Effect of Glutaric Anhydride Addition on the Properties of a Nadic Anhydride Epoxy Vitrimer Network

Vitrimers feature dynamic covalent bonds that can be thermally activated, allowing them to be repaired, remolded, and welded, similar to thermoplastics, but unheard of in traditional thermosetting networks. In this work, a glutaric anhydride (GA) hardener was systematically added to an epoxy anhydride vitrimer network made up of a diglycidyl ether of bis phenol F (DGEBF), methyl nadic anhydride (MNA), and a zinc transesterification catalyst. Increasing the GA content initially increased the Tgs of the networks from 61 °C up to a maximum of 85 °C, at a blend of 70/30 wt % of MNA to GA, but then decreased to 75 °C, as the flexibility of the GA began to dominate. Similarly, the flexural properties displayed a maximum strength of 90 MPa and modulus of 3.5 GPa for the 70/30 wt % MNA to GA network, although a consistent increase in strain to failure was observed with increasing GA content up to 3.65%. All vitrimer networks displayed good reprocessability after grinding, although it was clear that the flexibility of GA enabled improved reprocessability. The 70/30 wt % MNA to GA network showed very good dynamic behavior evidenced by repeated extreme deformation and impact, without brittle failure and excellent welding between vitrimer networks and indeed for carbon fiber composites. This work supports the potential of vitrimers to enable recycling and reuse of polymer networks, greatly enhancing their future sustainability.