Improving Oxygen Barrier Property of Biaxially Oriented PET/phosphate Glass Composite Films

A new formulation of low glass transition temperature phosphate glass (Pglass) was developed to avoid degradation of, then melt blended with poly(ethylene terephthalate), (PET), in the presence of a sulfonated PET copolymer compatibilizer, providing an effective dispersion of the filler in polymer matrix. Compression molded films were then stretched to a draw ratio of 3 x 3 at the polymer glass transition temperature; scanning electron microscopy confirmed that the Pglass droplets successfully transformed into platelets with high aspect ratio under the processing condition. A 20-fold reduction in oxygen permeability was obtained with oriented 20 vol% Pglass in the PET matrix. The experiment data were fitted with the Nielsen and Cussler models to extract the platelet filler aspect ratios; the fitting result also indicated that the compatibilizer was effective in bringing Pglass and PET together. Enhanced the moduli and significantly reduced ductility, typical of filled systems, were observed in this family of materials. (C) 2017 Elsevier Ltd. All rights reserved.