretching PET films containing oxygen scavengers is as low as 14.5792 cc mil m⁻² day⁻¹ 0.1 MPa⁻¹, synergistically improved by a factor of 11.99 compared to pristine PET films.