Preparation of Superelastic, Durable, and Lightweight Composite Foams Based on Multiple Cross-Linked Network Regulated Structures

The polymer material foaming technology plays an important role in energy conservation and emission reduction. However, modulating the structure of rubber/plastic foams to achieve low weight and high resilience is still a challenge. In this paper, ethylene vinyl acetate polymer (EVA)/epoxidized natural rubber (ENR) foams are prepared by chemical foaming kettle compression molding (KCM) with multiple cross-linked network structures consisting of covalent cross-links of EVA–EVA and ENR–ENR and hydrogen-bonded cross-linked networks between hydroxyl and ester groups. As influenced by the hydrogen-bonded cross-linked networks, the cellular restructuring of EVA/ENR foams is no longer limited to changes in the rubber/plastic content. Compared to pure EVA foams, EVA/ENR foams show advantages such as a low weight (13.95 × 1010 cells/density), a higher ductility (3.42 MJ/m3), a higher resilience (50%), and superior durability (more than 200 cycles at 50% compression). Moreover, due to the binding and anchoring effect of the ENR molecular chains, the thermal stability of EVA/ENR foams is greatly enhanced, with an initial decomposition temperature of around 320 °C, compared to that of EVA foams (∼150 °C). Considering the excellent properties of the EVA/ENR foams and the low cost of the KCM, the present strategy proposes an easy-to-industrialize method of fabricating rubber/plastic composite foams with high mechanical properties.