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

• Published in: ACS applied polymer materials Vol. 4; no. 9; pp. 6675 - 6686
• Main Authors: Sehl, Elmar, Timmins, Renee L., Ghosh, Dipannita, Breu, Josef, Agarwal, Seema
• Format: Journal Article
• Language: English
• Published: American Chemical Society 09-09-2022
• Subjects: nanocomposite; biodegradable; food packaging; polyester; layered silicates
• ISSN: 2637-6105; 2637-6105
• DOI: 10.1021/acsapm.2c01040

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 (PB x BDM y S) 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.