Polyimide Aerogel/Aramid Honeycomb Cylindrical Shells with Robust Static/Dynamic Mechanical Properties and Efficient Thermal Insulation

A novel integrally molded PIA/APH composite cylindrical shell is proposed. • The structure achieves a transition from brittleness to elastoplastic response. • Tensile strength and specific shear modulus increase by 5.28 and 66.32 times. • The composite shows enhanced flame retardancy and efficient thermal insulation. • It shows potential for lightweight, load-bearing, and thermal insulation. High-performance curved-shaped special components, as a focus in the aerospace field, the development of ultra-light, heat-insulating and flame-retardant cylindrical shells holds significant engineering significance. Herein, we report a novel integrally formed polyimide aerogel/aramid-paper honeycomb (PIA/APH) cylindrical shell, achieved by infusing PIA into an APH to create a monolithic PIA-rich cylindrical sandwich structure. This design yields an ultra‑lightweight cylindrical shell with a density as low as 0.11-0.20   g/cm³, creating a synergistic interplay between mechanical load‑bearing and thermal insulation that yields mutually reinforcing performance benefits: the rigid honeycomb framework suppresses aerogel shrinkage by 41.96% and boosts tensile failure strain 5.63 times, transforming the brittle PIA into a tough, ductile material exhibiting distinct elastic, yield, and hardening stages under lateral quasi-static compression and drop-weight impact. Concurrently, the PIA reinforcement increases the specific shear modulus of APH by 1.73 times and shear strength by 4.57 times. through improved interfacial load transfer and stress redistribution. Notably, the composite retains good post-damage thermal insulation, attributed to greater residual wall thickness after deformation, while flame retardancy is improved with self-extinguishing duration reduced from 10.27   s (APH) and 6.20   s (PIA) to 5.20   s. The fabricated PIA/APH cylindrical shell holds considerable promise for mechanically and thermally coupled aerospace environments, offering a new paradigm for multifunctional lightweight structure design.