Tamara Indrusiak

The development of lightweight radar‐absorbing structures (RAS) based on additively manufactured polymers offers an alternative route for geometry‐driven electromagnetic attenuation. In this study, the influence of structural architecture and layer sequencing on the electromagnetic absorption performance of 3D‐printed polylactic acid (PLA)‐based structures was systematically investigated. Three configuration categories were analyzed: (i) porous architectures (honeycomb, re‐entrant, and auxetic), (ii) surface geometries (rectangular, triangular, sinusoidal, and circular), and (iii) multilayer systems integrating the most effective porous and geometric profiles. Samples were fabricated via fused deposition modeling (FDM) and their performance was evaluated in the X‐band frequency range (8.2–12.4 GHz). Among the single‐layer designs, the honeycomb exhibited reflection loss (RL) of approximately −18 dB, while the triangular surface profile provided broadband absorption with RL of approximately −20 dB. When these geometries were combined in multilayer architectures (total thickness of 8 mm), enhanced absorption performance was observed, with the honeycomb–triangular system attaining RL of approximately −25 dB, depending on orientation. Additional investigation of hybrid multilayers incorporating conductive PLA (cPLA) demonstrated that insertion of a single conductive intermediate layer (PLA/cPLA/PLA) improved attenuation compared to fully dielectric or fully conductive stacks, indicating a balance between conduction‐related losses and impedance matching. The results demonstrate that electromagnetic absorption in polymer‐based RAS can be modulated through geometric optimization and controlled conductivity, providing an approach for design of lightweight, mechanically robust, and customizable stealth materials.

Microwave absorbing materials are of great interest in stealth technology due to their potential to reduce or prevent the detection of combat platforms such as missiles, submarines, aircraft, and vehicles. A key challenge in developing these coatings is broadening the absorption bandwidth while maintaining good mechanical properties without significantly increasing weight or thickness. This study demonstrates the feasibility of utilizing additive manufacturing, specifically fused deposition modeling (FDM), to fabricate three‐dimensional microwave‐absorbing structures using high‐density polyethylene (HDPE) composites modified with hybrid carbonaceous fillers such as carbon black (CB), graphite (GP), and carbon nanotubes (CNTs). The resulting composites were characterized through SEM, rheology, and reflectivity measurements. The incorporation of CNT and GP significantly enhanced the electrical conductivity of the material, resulting in superior electromagnetic wave (EMW) absorption performance compared to conventional systems. Notably, the HDPE/CNT/GP composite achieved a reflection loss (RL) of −41.4 dB and an effective absorption bandwidth (EAB) of 4.2 GHz, indicating over 99.99% attenuation of incident EMWs. These findings underscore the potential of employing cost‐effective materials and scalable manufacturing techniques for stealth applications in military and industrial sectors. Furthermore, the proposed approach facilitates the production of lightweight, low‐cost, and highly scalable materials—key characteristics for effective stealth technology in combat platforms. This research highlights the significance of advanced manufacturing techniques and structural design optimization in enhancing the performance of microwave absorbers.

The development of sophisticated telecommunication equipment and other electro-electronic devices resulted in a kind of electromagnetic pollution that affects the performance of other equipment as well as the health of human beings. Intrinsically conducting polymers (ICP), mainly polyaniline and polypyrrole, have been considered as promising candidates for applications in efficient electromagnetic interference shielding (EMI) due to their ease of preparation, light weight, good conductivity and corrosion resistance. One of the important advantages of these materials is the capability to interact with the EM radiation through both absorption and reflection mechanisms thus enlarging the field of application. In this context, this review article describes a recent overview of the existing methods to produce intrinsically conducting polymers and their blends for electromagnetic shielding application. Additionally, it highlights the relationship between preparation methods reported in the literature with the structure and properties, such as electrical conductivity, electromagnetic shielding effectiveness (EMI SE), complex permittivity and permeability of these materials. Furthermore, a brief theory related to the electromagnetic mechanism and techniques for measuring the microwave absorbing properties are also discussed.

Poly(vinylidene fluoride) (PVDF) based composites loaded with 3 wt% of carbon black (CB), graphite (GF), and the hybrid CB/GF (1.5/1.5 wt%) were prepared by melt mixing and tested as microwave absorbing material at X‐band frequencies (8–12 GHz). The materials were processed and pressed at 220°C into plates of 20 × 20 × 0.1 cm³. Dielectric and magnetic properties were evaluated using the wave‐guide accessory to simulate the reflectivity of single‐layered PVDF composites through impedance matching behavior. The best absorbing properties were achieved with the composite loaded with the CB/GF hybrid material, whose maximum of radiation attenuation of −33 dB at 9.3 GHz was predicted with 4 mm thickness. Afterwards, the reflectivity of sandwiched structures (20 × 20 cm² in size) with one‐layer honeycomb core sandwiched by two plates of PVDF composites was measured. The PVDF/HB‐honeycomb‐PVDF/HB structure reached reflection loss = −12 dB (E_a = 94%) on a broadband frequency. CB/GF hybrid material in PVDF composites has a promising future as a lightweight and cost‐effective microwave absorbing materials for both telecommunication and stealth technology.

Poly(vinylidene fluoride‐co‐hexafluoropropylene)/polyaniline (PVDF‐co‐HFP/PAni) conductive blends were prepared by two methodologies involving the in situ polymerization in two different media and dry blending approach using ball milling. Dodecylbenzenesulfonic acid (DBSA) was used both as surfactant and as protonating agent in PAni synthesis. X‐ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectroscopy, and thermogravimetric analysis were used for characterizing the blends. PAni and PVDF/PAni prepared by in situ polymerization in H₂O/toluene medium exhibited superior electrical conductivity, higher thermal stability and significantly higher electromagnetic interference shielding effectiveness (EMI SE) than those prepared in H₂O/dimethylformamide (DMF) medium. PVDF/PAni with high‐PAni content (>40%) prepared by the dry blend approach presented higher conductivity and EMI SE than those prepared by in situ polymerization. The molding temperature exerted significant influence on the conductivity and EMI SE for the blend containing higher amount of PAni. The free‐solvent dry blending approach using ball milling presented similar conductivity value but the higher EMI SE when compared with in situ polymerization, and is considered environmentally and technologically interesting.

In this work, electromagnetic radiation absorbent materials (ERAM) were prepared from expanded polyurethane and nano‐Fe3O4. The effect of porosity and charge content on the attenuation of incident radiation was investigated using helium gas pycnometry and the waveguide technique in the frequency range of 8 to 12 GHz (X‐band). ERAM were also characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and vibration sample magnetometer (VSM). Pure polyurethane absorbed 93.6% of the incident radiation at 11.8GHz. This result was attributed to its porous structure and low porosity. Although the content of open cells increases in ERAM with the increase in nanomagnetic content, materials containing 1% and 5% w/w absorbed more than 99% of the incident radiation. This behavior suggests that magnetic property of the charge is compensated for its action as a cell opener in these materials.