Feasibility of incorporating recycled multilayer LDPE/EVOH films into flexible packaging

Abstract

Multilayer films are widely used in the food industry because they allow the combination of properties of different materials to increase product shelf life without sacrificing product value. Despite the associated benefits, these films are difficult to recycle due to material immiscibility and difficult layer separation. Thus, the purpose of this research is to investigate the feasibility of incorporating recycled plastic material from the multi-material film industry into extruded films for food packaging. To simulate the thermomechanical recycling, two different post-industrial polymeric wastes of low-density polyethylene (LDPE) (with linear low-density polyethylene (LLDPE) or with ethylene vinyl alcohol (EVOH)), were reprocessed four times in a single-screw extruder. Moreover, these polymeric wastes were blended with virgin LDPE to improve the extrusion process control and to assess their effect on the blend properties. The extrusion experiments demonstrate that reprocessing of multilayer films and processing of their blends with virgin LDPE is feasible. Moreover, the mechanical and thermal properties of the corresponding films are not negatively affected when compared with those of virgin LDPE films. Nevertheless, the optical properties of recycled EVOH films, were lower than those of virgin LDPE or recycled LLDPE, with high haze and low gloss. Highlights: Two multilayer film scraps were reprocessed and blended with virgin LDPE. Thin film samples were produced by blown film extrusion. Films containing EVOH presented the worst optical properties. The presence of EVOH did not negatively affect the extrusion process. Mechanical and thermal properties were not significantly affected.