The impact of different multi-walled carbon nanotubes on the X-band microwave absorption of their epoxy nanocomposites

Abstract

BackgroundCarbon nanotube (CNT) characteristics, besides the processing conditions, can change significantly the microwave absorption behavior of CNT/polymer composites. In this study, we investigated the influence of three commercial multi-walled CNT materials with various diameters and length-to-diameter aspect ratios on the X-band microwave absorption of epoxy nanocomposites with CNT contents from 0.125 to 2 wt%, prepared by two dispersion methods, i.e. in solution with surfactant-aiding and via ball-milling.ResultsThe laser diffraction particle size and TEM analysis showed that both methods produced good dispersions at the microscopic level of CNTs. Both a high aspect ratio resulting in nanotube alignment trend and good infiltration of the matrix in the individual nanotubes, which was indicated by high Brookfield viscosities at low CNT contents of CNT/epoxy dispersions, are important factors to achieve composites with high microwave absorption characteristics. The multi-walled carbon nanotube (MWCNT) with the largest aspect ratio resulted in composites with the best X-band microwave absorption performance, which is considerably better than that of reported pristine CNT/polymer composites with similar or lower thicknesses and CNT loadings below 4 wt%.ConclusionsA high aspect ratio of CNTs resulting in microscopic alignment trend of nanotubes as well as a good level of micro-scale CNT dispersion resulting from good CNT-matrix interactions are crucial to obtain effective microwave absorption performance. This study demonstrated that effective radar absorbing MWCNT/epoxy nanocomposites having small matching thicknesses of 2–3 mm and very low filler contents of 0.25-0.5 wt%, with microwave energy absorption in the X-band region above 90% and maximum absorption peak values above 97%, could be obtained via simple processing methods, which is promising for mass production in industrial applications.Graphical AbstractComparison of the X-band microwave reflection loss of epoxy composites of various commercial multi-walled carbon nanotube materials.

Effect of the Morphology and Structure on the Microwave Absorbing Properties of Multiwalled Carbon Nanotube Filled Epoxy Resin Nanocomposites

“…So, the microwave absorption properties of CNT/epoxy nanocomposites depend on both intrinsic electrical conductivity of CNT and CNT-polymer matrix interactions, as well as the tendency of CNT grouping. These conditions result in polarization phenomena which may result in a good RAM performance 33,41 .…”

Enhanced corrosion protection performance with MWCNT dispersed epoxy coating prepared under supercritical CO2 assistance

“…The X‐ray diffraction patterns of the pristine MWCNT, cured epoxy, and MWCNT dispersed epoxy are given in Supporting Information (Figure S1). The sharp narrow peak (002 plane) at around 2θ = 25.99° for the pristine MWCNT was assigned to reflection of inter‐tubes with a d‐spacing (3.42 Å), while, a weak peak (100 plane) located at 2θ = 42.75° with d‐spacing (2.11 Å) was ascribed to reflection of graphite‐like structure . For the cured epoxy, the broad peak centered at 2θ = 19.50° was assigned to the amorphous structure of the epoxy .…”

“…The sharp narrow peak (002 plane) at around 2θ = 25.99°for the pristine MWCNT was assigned to reflection of inter-tubes with a d-spacing (3.42 Å), while, a weak peak (100 plane) located at 2θ = 42.75°with d-spacing (2.11 Å) was ascribed to reflection of graphite-like structure. 22,23 For the cured epoxy, the broad peak centered at 2θ = 19.50°was assigned to the amorphous structure of the epoxy. 23 The MWCNT dispersed epoxy exhibited characteristic peaks of both epoxy and MWCNT; however, the characteristic 002 peak of the MWCNT was weak in the composite.…”

Enhancing the Performance of the Microwave Absorbing Materials by Using Dielectric Resonator Arrays

“…In the geometry approach, the MA material is constructed in a certain structure with particular geometry and dimensions that reduce the reflection and enhance confinement and absorption of the EM waves inside the structure. Different types of materials can be used as MA material such as carbon, metal and metal particles, conducting polymers, polyaniline conducting polymer, tubules and filaments, and recently composite of nanomaterials [3][4][5][6][7][8][9]. Utilizing geometry to create MA structures of high performance is widely used in MA application such as the pyramidal shapes, Dallenbachm and Jaumann layers, honeycomb, and rectangular screen structures [2,3].…”

“…Utilizing geometry to create MA structures of high performance is widely used in MA application such as the pyramidal shapes, Dallenbachm and Jaumann layers, honeycomb, and rectangular screen structures [2,3]. Frequency selective surfaces and metamaterial structures are other techniques proposed in literature for producing high performance MA structures [5,6]. Many of these techniques can achieve high performance MA structures.…”