Vitrimers as a sustainable viable alternative to crosslinked polyethylene

The aim of this study is to explore a class of innovative materials called vitrimers as sustainable alternative to crosslinked polyethylene (XLPE). XLPE finds applications in specific fields as thermal insulation for pipes for hot fluids and electrical cables coating, thanks to its high thermal, insulation and mechanical properties. Despite these excellent qualities, XLPE is not recyclable and nowadays its end-of-life consists mainly of landfill or energy recovery. For this reason, an innovative material was investigated. Differently from XLPE, vitrimers can be recycled, which represents a huge advantage in terms of production costs and sustainability. This is possible due to the particular molecular structure of vitrimers, which confers them the characteristically high mechanical properties of thermosets materials, but also the ease of recycling typical of thermoplastics. Vitrimers contain Dynamic Covalent Bonds (DCB), which can be broken and reformed by providing thermal energy to the material, allowing its reprocessability. Many different compositions were produced by using melt extrusion, i.e. a very common industrial processing technique; all the polymers prepared were fully characterised. In order to assess the vitrimers’ characteristics, they underwent a hot set test in critical conditions applying loads at high temperature. Moreover, other analyses were performed to investigate fundamental characteristics as crosslinking degree, mechanical and rheological properties. The results obtained highlighted that the polymers produced in this work showed vitrimeric properties and were fully recyclable, although further enhancements are needed to obtain a material suitable to replace XLPE. Despite this, the research allowed to make a progress in this new field, which could lead to very interesting discovers in the world of sustainable plastic materials.