Strategies to recycle multilayer films based on polyolefins

VALERIA PETTARIN; FEDERICO MORALES; TALIA ECHEVERRIA; CAREN ROSALES; MARIA ALEJANDRA COSTANTINO; GUIDO PALAZZO

Kottayam, Kerala

Conferencia; International Online Conference on Reuse, Recycling, Upcycling, Sustainable Waste Management and Circular Economy ICRSC ? 2022; 2022

Mahatma Gandhi University

Due to the wide versatility and properties of plastics, they have replaced many other materials, such as glass and aluminum, in food packaging. Multilayer plastic films are highly used in the food industry since they bring together the properties of several polymers in the same container. Moreover, multilayer arrangements reduce costs and environmental impact, reducing the amount of plastic material used by increasing the overall packaging performance, thus reducing the amount of food discarded due to spoiling. However, their growing market has not been accompanied by an adequate recovery and recycling plan, currently leading to a large volume of garbage and no adequate solutions for the mismanaged plastic waste. This fact has generated a negative view of these materials, overshadowing the positive impact that they provide due to their numerous advantages in terms of low cost and products’ protection. Recycling of multilayer food packaging presents an extra difficulty due to its post-consumer nature, as it requires adequate extra processes of collection, classification, cleaning and drying before mechanical recycling. Moreover, since the preparation of multilayer films involves adhesives for lamination of interlayers, recycling of these materials involves additional steps of delamination. Another approach for recycling of polymer-based multilayers is through blending, in which multi composite materials can be blended all together without separation of layers. However, polymers present in multilayer films are incompatible and their mechanical recycling leads to immiscible and incompatible blends with low mechanical, rheological, optical and/or barrier properties. It is then evident that one of the big engineering challenges in recycling thermoplastic blends is to manufacture competitive products in terms of mechanical properties such as toughness or strength, i.e. to upcycling, understanding upcycling as a process by which recycled waste is transformed into materials with improved performance, adding value and widening their application field. In this work, several strategies to recycle different multilayer films based on polyethylene and polypropylene are presented. Studied films were milk pouches (PE/EVOH/PE), snack packs (PP/Al) and tetra packs (paper/PE/Al). Several techniques were applied to evaluate morphology and performance of the obtained products, such as XRD, DSC, flexural tests, tensile tests, and fracture tests. Results make evident the relevance of this work as an initial step, emphasizing the need for additional research.