A Review on the Formulation and Rupture Properties of Polyethylene Terephthalate in a Mechanical Recycling Context

The environmental stress caused by climate change has provided an impetus to the search for greener solutions. A striking example of this is plastic pollution. One of the main difficulties in finding alternatives is maintaining an ecological balance along with economic viability. Other than reducing the consumption of plastics, recycling is one useful approach. In this context, polyethylene terephthalate (PET) is in the spotlight. This saturated polyester with unique properties is one of the most used plastics, and its use is increasing year by year. Plus, it is the most recycled polymer in the world. Among different recycling methods used today, the well-established equipment for mechanical recycling is the most efficient process and has a lower carbon footprint. However, despite the effort spent on recycling PET and the extensive number of published papers on this matter, many challenges still restrain its industrial development. One of the reasons for this is a lack of understanding of the structural modifications caused by processing and the effect on the properties of the final product. This Review presents an overview of PET’s intrinsic properties, before and after mechanical recycling. By focusing on the mechanical process, the different degradation mechanisms and their effects are described. Widely used reinforcement techniques are explained along with their possible drawbacks. A better view of what is yet to be understood might guide new solutions for PET’s processing and reuse.