Recycling Poly(ethylene-vinyl acetate) with Improved Properties through Dynamic Cross-Linking

The low properties of recycled polymers associated with high cost of recycling hinder development of the thermoplastic recycling industry. Dynamic cross-linking of recycled thermoplastics with the formation of vitrimers enables superior mechanical properties, good reprocessability, and superior chemical and environmental resistance. Herein, a poly­(ethylene-vinyl acetate) (EVA) vitrimer was formed by cross-linking with triethyl borate with the catalyst (bis­(acetylacetonato)­dioxomolybdenum­(VI)). The resultant EVA vitrimer shows enhanced thermal stability and mechanical properties with up to two times improvement in Young’ modulus and storage modulus by comparison with the thermoplastic EVA. Moreover, 90% of Young’s modulus was maintained in the EVA vitrimer after five times of recycling, whereas only 72% can be maintained for recycling the thermoplastic EVA. This dynamic cross-linked EVA also exhibits superior UV and solvent resistance, which helps extend the service time of the recycled material. This work introduces a facile and efficient method to recycle and reuse EVA with low property loss. It has the potential to enable the production of high-performance EVA from EVA waste for different applications.