Although polyurethane–imide (PUI) foams combine the advantages of both polyurethane foam and polyimide foam, the performance of PUI might still not reach certain high-level requirements. Thus, expandable graphite (EG), as a kind of effective reinforcing filler, was introduced into the PUI matrix to improve the physical properties of the foam. Furthermore, to enhance the interfacial compatibility, EG was surface-modified with a silane coupling agent. The experimental results show that the addition of EG was beneficial for enhancing the comprehe...