High-performance ablative composites demonstrate promising applications in the field of aerospace for thermal protection. In this study, the preparation of flexible thermal ablative composites with fast room-temperature self-healing properties was reported. First, a facile route to synthesize transparent and self-healing PDMS-polyurethane (PU) elastomers was proposed. Results showed that the room-temperature self-healing efficiency of PDMS-PU elastomers can reach as high as 92.9% for 3 h. Low-field NMR analysis indicated that the mobility of molecular chains plays a critical role in determining the self-healing efficiency of PDMS-PU elastomers. Afterward, polymeric thermal protection composites which can be self-healed at room temperature within 24 h were prepared. Results indicated that the self-healed composites can withstand flame erosion at nearly 1300 °C. This work provides insights into expanding the application of self-healing materials in the aerospace industry, where heat ablation and the intactness of thermal protection systems are both primary concerns.

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Ablative materials will behave differently when cruising under different hyperthermal environments. Herein, liquid silicone rubber-based composites were employed as a model system to investigate the response behavior of ablative materials under different hyperthermal environments. The computational fluid dynamics simulation was used to examine the flow field of oxyacetylene flame under different heat fluxes. Results indicated that oxyacetylene flames with different heat fluxes have almost identical temperature distributions when the ratio of O2 and C2H2 is fixed, but the scouring force of the gas flow increases significantly with increasing heat flux. The ablation performance decreased when the heat flux increased from 1 to 5 MW/m2, and the ablation mechanism is mainly attributed to the hybrid coupling between mechanical denudation and oxidative erosion. The ceramization reaction to form SiC tended to occur under an inert atmosphere. In addition, the carbon fibers locating on the periphery of the core region tended to assume an orientation state with the progression of the ablation process. This work elaborated the influence of heat flux intensities on the ablative behavior of liquid silicone rubber composites, which also served as a reference to developing other types of ablative materials.

In this work, the acrylonitrile (AN)-styrene (St)-divinylbenzene (DVB) resin was synthesized via suspension polymerization in the presence of inert porogens as diluent. The relationship of the solubility parameter (SP) of the materials and the porous properties of the resin was investigated. These porous spherical resin particles (0.25-0.84 mm) can be used as precursors of amidoxime resin which has a high metal ion chelating efficiency. The results showed that the porous properties (surface area and mean pore width) of the resin changed with variation in the compatibility between monomers and porogens. According to the the BET theory to N 2 sorption and scanning electron microscopy (SEM), the specific surface area of the obtained beads was strongly dependent on the compatibility of the components of the system and achieved values from 3.3 to 66.8 m 2 /g. The surface area of the terpolymer beads was found to rise with a decrease in the content of acrylonitrile or an increase in the SP of the porogens. However, the variation of the pore size was just the opposite.