Magnetic foam (options)
(57) Abstract:The invention relates to magnetic pins and can be used to separate mixtures, adsorption to the interface air - water, wastewater, magnetic separation, magnetic protection against radiation. Magnetic foam contains a liquid phase (water, organic liquids, detergents, oligomers) in combination with a foaming agent or a solid phase (foams) and nanoparticles of magnetic material is barium ferrite or hard magnetic structures of type Nd-Fe-B, Sm-CO, Sm-Fe with a particle size of 2-30 nm, stabilized by surface-active substance. Magnetic foam (solid and liquid) are obtained in different ways - by a condensation method, method variance. The resulting foams have a low water absorption, low thermal conductivity, good magnetic properties. 2 S. p. f-crystals. The invention relates to foams, namely functional disperse systems - magnetic pins, and can be used for filtering, separating mixtures, adsorption to the interface air - water, wastewater, concentration of dispersed phases, magnetic separation, magnetic protection against radiation, etc.The number of known ways to remove spilled the physical spill containment and removal of oil from the water surface through the collection using floating barriers, installed around the perimeter of the spot (US 5372455, SU 338132, SU 628607); fenced oil spill can then be removed, for example, by pumping (US 5338132, 1990).Known methods of chemical treatment of oil slicks on the water surface using substances causing solidification of oil, the so-called solidification and dispersing substances (US 5112495, 5259973, 6054055, 4978459). After treatment of the oil slick by solidification solids oil, which is then removed by mechanical means; dispersing agents cause fragmentation of an oil slick into small droplets which are then deposited on the bottom. However, for effective removal of oil solidification requires a considerable number of them, as well as sophisticated equipment. The use of dispersing substances causing the contamination of the seabed, disrupting the ecology of the environment.There is a method of collecting oil from the surface of the water using different absorbing materials (sorbents), for example based on cellulose (US 5971659). Such absorbent material is placed on a layer of oil spilled, and after he absorbs oil, collected from the surface by mechanical methods; oil absorbing material then is removed or OTG is retene is the creation of tools (material), to effectively use it for removal and collection of oil and oil products, as well as for wastewater treatment, magnetic separation, magnetic radiation protection, namely magnetic foam both solid and liquid.The closest in technical essence of this invention is a magnetic foam based on an aqueous or organic solution of oligomers capable of subsequent polymerization, polycondensation, the formation of adducts, different target agents (initiators, catalysts, foaming agents, nanoparticles of magnetic material (Fe, CO, Ni, magnetic iron oxide - Fe3O4, - Fe2ABOUT3with size not more than 40 nm, the surface-active substance. The porous walls such received frothy mass containing particles of magnetic material, stabilized by surface-active substance (DD 299469, 08 J 9/00, 23.04.92).The main purpose of the magnetic foam at the specified patent - electromagnetic protection devices, camouflage radio-emitting devices. In the patent there are no data on such magnetic properties of the foam as moisture absorption, magnetic characteristics, which would allow to conclude on the possibility of using it in casti water.Requirements pins depend on its technical purpose. So, flotation foam should be, as a rule, unstable and contain dissolved substances providing selective elution of particles of minerals from the suspension (slurry). The foam used in a frozen state for insulation of the soil, must have a low rate and low rate of syneresis. Foam, designed for adsorptive concentration or foam chromatography, on the contrary, should be high and very stable. For washing gas and foam cleaning samalamig products, as well as for dust control is applied foam, resistant to organic liquids and solid particles of different nature. In large scale foam is used in the fire service. Depending on the interest of fire (indoors, oil, gasoline, alcohols, etc.,) and klimaticheskih conditions required foam with a complex of special physical and chemical properties necessary to ensure good fire-fighting ability.For the solution of several problems is the possibility to influence the foam of the external magnetic field; however, an additional lie is buckling, when the same composition and the ratio of the components of the foam dramatically increase its sorption capability, there are stealth properties, etc.The problem of creating magnetic foam with high and controlled stability is that necessary to stabilize the dispersed magnetic media with high magnetic characteristics directly in the walls of the foam bubbles, the thickness of which, as a rule, does not exceed 300 nm. Dispersed materials with the size of the dispersed phase equal to or greater than the specified value may not be retained in the foam long enough. In addition, the procedure of introducing dispermic materials in the foam is difficult because it is known that materials with a highly developed surface are effective defoamers and they actively destroy the foam.The problem of creating a liquid magnetic pins and their transformations in some cases, in solid magnetic foam in the first place connected with the search for highly efficient superfine magnetic carriers can be in the walls of the bubbles of foam of different composition and dispersion. In the present invention as such magnetic materials it is proposed to use magnetic nanoparticles composition of the surface atoms is comparable with the number of atoms inside the particle. This causes the high chemical activity of such particles and their special physical properties. In particular, magnetic nanoparticles of metals and alloys, being single, have high magnetization and magnetic anisotropy, and in some cases may have a high coercive force and to preserve the magnetic properties up to high temperatures. Methods of making such particles and to stabilize them well-known.Occupying an intermediate position between the molecules and the normal dispersion systems (with a particle size of from a few microns to a fraction of a micron), the nanoparticles can easily be stabilized both in liquid and gas phases. For their support in these phases as potential ligands using substances which are simultaneously active foaming agents and stabilizers.Containing magnetic nanoparticles foam depending on the nature of the liquid phase can be liquid (liquid magnetic foam) over time from several minutes to several hours or harden, taking, for example, the shape of the vessel in which it is located (hard magnetic foam). Solid magnetic foam can contain significantly more magnetic nanoparticles.Pantie nanoparticles, studiowanie surfactant molecules, and the foam can be introduced as a soft magnetic and hard magnetic materials. If the foam contains magnetic materials with a sufficiently large residual magnetization and coercive force, the foam can easily snap and be collected using, for example, ordinary sheet iron. If the foam contains a magnetic material with a relatively low residual magnetization when the external magnetic field, the magnetic moments are in the foam magnetic nanoparticles of metals, their alloys and compounds oriented in the direction of the field and due to this the foam is drawn to the source of the magnetic field.At the location of the source of the magnetic field near the surface of the foam moves easily on the surface of the partition on which it is located, in the direction defined by the gradient magnetic field, pulling all that is on the surface or in the cells of the foam. If the source of the magnetic field is above the surface of the partition, its magnetic field can cause separation of the foam from the surface and its "sticking" to the source of the field together with the contents of the foam. And in fact, and in another case is achieved by separating the foam from the cleaned surface For exemption from the absorbed impurities magnetic foam can be destroyed by conventional methods.Scarce magnetic materials can be separated from the formed product standard magnetic separation techniques.Desorption of indestructible hard magnetic pins can be carried out by standard methods of washing solvents.Solid magnetic foam (apparent density of 0.1-0.04 g/cm3), with a highly developed internal surface area and low thermal conductivity are also effective insulating materials (thermal conductivity from 0.1 to 0.02 W/(MK)) and simultaneously possess stealth properties in a wide range of radiation (105-1012Hz). Moreover, the range of absorption may vary due to selection of the optimal composition and size of nanoparticles.The resulting magnetic foam compositions suitable for storage in an aerosol or other similar containers under pressure.Magnetic foam according to this invention (liquid and solid) are released in the form of foam, forming a stable foam products suitable to the same (solid foam) for use as sealing and insulating (stealth) materials.They have low moisture absorption - in Premsa reduced water absorption, improved stability of the foam.The technical problem is solved by the fact that using nanoparticles of a certain size and a certain magnetic material was obtained magnetic foam liquid or solid, depending on its basis with a variety of high and stable magnetic characteristics, providing them with a wide range of use, low water-absorbing capacity.Thus according to the invention are the liquid magnetic foam containing liquid phase, the foaming agent and the nanoparticles of magnetic material, stable molecules of surface-active substances, as a magnetic material such foam contains nanoparticles of barium ferrite or hard magnetic structures of type Nd-Fe-B, Sm-CO, Sm-Fe with a particle size of 2-30 nm in an amount of from 2 to 30 wt.%, interoperable foam with an external magnetic field.The subject of this invention is also hard magnetic foam representing sasboy foam containing porous walls homogeneous distributed nanoparticles of magnetic material, stable molecules of surface-active substances, as a magnetic material such foam is as from 2 to 30 weight. % providing interaction foam with an external magnetic field.When receiving a liquid magnetic pins in the liquid phase is water, an organic liquid such as organic solvents (dimethylformamide, acetone, benzene, gasoline), synthetic detergents, such as detergents "News", "Progress", "Astra", on the basis of sodium alkyl sulphates, in particular sodium dodecyl sulfate, drugs sulfonol ("sulfonic acid-NP", "sulfonate" and others), silicone fluids, various oligomers such as oligoclonal, etc.As surfactants, stabilizing the nanoparticles of magnetic material, the use of different surfactants: anionic surfactants (avirol, alizarin oil, alkyl sulphates, sulfonates, alkylbenzenesulfonates, naphthalenesulfonate, nitrogen-containing compounds, perfluorinated surfactants), cationic surfactants on the basis of salts of alkylamines, including pyridine, sulfone (Quaternary ammonium base); nonionic surfactants based on ethoxylated alcohols, fatty acids, phenols and amines, for example, type OP 7, OP 6, OP 10; polymer atomitie surfactants of natural origin.As the foaming agent to obtain terapie various volatile liquids, aliphatic and halogenated hydrocarbons, low boiling alcohols, ethers, ketones, chemical foaming agents are substances that produce gaseous products in the reversible or irreversible thermal thermal decomposition (ammonium salts with mineral and organic acids, hydrogen carbonates and carbonates of alkali and alkaline earth metals, aromatic, fatty-aromatic and aliphatic azo - and diazocompounds, diatomite and other troop N2, CO2, NH3other gases, such as azodiisobutyronitrile (CHS-57), azodicarbonamide (brand CHS-21), etc. depending on the purpose magnetic foam.Foaming agents can serve and be used as stabilizers nanoparticles surface-active substances.The basis of solid magnetic foam are different foams-foams, penopolistirola, penopoluisooli, foam, pinoproblema, silicone foam and the other obtained by known conventional technologies using various standard target additives (catalysts, plasticizers) and foaming agent (physical or chemical foaming agents).to PPU-210, PMA-205-5 obtained on the basis of polyethers (LACRALO) and polyisocyanates, PPU-e based on polyesters, penopolistirolnye foams (PVH), for example, of PVC-1, winpar; polyethylene PES-2 PES-3, epoxy-Novolac foams PENG AND others.Such foams are widely described and are known (see, for example, Foams, their properties and application in industry" L., 1980, proceedings, S. 6-70; "Foamed plastic mass M, VNIIS, 1983, proceedings, S. 4-80; A. A. Berlin and others, "Chemistry and technology of gas-filled vysokopreosv M.: Nauka, 1980, S. 241-457; "encyclopedia of polymers" so 3.SU 910676, 07.03.82. ; SU 1735323, 23.05.92.; SU 68062, 15.04.46.; SU 618050, 30.10.75; SU 459482, 05.02.75 and others).As the magnetic material for the preparation of liquid and solid foams using nanoparticles of barium ferrite, hard magnetic structures, for example, Nd2Fe14B, SmCO5Sm2Fe17C8related to the type of hard magnetic compositions of Nd-Fe-B, Sm-CO, Sm-Fe different ratios with a particle size of 2-30 nm.Liquid and solid foams according to this invention receive traditional ways: by the condensation method, method variance.The method of condensation - foaming composition is of noobasaurus), and containing nanoparticles of magnetic material and a surfactant.The method of dispersion - foaming compositions by direct injection gas (physical foaming), through the introduction of gas (physical foaming) by mechanical mixing - kneading a composition containing nanoparticles of magnetic material and a surfactant.In the case of rigid foams nanoparticles of magnetic material can enter into the composition at the stage of synthesis of the polymer, with subsequent foaming compositions containing various additives target (hardeners, surfactants, plasticizers, solvents), and a composition containing the finished polymer and possible specific target additive and the subsequent foaming of the composition by formation of solid foam, depending on its destination.Rigid foam can be obtained in various ways of mixing the components.So, for example, mixing can be accomplished in a rocking mixer. When this polymer beads first homogeneous mix with different target additives (nucleating fillers, plasticizers, stabilizers, peroxide, curing catalysts, pigments, dyes, Academy of Sciences of Aut nanoparticles of magnetic material, and optionally a surfactant, if it has not been entered previously.The mixing is carried out on rollers, mixers, mills, extruder, depending on the nature of the resulting magnetic foam (liquid, solid) and its destination (for removing and collecting oil, sorption or as an insulating (radar absorbing material).In that case, if the solid foam is used to obtain the insulation, for example, radio-absorbing material composition is heated, for example, when 150-350oWith, the foaming agent decomposes and polymer foams with formation of a solid porous magnetic foam.Nanoparticles of magnetic material together with the surface-active substance can be entered into the molding composition comprising the polymer and additives target at the stage of molding her at the processing machines and the subsequent foaming.The heating temperature in each specific case upon receipt of a rigid foam used, for example, as a radar absorbing material depends on the temperature at which it is possible to process the polymer.Solid magnetic foam can be obtained, and the dispersion of nanoparticles of magnetic material in the presence of surfactant in outstay foaming agent.Nanoparticles of magnetic material is prepared in different ways: by evaporation or sputtering of metals, recovery of the salts of these and other methods.The following examples illustrate the invention.Example 1
In a mixer containing 100 g (100 wt.h) a composition comprising expandable polystyrene EPS, foam - carbon dioxide, stabilizer - surfactant (ethoxylated alkyl phenol OP-7), enter the nanoparticles of barium ferrite in the amount of 2 g (2 wt.%) with a particle size of 15 nm, stirred for 2-2,5 hours. Nanoparticles of magnetic material, stable molecules of surface-active substances, homogeneous distributed in the foamy mass.Frothy mass can be stored in an aerosol or other similar cylinders, which facilitates its application. When you release the foam from the container (tank), a solid stable porous foam with low moisture absorption and good magnetic properties (specific magnetization under normal conditions from 0.5 to 5 GSM3/g, apparent density of 0.2 g/cm3, water absorption - 0.03 kg/m224 hours).Example 2
In a mixer containing 100 g (100 wt.h.) composition is Prol L-5003, MDI PIZ, silicone prestabilization (SAS) CEP-1, the catalyst DABCO or octoate tin, dimethylethanolamine, water, introducing the hard magnetic nanoparticles composition of Sm-Fe (1:5) in an amount of 10 g (10 wt. %). Mix. In the interaction of the isocyanate with water allocated dioxide, fulfilling the role of a blowing agent.The foam composition can be stored in an aerosol container, when the release from the cylinder is formed stable porous solid foam, the walls of which contain nanoparticles of magnetic material having low water-absorbing ability and good magnetic properties (specific magnetization under normal conditions from 0.5 to 5 GSM3/g with an apparent density of 0.04 g/cm3the water absorption of 0.3 kg/m224 hours).Example 3
Analogously to example 2 get a solid magnetic foam based on polyurethane. Get a polyurethane matrix from a liquid reaction mixture containing a polyol as one component (polyether or complex PEF), blowing agent (HFC), water, mix, add the polyisocyanate and again mix. Pre-prepared mixture consisting of nanoparticles of magnetic material with melirovanie alkylphenol OP-7 in the number of traditional - required for wetting of the particles. Prepared polyurethane matrix is poured evenly into the form and then immediately back into the cavity forms a mixture of magnetic material and a surfactant. The filler impregnated with the reaction mixture. Under pressure is foaming. Get a solid magnetic foam with an apparent density of 0.035 g/cm3with specific magnetization under normal conditions from 0.5 to 5 GSM3/,Get a solid magnetic foam, which is a foam, porous walls which contain nanoparticles of magnetic material. Used as radio-absorbing insulating material.Examples 4-6
Similarly, get a solid magnetic foam-based penopoluisooli, polyethylene, penopolymermineral, blending the polymer powder in a ball mill or other apparatus with a foaming agent in a quantity depending on the desired density polymer foams, for example, azodiisobutyronitrile (CHS-57); depending on the requirements of a porous material to the polymer can also be added before mixing with the blowing agent or after a different target additives (fillers, plastiflora material, for example, the composition of Nd-Fe-B Nd2Fe14B), taken in an amount of 2 wt.%, 10 wt.% or 30 wt.% accordingly, with a particle size of 2 nm.By mixing the nanoparticles are stabilized by surface-active substance contained in the polymer composition.The mixing is carried out for 1-12 hours.The resulting mixture is pressed in a sealed mold at 100-200oWith depending on the softening temperature of the polymer and the decomposition temperature of the foaming agent. Get a solid magnetic foam with different densities of 0.2-0.04 g/cm3and low thermal conductivity (coefficient of thermal conductivity of 0.1-0.2 W/MK)), good stealth properties in a wide range of radiation (105-1012Hz). Moreover, the range of absorption can be used due to selection of the composition and size of nanoparticles of magnetic material.Liquid magnetic foam are simply mixing (dispersion) in the presence of surfactant nanoparticles of magnetic material and the foaming agent (physical or chemical).Example 7
Get liquid foam is a dispersion of 7.2 wt.% nanoparticles of magnetic material is barium ferrite (6:1) with a particle size of 2-15 nm, in the liquid phase on the basis of dodecyl alkylsulfate) (1x10 mol/l); foaming is carried out using physical blowing agents (foaming agents), which acts as air, CO2or chemical blowing agents from the group of surface-active substances in the composition of the synthetic detergent.Example 8
Get magnetic liquid foam is a dispersion of nanoparticles of magnetic material composition of Sm-CO5with a particle size of 5 nm in an amount of 5 wt.% in the liquid phase is a silicone oil, in the presence of surfactant - Na oleate and foaming agent (air, inert gases, CO2and so on).Examples 7-8 magnetic liquid foam was produced using the air-foam trunks, plants, generating foam by ozonation of air (CO2inert gases) through a solution of a foaming agent and foam with foam on the grid. Get foam of different composition and multiplicity. Existing designs of foam to provide up to 15000 litres of foam in 1 sec., that is sufficient to cover 150 m3the foam layer thickness of 0.1 m (with foam density of 0.1 g/cm3).Liquid foam is applied to the spot of dirt to remove various hydrophobic contaminants from the surface of the water, such as oil loading the surface of the water due to good buoyancy and magnetization.In addition, the solid foam can be used as a radar absorbing thermal insulation material; and
magnetic foam (solid or liquid) is applied to the oil spill by spraying by means of a pneumatic system (installation) installed on Board the aircraft.At the same time we specify that as the magnetic material comprises foam can also be used hard magnetic structures of type Nd-Fe-B, Sm-Co and Sm-Fe. Here, the term "type" refers to hard magnetic alloys and compounds based on rare-earth and transition material having magnetic properties similar or superior magnetic properties of the above compounds and alloys. 1. Magnetic foam containing liquid phase, the foaming agent and the nanoparticles of magnetic material, stable molecules of surface-active substances, characterized in that as the magnetic material, it contains nanoparticles of barium ferrite or hard magnetic structures of type Nd-Fe-B, Sm-Co, Sm-Fe with a particle size of 2-30 nm in an amount of from 2 to 30 weight. % providing interaction foam with an external magnetic field.2. Magnetic foam containing as a solid phase of the foam,Olami surfactants, characterized in that as the magnetic material, it contains nanoparticles of barium ferrite or hard magnetic structures of type Nd-Fe-B, Sm-Co, Sm-Fe with a particle size of 2-30 nm in an amount of from 2 to 30 wt. % providing interaction foam with an external magnetic field.
FIELD: composite materials.
SUBSTANCE: invention discloses a method for manufacturing composite material for shielding-mediated protection against electromagnetic emission and can be used in electronics, in radio engineering, and also in a series of special-destination articles. In addition, material may be used for anechoic boxes and in various assemblies of technical devices and radio apparatuses. Method comprises mixing modified graphite-containing conducting filler and polymeric binder at weight ratio (50-80):(20-50). Once ingredients combined, mixture is additionally subjected to thermal expansion in thermal shock mode at 250-310оС and then molded. Polymeric binder is selected from polyolefins, polystyrene, fluoroplastic, polyvinylchloride paste and modified graphite is product obtained by modifying graphite with concentrated sulfuric and nitric acids. Material is characterized by that, in wavelength band from 2 to 5 cm at thickness of material up to 0.1 mm, transmission coefficient is decreased from -40 to -85 dB.
EFFECT: improved performance characteristics.
6 cl, 1 tbl, 2 ex