Additive manufacturing of carbon nanotube‐photopolymer composite radar absorbing materials

Abstract

Additive manufacturing (AM) including Stereolithography (SLA) and more recent 3D printing derivatives is an innovative manufacturing technology, where objects can be manufactured by accumulation of successive layers of materials. Such technology enables the fabrication of highly customized radar absorbing materials (RAM) and novel RAM structures. The microwave absorption, printability, complex electromagnetic parameters were measured, acrylic ester photopolymer with carbon nanotubes (CNTs) content ranging from 0.5% to 1.5% prepared with digital masking AM technology. Good dispersion and the content of CNTs have major influences on the successful preparation. The printability limit of multiwalled CNT is found to be 1.6%.The maximum absorption of 6 mm‐thick composites is measured to be −15.98 dB with 1.5% CNT content. The real part ( ε′) of permittivity increases from 2.5 to 7 and the imaginary part ( ε″) of permittivity increases from 0.2 to 1.0 with the increasing content of CNTs. Frequencies, thickness, uniformly distribution of CNT and CNT content are the main factors affecting the RAM properties. The calculated reflection loss, for 12 mm‐thick composites, are −7 dB, −26 dB, and −34 dB for 0.5%, 1%, and 1.5% of CNT contents, respectively, and the matching frequency shifts to lower frequencies with the increase of thickness or CNT content, which is in agreement with electromagetic theory and experiment results. POLYM. COMPOS., 39:E671–E676, 2018. © 2016 Society of Plastics Engineers

Polymer/Carbon Nanotubes (CNT) Nanocomposites Processing Using Additive Manufacturing (Three-Dimensional Printing) Technique: An Overview

“…It was found that a MWCNT concentration of as low as 0.05% (w/v) increased the ultimate tensile stress and fracture stress on the nanocomposites to 17% and 37%, respectively, compared to that of the control sample. Increasing the MWCNT concentration to 0.5% (w/v) enhanced the integrity of the nanocomposite samples over much wider operating temperatures and showed an increase in the elastic modulus at temperatures beyond~200 • C. Zhang et al [70] used stereolithography (SL) technique as well to fabricate highly customized radar absorbing materials (RAM) and novel RAM structures. In this work, dispersion of CNTs in acrylic ester matrix was carried out by homogenization only and the microwave absorbing properties of CNTs/photopolymer composites was measured as a function of the concentration of CNTs.…”

Nanomaterial Patterning in 3D Printing

“…Several considerations must be evaluated for each printing technology. In bulk 3D printing methods, the size, shape, and type of nanomaterials, such as cellulose nanocrystals,158 nanowires,44,159 carbon nanotubes,160 and graphene nanosheets, can affect the printing process. For example, in SLA, high fill content (>50%) of nanowires, added to increase resilience to shape distortion due to shrinkage,159 will increase light scattering.…”

Stealth technology: Methods and composite materials—A review

“…This thing significantly reduces the cost and the weight of a RAM. CNTs is a nonmagnetic material and it absorbs the electromagnetic waves by Ohmic losses, polarization or the multi‐scattering of the waves due to the large specific area . Multi‐walled CNTs (MWCNTs) are more defected as compare to the single‐walled CNTs (SWCNTs) due to their higher permittivity and the complicated structure and they absorb the electromagnetic waves as a result of dielectric relaxation.…”