Mechanically Robust, Heat-Resistant, and Reprocessable Polyethylene Vitrimers Cross-Linked by β-Hydroxy Ester Bonds via Reactive Processing

The development of vitrimers, dynamic covalent bonds cross-liked polymers via the associative exchange mechanism, offers a feasible way to address the recycling issue of traditional chemically cross-linked polyethylene (PE). However, it is still a great challenge to simultaneously achieve recyclability and high performance through a route that is environmentally friendly and easy to scale up. In this work, low-density (LD) PE vitrimers cross-linked by β-hydroxy ester bonds were successfully obtained via reactive processing between polyethylene-co-glycidyl methacrylate (PE-GMA) and decanedioic acid (DA). The high reaction efficiency of epoxy and carboxy groups leads to a high gel content of 84.51%. The activation energy (Ea) of the transesterification reaction is calculated to be 111.33 kJ·mol–1. Thanks to the high Ea and cross-link density, the obtained (LD) PE vitrimer exhibits a superior tensile strength of 20.41 MPa and an elongation at break of 800.16%, which is one of the highest values among the currently reported PE vitrimers fabricated by reactive processing. Moreover, the (LD) PE vitrimers have good creep resistance, heat resistance, and electrical insulation, thus showing a great potential to be used in the field of cable insulation.