A strategy for fabricating high-strength polyimide/carbon nanotube composite aerogels with efficient electromagnetic interference shielding efficacy in the X-band using nanofiber reinforcement

In the aerospace field, the intricate working conditions impose stringent requirements on the application of electromagnetic interference (EMI) shielding materials. Such materials not only need to fulfill the EMI shielding performance criteria but also must possess the capability to endure high temperature and exhibit favorable mechanical property. In the present study, anisotropic composite aerogels were fabricated through directional freezing and thermal imidization, with polyimide (PI) serving as the foundational matrix, polyimide nanofibers (PINF) functioning as reinforcements and incorporating multi-walled carbon nanotubes (MWCNTs). These composite aerogels demonstrated remarkable thermal stability, with the weight loss of 5 % up to 565 degrees C, along with excellent flame retardancy. The incorporation of PINF served to interconnect the internal structure of the aerogels, enhancing the mechanical property, as evidenced by an elastic modulus reaching up to 275 KPa. Furthermore, the EMI shielding performance of anisotropic composite aerogels was also systematically analyzed. The average shielding effectiveness (SET) of the 9-mm-thick aerogel (PPC-1) within the X-band attained 79.7 dB in the vertical direction and 61.2 dB in the horizontal direction, signifying excellent EMI resistance. These composite aerogels hold great promise for application in the demanding aerospace industry characterized by complex environments. Overall, this study provides a novel approach for preparing composite aerogels possessing lightweight, high-strength and high-efficiency EMI shielding performance, thereby making a valuable contribution to the relevant research field.