Self-repairing wave-absorbing composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of wave-absorbing materials, and particularly relates to a self-repairing wave-absorbing composite material and a preparation method and application thereof. Porous biochar is used as a matrix to replace a traditional carbon base. Through the composite design of the manganese selenide nanosheets and the charcoal porous network, the problem that the charcoal loss mechanism is insufficient is solved, the magnetic-dielectric synergistic loss mechanism is realized, and the efficient electromagnetic wave absorption performance is realized by optimizing the filler. A dynamic chemical bond disulfide bond is introduced into polyurethane through a chain extender, so that a polyurethane matrix is endowed with self-repairing capability, the maintenance cost is effectively reduced, and the comprehensive protection of the electromagnetic wave absorbing coating on an electronic device is ensured. Meanwhile, the inherent flexible characteristic of polyurethane is also beneficial to multi-scene adaptation, and the environmental adaptability of the composite material is improved. In addition, a filler conductive network is coupled with the high strain characteristic of polyurethane, so that the composite material has heat insulation performance and strain induction capacity, and combination of an electromagnetic wave absorbing material and novel intelligent wearable heat management equipment is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of wave-absorbing materials, and in particular relates to a self-repairing wave-absorbing composite material and a preparation method and application thereof. Background Art

[0002] With the rapid development of 5G communications, new energy vehicles, and smart wearable devices, the frequent electromagnetic pollution and the single function of absorbing materials have become increasingly prominent. Although the current research on electromagnetic wave absorbing materials has made progress in improving the absorption effect and bandwidth, it still faces multiple contradictions. On the one hand, traditional materials rely on non-renewable resources or highly polluting processes. For example, metal-based materials require high-temperature smelting, and the synthesis of carbon-based materials (such as graphene and carbon nanotubes) involves fossil raw materials and high energy consumption, which seriously deviates from the concept of green manufacturing. On the other hand, existing technologies are mostly limited to single performance optimization, which makes it difficult to meet the comprehensive requirements of electromagnetic absorption, mechanical durability, thermal management, and intelligent response capabilities of materials in complex application scenarios. Summary of the Invention

[0003] The purpose of the present invention is to provide a self-repairing wave-absorbing composite material and a preparation method and application thereof.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention provides a self-repairing wave-absorbing composite material, comprising a polyurethane matrix and a filler filled in the polyurethane matrix;

[0006] The filler is porous biochar loaded with manganese selenide;

[0007] The raw materials for preparing the polyurethane matrix include polyol, isocyanate and chain extender;

[0008] The chain extender includes at least one of 2,2'-diaminodiphenyl disulfide, 4,4'-dithiodiphenylamine, 4,4'-dihydroxydiphenyl disulfide and 1,2-ethanedithiol.

[0009] Preferably, the ratio of manganese selenide to porous biochar in the filler is 10 mmol: 1-2 g;

[0010] The raw material for preparing the porous biochar is biomass, and the biomass includes at least one of bamboo, fruit shells and straw.

[0011] Preferably, the mass percentage of the filler in the self-repairing wave-absorbing composite material is 1 to 10%.

[0012] Preferably, the polyol comprises at least one of polytetramethylene ether glycol, propylene oxide polyether glycol, polycaprolactone and polyethylene glycol;

[0013] The isocyanate includes at least one of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate.

[0014] Preferably, the method for preparing the porous biochar comprises the following steps:

[0015] adding biomass and potassium hydroxide into water for ultrasonic dispersion, and then drying to obtain alkali-treated biomass;

[0016] sintering the alkali-treated biomass to obtain the porous biochar;

[0017] The ratio of the biomass to potassium hydroxide is 16 g: 20 to 50 mmol;

[0018] The sintering temperature is 600-1200° C., and the sintering time is 1-6 hours.

[0019] The present invention also provides a method for preparing the self-repairing wave-absorbing composite material described in the above technical solution, comprising the following steps:

[0020] Dispersing a manganese source, a selenium source and a complexing agent in water, and then adding a reducing agent to react to obtain a precursor solution;

[0021] Mixing the precursor solution and porous biochar, and performing a hydrothermal reaction to obtain a filler;

[0022] Dissolving polyol and isocyanate in an organic solvent, then sequentially adding a catalyst and a chain extender to react to obtain a polyurethane prepolymer;

[0023] The filler and the polyurethane prepolymer are mixed, and the obtained system is allowed to stand and cured in sequence to obtain the self-repairing wave-absorbing composite material.

[0024] Preferably, the manganese source includes at least one of manganese sulfate, manganese nitrate and manganese carbonate; the selenium source includes at least one of elemental selenium, selenium dioxide and sodium selenite; the complexing agent includes at least one of citric acid, oxalic acid and ethylenediaminetetraacetic acid; the reducing agent includes at least one of hydrazine hydrate and ethylenediamine;

[0025] The molar ratio of the manganese source to the selenium source is 1:1-2;

[0026] The molar ratio of the manganese source to the complexing agent is 1:10-15;

[0027] The reaction is carried out under stirring, and the stirring time is 1 to 3 hours.

[0028] Preferably, the ratio of the manganese source to the porous biochar is 10 mmol: 1-2 g;

[0029] The temperature of the hydrothermal reaction is 160-200° C., and the time is 12-24 hours.

[0030] Preferably, the molar ratio of the polyol, isocyanate and chain extender is 1:1-5:1-10;

[0031] The catalyst includes dibutyltin dilaurate; the usage ratio of the polyol to the catalyst is 0.002 mol: 60-100 μL;

[0032] The dissolving in the organic solvent is carried out under stirring, and the stirring time is 1 to 3 hours;

[0033] The stirring temperature after adding the catalyst is 60-80°C and the stirring time is 2-6 hours;

[0034] The reaction temperature after adding the chain extender is 60-80° C. and the reaction time is 1-3 hours.

[0035] Preferably, the mass ratio of the filler to the polyurethane prepolymer is 1 to 10:100;

[0036] The filler and the polyurethane prepolymer are mixed under stirring conditions, wherein the stirring temperature is 60 to 80° C. and the stirring time is 1 to 3 hours;

[0037] The static method is vacuum static, and the static time is 12 to 48 hours;

[0038] The curing temperature is 60-80° C. and the curing time is 24-48 hours.

[0039] The present invention provides a self-repairing wave-absorbing composite material, comprising a polyurethane matrix and a filler filled in the polyurethane matrix; the filler is porous biochar loaded with manganese selenide; the raw materials for preparing the polyurethane matrix include polyol, isocyanate and a chain extender; the chain extender includes at least one of 2,2'-diaminodiphenyl disulfide, 4,4'-dithiodiphenylamine, 4,4'-dihydroxydiphenyl disulfide and 1,2-ethanedithiol.

[0040] The present invention uses porous biochar as a matrix to replace traditional carbon-based materials and construct a green and environmentally friendly matrix. At the same time, through the composite design of manganese selenide and biochar porous network, the problem of insufficient biochar loss mechanism is optimized, the magnetic-dielectric synergistic loss mechanism is realized, and efficient electromagnetic wave absorption performance is achieved by optimizing the filler. At the same time, a dynamic chemical bond disulfide bond is introduced into the polyurethane through a chain extender, giving the polyurethane matrix self-repairing ability, so that it can quickly restore mechanical properties under mild heating conditions, solving the problem that electromagnetic wave absorbing materials are prone to forming small aging cracks during use, effectively reducing maintenance costs, and ensuring that the electromagnetic wave absorbing coating provides all-round protection for electronic devices. At the same time, the inherent flexibility of polyurethane is also conducive to the adaptation of multiple scenarios and improves the environmental adaptability of the composite material. In addition, the conductive network of the filler is coupled with the high strain characteristics of the polyurethane, so that the composite material has thermal insulation performance and strain sensing ability, which is conducive to the combination of electromagnetic wave absorbing materials and new intelligent wearable thermal management equipment, helping absorbing materials to broaden application scenarios, and providing ideas for the design of a new generation of electromagnetic protection materials in emerging fields such as new energy vehicles and flexible electronics. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The SEM image of MnSe2 / BC-1 prepared in Example 1 and the wave absorption performance, thermal insulation performance, self-repairing and strain sensing performance of MnSe2 / BC / PU-1 are shown;

[0042] Figure 2 The following are the SEM images of MnSe2 / BC-2 prepared in Example 2 and the microwave absorption, thermal insulation, self-repair and strain sensing performance of MnSe2 / BC / PU-2;

[0043] Figure 3 These are the SEM images of MnSe2 / BC-3 prepared in Example 3 and the wave absorption performance, thermal insulation performance, self-repairing and strain sensing performance of MnSe2 / BC / PU-3. DETAILED DESCRIPTION

[0044] The present invention provides a self-repairing wave-absorbing composite material, comprising a polyurethane matrix and a filler filled in the polyurethane matrix;

[0045] The filler is porous biochar loaded with manganese selenide;

[0046] The raw materials for preparing the polyurethane matrix include polyol, isocyanate and chain extender;

[0047] The chain extender includes at least one of 2,2'-diaminodiphenyl disulfide, 4,4'-dithiodiphenylamine, 4,4'-dihydroxydiphenyl disulfide and 1,2-ethanedithiol.

[0048] In the present invention, the ratio of manganese selenide to porous biochar in the filler is preferably 10 mmol: 1-2 g. The porous biochar is preferably prepared from biomass, preferably including at least one of bamboo, fruit shells, and straw. In the present invention, the filler preferably comprises 1-10% by weight of the self-healing absorbing composite material, specifically 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0049] In the present invention, the method for preparing porous biochar preferably includes the following steps: ultrasonically dispersing biomass and potassium hydroxide in water, followed by drying to obtain alkali-treated biomass; and sintering the alkali-treated biomass to obtain the porous biochar. In the present invention, the water is preferably deionized water. The ratio of biomass to potassium hydroxide is preferably 16 g:20-50 mmol; and the ultrasonic dispersion time is preferably 1-3 hours. The drying temperature is preferably 60-80°C, and the time is preferably 12-48 hours. The sintering temperature is preferably 600-1200°C, and the time is preferably 1-6 hours. The sintering is preferably carried out under an inert atmosphere, preferably argon. After sintering, the resulting material is preferably washed and dried, preferably by alternating multiple centrifugal washes using anhydrous ethanol and deionized water. The drying temperature is preferably 60-80°C, and the time is preferably 12-8 hours.

[0050] In the present invention, the raw materials for preparing the polyurethane matrix include a polyol, an isocyanate, and a chain extender. The polyol preferably includes at least one of polytetramethylene glycol (PTMG), propylene oxide polyether glycol, polycaprol, and polyethylene glycol. The relative molecular weight of the polytetramethylene glycol is preferably 1000 (i.e., PTMG1000). The isocyanate preferably includes at least one of isophorone diisocyanate (IPDI), 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate. The chain extender includes at least one of 2,2'-diaminodiphenyl disulfide, 4,4'-dithiodiphenylamine, 4,4'-dihydroxydiphenyl disulfide, and 1,2-ethanedithiol. In the present invention, the molar ratio of the polyol, isocyanate, and chain extender is preferably 1:1 to 5:1 to 10.

[0051] The present invention also provides a method for preparing the self-repairing wave-absorbing composite material described in the above technical solution, comprising the following steps:

[0052] Dispersing a manganese source, a selenium source and a complexing agent in water, and then adding a reducing agent to react to obtain a precursor solution;

[0053] Mixing the precursor solution and porous biochar, and performing a hydrothermal reaction to obtain a filler;

[0054] Dissolving polyol and isocyanate in an organic solvent, then sequentially adding a catalyst and a chain extender to react to obtain a polyurethane prepolymer;

[0055] The filler and the polyurethane prepolymer are mixed, and the obtained system is allowed to stand and cured in sequence to obtain the self-repairing wave-absorbing composite material.

[0056] The invention disperses a manganese source, a selenium source and a complexing agent in water, then adds a reducing agent to react to obtain a precursor solution.

[0057] In the present invention, the manganese source preferably includes at least one of manganese sulfate, manganese nitrate, and manganese carbonate; the selenium source preferably includes at least one of elemental selenium, selenium dioxide, and sodium selenite; the complexing agent preferably includes at least one of citric acid, oxalic acid, and ethylenediaminetetraacetic acid; the reducing agent preferably includes at least one of hydrazine hydrate and ethylenediamine; and the water is preferably distilled water. In the present invention, the molar ratio of the manganese source to the selenium source is preferably 1:1-2; and the molar ratio of the manganese source to the complexing agent is preferably 1:10-15. In the present invention, when the reducing agent is hydrazine hydrate, the ratio of the manganese source to hydrazine hydrate is preferably 2 mmol:8-16 mL. In the present invention, the reaction is preferably carried out with stirring, and the stirring time is preferably 1-3 hours.

[0058] After obtaining the precursor solution, the present invention mixes the precursor solution with porous biochar and performs a hydrothermal reaction to obtain a filler.

[0059] In the present invention, the ratio of the manganese source to the porous biochar is 10 mmol: 1-2 g. The hydrothermal reaction temperature is preferably 160-200°C, specifically 160°C, 170°C, 180°C, 190°C, or 200°C. The reaction time is preferably 12-24 hours, specifically 12 hours, 16 hours, 20 hours, or 24 hours. The hydrothermal reaction is preferably carried out in a polytetrafluoroethylene-lined hydrothermal reactor. After the hydrothermal reaction, the resulting reaction system is preferably post-treated. The post-treatment preferably includes cooling the reaction system, filtering it, obtaining a precipitate, and washing and drying the precipitate. The washing method is preferably five washes with distilled water. The drying temperature is preferably 60-80°C, and the drying time is preferably 12-48 hours.

[0060] The invention dissolves polyol and isocyanate in an organic solvent, then sequentially adds a catalyst and a chain extender to react to obtain a polyurethane prepolymer.

[0061] In the present invention, the organic solvent preferably includes N,N-dimethylformamide; the ratio of the polyol to the organic solvent is preferably 0.002 mol:20 mL. In the present invention, the molar ratio of the polyol, isocyanate, and chain extender is preferably 1:1-5:1-10. In the present invention, the dissolution in the organic solvent is preferably carried out under stirring, and the stirring time is preferably 1-3 hours. In the present invention, the catalyst preferably includes dibutyltin dilaurate; the ratio of the polyol to the catalyst is preferably 0.002 mol:60-100 μL. In the present invention, the stirring temperature after adding the catalyst is preferably 60-80°C, and the stirring time is preferably 2-6 hours. The reaction is preferably carried out under stirring, and the reaction temperature after adding the chain extender is preferably 60-80°C, and the stirring time is preferably 1-3 hours.

[0062] After obtaining the filler and the polyurethane prepolymer, the present invention mixes the filler and the polyurethane prepolymer, and sequentially allows the obtained system to stand and solidify to obtain the self-repairing wave-absorbing composite material.

[0063] In the present invention, the mass ratio of the filler to the polyurethane prepolymer is preferably 1 to 10:100; the mixing of the filler and the polyurethane prepolymer is preferably carried out under stirring, the stirring temperature is preferably 60 to 80° C., and the time is preferably 1 to 3 hours; the standing method is preferably vacuum standing, and the standing time is preferably 12 to 48 hours; the curing temperature is preferably 60 to 80° C., and the time is preferably 24 to 48 hours.

[0064] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0065] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0066] Example 1

[0067] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 hour, and dried at 80°C for 48 hours to obtain alkali-treated bamboo.

[0068] The alkali-treated bamboo material was placed in a muffle furnace, sintered at 800° C. for 3 h in an argon atmosphere, then alternately centrifuged and washed with anhydrous ethanol and deionized water, and dried at 60° C. for 48 h to obtain porous biochar;

[0069] 2 mmol MnSO4, 4 mmol selenium powder and 25 mmol citric acid were dispersed in 44 mL distilled water, and then 16 mL hydrazine hydrate was added and magnetically stirred for 1 h until no obvious granular solids were present to obtain a precursor solution;

[0070] The obtained precursor solution and 0.26 g of porous biochar were placed in a hydrothermal reactor lined with polytetrafluoroethylene, and the reaction was carried out at 180°C for 12 h. After natural cooling, the product was filtered and washed alternately with deionized water five times. Finally, it was vacuum-dried at 80°C for 10 h to obtain a filler, which was recorded as MnSe2 / BC-1.

[0071] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL dibutyltin dilaurate was added, and the mixture was stirred at 80°C for 2 h; 0.002 mmol 2,2'-diaminodiphenyl disulfide was further added, and the mixture was stirred at 80°C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0072] 0.14 g of MnSe2 / BC-1 was added to the polyurethane prepolymer, heated and stirred at 80°C for 2 h to mix evenly, the mixed system was placed in a vacuum for 24 h, and finally cured at 80°C for 48 h to obtain a self-healing absorbing composite material, recorded as MnSe2 / BC / PU-1.

[0073] Example 2

[0074] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 hour, and dried at 80°C for 48 hours to obtain alkali-treated bamboo.

[0075] The alkali-treated bamboo material was placed in a muffle furnace, sintered at 800° C. for 3 h in an argon atmosphere, then alternately centrifuged and washed with anhydrous ethanol and deionized water, and dried at 60° C. for 48 h to obtain porous biochar;

[0076] 2 mmol MnSO4, 4 mmol selenium powder and 25 mmol citric acid were dispersed in 44 mL distilled water, and then 16 mL hydrazine hydrate was added and magnetically stirred for 1 h until no obvious granular solids were present to obtain a precursor solution;

[0077] The obtained precursor solution and 0.39 g of porous biochar were placed in a hydrothermal reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 180°C for 12 h. After natural cooling, the product was filtered and washed alternately with deionized water five times. Finally, it was vacuum-dried at 80°C for 10 h to obtain a filler, which was recorded as MnSe2 / BC-2.

[0078] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL dibutyltin dilaurate was added, and the mixture was stirred at 80°C for 2 h; 0.002 mmol 2,2'-diaminodiphenyl disulfide was further added, and the mixture was stirred at 80°C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0079] 0.14 g of MnSe2 / BC-2 was added to the polyurethane prepolymer, heated and stirred at 80°C for 2 h to mix evenly, the mixed system was placed in a vacuum for 24 h, and finally cured at 80°C for 48 h to obtain a self-healing absorbing composite material, recorded as MnSe2 / BC / PU-2.

[0080] Example 3

[0081] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 hour, and dried at 80°C for 48 hours to obtain alkali-treated bamboo.

[0082] The alkali-treated bamboo material was placed in a muffle furnace, sintered at 800° C. for 3 h in an argon atmosphere, then alternately centrifuged and washed with anhydrous ethanol and deionized water, and dried at 60° C. for 48 h to obtain porous biochar;

[0083] 2 mmol MnSO4, 4 mmol selenium powder and 25 mmol citric acid were dispersed in 44 mL distilled water, and then 16 mL hydrazine hydrate was added and magnetically stirred for 1 h until no obvious granular solids were present to obtain a precursor solution;

[0084] The obtained precursor solution and 0.26 g of porous biochar were placed in a hydrothermal reactor lined with polytetrafluoroethylene, and the reaction was carried out at 180°C for 12 h. After natural cooling, the product was filtered and washed alternately with deionized water five times. Finally, it was vacuum-dried at 80°C for 10 h to obtain a filler, which was recorded as MnSe2 / BC-3.

[0085] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL dibutyltin dilaurate was added, and the mixture was stirred at 80°C for 2 h; 0.002 mmol 2,2'-diaminodiphenyl disulfide was further added, and the mixture was stirred at 80°C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0086] 0.29 g of MnSe2 / BC-3 was added to the polyurethane prepolymer, heated and stirred at 80°C for 2 h to mix evenly, the mixed system was placed in a vacuum for 24 h, and finally cured at 80°C for 48 h to obtain a self-healing absorbing composite material, recorded as MnSe2 / BC / PU-3.

[0087] Comparative Example 1

[0088] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 hour, and dried at 80°C for 48 hours to obtain alkali-treated bamboo.

[0089] The alkali-treated bamboo material was placed in a muffle furnace, sintered at 800° C. for 3 h in an argon atmosphere, then alternately centrifuged and washed with anhydrous ethanol and deionized water, and dried at 60° C. for 48 h to obtain porous biochar;

[0090] 2 mmol MnSO4, 4 mmol selenium powder and 25 mmol citric acid were dispersed in 44 mL distilled water, and then 16 mL hydrazine hydrate was added and magnetically stirred for 1 h until no obvious granular solids were present to obtain a precursor solution;

[0091] The obtained precursor solution and 0.26 g of porous biochar were placed in a hydrothermal reactor lined with polytetrafluoroethylene, and the reaction was carried out at 180°C for 12 h. After natural cooling, the product was filtered, and the product was washed alternately with deionized water five times, and finally vacuum-dried at 80°C for 10 h to obtain the absorbing material.

[0092] After testing, the minimum reflection loss of the absorbing material at 3.12mm and 12.063GHz is -15.72dB, and the effective absorption bandwidth is 0.494GHz.

[0093] Comparative Example 2

[0094] 50 mmol of potassium hydroxide was mixed with 16 g of bamboo powder, added to deionized water, ultrasonically dispersed at 60°C for 1 hour, and dried at 80°C for 48 hours to obtain alkali-treated bamboo.

[0095] The alkali-treated bamboo material was placed in a muffle furnace, sintered at 800° C. for 3 h in an argon atmosphere, then alternately centrifuged and washed with anhydrous ethanol and deionized water, and dried at 60° C. for 48 h to obtain porous biochar;

[0096] 2 mmol MnSO4, 4 mmol selenium powder and 25 mmol citric acid were dispersed in 44 mL distilled water, and then 16 mL hydrazine hydrate was added and magnetically stirred for 1 h until no obvious granular solids were present to obtain a precursor solution;

[0097] The obtained precursor solution and 0.52 g of porous biochar were placed in a hydrothermal reactor lined with polytetrafluoroethylene, and the reaction was carried out at 180°C for 12 h. After natural cooling, the product was filtered and washed alternately with deionized water five times. Finally, it was vacuum-dried at 80°C for 10 h to obtain a filler, which was recorded as MnSe2 / BC-4.

[0098] 0.002 mmol PTMEG1000 and 0.004 mmol IPDI were dissolved in 20 mL DMF, stirred for 1 h, 80 μL dibutyltin dilaurate was added, and the mixture was stirred at 80°C for 2 h; 0.002 mmol 2,2'-diaminodiphenyl disulfide was further added, and the mixture was stirred at 80°C for 2 h to obtain 3.329 g of polyurethane prepolymer;

[0099] 0.14 g of MnSe2 / BC-4 was added to the polyurethane prepolymer, heated and stirred at 80°C for 2 h to mix evenly, the mixed system was placed in a vacuum for 24 h, and finally cured at 80°C for 48 h to obtain a self-healing absorbing composite material, recorded as MnSe2 / BC / PU.

[0100] After testing, the minimum reflection loss of the MnSe2 / BC / PU-4 absorbing material at 10.12 GHz at a distance of 2.98 mm is -12.31 dB, and the effective absorption bandwidth is 0.508 GHz.

[0101] Comparative Example 3

[0102] Filler and polyurethane prepolymer were prepared in the same manner as in Example 1;

[0103] 0.59 g of filler was added to 3.329 g of polyurethane prepolymer, heated and stirred at 80° C. for 2 h, and uniformly mixed. The mixed system was placed in a vacuum for 24 h, and finally cured at 80° C. for 48 h to obtain a composite absorbing material.

[0104] After testing, the minimum reflection loss of the composite material at 12.01GHz at 2.66mm is -24.75dB, the effective absorption bandwidth is 0.83GHz, the self-repair effect is 92.2%, the thermal insulation effect is 33.2%; the strain sensing sensitivity GF = 0.519.

[0105] Performance Testing

[0106] Test Example 1

[0107] Figure 1 The SEM image of MnSe2 / BC-1 prepared in Example 1 and the wave absorption performance, thermal insulation performance, self-repair and strain sensing performance of MnSe2 / BC / PU-1 are shown;

[0108] Figure 1 (a) is the SEM image of MnSe2 / BC-1, which shows the pore structure of the activated porous biochar and MnSe2 attached to the surface of the porous biochar in a cubic shape;

[0109] Figure 1(b) is the three-dimensional reflection loss diagram of MnSe2 / BC / PU-1. The minimum reflection loss is -13.98dB at 2.95mm and 12.022GHz, and the effective absorption bandwidth is 0.168GHz.

[0110] Figure 1 (c) is the temperature change curve of MnSe2 / BC / PU-1 placed on a 100℃ hot stage. The top insulation equilibrium temperature is only 82.3℃, and the insulation effect reaches 17.7% (the percentage of the reduced temperature to the hot stage temperature);

[0111] Figure 1 (d) is a stress-strain diagram of MnSe2 / BC / PU-1 after being cut with a knife and then repaired at 80°C for 3 hours. The strain repair effect (the ratio of the elongation at break before and after repair) is 93.8%;

[0112] Figure 1 (e) is the resistance change rate of MnSe2 / BC / PU-1 under 100% strain, and the sensitivity reaches 0.427;

[0113] Figure 1 (f) is the resistance sensing signal generated by MnSe2 / BC / PU-1 when the finger is bent 90°. It can be seen that the relative resistivity changes greatly, reaching a maximum of 4.7, and similar electrical signals are generated in the three bends, indicating stable signal transmission.

[0114] Test Example 2

[0115] Figure 2 The SEM image of MnSe2 / BC-2 prepared in Example 2 and the wave absorption performance, thermal insulation performance, self-repair and strain sensing performance of MnSe2 / BC / PU-2 are shown;

[0116] Figure 2 (a) is the SEM image of MnSe2 / BC-2, which shows that the content of active porous biochar increases and MnSe2 adheres to the surface of porous biochar;

[0117] Figure 2 (b) is the three-dimensional reflection loss diagram of MnSe2 / BC / PU-2. The minimum reflection loss is -25.76dB at 2.45mm and 12.106GHz, and the effective absorption bandwidth is 1.241GHz.

[0118] Figure 2 (c) is the temperature change curve of MnSe2 / BC / PU-2 placed on a 100℃ hot plate. The top insulation equilibrium temperature is only 74.3℃, and the insulation effect reaches 25.7%;

[0119] Figure 2(d) is the stress-strain diagram of MnSe2 / BC / PU-2 after being cut with a knife and then repaired at 80℃ for 3h, where the strain repair effect is 93.4%;

[0120] Figure 2 (e) is the resistance change rate of MnSe2 / BC / PU-2 under 100% strain, and the sensitivity reaches 0.412;

[0121] Figure 2 (f) is the resistance sensing signal generated by MnSe2 / BC / PU-2 when the finger is bent 90°. It can be seen that the relative resistivity changes greatly, reaching a maximum of 4.1. Similar electrical signals are generated in the three bendings, and the signal transmission is stable.

[0122] Test Example 3

[0123] Figure 3 The following are the SEM images of MnSe2 / BC-3 prepared in Example 3 and the microwave absorption performance, thermal insulation performance, self-repair and strain sensing performance of MnSe2 / BC / PU-3;

[0124] Figure 3 (a) is the SEM image of MnSe2 / BC-3. It can be seen that the pores of the activated porous biochar continue to increase, and the amount of MnSe2 attached to the surface of the porous biochar increases;

[0125] Figure 3 (b) is the three-dimensional reflection loss diagram of MnSe2 / BC / PU-3. The minimum reflection loss is -41.53dB at 3.95mm and 8.221GHz, and the effective absorption bandwidth is 1.271GHz.

[0126] Figure 3 (c) is the temperature change curve of MnSe2 / BC / PU-3 placed on a 100℃ hot plate. The top insulation equilibrium temperature is only 69.9℃, and the insulation effect reaches 31.1%;

[0127] Figure 3 (d) is the stress-strain diagram of MnSe2 / BC / PU-3 after being cut with a knife and then repaired at 80℃ for 3h, where the strain repair effect is 90.7%;

[0128] Figure 3 (e) is the resistance change rate of MnSe2 / BC / PU-3 under 100% strain, and the sensitivity reaches 0.522;

[0129] Figure 3(f) is the resistance sensing signal generated by MnSe2 / BC / PU-3 when the finger is bent 90°. It can be seen that the relative resistivity changes greatly, reaching a maximum of 5.6. Similar electrical signal peaks are generated in the three bendings, and the signal transmission is stable.

[0130] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A self-repairing wave-absorbing composite material, characterized in that: The invention comprises a polyurethane matrix and a filler filled in the polyurethane matrix; The filler is porous biochar loaded with manganese selenide; The raw materials for preparing the polyurethane matrix include polyol, isocyanate and chain extender; The chain extender includes at least one of 2,2'-diaminodiphenyl disulfide, 4,4'-dithiodiphenylamine, 4,4'-dihydroxydiphenyl disulfide and 1,2-ethanedithiol.

2. The self-repairing wave-absorbing composite material according to claim 1, characterized in that: The ratio of manganese selenide to porous biochar in the filler is 10 mmol: 1-2 g; The raw material for preparing the porous biochar is biomass, and the biomass includes at least one of bamboo, fruit shells and straw.

3. The self-repairing wave-absorbing composite material according to claim 1 or 2, characterized in that: The mass percentage of the filler in the self-repairing wave-absorbing composite material is 1-10%.

4. The self-repairing wave-absorbing composite material according to claim 1, characterized in that: The polyol comprises at least one of polytetramethylene ether glycol, propylene oxide polyether glycol, polycaprolactone and polyethylene glycol; The isocyanate includes at least one of isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate.

5. The self-repairing wave-absorbing composite material according to claim 1, characterized in that: The method for preparing the porous biochar comprises the following steps: adding biomass and potassium hydroxide into water for ultrasonic dispersion, and then drying to obtain alkali-treated biomass; sintering the alkali-treated biomass to obtain the porous biochar; The ratio of the biomass to potassium hydroxide is 16 g: 20 to 50 mmol; The sintering temperature is 600-1200° C., and the sintering time is 1-6 hours.

6. The method for preparing the self-repairing wave-absorbing composite material according to any one of claims 1 to 5, characterized in that: The following steps are involved: Dispersing a manganese source, a selenium source and a complexing agent in water, and then adding a reducing agent to react to obtain a precursor solution; Mixing the precursor solution and porous biochar, and performing a hydrothermal reaction to obtain a filler; Dissolving polyol and isocyanate in an organic solvent, then sequentially adding a catalyst and a chain extender to react to obtain a polyurethane prepolymer; The filler and the polyurethane prepolymer are mixed, and the obtained system is allowed to stand and cured in sequence to obtain the self-repairing wave-absorbing composite material.

7. The preparation method according to claim 6, characterized in that The manganese source includes at least one of manganese sulfate, manganese nitrate and manganese carbonate; the selenium source includes at least one of elemental selenium, selenium dioxide and sodium selenite; the complexing agent includes at least one of citric acid, oxalic acid and ethylenediaminetetraacetic acid; the reducing agent includes at least one of hydrazine hydrate and ethylenediamine; The molar ratio of the manganese source to the selenium source is 1:1-2; The molar ratio of the manganese source to the complexing agent is 1:10-15; The reaction is carried out under stirring, and the stirring time is 1 to 3 hours.

8. The preparation method according to claim 6, characterized in that The ratio of the manganese source to the porous biochar is 10 mmol: 1-2 g; The temperature of the hydrothermal reaction is 160-200° C., and the time is 12-24 hours.

9. The preparation method according to claim 6, characterized in that The molar ratio of the polyol, isocyanate and chain extender is 1:1-5:1-10; The catalyst includes dibutyltin dilaurate; the usage ratio of the polyol to the catalyst is 0.002 mol: 60-100 μL; The dissolving in the organic solvent is carried out under stirring, and the stirring time is 1 to 3 hours; The stirring temperature after adding the catalyst is 60-80°C and the stirring time is 2-6 hours; The reaction temperature after adding the chain extender is 60-80° C. and the reaction time is 1-3 hours.

10. The preparation method according to claim 6, characterized in that The mass ratio of the filler to the polyurethane prepolymer is 1 to 10:100; The filler and the polyurethane prepolymer are mixed under stirring conditions, wherein the stirring temperature is 60 to 80° C. and the stirring time is 1 to 3 hours; The static method is vacuum static, and the static time is 12 to 48 hours; The curing temperature is 60-80° C. and the curing time is 24-48 hours.

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