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CN-121974650-A - Graphene modified gypsum-based wave-absorbing material and preparation method thereof

CN121974650ACN 121974650 ACN121974650 ACN 121974650ACN-121974650-A

Abstract

The invention discloses a graphene modified gypsum-based wave-absorbing material and a preparation method thereof, and belongs to the technical field of wave-absorbing materials. The material consists of gypsum cementing material, modified graphene, a water reducing agent, a retarder, magnetic wave absorbing filler and water, wherein the modified graphene is prepared into a double-anchoring block copolymer through RAFT polymerization, and the double-anchoring block copolymer is prepared through mechanochemical modification and DA click chemical grafting. The stable dispersion of graphene in a gypsum system is realized by means of the bi-anchoring block copolymer, high-efficiency wave absorption is realized by means of the dielectric-magnetic loss synergistic effect, and the antagonism relation between the wave absorption performance and the mechanical performance is broken. The material has excellent wave absorbing efficiency, mechanical strength and water resistance, is suitable for the scenes of indoor electromagnetic protection of buildings, shielding of industrial plants and the like, and has good industrialization prospect.

Inventors

  • LIU ZHEN
  • Mu Xirui
  • WANG QINGHUI
  • SUN XUE
  • Bo Huacui

Assignees

  • 辽宁瑞丰新型建材有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. The graphene modified gypsum-based wave-absorbing material is characterized by comprising, by weight, 100 parts of a gypsum gel material, 0.2-1 part of modified graphene, 0.1-0.3 part of a water reducer, 0.1-0.3 part of a retarder, 10-20 parts of a magnetic wave-absorbing filler and 50-80 parts of water; The preparation method of the modified graphene comprises the following steps: (1) Under the protection of nitrogen, adding furfuryl methacrylate, benzyl dithiobenzoate and azodiisobutyronitrile into anhydrous DMF, heating to 70-80 ℃, stirring for reacting for 5-8 hours, then placing in an ice-water bath, cooling to room temperature, adding the reaction solution into 0 ℃ methanol for precipitation, washing the precipitate with deionized water, and drying to obtain the poly furfuryl methacrylate; (2) Under the protection of nitrogen, adding poly furfuryl methacrylate, 2-acrylamido-2-methylpropanephosphonic acid and azodiisobutyronitrile into anhydrous DMF, heating to 80-90 ℃, stirring for reaction for 6-10h, then placing in an ice-water bath, cooling to room temperature, adding the reaction solution into 0 ℃ methanol for precipitation, washing the precipitate with deionized water, and drying to obtain a double-anchoring block copolymer; (3) Placing the few-layer graphene powder in a vacuum drying oven at 70-80 ℃ for 8-12 hours to obtain dry few-layer graphene powder, then adding the dry few-layer graphene powder, prehydrolyzed N- (2-aminoethyl) -3-aminopropyl trimethoxysilane and N-maleimidoglycine into a planetary ball mill under the protection of nitrogen, ball milling for 2-4 hours at room temperature, preparing a product into a suspension of 5mg/ml by using absolute ethyl alcohol after ball milling, centrifuging for 5-10 minutes, discarding supernatant, repeatedly washing and centrifuging the obtained precipitate by using absolute ethyl alcohol for 3 times, and freeze-drying to obtain modified graphene with edge-oriented grafting maleimide; (4) Adding modified graphene with edge oriented grafting maleimide into anhydrous tetrahydrofuran under the protection of nitrogen, stirring for 5-10min, then adding a bi-anchoring block copolymer and hydroquinone monomethyl ether, heating to 60-70 ℃, stirring for reaction for 12-18h, centrifuging for 5-10min after cooling to room temperature, discarding supernatant, repeatedly washing and centrifuging the obtained precipitate with anhydrous ethanol for 3 times, and then freeze-drying to obtain the modified graphene.
  2. 2. The graphene-modified gypsum-based wave absorbing material according to claim 1, wherein the gypsum gel material refers to at least one of β -hemihydrate gypsum, α -hemihydrate gypsum, desulfurized building gypsum or phosphogypsum.
  3. 3. The graphene modified gypsum-based wave absorbing material according to claim 1, wherein the water reducing agent is a polycarboxylic acid water reducing agent for gypsum, the solid content is 35% -40%, and the water reducing rate is not less than 30%.
  4. 4. The graphene-modified gypsum-based wave absorbing material according to claim 1, wherein the retarder refers to at least one of SGR-1801 protein retarder, citric acid, or sodium polyphosphate.
  5. 5. The graphene-modified gypsum-based wave absorbing material according to claim 1, wherein the magnetic wave absorbing filler is at least one of a hydroxy iron powder, ferrite or ultra-fine steel slag powder.
  6. 6. The graphene-modified gypsum-based wave absorbing material according to claim 1, wherein the weight ratio of furfuryl methacrylate, benzyl dithiobenzoate, azobisisobutyronitrile, anhydrous DMF and methanol in (1) is 1:0.03-0.05:0.008-0.012:7-9:8-12.
  7. 7. The graphene-modified gypsum-based wave absorbing material according to claim 1, wherein the weight ratio of the poly (furfuryl methacrylate), the 2-acrylamido-2-methylpropanephosphonic acid, the azobisisobutyronitrile, the anhydrous DMF and the methanol in (2) is 1:2.8-3.2:0.03-0.04:10-15:15-25.
  8. 8. The graphene modified gypsum-based wave absorbing material according to claim 1, wherein the few-layer graphene powder in the step (3) is 1-5 layers, the sheet diameter is 1-5 mu m, the specific surface area is 300-500m 2 /g, the carbon purity is more than or equal to 99%, the weight ratio of the dry few-layer graphene powder to the pre-hydrolyzed N- (2-aminoethyl) -3-aminopropyl trimethoxysilane to the N-maleimidoglycine is 1:0.01-0.03:0.02-0.04, the ball milling condition is that zirconium oxide grinding balls with the diameter of 3mm are adopted, the ball material ratio is 5:1, the rotating speed is 200-260rpm, and the centrifugal rotating speed is 8000-10000rpm.
  9. 9. The graphene-modified gypsum-based wave absorbing material according to claim 1, wherein the modified graphene with edge-oriented grafting maleimide in (4), anhydrous tetrahydrofuran, a bi-anchored block copolymer and hydroquinone monomethyl ether are mixed according to a weight ratio of 1:180-220:0.2-0.5:0.001-0.005, and the rotational speed of centrifugation is 8000-12000rpm.
  10. 10. The method for preparing a graphene-modified gypsum-based wave-absorbing material according to any one of claims 1 to 9, comprising the steps of: S1, adding modified graphene into water, and stirring at 60-120rpm for 10-30min to obtain graphene dispersion; S2, adding the gypsum cementing material, the water reducer, the retarder and the magnetic wave absorbing filler into a dry powder mixer, and dry-mixing for 1-2min at 150-300rpm to obtain dry-mixed powder; S3, adding the dry mixed powder into the graphene dispersion liquid, and mechanically stirring for 1-3min at rotation of 60-130rpm and revolution of 120-260rpm to obtain the graphene modified gypsum-based wave absorbing material.

Description

Graphene modified gypsum-based wave-absorbing material and preparation method thereof Technical Field The invention relates to the technical field of wave-absorbing materials, in particular to a graphene modified gypsum-based wave-absorbing material and a preparation method thereof. Background With the rapid development of modern electronic information technology, the problem of electromagnetic radiation pollution is increasingly prominent due to the wide application of various electronic devices and communication base stations, so that the normal operation of precise electronic instruments can be interfered, and potential harm to human health can be caused, and therefore, the material requirements for the wave absorbing function and the building service performance are urgent in the scenes of indoor protection of buildings, shielding of industrial plants, environmental management and the like. As a traditional building material, the gypsum-based material has the remarkable advantages of wide raw material sources, environmental protection, no pollution, high setting and hardening speed, good construction workability and the like, has stable self dielectric property and moderate density, is an ideal matrix for preparing the building wave-absorbing material, is compounded with graphene with high dielectric loss and magnetic filler with high magnetic loss, can endow the material with electromagnetic wave-absorbing function, and meets the special requirements of building scenes, so that the graphene-modified gypsum-based wave-absorbing material becomes a research hot spot in recent years. In order to solve the problems of easy agglomeration and poor dispersion stability of graphene in a gypsum-based system, the prior art mostly adopts mixed acid oxidation modification, silane coupling agent surface modification or copolymer grafting and other modes to modify graphene, and meanwhile, the magnetic wave-absorbing filler is compounded, so that the wave-absorbing performance is improved through the synergistic effect of dielectric loss and magnetic loss. The method is characterized in that oxygen-containing functional groups such as carboxyl and hydroxyl are introduced to the surface of graphene to improve the hydrophilicity and dispersibility of the graphene, but the method can seriously damage the integral sp 2 conjugated structure of the graphene basal plane, so that the intrinsic dielectric loss capability of the graphene is greatly reduced, the functional groups are distributed randomly, directional grafting cannot be realized, long-term dispersion stability is still not ideal, the silane coupling agent modification can improve the interfacial compatibility of graphene and a gypsum matrix, the steric hindrance effect of a single silane molecule is limited, pi-pi stacking between graphene sheets is difficult to effectively inhibit, the agglomeration problem is not solved basically, and the copolymer grafting modification is easy to lead to mutual shielding of reaction sites due to disordered functional group distribution, has low grafting efficiency, and cannot accurately regulate the synergistic effect of graphene, gypsum hydrated crystal and magnetic filler. Meanwhile, the prior art has the key defects that firstly, the synergy matching performance of graphene and a magnetic wave-absorbing filler is poor, the dielectric constant and the magnetic permeability are unbalanced, so that the impedance matching of electromagnetic waves is poor, the absorption capacity is weak, the effective absorption bandwidth is narrow, secondly, the grafting selectivity is poor, the base surface and the edge are not differently grafted in the graphene modification process, the intrinsic performance of the graphene is damaged, a continuous electromagnetic loss network cannot be formed, the uniformity of the wave-absorbing performance is poor, thirdly, the aggregation phenomenon of the graphene causes a large number of interface defects in the gypsum matrix, the mechanical performance is obviously reduced, the antagonism effect of 'the improvement of the wave-absorbing performance and the reduction of the mechanical performance' is generated, fourthly, the water resistance of the gypsum matrix per se is poor, the existing modification scheme focuses on the dispersion and the optimization of the wave-absorbing performance, the improvement effect on the water resistance is limited, and the service stability of the material in a humid environment is restricted. The existing graphene modified gypsum-based wave-absorbing material is difficult to meet the actual application requirements at the same time due to the existence of the problems, and the large-scale popularization of the existing graphene modified gypsum-based wave-absorbing material in the building field is limited, so that the development of the graphene modified gypsum-based wave-absorbing material with the performance synergistically optimized has important practical signif