▎ 摘　　要

NOVELTY - Producing polymeric nanocomposite with electrical and electromagnetic properties involves adding suspension of graphene nanoplatelets (GNPs) in solvent with thermosetting polymer; subjecting the formulation obtained to sonication with ultrasound processor for 30 seconds, and with amplitude comprising 40-70% of maximum amplitude according to concentration of GNPs; subjecting mixture to magnetic stirring; with appropriate suction rate of hood or level of vacuum to be applied during the mixing step in order to prevent formulation of cluster and aggregates. USE - For producing polymeric nanocomposite useful for electromagnetic applications such as shielding and/or absorption of the energy associated to electromagnetic fields; as polymeric-matrix nanocomposite for producing electromagnetic devices, such as shields for control and suppression of radiofrequency electromagnetic interference, radar-absorbent materials (RAMs) for stealth applications, and for all applications in which the use of materials with lightness and desired electrical properties is required; for production of single-layer or multilayer radar-absorbent shields (claimed); and for applications of electromagnetic shielding or for suppression of electromagnetic interference (EMI) by absorption of electromagnetic energy, which requires in general use as fillers of conductive particles, typically having spherical or pseudo-spherical shape, at high concentrations. ADVANTAGE - The method has controlled electrical and electromagnetic properties, characterized by a high degree of lightness, easy workability, versatility, and low cost. DETAILED DESCRIPTION - Producing (P1) polymeric nanocomposite with electrical and electromagnetic properties controlled and predictable by applying the equivalent-effective-medium model, for electromagnetic applications such as shielding and/or absorption of the energy associated to electromagnetic fields, comprises carrying out a controlled synthesis of graphene nanoplatelets (GNPs) modifying, through the parameters of the production process, the morphological and its electrical properties and using them as nanofillers in a polymeric matrix selected on the basis of its chemical compatibility with the GNPs, distributing them evenly and dispersing them finely in the entire mass of the matrix by means of the solution-processing technique, involving: a) adding the suspension of GNPs in solvent, previously subjected to ultrasound treatment, with the thermosetting polymer in appropriate wt.%, previously added with accelerator for the types of resins that require it; b) subjecting the new formulation obtained to sonication with an ultrasound processor in continuous regime for 30 seconds, and with an amplitude comprising 40-70% of the maximum amplitude according to the concentration of GNPs; c) subjecting the mixture thus obtained to magnetic stirring, possibly assisted by the action of a suction hood or by vacuum, in order to control appropriately the rate of evaporation of the solvent; the appropriate suction rate of the hood or the level of vacuum to be applied during the mixing step, in relation to the concentration of GNPs in the solution, so as to guarantee a variable duration of the process comprising 0.5-24 hours, in order to prevent formation of clusters and aggregates of GNPs and trapping of molecules of solvent in the mixture; thus obtaining the possibility of controlling separately both the imaginary part and the real part of the effective permittivity of the nanocomposite intervening, through the process parameters, both on the effect at a nanoscale linked to the high aspect ratio of the GNPs, which affects significantly the properties of electrical transport of the material and hence the imaginary part of the effective dielectric permittivity, and on the effect on macroscale linked to the high surface extension of the GNPs themselves, which significantly affects the properties of polarization of the material and the real part of the effective dielectric permittivity of the composite. INDEPENDENT CLAIMS are included for the following: (1) shielding or radar-absorbent panel obtained by pouring the mixture in an appropriately shaped mold, with a mask sized for obtaining the desired thickness, typically comprising 0.1-3 (preferably less than or equal to 1) mm, with reference to the frequency of 6-18 GHz; and (2) a nanocomposite with nanofiller-based polymeric matrix constituted by a polymeric matrix, dispersed in which are graphite/GNPs synthetized so as to optimize the electromagnetic properties of the composite, at a concentration of not greater than 15 (preferably 6, especially 4) wt.% with respect to the weight of resin used.