Recycling of PE/PA/EVOH Multilayer Flexible Packaging Films via Reactive Compatibilization

Abstract

The recycling of a 7-layer co-extruded blown flexible film composed of polyethylene (LLDPE/LDPE blend), polyamide-6/6.6 (PA), and random copolymer of ethylene vinyl alcohol (EVOH) was assessed via reactive compatibilization using a maleic anhydride grafted polyethylene. Flat monolayer films were obtained from mechanical recycling of the multilayer film using a co-corotating twin screw extruder, with and without the compatibilizer. After that, they were characterized for their morphological, rheological, thermal, and mechanical properties. According to Harkin's spreading coefficient concept, the Relative Interfacial Energy (RIE) approach, and SEM images, a core-shell morphology was revealed, with the dispersed phase consisting of a thin EVOH layer and a PA6/6.6 copolymer core embedded within a continuous LLDPE/LDPE matrix. Adding up to 10 phr of the compatibilizer induced significant changes in the size and distribution of the dispersed phase. Moreover, compatibilized monolayer films exhibited enhanced mechanical properties, such as tensile, puncture, tear propagation strength, and dart drop impact resistance, compared to the uncompatibilized blend. Nonetheless, the compatibilizer presence negatively impacted the film's optical properties, although its clarity remained suitable for flexible packaging applications.