Improvement of silicon and epoxy phase interface by constructing rigid interpenetrating networks based on bismaleimide to enhance ablative, mechanical and thermal properties

Polysiloxanes are widely used in the preparation of ablative-resistant resins due to their tailored reactivity and ceramisable properties. Nevertheless, the mechanical and thermal properties may be negatively impacted by the presence of flexible chain segments and poor compatibility. In this study, the phase interface of silicon between epoxy was improved by a rigid interpenetrating crosslinked network constructing by bismaleimide. The pyrolysis of the silicone was inhibited and the oxidation resistance of the resin was enhanced. Both graphitization and ceramisation of the char layer during ablation are significantly improved. This endows the modified resin with outstanding ablative properties, with mass and linear ablation rates reduced to 0.0666 g/s and 0.0512 mm/s, respectively, which exceed those of some conventional ablative-resistant resins. Remarkably, the thermal and mechanical properties are significantly enhanced benefiting from the rigid crosslinked network and improved phase interfaces. Moreover, the destruction of mechanical properties of composites in high temperature environments caused by organosilicones has been effectively addressed. Bismaleimide/silicone co-modified epoxy resins can be used not only as ablative-resistant coatings, but also for the preparation of fire-resistant carbon fibre composites, providing a novel approach to the production of cost-effective, recyclable structural integrated materials for thermal protection.