Facile fabrication of thermoplastic starch/poly (lactic acid) multilayer films with superior gas and moisture barrier properties

• Published in: Polymer (Guilford) 2021-05, Vol.223, p.123679, Article 123679
• Main Authors: Trinh, Binh M., Chang, Christina C., Mekonnen, Tizazu H.
• Format: Article
• Language: English
• Subjects: Coating processes; Compacting; Composting; Compression; Extrusion coating; Extrusion molding; Fabrication; Food packaging; Fourier analysis; Fourier transforms; Immersion coating; Infrared spectroscopy; Maleic anhydride; Maleic anhydride (MA); Mechanical properties; Moisture; Multilayer films; Multilayers; Nanoclays; NMR; Nuclear magnetic resonance; Oxygen; poly(lactic acid) (PLA); Polylactic acid; Pressure molding; Starch; Tensile properties; Thermogravimetric analysis; Thermoplastic starch (TPS); Thickness; Titration
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2021.123679

Multilayer films comprised of thermoplastic starch (TPS) and poly (lactic acid) (PLA) were fabricated via a reactive extrusion, compression molding, and dip coating processes. Maleic anhydride (MA) modification of TPS was employed to improve the interfacial adhesion between TPS and PLA layers of the film. The level and effect of TPS modification were evaluated using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (H NMR), titration, and thermogravimetric analysis (TGA). Nanoclays were incorporated in the TPS and maleated TPS (MTPS) matrices to further enhance the physico-mechanical properties of the multilayer films. The optimized multilayer film fabricated in this study, which was the nanoclays-filled maleated thermoplastic starch and PLA multilayer film (MTPS-3C/PLA) displayed good transparency and tensile properties, and excellent moisture and oxygen barrier properties. This multilayer film assembly provided 1300% improvement in moisture barrier compared to TPS films, and 3300% improvement in oxygen barrier properties as compared to PLA films adjusted for thickness. Moreover, these multilayer films are composed of compostable, food-grade, inexpensive, and bio-based ingredients and as such they are expected to be compostable with great cost structure and environmentally friendly. [Display omitted] •Multilayer film assembly of TPS and PLA provided superior moisture and oxygen barrier properties.•The interfacial adhesion between the multilayers was improved via maleation of the TPS.•The incorporation of montmorillonite nanoclay platelets enhanced the oxygen barrier properties.•The multilayer film assembly is expected to have reasonable cost structure and compostable.