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By leveraging the principles of electromagnetic theory and materials science, the characteristics of dielectric polymer composites can be optimized, eliminating repetitive trial‐and‐error in their application as electromagnetic absorbers (EMAs). Herein, a systematic framework for optimizing the thickness and composition of double‐layer EMAs is proposed, using a combination of transmission line, Debye relaxation, and Maxwell–Garnett theories. Following theoretical optimization, a double‐layered electrospun EMA is fabricated, which comprises a ≈1.17 mm thick matrix of styrene–butadiene–styrene (SBS) decorated with MXene on its fibrous structure. The second SBS layer, with a thickness of ≈0.52 mm, incorporates a hybrid of MXene and graphene nanoribbons (GNR) as conductive additives. The EMA exhibits durable electrical performance after 2000 tensile cycles, owing to the surface chemistry engineering and the novel in situ assembly technique. It is capable of shielding 99.9% of the incident wave and >80% absorptivity (A) over almost the entire Ku‐band. The EMA also exhibits desirable mechanical characteristics, such as >300% stretchability and full twist and wrinkle recoveries, making it an excellent choice for protective attire applications. Additionally, the introduced approach provides solutions for the advancement of tailorable polymer composite EMAs, with respect to specific criteria of the target wave frequency, effective absorption bandwidth, and absorption levels. [ABSTRACT FROM AUTHOR]

Abstract: In this study, sintered porous polymeric materials made of high density polyethylene (HDPE) were fabricated through controlling the chain interdiffusion time at the transition temperature of semicrystalline and melt states. At this intermediate state, where both crystalline and amorphous phases coexist, the interfacial welding of HDPE particles is facilitated thanks to interdiffusion caused by chain relaxation phenomena. Then, by assuming a spherical shape and a cubic packing configuration of particles, a geometrical model was developed to predict porosity variations as sintering progresses. Moreover, the HDPE used, as a broad molecular weight distributed polymer, has different family chains with different specific molecular weight ranges. Accordingly, the melt coalescence rate of the particles was tracked using an optical microscope equipped with a hot stage, in order to determine the diffusion characteristic times for each family. During the characterization stage, SEM images proved the presence of porous structures in the sintered samples. In addition, mechanical properties were assessed through the shear punch test. It was shown that the mechanical properties are governed by the interdiffusion of long chains which occurs at relatively long sintering times. The results also demonstrated the role of reptation motion of long chains in the interfacial welding of polymeric particles. They revealed the compatibility of macroscopic properties of the samples and chain motions at microscopic levels. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]