Morphological, thermo-mechanical, and barrier properties of coextruded multilayer polylactide composite films reinforced with graphene nanoplatelets and encapsulated thyme essential oil

Abstract

The food industry has been looking for biodegradable active packaging film, which has a lower environmental footprint and can extend shelf-life. This work aimed to develop a polylactide-based antibacterial nanopackaging with a tri-layer structure. This coextruded tri-layer film was composed of an internal extruded layer of polylactide (PLA), a central layer of PLA loaded with encapsulated thyme essential oil, and an outer layer of PLA with graphene nanoplatelets. The tri-layer packaging films' morphological, rheological, thermal, barrier, and antibacterial properties were evaluated and compared to those of their single-layer counterparts. Dispersion of nanoparticles in PLA matrix or in composites is described by rheological, thermal, and XRD analysis. The multilayer films displayed some roughness on the surface, and heterogeneity can be seen through phase imaging compared to single-layer films. Antibacterial assays of the film confirmed a strong bactericidal effect against gram-positive and gram-negative bacteria, maintaining this activity for 21 days.