Polyimide Aerogel Fiber Bundles for Extreme Thermal Management Systems in Aerospace Applications.

Aerogel fibers are an emerging class of ultralightweight materials, which, compared to conventional bulk monolithic and aerogel films, provide better flexibility and extensibility. Despite the recent advancements in this field, due to their highly porous structure, their mechanical properties can be deteriorated. Inspired by the textile industry, we report the development of aerogel fiber bundles with twisted structures as a promising strategy to enhance the mechanical performance and practicality of aerogel fibers. Polyimide (PI) aerogel fibers were prepared via the sol-gel confined transition method. The fibers showed a unique nanostructured assembly with high specific surface area, excellent optical transparency, outstanding flexibility at diverse extreme conditions, self-extinguishing behavior, and superior thermal insulation performance. Using PI aerogel fibers as the backbone, aerogel fiber bundles in various configurations were designed and fabricated. A systematic study was performed to analyze the effect of design parameters on the mechanical performance of the bundles. Results revealed an optimal twist level for bundles, leading to a peak in mechanical properties across various bundle configurations. The observed improvement in mechanical properties was attributed to increased fiber-to-fiber binding strength, enhanced friction, and interlocking mechanism of fibers, underscoring the potential of the optimized twist level for enhancing the performance of aerogel fiber bundles. Overall, the development of aerogel fiber bundles holds great promise in revolutionizing the production of high-performance ultralightweight materials for thermal management applications.