Conducting composite materials based on epoxy matrix loaded with graphene nanoplatelets (GNP) were prepared by different procedures using ultrasonication. The dispersions of GNP in a mixture of epoxy/methyl-tetrahydrophthalic anhydride without solvent, resulted in composites with better conductivity, higher storage modulus and higher glass transition temperature than those prepared with solvent assisted procedure, indicating better filler dispersion. The non-covalent functionalization of GNP with the ionic liquid, 1-butyl-3-methyl-imidazolium bis(trifluorosulfonyl) imide (bmim.TFSI) contributed for an increase of the modulus for the systems containing low amount of filler. The electrical conductivity was not influenced by the presence of ionic liquid. Nevertheless, the micro-wave absorption effectiveness in the frequency range of 8-12 GHz (X-band frequency) was improved by the presence of IL mainly for the composites containing 0.9 and 1.5 vol.% of filler. All systems were characterized by low viscosity, comparable to that of neat epoxy resin, thus making easier their application on the development of coatings, conducting adhesives, etc.

Magnetic ionic liquid (MIL) based on alkyl phosphonium cation was used as a curing agent for developing epoxy nanocomposites (ENCs) modified with a graphene nanoplatelet (GNP)/carbon nanotube (CNT) hybrid filler. The materials were prepared by a solvent-free procedure involving ball-milling technology. ENCs containing as low as 3 phr of filler (GNP/CNT = 2.5:0.5 phr) exhibited electrical conductivity with approximately six orders of magnitude greater than the system loaded with GNP = 2.5 phr. Moreover, the use of MIL (10 phr) resulted in ENCs with higher conductivity compared with the same system cured using conventional aliphatic amine. The filler dispersion within the epoxy matrix was confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electromagnetic interference shielding effectiveness (EMI SE), evaluated in the X- and Ku-band frequency range, revealed a great contribution of the absorption mechanism for the ENC containing the hybrid filler and cured with MIL. Moreover, the best microwave-absorbing response was achieved with the ENC containing GNP/CNT = 2.5/0.5 phr, and cured with ML, which a minimum RL of −23.61 dB and an effective absorption bandwidth of 5.18 GHz were observed for thickness of 1.5 mm. In summary, this system is a promising material for both civilian and military applications due to its simple and scalable nanocomposite preparation method, the lightweight nature of the composites resulting from the low filler content, the commercial availability and cost-effectiveness of GNP, and its high electromagnetic wave attenuation across a broad frequency range.

Octaglycidyl polyhedral oligomeric silsesquioxane (OG‐POSS) was incorporated at 0, 1.5, 3.0, and 5.0 phr into a diglycidyl ether of bisphenol‐A (DGEBA) epoxy cured with a polyamidoamine (PAA) hardener to raise the thermal ceiling of flexible PAA networks without sacrificing liquid processing. Steady‐state rheometry showed a non‐monotonic effect on uncured viscosity: 1.5 and 3.0 phr reduced it by 17% and 15% (to 10.7 and 11.0 Pa s at 10 s ⁻¹ ), while 5.0 phr raised it by 43%; all formulations were essentially Newtonian in ascending sweeps, with mild descending‐ramp thixotropy. Gel time was likewise non‐monotonic: essentially unchanged at 1.5 and 5.0 phr but 18% shorter at 3.0 phr, where the processing window also contracted most. Dynamic mechanical analysis showed glass transition temperature ( T _g ) rising up to 19°C at 1.5 phr (73°C–92°C), while the glassy storage modulus decreased 29%–34% and the apparent crosslink density increased non‐monotonically by 47%–71% at all three loadings. Both trends are consistent with the octafunctional Si ₈ O ₁₂ cage acting as a network junction that increases crosslink density, with the concurrent T _g increase reflecting greater network constraint. Among the loadings studied, 1.5 phr OG‐POSS gave the most favorable balance of T _g enhancement, uncured viscosity, and processing window.