Preparation and characterization of porous polyimide fibers with electromagnetic wave absorption properties

Abstract

The porous polyimide (PI) composite fibers, which exhibit high-efficiency electromagnetic wave adsorption (EMWA) performance, were successfully fabricated by controlling temperature of the coagulation bath during the wet spinning process. The mechanical properties of composite fiber decreased and average radius of micropores increased gradually with the rise of coagulation bath temperature. In addition, carbon nanotubes (CNTs) and nano-Fe 3 O 4 were introduced into the system by in situ polymerization. CNTs and nano-Fe 3 O 4 contribute to the attenuation of electromagnetic wave (EMW) through microwave absorption and reflection loss (RL), and the porous structure was able to provide multiple reflection paths for incident EMW and achieved higher attenuation. Particularly, when the temperature of coagulation bath was 50 C, the minimum RL (RL min ) value of the PI/CNTs/nano-Fe 3 O 4 (PI/C-Fe) composite fibers was demonstrated to be À54.61 dB with the matching thickness of 2.10 mm. The successful preparation of PI/C-Fe composite fiber in this study pointed out a new direction for the application of PI-based fiber materials in structural EMWA materials.

Recent advances in structural design of conductive polymer composites for electromagnetic interference shielding

“…The polymer foams (including polyurethane foam, melamine foam, PDMS foam, polyimide foam, and formaldehyde resin foam) were highly suitable as the framework and template for the deposition of nanofillers due to their continuous 3D skeleton and porous structure 238–242 . The porous polymers have been utilized for the large‐scale fabrication of porous conductive foams and CPCs, which possessed the advantages of high porosity, low modulus, excellent mechanical properties, durability and low price 243–245 . For example, Shen et al 243 prepared the porous and compressible conductive PU/graphene (PUG) composite foam by impregnating the commercial porous PU sponge into GO solution and then chemical reduction, where a 3D conductive rGO network around the PU skeleton was constructed, as presented in Figure 9A.…”

“…[238][239][240][241][242] The porous polymers have been utilized for the large-scale fabrication of porous conductive foams and CPCs, which possessed the advantages of high porosity, low modulus, excellent mechanical properties, durability and low price. [243][244][245] For example, Shen et al 243 prepared the porous and compressible conductive PU/graphene (PUG) composite foam by impregnating the commercial porous PU sponge into GO solution and then chemical reduction, where a 3D conductive rGO network around the PU F I G U R E 8 (A-C) SEM images of GA, unfoamed TPU/GA and foamed TPU/GA composites; (D) EMI SEs of unfoamed TPU/GA and foamed TPU/GA composites in X-band frequency; (E) Schematic of attenuation mechanism of incident EMWs for TPU/CRGO composite foams. 237 skeleton was constructed, as presented in Figure 9A.…”

Preparation and tribological behavior of high‐temperature oil‐containing porous polyimides

“…Owing to rigid aromatic ring configuration and strong polar imide structure in the molecular backbone, polyimide has higher strength and stiffness, as well as lower thermal expansion coefficient and good dimensional stability. [18][19][20][21] Low outgassing rates, excellent mechanical properties, and long service life of polyimide are essential criteria for the manufacture of bearing bushes used in modern aerospace equipment. [22][23][24] Hence, polyimide resin is the earliest and most widely applied in porous bearing cages.…”

Investigation on flame‐retardant, thermal and mechanical properties of glass fiber reinforced polyimide composites

“…However, limitations such as relatively low mechanical properties, high cost, poor machinability, and susceptibility to mechanical damage under extreme conditions significantly restrict its application in demanding engineering scenarios 5,6 . To effectively address these challenges, a common approach employed to improve the overall performance of PI involves incorporating inorganic particles of varying sizes into the PI matrix 7–9 . Wu et al reported the PI‐based composites with aligned large‐size graphite sheets exhibiting excellent thermal conduction (as high as 65.6 W/[m·K]) and electromagnetic interference shielding properties (101 dB in X‐band) 10 .…”

“…5,6 To effectively address these challenges, a common approach employed to improve the overall performance of PI involves incorporating inorganic particles of varying sizes into the PI matrix. [7][8][9] Wu et al reported the PI-based composites with aligned large-size graphite sheets exhibiting excellent thermal conduction (as high as 65.6 W/[mÁK]) and electromagnetic interference shielding properties (101 dB in X-band). 10 Han et al fabricated a composite film of porous graphene oxide (GO) and fluorinated PI, which exhibited a high tensile strength of 122 MPa-an increase of 26.99% compared to the flat PI film-with only 0.5 wt% GO/surfactant loading.…”