Bioinspired lightweight para-aramid/SiO2 aerogel thermal insulation materials for firefighting protection

Protective materials used in high-temperature environments often suffer from reduced thermal insulation performance under open-flame exposure, sustained heating and repeated compression, increasing the risk of thermal injury. In this study, a feather-inspired lightweight para-aramid/SiO 2 aerogel thermal insulation composite with a fluffy porous structure was developed for firefighting thermal protection. Poly(p-phenylene terephthalamide) (PPTA) fibers were used as a heat-resistant fibrous skeleton to construct a porous insulation network through fiber carding, impregnation and aerogel compounding processes. Among the tested samples, the composite prepared with a nominal SiO 2 aerogel addition of 1.5 g has exhibited the lowest surface temperature under a thermal load of 100 °C. Repeated-heating and cyclic-compression tests were conducted separately. The composite exhibited a relatively stable thermal response during repeated heating and a repeatable mechanical response during cyclic compression under the applied test conditions. At the fabric-assembly level, the limiting oxygen index (LOI) increased from 29% for the PPTA fabric-only reference to 35% for the PPTA + PPTA/SiO 2 -1.5 assembly, indicating improved flame resistance. A simplified PPTA-based protective assembly containing the composite filling has demonstrated a remarkable thermal-barrier behavior under direct-flame conditions with a flame temperature of ~600 °C. The feather-inspired porous structure provides lightweight, fluffy and deformable filling characteristics while improving the thermal-protection performance of the composite. This work provides a potential structural design strategy for lightweight thermal insulation materials used in firefighting protective equipment.