Stretchable and Fast Composting Polyester Films with High-Performance Oxygen Barrier

Abstract

This work presents one of the fastest composting aliphatic–aromatic polyesters with a good balance of mechanical and barrier properties, making it a sustainable alternative for low-density polyethylene in packaging. The polyesters (PBxBDMyS) are prepared by melt polycondensation of 1,4-butanediol (B), 1,4-benzenedimethanol (BDM), and succinic acid (S). One composition exhibited a tensile strength of 20 ± 2 MPa, a modulus of 150 ± 8 MPa, and a very high elongation at break of 581 ± 46%. The low oxygen transmission rate (152 cm3·m–2·day–1·bar–1) measured at 65% relative humidity and 23 °C confirms excellent barrier performance. A 3 μm water-borne nanocomposite coating of glycol chitosan and sodium fluorohectorite further reduced the gas permeability to a value of 0.75 cm3·m–2·day–1·atm–1, which is competitive with materials suitable for demanding packaging applications such as poly(vinylidene chloride) while maintaining good mechanical properties and high stretchability. After studying the enzyme-catalyzed hydrolysis under controlled conditions, the full fragmentation, assimilation, and mineralization in thermophilic, aerobic composting could be confirmed in less than 5 weeks using a combination of different analytical methods. The mechanism of degradation was proven to be bulk degradation.