Synthesis of a Lightweight Nanocomposite Based on Polyaniline 3D Hollow Spheres Integrated Milled Carbon Fibers for Efficient X-Band Microwave Absorption

Abstract

In the present study, the milled carbon fiber (MCF) and conductive polyaniline (PANI) are impregnated in the epoxy matrix to synthesize a lightweight nanocomposite, providing efficient microwave absorption in the X band. The PANI 3D hollow spheres are uniquely synthesized by removing the polystyrene (PS) core structure of PS/PANI composites. The MCF and as-synthesized PANI hollow spheres are characterized by Raman spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The FESEM analysis confirmed the formation of 3D hollow PANI conductive spheres, which exhibited numerous porosity and high roughness on PANI sphere surfaces. The XRD revealed that the size reduction of carbon fibers down to the micro level resulted into more graphitic carbon. The MCF-and PANI-impregnated epoxy nanocomposites are evaluated by reflectivity measurements for their microwave absorption capabilities, exclusively in the X band. The correlation of the results shows that the ratio of MCF and PANI fillers in the epoxy matrix can be customized to obtain the desired microwave absorption performance of the synthesized nanocomposite. A maximum absorption value of −49.3 dB (99.998% absorption) as well as 1.7 GHz −10 dB effective bandwidth is achieved using a nanocomposite sample of 1.8 mm thickness comprising 4 wt % MCF and 1 wt % PANI filler loadings. The strong microwave absorption in the present situation for a very thin sample using just 5% of the total filler results into quite a lightweight composite, which basically originates from the electric/dipolar polarization in the interfacial polarization dominant in the micron length fibers and hollow 3D PANI spherical structures. The hollow 3D morphology here improves the impedance matching of the resulting nanocomposite sample due to multiple reflections and scattering of EM waves inside the structure, which substantially increases the reflection loss of EM waves in the specified frequency band. The novelty of this work lies in synthesizing the PANI/MCF-based filler for the first time and using it to develop a lightweight nanocomposite, which is found to be quite an efficient microwave absorber, especially for X band applications.

Enhanced Thermally Conductive and Microwave Absorbing Properties of Polymethyl Methacrylate/Ni@GNP Nanocomposites

“…Interestingly, the RL min value of sample S4 (cf. Figure e) was −7 dB in the measured wavelength range when the filling amount was increased to 40 wt %, which was primarily because too much Ni@GNP filling led to poor impedance matching conditions of the samples (i.e., no effective absorption could be observed in the testing frequency range) . In summary, S3 showed the best performance among all samples and also had excellent RL performance in the C band (from 4 to 8 GHz), which is well known as the frequency band of communication satellite downlink transmission signals.…”

A comprehensive investigation of dielectric properties of epoxy composites containing conducting fillers: Fluffy carbon black and various types of reduced graphene oxide

“…The electromagnetic characteristics of epoxy nanocomposites with hierarchial carbon nanotube grown on the carbon fiber (CNTCF), Al-substituted copper ferrite (CAF) infused rGO, polyaniline 3D Hollow spheres integrated milled carbon fibers and hetero atom doped carbon derived from chicken feather fibers (CFF) were investigated exclusively in the X band (8.2-12.4 GHz) using the network analyzer by Sandeep Kumar Singh et al and they found that fabricated composites are potential candidates to design a light weight and efficient microwave absorber. [35][36][37][38] However, a review of the literature finds that epoxy composite dielectric investigations are sparse. Epoxy composites are essential because they can be molded into intricate shapes and are suited for devices where flexibility is a key characteristic.…”

“…The electromagnetic characteristics of epoxy nanocomposites with hierarchial carbon nanotube grown on the carbon fiber (CNTCF), Al‐substituted copper ferrite (CAF) infused rGO, polyaniline 3D Hollow spheres integrated milled carbon fibers and hetero atom doped carbon derived from chicken feather fibers (CFF) were investigated exclusively in the X band (8.2–12.4 GHz) using the network analyzer by Sandeep Kumar Singh et al and they found that fabricated composites are potential candidates to design a light weight and efficient microwave absorber 35–38 …”

Heterolayered Composite of Carbon Nanofibers Sandwiched between Poly(ethylene terephthalate) and Polyurethane for Flexible Electromagnetic Shielding Application

“…Electromagnetic [EM] wave pollution has been growing exponentially in the last couple of years due to the extensive use of EM devices in electronic gadgets and wireless networks for civil, military, and space applications. EM pollution affects the health of humans and disturbs the conventional performance of nearby electronic gadgets in the mode of electromagnetic interference (EMI). − The growing flexible electronic requirements for EMI shielding for the next generation are being feather-light, flexible, and thin with a low filler loading, have a uniform dispersion, are easy to process, are environmentally stable, and possess absorption dominant EM shielding. Recently, polymer matrix composites (PMCs) containing electrically conducting carbon nanofillers are considered to be promising EMI shielding materials due to their high conductivity and high dielectric losses along with ease in processing, − excellent resistance to corrosion, transparency, , flexibility, thermal stability, tunable performance, and low density as compared to traditional available metal-based EMI shielding materials .…”