阅读说明：本技术 屏蔽电磁辐射的复合材料、增材制造方法的原材料和包含该复合材料的产品及其制造方法 (Composite material for shielding electromagnetic radiation, raw material for additive manufacturing method, product comprising the composite material and manufacturing method thereof ) 是由 Z·马瑞兹 J·加瑞斯劳 J·克兹斯托夫 D·安娜 Z-C·克劳迪亚 W·安娜 L·安娜 于 2020-02-27 设计创作，主要内容包括：本发明涉及屏蔽电磁辐射的复合材料、增材制造方法的原材料和包含该复合材料的产品及其制造方法。根据本发明的复合材料可以用作保护电子元件、电子装置或生物有机体免受在微波和太赫兹范围(0.3-10000GHz)内的电磁辐射的材料。(The present invention relates to a composite material shielding electromagnetic radiation, a raw material for an additive manufacturing method and a product comprising the composite material and a manufacturing method thereof. The composite material according to the present invention can be used as a material for protecting electronic components, electronic devices or biological organisms from electromagnetic radiation in the microwave and terahertz range (0.3-10000 GHz).)

1. A composite material for shielding electromagnetic radiation, the composite material comprising:

from 88% to 99.88% by weight of a thermoplastic, electrically non-conductive polymer;

0.1-10% by weight of nanocarbon material in the form of flakes having a diameter to thickness ratio higher than 3, the flakes having a thickness of not more than 30nm and a diameter of 100-5000 nm,

0.01% to 1% by weight of nanoparticles which introduce losses independent of the conductivity in a given frequency range, i.e. independent of the dispersion of electromagnetic waves on free carriers,

0.01-1 wt% of an auxiliary material allowing to control the dispersion of the nanocarbon material and the nanoparticles in the polymer matrix and/or being able to change the properties of the nanocarbon material and the nanoparticles,

wherein the composite material is in the form of a homogeneous mixture.

2. The material according to claim 1, wherein the thermoplastic polymer is selected from Polystyrene (PS), Polyethylene (PE), polypropylene (PP), Polyurethane (PU), terpolymers of acrylonitrile-butadiene-styrene (ABS), polyesters like in particular poly (ethylene terephthalate) (PET), poly (tetrafluoroethylene) (PTFE), Polyamides (PA), terpolymers of acrylonitrile-styrene-acrylic acid (ASA), poly (vinyl chloride) (PVC), modified poly (phenylene ether) (MPPE), LSZH, derivatives of one of said polymers or combinations thereof.

3. The material according to claim 1 or 2, wherein the nanocarbon material is selected from graphene flakes, graphene oxide, reduced graphene oxide, modified graphene flakes, nanographite or a combination thereof.

4. Material according to one of claims 1 to 3, wherein said nanoparticles are dielectric particles having ferromagnetic resonance frequencies (suitable for attenuating significant frequency bands) and/or anisotropy coefficients of permeability and/or permittivity and/or dielectric losses of the alternating electromagnetic field (EM) caused by the polarization of the components constituting said particles.

5. The material of claim 4, wherein the nanoparticles are selected from silicon carbide (SiC), aluminum oxide (Al)₂O₃) Nanoparticles of Fe-BN; ferrite-based nanoparticles, preferably of hexagonal structure, containing cobalt or barium or strontium, preferably CoFe₂O₄、BaFe₁₂O₁₉、SrFe₁₂O₁₉、Ba₃Me₂Fe₂₄O₄₁、Ba₃Sr₂Fe₂₄O₄₁、Ba₂Co₂Fe₁₂O₂₂、BaCo₂Fe₁₆O₂₇、Ba₂Co₂Fe₂₈O₄₆、Ba₄Co₂Fe₃₆O₆₀(ii) a Iron-based nanoparticles, preferably Fe-Cr, Fe-Ni, Fe-Si, Fe-Co nanoparticles; or a combination thereof.

6. The material of any of claims 1-5, wherein the auxiliary material is a graphene functional compound comprising a plasticizer, an antioxidant, a hardener, or a combination thereof.

7. The material of claim 6, wherein the plasticizer is an organic oil, an alcohol, an anhydride, or a combination thereof.

8. Material according to claim 6 or 7, wherein the antioxidant is a natural antioxidant, preferably a carotenoid, a flavonoid, vitamin C, vitamin E, a phenolic or a combination thereof.

9. A raw material for an additive method for manufacturing an element for shielding electromagnetic radiation, characterized in that the raw material comprises a material as defined according to at least one of claims 1 to 8, preferably in the form of particles, filaments or tapes.

10. Product for shielding electromagnetic radiation, characterized in that it comprises a composite material as defined according to at least one of claims 1 to 8.

11. A method for obtaining the product according to claim 10, characterized in that it comprises the following steps:

(i) mixing

From 88% by weight to 99.88% by weight of a thermoplastic, electrically non-conductive polymer, preferably in the form of particles having a size of not more than 1mm,

0.1-10% by weight of nanocarbon material in the form of flakes having a diameter to thickness ratio higher than 3, the flakes having a thickness of not more than 30nm and a diameter of 100-5000 nm,

0.01 wt% to 1 wt% of nanoparticles, said nanoparticles introducing conductivity independent losses,

0.01-1 wt% of an auxiliary material allowing to control the dispersion of the nanocarbon material and the nanoparticles in the polymer matrix and/or capable of modifying the properties of the nanocarbon material and the nanoparticles;

(ii) injecting the molten mixture into a mold defining the shape of the product;

(iii) hardening the material to obtain the final product.

12. The method of claim 11, wherein the mixing step (i) is performed by dry mechanical mixing at room temperature.

13. The process of claim 11, wherein the mixing step (i) is carried out by mechanical mixing at a temperature above the polymer flow temperature.

Technical Field

The object of the invention is a composite material for shielding electromagnetic radiation, a raw material for an additive manufacturing method and a product comprising said material, and a method for manufacturing said product. The composite material according to the present invention can be used as a material for protecting electronic components, electronic devices or biological organisms from electromagnetic radiation in the microwave and terahertz range (0.3-10000 GHz).

Background

Currently, the surrounding environment is increasingly filled with various electromagnetic radiations, mainly in the radio and microwave range, and increasingly also in the terahertz range of 100-0.03mm, generally limited to the frequency range of 0.3-10000 GHz. This radiation may have negative effects on both the operation of electronic devices and biological organisms, including humans. The following examples may be given: medical equipment failure monitoring human body signals, public transportation systems or air/car transportation suffer from sensitive electronics failure, audio/video/GPS signal interference in various telecommunication systems. There is therefore a need to effectively block or shield this type of radiation, which is of great importance in many industries and to the average consumer. This problem is commonly defined as electromagnetic interference (EMI). EMI problems can be addressed using shields and can be physically realized by absorbing and/or reflecting electromagnetic radiation by the material that acts as a shield. The relationship between shielding effectiveness (in dB) and shielding efficiency in%: an efficacy of 10dB means that 90% of the incident electromagnetic radiation power is blocked by the material. Further, by analogy: 20 dB-99%, 30 dB-99.9%, 40 dB-99.99%, 50 dB-99.999%, 60 dB-99.9999%.

Currently, metal is the most commonly used shielding material. However, metals are non-selective materials that simultaneously shield electromagnetic radiation over a very wide range of spectrum, including the microwave and terahertz ranges. Notably, metals are materials that primarily reflect and do not absorb radiation. In addition, since metal is a conductive material having poor plasticity and inflexibility and generally has a high specific gravity, metal cannot always be used.

Other materials that can be used as shields for electromagnetic radiation are also contemplated in the literature. Electrically conductive polymer Composites with metal fillers, like Composites filled with aluminum or stainless steel flakes (up to 40%), characterized by shielding effectiveness higher than 50dB (Composites [ Composites ], are known to be useful as EMI shielding materials]25,215,1994). It has been demonstrated that mixing aluminum powder with PVDF polymer followed by hot pressing yields shielding composites at a level of about 20dB in the range of 8-12GHz (journal of Applied Physics)]117,2249032015). Silver nanowires containing as filler produced by drop-casting (<14 vol.%) also exhibited shielding properties (50dB, 8-12GHz) (j]4,419,2016). In Gelves et al (J.Mater.chem. [ J.Material Chem. ]]21,829,2011), polystyrene and silver nanowires (by volume) are produced<3%) of a 200 μm thick composite showing a shielding efficiency in the range of 8-12GHz in excess of 20dB and 10⁴Conductivity of S/m. In the publication "compositions PartA: Applied Science and Manufacturing [ Complex part A: application science and manufacturing]"(2011), use of copper nanowires at 2% (vol.) content in polystyrene resulted in shielding efficiencies of greater than 30 dB. In both cases, the compound is prepared by dry direct mixing of the ingredients at room temperature, and then melting the obtained powder. These examples of composites with metal fillers are electrically conductive in the Direct Current (DC) range,and the shielding mechanism is based on the presence of metallic paths (metallic paths) in the material.

The material that absorbs electromagnetic radiation in the microwave range is carbon as such in the following various forms: graphite, carbon nanotubes, and graphene. Graphene is a carbon allotrope with a two-dimensional hexagonal structure. Furthermore, carbon nanotubes are composed of one or more graphene monolayers rolled into a coaxial cylindrical shape, with diameters of 0.5 to tens of nanometers and lengths up to several centimeters. For example, a thin and large surface layer of reduced graphene oxide forming a laminate with a thickness of 10 μm has a shielding capability of 20dB in the range of 1-4GHz (Carbon [ Carbon ]]94,494,2015). Another example is to have magnetic nanoparticles (e.g., Fe)₃O₄) The thin graphene layer of the blend of (a), is prepared by filtration from a suspension of the blend with ferrite. These layers achieve a shielding effectiveness of about 20dB in the 8-12GHz range (j. mater. chem. a. journal of materials chemistry a)]3,2097,2015). These materials are conductive in the DC range and the shielding mechanism is based on the presence of metallic paths in the material.

Polymer composites containing nanocarbon fillers with barrier properties are also known, such as composites containing a blend of multi-walled carbon nanotubes in a polypropylene matrix. The composite has shielding characteristics at a level of 30dB over the range of 8-12GHz at about 7% blend concentration. The compound is prepared by dry direct mixing of the ingredients at room temperature and then melting and compressing the obtained powder into a sheet (Carbon 47,1738,2009). The composite is electrically conductive in the DC range.

Foam composites based on polystyrene and carbon nanotubes are also known, exhibiting shielding properties reaching almost 20dB in the range of 8-12 GHz. The composite is prepared by mixing the filler in toluene solution with polystyrene containing the blowing agent and by spraying the suspension mixed in this way, wherein in the next stage the foam concentrate is removed by heating (Nano Letters [ Nano Letters ]11,2131,2005). The composite is electrically conductive in the DC range.

Various forms of graphene are also used as fillers in polymer composites, acting as effective elements for shielding electromagnetic radiation. For example, a porous composite is known, consisting of polystyrene and functionalized graphene (up to 30% by weight) and exhibiting shielding efficiency in the range of 8-12GHz up to 30 dB. The composite material is prepared by direct mixing and hot pressing of the ingredients and by using a method of forming a porous structure (j. mater. chem. [ journal of materials chemistry ],22,18772,2012). The composite is electrically conductive in the DC range.

Methods for producing thermally reduced graphene oxide based conductive (in the DC range) composites that achieve 30dB shielding capability at low filler concentrations (< 1%) are also known. The composite is prepared by mechanically mixing graphene oxide and polyethylene particles and then thermally compressing them. Importantly, this method simultaneously leads to the reduction of graphene oxide (Nanotechnology [ Nanotechnology ]25,145705,2014).

Polymeric materials having a two-dimensional structure of a carbide/nitride blend of rare earth metals are also disclosed. Ti in the form of a thin layer₃C₂T_x、Mo₂TiC₂T_x、Mo₂Ti₂C₃T_xThe use of structures, and polymer complexes (sodium aluminate) produced from suspensions of these compounds by vacuum filtration methods, are known. These materials have excellent shielding properties of over 50dB (Science scientific)]353,1137,2016). The composite is electrically conductive in the DC range.

Polymer composites with nanocarbon fillers are also known. Publication by das et al (appl. phys. lett. [ flash of applied physics ]]98,174101,2011) relates to a polymer composite containing a blend of carbon nanostructures having the characteristics of a hydrophobic material. The composite exhibited a shielding characteristic of 32dB in a narrow range of 0.57-0.63 THz. The composite contains a mixture of carbon fibers and several polymers and is obtained by adding a homogeneous suspension of nanostructures in acetone to the polymer mixture and then slowly drying. Materials with these shielding parameters are conductive (about 10)³S/m)。

Also disclosed is the use of a thin layer of carbon nanotubes applied on a flexible polyethylene terephthalate (PET) substrate as a material shielding THz radiation in the range of 0.1-1.2 THz. This material also maintains good electrical conductivity and transparency to visible light. This material was prepared by applying nanotubes in a solution of ethylene dichloride several times on a PET substrate using a centrifuge (appl. phys. lett. [ fast physical applications ]93,231905,2008). Materials with these shielding parameters are conductive (85 Ω/sq).

WO 201253063 discloses a method for preparing polymer-carbon composites containing nanocarbons, preferably carbon nanotubes, in various forms. In this method, the material is prepared by preparing a pre-mix comprising from 3 to 50% by weight of carbon nanoparticles and at least one polymeric binder. To obtain a pre-mix, the carbon nanoparticles and the binder are mixed until a stable polymer emulsion or suspension in the aqueous phase is obtained. If the material matrix is a thermosetting polymer, the concentrated premix is dispersed in a matrix of this polymer, such as, for example: bisphenols, epoxy resins, vinyl ester resins, unsaturated polyesters, polyols, polyurethanes. The polymer-specific hardener is then added to the mixture in order to obtain the final composite. The introduction of carbon nanotubes in the form of a concentrate allows to obtain a uniform distribution of the nanotubes in the material and therefore a better electrical conductivity. The material according to the present application is characterized by a radiation attenuation characteristic of only up to 0.1 THz.

US 8610617 proposes the use of individual large-sized graphene layers applied one after the other to an object to be protected, which is protected against electromagnetic radiation in the microwave and terahertz range by absorption of the graphene layers. It also discloses that graphene can be used in the form of a coating or fabric and used to cover objects. The material is conductive in the DC range.

US 9215835 discloses a method of protecting an object from electromagnetic radiation of a frequency above 1MHz directed directly at the object by directly covering the object one by one with graphene layers, which are in contact with each other, wherein at least one of the layers is doped with an inorganic acid or/and a metal salt. The proposed solution exhibits radiation shielding capabilities at a level above 30 dB.

CN 103232637 discloses a conductive composite comprising 92.5-97.5 parts by weight of polypropylene, 1-3 parts by weight of graphene and 1.5-4.5 parts by weight of polypropylene grafted with maleic anhydride. The obtained material is used as a conductive material or a material for shielding electromagnetic radiation.

From PL 405420, an electromagnetic radiation absorbing conductive (DC) panel is known, consisting of dielectric separators with a low relative dielectric constant and a non-uniform resistive layer. The resistive layer is formed from at least one layer of a polymer composite comprising 1-80 wt% of graphene nanoplatelets having an average diameter of 2-25 μm and a thickness of up to 10nm, which are applied onto a thin polymer film by a screen printing technique.

WO2018081394 a1 discloses a composite for shielding electromagnetic radiation, which comprises about 5 wt.% to 50 wt.% of a matrix material having low dielectric losses, such as in particular polysiloxanes, but also polyethylene, polystyrene, polypropylene, poly (phenylene sulfide), polyimide, poly (ethylene terephthalate), butyl rubber, terpolymers of acrylonitrile-butadiene-styrene (ABS), polycarbonate or polyurethane, and about 50 wt.% to 95 wt.% of copper oxide CuO particles dispersed in the matrix material. Optionally, the composite may also contain 0.1 wt% to 10 wt% of conductive fillers dispersed in the matrix material, such as, for example, carbon black, carbon spheres and foams, graphene, carbon fibers, graphite nanoplates, carbon nanotubes, metal particles and nanoparticles, metal alloy particles, metal nanowires, polyacrylonitrile fibers, or particles coated with a conductive material. A relatively high content of CuO particles (at least 50 wt%, preferably 70 wt%) is an essential element, whereas the optional addition of a conductive filler selected from a number of very different carbonaceous, metallic and polymeric materials does not exceed 10 wt%, and preferably the conductive filler is carbon black in an amount of 0.3 to 4 wt%. The composite is intended for shielding electromagnetic radiation in the range of about 0.01-100GHz primarily by absorption. WO2018081394 a1 lacks detailed information about the type, content and form of optional conductive additives for carbon fillers other than carbon black, and about shielding efficiency.

CN 104650498B discloses a composite in the form of a thin conductive layer containing graphene in an amount of 0.5 wt% to 5 wt%, dispersed in a polymer matrix (e.g. PVC) and forming a sterically conductive (DC) network in the polymer matrix. CN 104650498B only briefly mentions the possibility of shielding electromagnetic radiation without specifying any range or determining the efficiency of the shielding, or using any additives that introduce dielectric losses independent of conductivity.

Furthermore, from US 9252496B 2, compositions are known which dissipate energy at least in the range of about 1-20GHz, said compositions containing graphene in a dielectric matrix (such as a thermoplastic polymer, preferably ABS), wherein the graphene content is preferably about 5-20%, in particular 15-20%, by volume of the composition. US 9252496B 2 does not mention the form of graphene used, the shielding efficiency, nor does it use any additive that introduces dielectric losses independent of conductivity, nor is it an agent that allows to control the dispersion of graphene in the polymer matrix.

Furthermore, CN 103232637B describes a conductive nanocomposite, which contains 92.5 to 97.5 parts by weight of polypropylene as a matrix, 1 to 3 parts by weight of graphene as a conductive filler, and 1.5 to 4.5 parts by weight of polypropylene grafted with maleic anhydride as a graphene dispersion promoter. CN 103232637B only briefly mentions shielding of electromagnetic radiation without specifying any range or determining the efficiency of the shielding, or using any additives that introduce dielectric losses independent of conductivity, or the specific form of graphene used. The experimental results provided are limited to the study of conductivity, which generally increases with the addition of graphene.

It is an object of the present invention to provide a flexible and lightweight composite material which allows shielding of electromagnetic radiation in a wide frequency range, i.e. in the microwave and terahertz range (0.3-10000GHz), with an efficiency of more than 10dB (thickness per millimeter) at least in part of this range. Another object of the invention is that such a composite will allow control of the dominant shielding mechanism (reflection, absorption) and of the specific range of the shielded electromagnetic field, by appropriate choice of the specific composition and manufacturing method. Another object of the present invention is that a suitable choice of the specific composition and of the method for manufacturing the composite material will allow to obtain materials that conduct or do not conduct direct current, and that have different selective shielding efficiencies in different ranges of electromagnetic radiation.

Disclosure of Invention

The object of the present invention is a composite material for shielding electromagnetic radiation, said composite material comprising:

from 88% to 99.88% by weight of a thermoplastic, electrically non-conductive polymer;

0.1-10 wt% of nanocarbon material in the form of flakes having a diameter to thickness ratio higher than 3, the flakes having a thickness of not more than 30nm and a diameter of 100nm to 5000nm,

0.01% to 1% by weight of nanoparticles which introduce losses independent of the conductivity in a given frequency range, i.e. independent of the dispersion of electromagnetic waves on free carriers,

0.01-1 wt% of an auxiliary material which allows to control the dispersion of the nanocarbon material and the nanoparticles in the polymer matrix and/or which is capable of altering the properties of the nanocarbon material and the nanoparticles,

wherein the composite material is in the form of a homogeneous mixture.

The composite material according to the invention allows shielding against electromagnetic radiation at frequencies in the microwave and terahertz range (0.3-10000GHz), with an efficiency of more than 10dB (thickness per millimeter) in at least part of this range. The nanocarbon material, in the form of flakes having a ratio of diameter to thickness higher than 3, the thickness of the flakes being not more than 30nm and the diameter being 100 to 5000nm, provides a quasi-two-dimensional charge distribution in each nanocarbon object respectively and easier formation of percolation paths in the polymer matrix promoting charge and heat transport and allows to obtain materials conducting or not conducting direct current. Furthermore, the introduction of specific types and proportions of nanoparticles, independent of the electrical conductivity in a given frequency range, and in particular with ferromagnetic resonance frequencies suitable for attenuating significant frequency bands, is an important parameter allowing to control the dominant shielding mechanism (reflection, absorption) and the specific range of the shielded electromagnetic field and the selective shielding efficiency for a given radiation range.

Preferably, the thermoplastic polymer is selected from Polystyrene (PS), Polyethylene (PE), polypropylene (PP), Polyurethane (PU), terpolymers of acrylonitrile-butadiene-styrene (ABS), polyesters such as in particular poly (ethylene terephthalate) (PET), poly (tetrafluoroethylene) (PTFE), Polyamides (PA), terpolymers of acrylonitrile-styrene-acrylic acid (ASA), poly (vinyl chloride) (PVC), modified poly (phenylene ether) (MPPE), non-flammable and self-extinguishing LSZH plastics (low smoke zero halogen), derivatives of one of these polymers or combinations thereof.

Preferably, the nanocarbon material is selected from the group consisting of graphene flakes, graphene oxide, reduced graphene oxide, modified graphene flakes, nanographite, or a combination thereof.

Preferably, the nanoparticles are dielectric particles having an anisotropy coefficient of ferromagnetic resonance frequency (suitable for attenuating significant frequency bands) and/or permeability and/or permittivity, and/or a dielectric loss of the alternating electromagnetic field (EM) caused by the polarization of the components constituting the particles. More preferably, the nanoparticles are selected from silicon carbide (SiC), alumina (Al)₂O₃) Nanoparticles of Fe-BN; ferrite-based nanoparticles, preferably of hexagonal structure, containing cobalt or barium or strontium, preferably CoFe₂O₄、BaFe₁₂O₁₉、SrFe₁₂O₁₉、Ba₃Me₂Fe₂₄O₄₁、Ba₃Sr₂Fe₂₄O₄₁、Ba₂Co₂Fe₁₂O₂₂、BaCo₂Fe₁₆O₂₇、Ba₂Co₂Fe₂₈O₄₆、Ba₄Co₂Fe₃₆O₆₀(ii) a Iron-based nanoparticles, preferably Fe-Cr, Fe-Ni, Fe-Si, Fe-Co nanoparticles; or a combination thereof.

Preferably, the auxiliary material is a graphene functionalizing compound comprising a plasticizer, an antioxidant, a hardener, or a combination thereof. Preferably, the plasticizer is an organic oil, alcohol, anhydride, or combination thereof. Preferably, the antioxidant is a natural antioxidant, preferably a carotenoid, flavonoid, vitamin C, vitamin E, phenolic or combinations thereof.

The object of the present invention is also a raw material for an additive manufacturing method (commonly referred to as 3D printing) of an element shielding electromagnetic radiation, said raw material comprising a material according to the invention as defined above, preferably in the form of particles, filaments or tapes.

Furthermore, the object of the present invention is a product for shielding electromagnetic radiation, said product comprising a composite material according to the invention as defined above.

In another aspect, the invention also relates to a process for preparing a product according to the invention, i.e. comprising a composite material according to the invention as defined above, said process comprising the steps of:

(i) mixing

From 88% by weight to 99.88% by weight of a thermoplastic, electrically non-conductive polymer, preferably in the form of particles having a size of not more than 1mm,

0.1-10% by weight of nanocarbon material in the form of flakes having a diameter to thickness ratio higher than 3, the flakes having a thickness of not more than 30nm and a diameter of 100-5000 nm,

0.01% to 1% by weight of nanoparticles, which introduce losses independent of the electrical conductivity,

0.01-1% by weight of an auxiliary material which allows to control the dispersion of the nanocarbon material and the nanoparticles in the polymer matrix and/or which is capable of modifying the properties of the nanocarbon material and the nanoparticles;

(ii) injecting the molten mixture into a mold defining the shape of the product;

(iii) hardening the material to obtain the final product.

Preferably, the mixing step (i) is carried out by dry mechanical mixing at room temperature. In another preferred variant, the mixing step (i) is carried out by dry mechanical mixing at a temperature above the polymer flow temperature.

The composite material can be used as a material for protecting electronic components, devices, modules and electronic parts, wires or biological organisms from electromagnetic radiation in the microwave and terahertz range (0.3-10000 GHz). The element or product shielding electromagnetic radiation from the composite material according to the invention may be manufactured by injection moulding, extrusion or 3D printing.

As mentioned above, the composite material may be non-conductive or conductive under direct current, depending on the percentage composition of the filler and premix structure. Depending on the composition and manufacturing method, the composite material may have a selective shielding efficiency (different in different ranges), wherein the dominant shielding mechanism (reflection, absorption) and the control of the range in which the electromagnetic field is to be shielded is performed by appropriate selection of the composition and manufacturing method.

Drawings

The objects of the invention are presented in more detail in the embodiments in the attached drawings, in which:

FIG. 1 shows the transmission mode measurements of the shielding efficiency of the composite from example 1 in the range of 0.1-12,5GHz (results on a logarithmic scale; the symbol "-" in the graph means that the EM wave weakens after passing through the material);

FIG. 2a shows the degree of attenuation (logarithmic scale) of electromagnetic radiation in the range of 0.1-0.95THz for the material from example 2;

FIG. 2b shows the transmission level (logarithmic scale) of electromagnetic radiation in the range of 0.1-1.8GHz from the material of example 2;

fig. 3 shows the current-voltage characteristic for the material from example 3 with an electrode distance equal to 1 mm.

Detailed Description