Innovative processes for recycling cross-linked polyethylene

The aim of this work is to study innovative processes for enabling the recycling of cross-linked polyethylene. This objective is pursued first by the synthesis of a formulation belonging to a new class of polymeric materials called vitrimers. These materials can alter their topology without changing the number of cross-linking chemical bonds, allowing for their reprocessing and subsequent recycling. The results demonstrated that the optimized vitrimer retains properties comparable to those of the material currently produced by industries while being recyclable. Even though the vitrimer has been successfully produced, a focus on innovative recycling technologies that can be more easily implemented nowadays on an industrial scale is given. Recycling methodologies through mechano- chemical methods (i.e., milling and reactive extrusion), which allow for the breaking of the material’s cross-links are investigated. In addition, another innovative technology, including the treatment of materials with microwaves, which can directly deliver energy, has been also studied. Several characterization have been carried out and the results helped to understand the effectiveness of the de cross-linking process. The use of the Horikx model makes it possible to understanding if the de cross-linking mechanism is random or selective. Additionally, Flory’s theory is used to describe the evolution of the molecular weight between cross-links during a specific treatment.