Microstructural, mechanical, thermo‐rheological, barrier, and antimicrobial properties of coextruded tri‐layer polylactide/encapsulated geraniol/polylactide‐graphene nanoplatelets films

Abstract

A sustainable polylactide (PLA)‐based multilayer food packaging film was developed to improve neat PLA films' modest mechanical, thermal, and water/gas barrier properties. To improve the desired properties and impart antimicrobial aspects to the composite films, graphene nanoplatelets (GNP), and geraniol (GER) were reinforced into single‐layered PLA films. The project aimed to assemble three monolayers into multilayer films (MLF) through a coextrusion process, keeping the PLA‐GER layer in the core. X‐ray diffractograms, micrographs, and roughness parameters of the films demonstrated the dispersion of GNP in the film. Thermogravimetric analysis confirmed an enhancement in the thermal stability of the MLF by around 8°C when compared against single‐layer PLA films. An improvement in mechanical rigidity was supported by tensile (>87%) and rheological measurements. The polymers exhibit liquid‐like behavior in melts. Barrier properties did not improve for the MLF due to the agglomeration of GNP. The excellent antimicrobial properties of the MLFs for 3 weeks of storage at refrigerated conditions against both gram‐positive and gram‐negative pathogens were attributed to the release of GER from the film into the packed chicken samples and proved their potential for use in the food industry.