University of Pittsburgh team develops multifunctional polyethylene monomaterial for packaging

November 22, 2019 | Case Study

Flexible barrier packaging is growing in popularity because it is low-cost and lightweight and provides the necessary performance for protecting goods. Most flexible barrier packaging is made up of multiple layers of different materials. Aside from films being difficult form factors to recycle, the process to separate these individual materials creates additional challenges for recycling. Making barriers from monomaterials is of growing interest, especially as solutions for recycling flexible packaging are being developed. In fact, a team of researchers from the University of Pittsburgh (UPIT) proposed a fully polyethylene-based alternative to multimaterial flexible barrier packaging. The UPIT solution was developed in 2018, the team participated in the 2018 Ellen Macarthur Circular Materials Challenge and were one of the winners. The team won $200,000 and were supposed to join a 12 month accelerator programme, in collaboration with Think Beyond Plastic but have not made any public progress since 2018. 

There is a lot of ambiguity about the definition of multimaterials, monomaterials, and coated monomaterials for packaging. To help guide clients, we propose these definitions: Multimaterials combine thin layers of different materials, ensuring the optimal properties of the different materials are integrated into a common structure that performs better than its individual parts. Because the multiple layers are adhered together, it is difficult to separate the layers; thus, recycling these materials is economically unfeasible. To overcome this issue, a new approach to reduce the content of the film to one dominant material is being developed. Monomaterial films would be an economical choice and have better end-of-life processing. Currently, monomaterials are not fully developed and do not have the same performance as multimaterial films, specifically for barrier properties. Coated monomaterials are far more likely to replace multimaterials in the near future, as they would have the same performance while being recyclable or biodegradable. Under these definitions, the UPIT solution is a true monomaterial.