Polyurethane/Graphite composite foam samples with different filler loadings were synthesized for application in electromagnetic shielding. The samples were characterized using Fourier transform infra‐red, thermal gravimetric analysis, scanning electron microscope, universal testing machine, and rheometer. Moreover, to adapt and customize this work in the field of aerospace, the measurements were performed in the X‐band at the range of (8–12) GHz. The results showed that the increase in filler content improves the mechanical properties and thermal stability of the composite materials. The electromagnetic interference shielding effectiveness reached (− 45) dB with 30 wt% filler content. It is expected that the polyurethane/graphite composite foamy materials may be considered a promising material to be used in electromagnetic shielding applications.
Reduced graphene oxide (RGO) is an effective polymer filler for shielding against electromagnetic interference (EMI). Its shielding efficiency rises as its concentration in polymer matrices increases. However, higher filler loading impedes polymer foaming and deteriorates the mechanical properties of the resulting foam. The goal of this work is to determine the optimal RGO concentration that can be loaded into polyurethane (PU) matrix to produce a composite foam with a high level of electromagnetic shielding along with good mechanical properties. To that end, different PU foam samples containing varying amounts of RGO were synthesized. The synthesized samples were characterized by scanning electron microscope (SEM), thermogravimetric analysis (TGA), Fourier transform infra-red (FT/IR) and universal testing machine. Furthermore, the shielding efficiency of the samples was measured using a vector network analyzer over the frequency range of 8-12 GHz. The results revealed that the increase in RGO concentration enhances the mechanical and thermal properties of the prepared composite foam materials. The shielding effectiveness reached À23 dB at 5 wt% RGO concentration. The polyurethane-RGO composite foam materials have been identified as potentially viable materials for use in electromagnetic shielding applications.
Electromagnetic interference (EMI) has been recognized as a new sort of pollution and can be considered as the direct interference of electromagnetic waves among electronic equipment that frequently affects their typical efficiency. As a result, shielding the electronics from this interfering radiation has been addressed as critical issue of great interest. In this study, different hybrid nanocomposites consisting of magnetite nanoparticles (Fe3O4) and reduced graphene oxide (rGO) as (conductive/magnetic) fillers, taking into account different rGO mass ratios, were synthesized and characterized by XRD, Raman spectroscopy, TEM and their magnetic properties were assessed via VSM. The acquired fillers were encapsulated in the polyurethane foam matrix with different loading percentages (wt%) to evaluate their role in EMI shielding. Moreover, their structure, morphology, and thermal stability were investigated by SEM, FTIR, and TGA, respectively. In addition, the impact of filler loading on their final mechanical properties was determined. The obtained results revealed that the Fe3O4@rGO composites displayed superparamagnetic behavior and acceptable electrical conductivity value. The performance assessment of the conducting Fe3O4@rGO/PU composite foams in EMI shielding efficiency (SE) was investigated at the X-band (8–12) GHz, and interestingly, an optimized value of SE −33 dBw was achieved with Fe3O4@rGO at a 80:20 wt% ratio and 35 wt% filler loading in the final effective PU matrix. Thus, this study sheds light on a novel optimization strategy for electromagnetic shielding, taking into account conducting new materials with variable filler loading, composition ratio, and mechanical properties in such a way as to open the door for achieving a remarkable SE.
Research has been devoted to the desalination of saline water to fresh water suitable for human demands because of the shortage of water in some countries. Therefore, in this study, reverse-osmosis membranes were prepared via the g-radiation graft copolymerization of acrylic acid onto high-density and low-density polyethylene. The factors that could affect the grafting process, such as the solvent type, monomer and inhibitor concentration, and irradiation dose, were investigated to determine the optimum conditions for radiation grafting. The polyethylene grafted acrylic acid copolymers (PAAc-g-PE) graft copolymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical, rheological, and thermal property testing to illustrate the possibility of practical use in water desalination. The prepared grafted membranes showed significant results in the reverse-osmosis desalination method with underground saline water. The factors affecting the desalination of water, such as the water flux, operation time, and grafting percentage, were studied.
Thermally exfoliated graphene (TEG)/polyurethane (PU) expanded composite samples were synthesized for application in electromagnetic interference shielding (EMIS) in the 8-12 GHz frequency range. The effect of TEG concentration on both the shielding efficiency (SE) and mechanical characteristics of the resultant composite foam was investigated in detail, with the goal of determining the optimal TEG concentration that delivers the best performance in terms of SE and mechanical properties. The TEG filler was characterized using x-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Whereas the prepared composite foam samples were examined by Fourier Transform Infrared (FTIR), SEM, Thermogravimetric analysis (TGA) and mechanical testing. The experimental results revealed that the composite foam sample with 5 wt% TEG content exhibits the highest SE to be À25.6 dB (À430.3 dB cm 3 g À1 ). It was also found that the optimal loading of TEG is 3 wt%, resulting in a compromise between SE (À20.4 dB; À345.68 dB cm 3 g À1 ) and mechanical characteristics (compressive strength of 15.5 MPa and compressive modulus of 5.06 MPa). These findings highlight the potential applicability of the synthesized composite foam to a variety of EMIS applications.
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