Carbon nanotube/thick-walled polymethacrylimide foam core with enhanced mechanical and electromagnetic properties for radar absorbing sandwich structures

초록

Carbon nanotube (CNT)/polymethacrylimide foam core with thick cell walls (TWPMI) was proposed as radar absorbing core material. The relationship between the cellular structure, and the mechanical and electromagnetic performance of CNT/TWPMI foam core was investigated by controlling polymerization temperature and CNT loading. Higher polymerization temperatures led to larger cell size with thicker cell walls. The specific compressive modulus was 1.15 times higher, and the specific compressive strength was 1.75 times higher than that of low polymerization temperature. In addition, CNTs enhanced the compressive modulus to 55.6 MPa and the compressive strength to 3.28 MPa in 2 wt% CNT/TWPMI. Due to the synergistic effect of the TWPMI structure and CNTs, the electromagnetic properties were significantly improved, achieving a real part of permittivity of 4.37 and a loss tangent of 0.89 at 2 wt% CNT/TWPMI. As a result, the rigid CNT/TWPMI foam core with excellent radar absorbing performance was developed. The optimized radar-absorbing structure, designed using a genetic algorithm, exhibited a thickness of 6.2 mm and a density of 0.32 g/cm3 without a carbon fiber reinforced polymer (CFRP) back plate, and 0.43 g/cm3 with the back plate, achieving over 90 % absorption in the X-band.

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