CN115999460A - Reversible fire early warning composite aerogel and preparation method thereof - Google Patents
Reversible fire early warning composite aerogel and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a reversible fire early warning composite aerogel and a preparation method thereof, wherein the reversible fire early warning composite aerogel is a magnetic graphene oxide/expanded graphite/biomass matrix composite aerogel, and a three-dimensional network structure is constructed by uniformly dispersing functional bodies of the composite aerogel in a biomass aqueous solution matrix and utilizing intermolecular hydrogen bond crosslinking; make full use of Fe 3 O 4 The reversible resistance-temperature response characteristic of the nano particles and the semiconductor behavior of the fire disaster early warning in cooperation with graphene oxide, the expanded graphite expands at high temperature to the char formation characteristics of the heat insulation layer and the biomass matrix, so that the reversible fire disaster early warning composite aerogel with excellent flame retardant property and capability of breaking through the limit of single temperature monitoring is prepared, and meanwhileThe friction nano generator can be used as an anode friction material to construct a friction nano generator, self-power in an early warning process is realized, fire safety performance of the friction nano generator can be further improved, and application in fields of high-rise buildings, chemical industry, electricity, fire protection and the like is widened.
Description
Technical Field
The invention relates to the technical field of functional nano composite materials, in particular to a reversible fire early warning composite aerogel and a preparation method thereof.
Background
In recent years, fire accidents caused by organic combustible materials occur in the fields of lithium batteries, high-rise building heat preservation, electric and the like, and huge life and property losses are caused, so that more stringent requirements are put on fire safety performance of application materials. Aerogel becomes an ideal substitute for traditional combustible materials by virtue of ultra-light, high porosity and excellent heat insulation performance, and has wide application potential in the fields of petrochemical industry, military industry, aerospace, chemical engineering, construction, batteries, environmental protection, traffic and the like. However, the organic aerogel has a certain fire hazard, which severely limits the practical application in the above fields, so that the improvement of the fireproof safety performance is imperative. Research shows that the flame retardant property of the organic aerogel can be obviously improved by adding inorganic fillers such as layered montmorillonite, sodium bicarbonate, expanded graphite, graphene and the like, so that the preparation of the flame retardant aerogel is a basic strategy for improving the fire safety performance of the flame retardant aerogel. In addition, by monitoring the change of resistance, temperature, smoke concentration or infrared intensity, before a fire disaster occurs, a fire disaster prevention gateway can be moved forward by triggering an early warning signal by a specific functional material, and the aerogel is endowed with sensitive fire disaster early warning capability, so that the fire disaster prevention gateway is an effective way for further improving fire disaster safety performance.
At present, the research of a flame-retardant aerogel system is systematic and perfect, and the early warning aerogel research of a higher fire safety performance grade is in an initial stage. Since 2020, "An ultrasensitive fire-rolling chirosan/montmorillonite/carbon nanotube composite aerogel with high fire-resistance". Chem.eng.j., "399 (2020) 125729 and" Flame-retardant cellulose nanofiber aerogel modified with graphene oxide and sodium montmorillonite and its fire-alarm application ". Polym.adv.technology., 32 (2021) 1877-1887. Researchers have reported thermal reduction based on carbon-based nanomaterials such as carbon nanotubes, graphene oxide, etc., respectively, for the first time, carbon-based composite aerogels capable of achieving rapid temperature response at high temperature/early stage of fire were prepared, but the type of aerogels have no more change in resistance once thermal reduction occurs at high temperature, lacking repeatable temperature monitoring capability; and when the aerogel is used as a temperature sensor, the aerogel generally needs to be powered by an external power supply, the external power supply is easy to damage at high temperature, the failure of a fire alarm material due to power interruption can be caused, the aerogel capable of giving an alarm against fire is prepared, and the aerogel still faces a great challenge for constructing a self-powered sensor.
Chinese patent publication CN114210276a discloses a magnetic carbon-based composite aerogel having both fire early warning and flame retardance and a preparation method thereof, and the prepared magnetic carbon-based composite aerogel has both fire early warning and flame retardance characteristics by reasonable setting, but does not have the characteristic of reversible fire early warning.
Disclosure of Invention
Aiming at the current situation that the carbon-based composite aerogel in the prior art can only realize single high temperature/early-stage rapid response of fire, constructing a sensor capable of repeatedly monitoring temperature and achieving self power supply still faces challenges, the invention aims to provide the reversible fire early-warning composite aerogel and the preparation method thereof.
In order to achieve the aim of the invention, the technical scheme of the invention is as follows:
the composite aerogel for early warning the reversible fire is prepared by self-assembling a 3D structure through intermolecular hydrogen bond crosslinking of a magnetic graphene oxide nano sheet, an expanded graphite nano sheet and a biomass matrix and then freeze-drying.
The magnetic graphene oxide nanosheets are magnetic Fe 3 O 4 Nanoparticle modified graphene oxide nanoplatelets.
The expanded graphite nano sheet can instantaneously expand 100-250 times in volume at high temperature, and becomes vermiform from sheet shape, so that a good heat insulation layer is formed.
The biomass matrix is one or more of carboxymethyl chitosan, hydroxypropyl methylcellulose, cellulose nanofiber and sodium alginate.
Preferably, the magnetization graphene oxide nano-sheets account for 10-60 wt% of the reversible fire early warning composite aerogel, wherein the magnetization graphene oxide nano-sheets account for magnetic Fe 3 O 4 The content of the nano particles is that the graphene oxide sheets can grow and/or graft magnetic Fe 3 O 4 An upper limit of the nanoparticle; the mass ratio of the expanded graphite nano-sheets in the reversible fire early warning composite aerogel is 0.5-6wt%.
Preferably, the magnetic Fe 3 O 4 The nano particles and the expanded graphite nano sheets are flame-retardant functional bodies in the reversible fire early warning composite aerogel, and play roles of catalytic carbonization and expansion physical barrier respectively; the expanded graphite nano-sheets and the biomass matrix are used as carbon sources to form a stable compact carbon layer.
Preferably, the composite aerogel for early warning against reverse fire is the composite aerogel for early warning against reverse fire according to any one of claims 1 to 3, and the preparation method comprises the following steps:
(1) Magnetization modification of graphene oxide nanoplatelets:
grafting magnetic Fe by utilizing reaction between functional groups 3 O 4 Nanoparticle or coprecipitation in situ growth of magnetic Fe 3 O 4 One of two methods of nanoparticle yields magnetic graphene oxide nanoplatelets.
The magnetic Fe is grafted by utilizing the reaction between functional groups 3 O 4 The method of the nano-particles comprises the following steps: for existing magnetic Fe by silane ligand exchange 3 O 4 Amino modification is carried out on the surfaces of the nano particles, and magnetic Fe is utilized 3 O 4 The magnetic graphene oxide nanosheets are obtained by magnetization modification through the reaction between the nanoparticle and carboxyl functional groups on the surface of the graphene oxide nanosheets; the magnetic Fe 3 O 4 The size of the nano particles is 10-200 nm.
The coprecipitation in-situ growth of magnetic Fe 3 O 4 The method of the nano-particles comprises the following steps: adding Fe into graphene oxide dispersion liquid 2+ And Fe (Fe) 3+ The precursor of the magnetic graphene oxide nano-sheet is generated in situ by coprecipitation under the heating condition through alkaline catalysis.
(2) Preparing the composite aerogel for early warning of backfire: adding expanded graphite nano-sheets accounting for 1.12-17.65 wt% of the mass of the biomass matrix aqueous solution and magnetic graphene oxide nano-sheets prepared in the step (1) accounting for 11.2-176.5 wt% of the mass of the biomass matrix aqueous solution into the biomass matrix aqueous solution under the conditions that the ultrasonic frequency is 38-42 KHz (preferably 40 KHz) and the temperature is 22-28 ℃ (preferably 25 ℃), wherein the mass ratio of the magnetic graphene oxide nano-sheets to the expanded graphite nano-sheets is (20-5): 1; performing ultrasonic dispersion for 0.5-1 h, realizing three-dimensional network structure construction by using intermolecular hydrogen bond induced self-assembly, performing aging treatment for 2-6 h, and performing freeze-drying treatment at-20 to (-80) DEG C for 12-24 h to obtain the reversible fire early warning composite aerogel.
Preferably, the grafting of magnetic Fe by the reaction between functional groups 3 O 4 The nanoparticle method comprises the following steps:
i, mixing 0.18-0.22M sodium oleate aqueous solution and 0.18-0.22M anhydrous ferric trichloride aqueous solution according to the volume ratio of 1 (0.9-1.1), fully stirring to generate reddish brown precipitate, filtering, washing with deionized water, drying in a vacuum oven, drying to obtain wax, dissolving the obtained wax in ethanol, adding oleic acid into ethanol with the volume of 55-65% of the sodium oleate aqueous solution, uniformly mixing, transferring the mixture into a polytetrafluoroethylene autoclave with the addition of 8-12% of the ethanol volume, reacting for 4-6 h at the temperature of 175-185 ℃, washing with absolute ethanol, separating with a magnet, and dispersing the separated substance in toluene to obtain Fe 3 O 4 Nanoparticle toluene dispersion.
II, modifying by silane ligand exchange method, namely under the condition of ultrasonic frequency of 38-43 KHz (preferably 40 KHz) and temperature of 21-28 ℃ (preferably 25 ℃), adding Fe obtained in step I 3 O 4 Adding 0.4-0.6% of aminosilane and 0.008-0.015% of acetic acid into the nanoparticle toluene dispersion liquid, and carrying out ultrasonic treatment for 15-30min; then stirring and reacting for 22-48 h at room temperature; then washing with toluene, separating with magnet, and freeze drying to obtain amino modified magnetic Fe 3 O 4 A nanoparticle; realizing the exchange of silane ligand to the existing magnetic Fe 3 O 4 The surface of the nano-particles is modified by amino groups.
III then amino-modified magnetic Fe using step II 3 O 4 Magnetization modification is realized through the reaction between the nano particles and carboxyl functional groups on the surface of the graphene oxide nano sheet, and the magnetic graphene oxide nano sheet is obtained.
The amino-modified magnetic Fe 3 O 4 The reaction between the carboxyl functional groups on the surfaces of the nano particles and the graphene oxide nano sheets is preferably as follows: uniformly dispersing graphene oxide nano-sheets in water by ultrasonic (preferably, for example, the two graphene oxide nano-sheets are dispersed in 50mL of water according to the ratio of each g of graphene oxide nano-sheets), adding 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) (preferably, the two graphene oxide nano-sheets are in the ratio of 1.5-2.5:1), performing normal-temperature activation reaction for 10-18 min, and adding the amino-modified magnetic Fe prepared in the step II into the mixture 3 O 4 The nano particles (the adding proportion is preferably 8-12 wt percent of the graphene oxide nano sheet) are subjected to ultrasonic reaction for 10-15 hours, so that the magnetic carbon nano tube (namely the magnetic graphene oxide nano sheet) is prepared.
Preferably, the aminosilane is one or more of 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3- (2-aminoethylamino) propyl trimethoxysilane, 4-aminobutyl dimethylmethoxysilane, 4-aminobutyl triethoxysilane, 3- [ (2-aminoethylamino) propyl ] dimethoxysilane, and (3-aminopropyl) dimethylethoxysilane.
Preferably, the coprecipitation in-situ growth of magnetic Fe 3 O 4 The method of the nano-particles comprises the following steps: under the magnetic stirring with the rotating speed of 500-800rpm, the graphene oxide nano-sheets are ultrasonically dispersed in the deionized waterObtaining graphene oxide dispersion liquid in the sub-water, wherein graphene oxide nano-sheets are obtained by the method: deionized water (1.5-2.5 g): (48-52) mL; then inert gas is introduced to deoxidize for 1.8 to 2.2 hours, and then Fe with the mole ratio of (1.5 to 2.5) 1 is added in the deionized water with the volume of 0.8 to 1.5 percent 3+ And Fe (Fe) 2+ Stirring for 2-5 h at room temperature under the protection of inert gas, then heating to 70-90 ℃, then adding ammonia water to adjust the pH value of the solution to 9-12, and continuously keeping the temperature of 70-90 ℃ for reacting for 1-2 h to obtain the magnetic graphene oxide nano-sheet.
Preferably, the inert gas is N 2 。
Preferably, the mass ratio of the magnetic graphene oxide nano-sheets to the expanded graphite nano-sheets is 10:1.
The application of the reversible fire early warning composite aerogel is in the fields of fire alarms of high-rise buildings, flame retardance, heat insulation and fire protection; the reversible fire early-warning composite aerogel is prepared from the reversible fire early-warning composite aerogel or the preparation method.
Preferably, the application is to use magnetic Fe with reversible resistance-temperature response 3 O 4 The nano particles are used as fire early warning functional bodies, and graphene oxide nano sheets with single heat reduction and multiple heat conduction characteristics are used as Fe 3 O 4 The carrier of the composite aerogel for the reversible fire early warning can be realized by breaking through the limit of single temperature monitoring under the synergistic effect, and the composite aerogel for the reversible fire early warning can not trigger the fire early warning and light the early warning lamp under the normal state; when first subjected to fire or high temperature, magnetic Fe 3 O 4 The resistance of the nano particles is reduced, and meanwhile, the resistance of the graphene oxide nano sheet is rapidly reduced due to the removal of functional groups by thermal reduction, so that the resistance and current change in a closed circuit are obvious, and then the early warning and/or the early warning lamp is triggered and/or lightened; when the Nth fire disaster occurs and the high temperature is received, wherein N is more than or equal to 2, magnetic Fe 3 O 4 Nanoparticle resistance remains reversibly reduced, while graphene sheets only provide a conduction path for continuous electrons, in turn assisting magnetic Fe 3 O 4 Nanometer particleThe particles realize repeated fire early warning and/or light up the early warning lamp.
The composite aerogel for early warning of the reversible fire disaster has excellent flame retardant property, wherein: the inorganic Fe 3 O 4 The nano particles and the expanded graphite nano sheets are used as flame-retardant functional bodies to respectively play roles of catalytic carbonization and lamellar physical barrier; the biomass matrix such as cellulose is favorable for forming carbon, and a stable compact carbon layer is formed; the components cooperate to improve the flame retardant property. The excellent flame retardant property is the basis of the material capable of fire disaster early warning, and for the purposes of rapid flame detection and fire disaster early warning response, the material has thermal stability and flame retardance in the detection process, otherwise, timely and reliable warning cannot be realized.
The reversible fire early warning composite aerogel has repeatable temperature monitoring performance and reversible resistance-temperature response Fe 3 O 4 The nano particles are used as fire early warning functional bodies, and graphene oxide nano sheets with single heat reduction and multiple heat conduction characteristics are used as Fe 3 O 4 The carrier and the synergy break through the limit of single temperature monitoring. Under the normal state, the composite aerogel can not trigger fire early warning and light an early warning lamp; when first subjected to fire/high temperature, fe 3 O 4 The resistance of the nano particles is reduced, meanwhile, the resistance of the graphene oxide for removing the functional groups is rapidly reduced due to the thermal reduction effect, the resistance/current change in a closed circuit obviously triggers early warning, and an early warning lamp is lightened; fe in the N (N is more than or equal to 2) th fire disaster/high temperature state 3 O 4 The resistance of the nano particles is still reduced reversibly, and the graphene sheets are only responsible for providing continuous electron conduction paths to assist Fe 3 O 4 The nano particles realize repeated fire early warning, and the early warning lamp is lightened.
A reversible fire early warning performance test scheme of the reversible fire early warning composite aerogel is influenced by a non-constant resistance change rule of graphene oxide, a reasonable test method is required to be designed, a three-step test scheme is selected, and the method specifically comprises the steps of firstly measuring 3 aerogel splines (GO-Fe by using a four-probe resistivity meter 3 O 4 GO only and Fe only 3 O 4 ) A resistance-temperature response curve in the range of 30-400 ℃;secondly, placing the spline in a heating plate for alternately heating (300 ℃) and cooling (room temperature), measuring an output current curve by using a digital multimeter, characterizing the reversibility of resistance-temperature response, and setting a reasonable trigger early warning resistance value; finally, a complete loop comprising aerogel sample strips, an alarm indicator lamp and a power supply is designed, the sample strips are exposed to the flame of the alcohol lamp in a period of 20s or 40s, and the current change and the lighting condition of the alarm lamp are recorded.
The invention has the technical effects that:
according to the invention, through reasonably and specifically setting the composition of each component for early warning of the reversible fire and the production parameters of each step in the preparation method, the series of composite aerogel is prepared, the internal relation of material composition, structure and performance is established, and the performance is used as a guide to realize the optimization design of aerogel preparation parameters and process.
The invention sets the composition of the specific product by exploring the fire-retarding and reversible fire early-warning mechanism and revealing the mechanism for generating the performance from the molecular level, further improves the fire safety performance of aerogel materials, and can be applied to the fields of fire alarms, fire retarding, heat insulation, fire protection and the like of high-rise buildings.
Drawings
Fig. 1 is a schematic structural diagram of a reversible fire early warning composite aerogel (magnetic graphene oxide/expanded graphite/biomass matrix).
Fig. 2 is a fire early warning schematic diagram of a reversible fire early warning composite aerogel.
FIG. 3 is a schematic diagram of repeatable temperature monitoring of a reversible fire early warning composite aerogel.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to examples. It is to be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the present invention. Various modifications and alterations of this invention may be made by those skilled in the art without departing from the spirit and scope of this invention.
The experimental methods used in the following examples are conventional methods unless otherwise specified. Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
Example 1
The embodiment provides a preparation method of graphene oxide in-situ magnetization modified composite aerogel with high fire safety performance and reversible fire early warning, which has a preparation structure shown in figure 1 and specifically comprises the following steps:
(1) Preparation of magnetic graphene oxide nanosheets
Synthesized by a coprecipitation method, specifically, 2g of graphene oxide nano sheets are dispersed in 50mL of deionized water by ultrasonic, and N is introduced 2 After deoxygenation for 2h, 0.5mL of Fe was added thereto in a molar ratio of 2:1 3+ /Fe 2+ Namely (1.6 g FeCl) 3 ·6H 2 O and 0.93g FeSO 4 ·7H 2 O)，N 2 Stirring for 5 hours at room temperature under protection, heating to 80 ℃, adding ammonia water, adjusting the pH value of the solution to be 12, finishing the reaction for 1 hour, collecting the magnet, and washing 3 times with deionized water to obtain the magnetic graphene oxide nano-sheet, wherein the mark is GO@Fe 3 O 4 。
(2) Preparation of reversible fire early warning composite aerogel
3g of cellulose nanofibers were dispersed in 6mL of deionized water and sonicated to make them uniformly dispersed. To which 0.5g of GO@Fe are added, respectively 3 O 4 And 0.25g of expanded graphite nano-sheet, and carrying out ultrasonic reaction for 2 hours. And then aging the obtained crosslinked hydrogel for 3 hours at room temperature, and freeze-drying (-45 ℃ and 260 Pa) for 18 hours to prepare the reversible fire early warning composite aerogel.
Example 2
The embodiment provides a preparation method of graphene oxide grafted magnetic particle modified composite aerogel with high-fire safety performance and reversible fire disaster early warning, which comprises the following preparation processes:
(1)Fe 3 O 4 nanoparticle preparation
100mL of aqueous sodium oleate (0.2M) was mixed with 100mL of anhydrous ferric trichloride (0.2M), thoroughly stirred to produce a reddish brown precipitate, filtered, rinsed with deionized water and dried in a vacuum oven. The dried wax is dissolved in 60mL of ethanol, 6mL of oleic acid is added for uniform mixing, and the mixture is transferred to a polytetrafluoroethylene high-pressure reaction kettle for reaction for 5h at 180 ℃. Washing with absolute ethyl alcohol, separating by magnet, and dispersing in toluene for standby.
(2)Fe 3 O 4 Nanoparticle surface amino modification
Modified by silane ligand exchange, i.e. 100mL Fe 3 O 4 To a toluene dispersion of the nanoparticles (0.1 g) were added 0.5% (v/v) 3-aminopropyl triethoxysilane and 0.01% (v/v) acetic acid, and the mixture was stirred at room temperature to react for 24 hours. Washing with toluene, separating with magnet, and freeze drying to obtain Fe 3 O 4 @NH 2 。
(3) Preparation of magnetic graphene oxide nanosheets
1g graphene oxide nano-sheets are evenly dispersed in 50mL of water by ultrasonic, 0.62g 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC) and 0.31g N-hydroxysuccinimide (NHS) are added into the water, and after the activation reaction is carried out for 15min at normal temperature, 0.1g Fe is added into the water 3 O 4 @NH 2 The nano particles are subjected to ultrasonic reaction for 12 hours to prepare the magnetic carbon nano tube, and the magnetic carbon nano tube is marked as GO@Fe 3 O 4 。
(4) Preparation of reversible fire early warning composite aerogel
3g of cellulose nanofibers were dispersed in 6mL of deionized water and sonicated to make them uniformly dispersed. To which 0.75g of GO@Fe are added, respectively 3 O 4 And 0.375g of expanded graphite nanoplatelets, and performing ultrasonic reaction for 2 hours. Subsequently, the resulting crosslinked hydrogel was aged at room temperature for 3 hours, and freeze-dried (-45 ℃,260 Pa) for 18 hours to prepare a composite aerogel.
Application example
The reversible fire early warning composite aerogel fully utilizes Fe 3 O 4 Reversible resistance-temperature response characteristics of nanoparticles, fe 3 O 4 The single thermal reduction and multiple thermal conduction characteristics of the graphene oxide nanosheets of the carrier break through the limit of single temperature monitoring. In a normal state, the composite aerogel does not trigger fire early warning and lights an early warning lamp (shown as a in fig. 2); when first subjected to fire/high temperature, fe 3 O 4 The resistance of the nano particles is reduced, and meanwhile, graphene oxide is returned due to heatThe resistance of the original functional groups removed is sharply reduced, the resistance/current change in the closed circuit obviously triggers early warning, and an early warning lamp is lightened (shown as b1 in fig. 2); fe in the N (N is more than or equal to 2) th fire disaster/high temperature state 3 O 4 The resistance of the nano particles is still reduced reversibly, and the graphene sheets are only responsible for providing continuous electron conduction paths to assist Fe 3 O 4 The nanoparticles realize repeated fire early warning, and the early warning lamp is lighted (shown as b2 in fig. 2).
The application example provides a reversible fire early warning performance characterization scheme of the composite aerogel with high fire safety performance, which is influenced by the non-constant resistance change rule of graphene oxide, a reasonable test method is required to be designed, a three-step test scheme is selected, and the method specifically comprises the steps of firstly measuring 3 aerogel splines (GO-Fe by using a four-probe resistivity meter 3 O 4 GO only and Fe only 3 O 4 ) A resistance-temperature response curve in the range of 30-400 ℃; secondly, placing the spline in a heating plate for alternately heating (300 ℃) and cooling (room temperature), measuring an output current curve by using a digital multimeter, characterizing the reversibility of resistance-temperature response, and setting a reasonable trigger early warning resistance value; finally, a complete loop comprising aerogel sample strips, an alarm indicator lamp and a power supply is designed, the sample strips are exposed to the flame of the alcohol lamp in a period of 20s or 40s, and the current change and the lighting condition of the alarm lamp are recorded. The experimental result is obviously different from the single change of the current of the graphene-based aerogel and the subsequent constant result (left graph of fig. 3), and the corresponding periodic change of the current (right graph of fig. 3) is shown, so that the repeatability of temperature monitoring is proved. The left graph of FIG. 3 shows that the resistance becomes smaller and the current becomes larger after the functional groups such as amino, carboxyl and the like are removed when the graphene aerogel is subjected to high temperature for the first time; however, the functional group removal process is irreversible, no functional group can be removed when the nth time meets high temperature, the resistance is not changed any more, and only single early warning is performed. FIG. 3 right is a diagram of Fe in the present invention 3 O 4 The semiconductor effect and the resistance are reversible along with the temperature change, so that the repeated monitoring can be realized.
The reversible fire early warning composite aerogel has improved fire safety performance and can be applied to the fields of fire alarms, flame retardance, heat insulation, fire protection and the like of high-rise buildings.
While the invention has been described in detail in the general context and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (10)
1. The composite aerogel for early warning the reversible fire is characterized by being prepared by crosslinking a magnetic graphene oxide nano sheet, an expanded graphite nano sheet and a biomass matrix through intermolecular hydrogen bonds, self-assembling into a 3D structure and then freeze-drying;
the magnetic graphene oxide nanosheets are magnetic Fe 3 O 4 Nanoparticle modified graphene oxide nanoplatelets;
the volume of the expanded graphite nano sheet can be instantaneously expanded by 100-250 times when the expanded graphite nano sheet is subjected to high temperature, and the expanded graphite nano sheet is changed into a worm shape from a sheet shape, so that a good heat insulation layer is formed;
the biomass matrix is one or more of carboxymethyl chitosan, hydroxypropyl methylcellulose, cellulose nanofiber and sodium alginate.
2. The composite aerogel for early warning of backfire according to claim 1, wherein,
the weight ratio of the magnetized graphene oxide nano-sheets in the reversible fire early warning composite aerogel is 10-60 wt%, wherein the magnetized graphene oxide nano-sheets are magnetic Fe 3 O 4 The content of the nano particles is that the graphene oxide sheets can grow and/or graft magnetic Fe 3 O 4 An upper limit of the nanoparticle; the mass ratio of the expanded graphite nano-sheets in the reversible fire early warning composite aerogel is 0.5-6wt%.
3. The reversible fire early warning composite aerogel according to claim 1 or 2, wherein the magnetic Fe 3 O 4 Nanometer particleThe grain and the expanded graphite nano-sheets are flame-retardant functional bodies in the reversible fire early warning composite aerogel, and play roles of catalytic carbonization and expansion physical barrier respectively; the expanded graphite nano-sheets and the biomass matrix are used as carbon sources to form a stable compact carbon layer.
4. A method for preparing the composite aerogel for early warning of reversible fire, which is characterized in that the composite aerogel for early warning of reversible fire is the composite aerogel for early warning of reversible fire according to any one of claims 1 to 3, and comprises the following steps:
(1) Magnetization modification of graphene oxide nanoplatelets:
grafting magnetic Fe by utilizing reaction between functional groups 3 O 4 Nanoparticle or coprecipitation in situ growth of magnetic Fe 3 O 4 One of two methods of nano-particles is to obtain a magnetic graphene oxide nano-sheet;
the magnetic Fe is grafted by utilizing the reaction between functional groups 3 O 4 The method of the nano-particles comprises the following steps: for existing magnetic Fe by silane ligand exchange 3 O 4 Amino modification is carried out on the surfaces of the nano particles, and magnetic Fe is utilized 3 O 4 The magnetic graphene oxide nanosheets are obtained by magnetization modification through the reaction between the nanoparticle and carboxyl functional groups on the surface of the graphene oxide nanosheets; the magnetic Fe 3 O 4 The size of the nano particles is 10-200 nm;
the coprecipitation in-situ growth of magnetic Fe 3 O 4 The method of the nano-particles comprises the following steps: adding Fe into graphene oxide dispersion liquid 2+ And Fe (Fe) 3+ The precursor of (2) is subjected to alkaline catalysis, and the magnetic graphene oxide nano-sheets are generated in situ through coprecipitation under the heating condition;
(2) Preparing the composite aerogel for early warning of backfire: adding expanded graphite nano-sheets accounting for 1.12-17.65 wt% of the mass of the biomass matrix aqueous solution and magnetic graphene oxide nano-sheets prepared in the step (1) accounting for 11.2-176.5 wt% of the mass of the biomass matrix aqueous solution into the biomass matrix aqueous solution at the ultrasonic frequency of 38-42 KHz and the temperature of 22-28 ℃, wherein the mass ratio of the magnetic graphene oxide nano-sheets to the expanded graphite nano-sheets is (20-5): 1; performing ultrasonic dispersion for 0.5-1 h, realizing three-dimensional network structure construction by using intermolecular hydrogen bond induced self-assembly, performing aging treatment for 2-6 h, and performing freeze-drying treatment at-20 to (-80) DEG C for 12-24 h to obtain the reversible fire early warning composite aerogel.
5. The method for preparing a composite aerogel for early warning against fire according to claim 4, wherein the method comprises grafting magnetic Fe by using the reaction between functional groups 3 O 4 The nanoparticle method comprises the following steps:
i, mixing 0.18-0.22M sodium oleate aqueous solution and 0.18-0.22M anhydrous ferric trichloride aqueous solution according to the volume ratio of 1 (0.9-1.1), fully stirring to generate reddish brown precipitate, filtering, washing with deionized water, drying in a vacuum oven, drying to obtain wax, dissolving the obtained wax in ethanol, adding oleic acid into ethanol with the volume of 55-65% of the sodium oleate aqueous solution, uniformly mixing, transferring the mixture into a polytetrafluoroethylene autoclave with the addition of 8-12% of the ethanol volume, reacting for 4-6 h at the temperature of 175-185 ℃, washing with absolute ethanol, separating with a magnet, and dispersing the separated substance in toluene to obtain Fe 3 O 4 Nanoparticle toluene dispersion;
II, modifying by adopting a silane ligand exchange method, namely, under the conditions that the ultrasonic frequency is 38-43 KHz and the temperature is 21-28 ℃, adding Fe obtained in the step I 3 O 4 Adding 0.4-0.6% of aminosilane and 0.008-0.015% of acetic acid into the nanoparticle toluene dispersion liquid, and carrying out ultrasonic treatment for 15-30min; then stirring and reacting for 22-48 h at room temperature; then washing with toluene, separating with magnet, and freeze drying to obtain amino modified magnetic Fe 3 O 4 A nanoparticle; realizing the exchange of silane ligand to the existing magnetic Fe 3 O 4 Modifying the surface of the nano particles by amino groups;
III, magnetic Fe modified with amino group of step II 3 O 4 Magnetization modification is realized through the reaction between the nano particles and carboxyl functional groups on the surface of the graphene oxide nano sheet, and the magnetic graphene oxide nano sheet is obtained.
6. The method for preparing the composite aerogel for early warning against backfire according to claim 5, wherein the aminosilane is one or more of 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3- (2-aminoethylamino) propyl trimethoxysilane, 4-aminobutyl dimethylmethoxysilane, 4-aminobutyl triethoxysilane, 3- [ (2-aminoethylamino) propyl ] dimethoxy silane and (3-aminopropyl) dimethylethoxy silane.
7. The method for preparing the composite aerogel for early warning of reversible fire according to claim 4, wherein the coprecipitation in-situ growth of magnetic Fe 3 O 4 The method of the nano-particles comprises the following steps: under the magnetic stirring with the rotating speed of 500-800rpm, ultrasonically dispersing the graphene oxide nano-sheets in deionized water to obtain graphene oxide dispersion liquid, wherein the graphene oxide nano-sheets are prepared by the steps of: deionized water (1.5-2.5 g): (48-52) mL; then inert gas is introduced to deoxidize for 1.8 to 2.2 hours, and then Fe with the mole ratio of (1.5 to 2.5) 1 is added in the deionized water with the volume of 0.8 to 1.5 percent 3+ And Fe (Fe) 2+ Stirring for 2-5 h at room temperature under the protection of inert gas, then heating to 70-90 ℃, then adding ammonia water to adjust the pH value of the solution to 9-12, and continuously keeping the temperature of 70-90 ℃ for reacting for 1-2 h to obtain the magnetic graphene oxide nano-sheet.
8. The method for preparing the composite aerogel for early warning of reversible fire according to claim 4, wherein the mass ratio of the magnetic graphene oxide nano-sheets to the expanded graphite nano-sheets is 10:1.
9. The application of the reversible fire early warning composite aerogel is characterized in that the application is in the fields of fire alarms of high-rise buildings, flame retardance, heat insulation and fire protection; the composite aerogel for early warning against the reverse fire is prepared by the composite aerogel for early warning against the reverse fire according to any one of claims 1 to 3 or the preparation method according to any one of claims 4 to 8.
10. The use of a reversible fire early warning composite aerogel according to claim 9, characterized in that it uses magnetic Fe with reversible resistance-temperature response 3 O 4 The nano particles are used as fire early warning functional bodies, and graphene oxide nano sheets with single heat reduction and multiple heat conduction characteristics are used as Fe 3 O 4 The carrier of the composite aerogel for the reversible fire early warning can be realized by breaking through the limit of single temperature monitoring under the synergistic effect, and the composite aerogel for the reversible fire early warning can not trigger the fire early warning and light the early warning lamp under the normal state; when first subjected to fire or high temperature, magnetic Fe 3 O 4 The resistance of the nano particles is reduced, and meanwhile, the resistance of the graphene oxide nano sheet is rapidly reduced due to the removal of functional groups by thermal reduction, so that the resistance and current change in a closed circuit are obvious, and then the early warning and/or the early warning lamp is triggered and/or lightened; when the Nth fire disaster occurs and the high temperature is received, wherein N is more than or equal to 2, magnetic Fe 3 O 4 Nanoparticle resistance remains reversibly reduced, while graphene sheets only provide a conduction path for continuous electrons, in turn assisting magnetic Fe 3 O 4 The nanoparticles enable repeated fire early warning and/or ignition of the early warning lights.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116580520A (en) * | 2023-07-14 | 2023-08-11 | 江苏恒力化纤股份有限公司 | Fire disaster early warning aerogel and preparation method thereof |
| CN116580520B (en) * | 2023-07-14 | 2023-09-19 | 江苏恒力化纤股份有限公司 | Fire disaster early warning aerogel and preparation method thereof |
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