Flame-retardant fire warning bacterial cellulose aerogel fiber and preparation method thereof

Abstract

The application discloses a preparation method of a fire-retardant fire warning bacterial cellulose aerogel fiber, and belongs to the technical field of materials.The application takes bacterial cellulose as a core raw material, then constructs a phytic acid polypyrrole conductive network in the internal member of the fiber through solvent replacement, and further covers the surface of the fiber with ZnO MXene sensing material with high flame sensitivity, so that the fire-retardant fire warning bacterial cellulose aerogel fiber with green environmental protection, excellent fire-retardant performance and high flame sensitivity is prepared.The preparation method is simple and efficient, effectively promotes resource recycling, and the prepared fire-retardant fire warning bacterial cellulose aerogel fiber has a wide application prospect in the fields of vehicle interior decoration, clothing and furniture.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of flame-retardant fire early warning bacterial cellulose aerogel fiber and its preparation method, belong to material technical field. BACKGROUND

[0002] Aerogel fiber is a kind of highly porous solid material with low density and exhibits extremely low thermal conductivity characteristics, its unique continuous network hole structure endows it with excellent thermal insulation and heat preservation performance, so it becomes the ideal candidate material for preparing advanced thermal insulation textiles. The application of such materials significantly promotes the development of thermal insulation textiles to lightweight and high-efficiency thermal insulation performance. The unique feature of aerogel fiber is that it successfully combines the lightweight porous advantage of aerogel material and the inherent flexible and slender characteristics of fiber material, thereby giving it good weaving potential. By directly weaving aerogel fibers or implementing blending strategies with other fiber materials, the inherent properties of various materials can be effectively integrated and optimized, achieving performance complementation and enhancement, and opening up new paths for innovative design and manufacturing of thermal insulation textiles. Among them, the bacterial cellulose-based aerogel fiber prepared using bacterial cellulose as raw material not only has the inherent advantages of aerogel fiber, but also shows good biocompatibility and biodegradability. However, it is flammable and has low skeletal strength, poor mechanical properties, which limits the large-scale application of bacterial cellulose aerogel fiber. Therefore, developing a new method to increase the strength of bacterial cellulose aerogel fiber, increase its flame retardant performance and add flame warning performance is of great significance to further expand the application range of bacterial cellulose aerogel fiber.

[0003] Currently, the prior art patent CN 118390291 A discloses a MoS2@MXene-based gas-sensitive flame-retardant coating and its application on textiles, but it is aimed at ordinary fabrics, not bacterial cellulose-based aerogel fibers, and the scheme disclosed therein does not have excellent effect when applied to bacterial cellulose-based aerogel fibers. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] Bacterial cellulose aerogel fiber is a material with advantages such as soft warmth, high biocompatibility and biodegradability, but it is flammable and has low skeletal strength, poor mechanical properties, which limits its large-scale application, therefore a new bacterial cellulose aerogel fiber preparation method needs to be developed and given flame retardant effect.

[0006] TECHNICAL SCHEME

[0007] To solve the above problems, the application constructs a phytic acid doped polypyrrole flame-retardant conductive layer on the surface of the bacterial cellulose hydrogel fiber through in-situ chemical oxidation polymerization, and finally constructs a fire warning layer outside the flame-retardant conductive layer, to obtain a flame-retardant fire warning bacterial cellulose aerogel fiber.

[0008] The application provides a preparation method of the flame-retardant fire warning bacterial cellulose aerogel fiber, and the preparation method comprises the following steps:

[0009] (1) Preparation of bacterial cellulose hydrogel fiber: bacterial cellulose powder is placed in an organic solvent for stirring to prepare a spinning solution, and the spinning solution is subjected to wet spinning to obtain the bacterial cellulose hydrogel fiber.

[0010] (2) Preparation of PA@PPy flame-retardant conductive layer: phytic acid, pyrrole and a low-molecular-weight alcohol are mixed to obtain a mixed solution, the bacterial cellulose hydrogel fiber prepared in step (1) is immersed in the mixed solution, an ammonium persulfate solution is added, and after standing, the bacterial cellulose hydrogel fiber is taken out and washed to obtain the conductive bacterial cellulose hydrogel fiber.

[0011] (3) Preparation of fire warning layer: ZnO@MXene nanohybrid material is added to water for stirring to form a dispersion solution, the conductive bacterial cellulose hydrogel fiber obtained in step (2) is immersed in the dispersion solution, and then the conductive bacterial cellulose hydrogel fiber is taken out and freeze-dried to obtain the flame-retardant fire warning bacterial cellulose aerogel fiber.

[0012] In an embodiment of the application, the organic solvent in step (1) comprises N, N dimethylacetamide, N methylpyrrolidone, acetone, dimethyl sulfoxide, toluene, tetrahydrofuran, acetonitrile, cyclohexanone, cyclohexane, ethyl acetate.

[0013] In an embodiment of the application, the stirring in step (1) comprises ultrasonic stirring and / or mechanical stirring.

[0014] In an embodiment of the application, the stirring time in step (1) is 5 min to 24 h.

[0015] In an embodiment of the application, the concentration of the bacterial cellulose in the spinning solution in step (1) is 5-15 wt%.

[0016] In an embodiment of the application, the process of wet spinning in step (1) comprises pressing the spinning solution out of the jet orifice of a spinning device to form a spinning stream, and the spinning stream is solidified and drawn into a nascent fiber in a coagulation bath.

[0017] In an embodiment of the present application, the wet spinning in step (1) is performed by using a wet spinning device; the inner diameter of the spinning needle is 0.5-1 mm, and the extrusion rate is 50-100 μL / min.

[0018] In an embodiment of the present application, the coagulation bath in the wet spinning in step (1) is deionized water.

[0019] In an embodiment of the present application, the draw ratio in the wet spinning in step (1) is 1.2-2 times.

[0020] In an embodiment of the present application, the concentration of phytic acid in the mixed solution in step (2) is 0.2-0.3 g / mL.

[0021] Preferably, the concentration of phytic acid in the mixed solution in step (2) is 0.25-0.28 g / mL.

[0022] More specifically, the concentration of phytic acid in the mixed solution in step (2) is 0.27 g / mL.

[0023] In an embodiment of the present application, the concentration of pyrrole in the mixed solution in step (2) is 0.1-0.2 g / mL.

[0024] In an embodiment of the present application, the low-molecular-weight alcohol in step (2) includes one or more of methanol, ethanol, propanol, and isopropanol.

[0025] In an embodiment of the present application, the immersion time in step (2) is 1-10 min.

[0026] In an embodiment of the present application, the concentration of the ammonium persulfate solution in step (2) is 0.1-0.2 g / mL.

[0027] In an embodiment of the present application, the mass ratio of phytic acid to ammonium persulfate in step (2) is 1-1.5:1.

[0028] In an embodiment of the present application, the standing time in step (2) is 1-10 min.

[0029] In an embodiment of the present application, the cleaning in step (2) is performed by using water, the number of cleaning times is 1-5 times, and drying is performed after cleaning.

[0030] In an embodiment of the present application, the preparation method of the ZnO@MXene nanohybrid material in step (3) is as follows:

[0031] The lithium fluoride is added into an aqueous hydrochloric acid solution to react, then Ti3AlC2 is added to continue the reaction, then the reaction liquid is centrifuged, the precipitate is reserved and the precipitate is washed with water until the pH of the precipitate is neutral, then the precipitate washed with water is mixed with water and ultrasonically treated, the upper suspension is collected and freeze-dried to obtain a MXene powder; a zinc source, sodium hydroxide and the MXene powder are weighed and added into water, stirred and then subjected to a hydrothermal reaction, then the reaction product is washed with water and dried to obtain a ZnO@MXene nanohybrid material.

[0032] Further, the concentration of the aqueous hydrochloric acid solution is 5-10 M.

[0033] Further, the mass ratio of the lithium fluoride to the volume of the aqueous hydrochloric acid solution is 1 g:10-30 mL.

[0034] Further, the mass ratio of the lithium fluoride to Ti3AlC2 is 1-1.5:1.

[0035] Further, the temperature of the reaction before adding Ti3AlC2 is 20-30℃ and the time is 20-60 min.

[0036] Further, the temperature of the reaction after adding Ti3AlC2 is 30-40℃ and the time is 20-24 h.

[0037] Further, the zinc source includes one or more of zinc acetate, zinc nitrate and zinc chloride.

[0038] Further, the mass ratio of the zinc source to sodium hydroxide is 1-3:3-8.

[0039] Further, the mass ratio of the zinc source to the MXene powder is 1-3:1-5.

[0040] Further, the temperature of the hydrothermal reaction is 120-170℃ and the time is 10-20 h.

[0041] In an embodiment of the present application, the concentration of the ZnO@MXene nanohybrid material in the dispersion liquid in step (3) is 3-10 mg / mL.

[0042] Preferably, the concentration of the ZnO@MXene nanohybrid material in the dispersion liquid in step (3) is 4-6 mg / mL.

[0043] More preferably, the concentration of the ZnO@MXene nanohybrid material in the dispersion liquid in step (3) is 5 mg / mL.

[0044] In an embodiment of the present application, the soaking time in step (3) is 10 min-60 min and the soaking temperature is 15-30℃.

[0045] The application provides the fire-retardant fire warning bacterial cellulose aerogel fiber prepared according to the preparation method.

[0046] The application provides a fire-retardant fire warning bacterial cellulose aerogel fiber, which is composed of, from inside to outside, a fiber layer, a phytic acid-doped polypyrrole fire-retardant conductive layer and a ZnO@MXene nanohybrid material flame sensing layer.

[0047] Further, the fiber layer has a diameter of 150-250 μm, the phytic acid-doped polypyrrole fire-retardant conductive layer has a diameter of 10-30 μm, and the ZnO@MXene nanohybrid material flame sensing layer has a diameter of 30-60 nm.

[0048] Further, the fiber layer is prepared by wet spinning of a spinning solution prepared from bacterial cellulose powder.

[0049] Further, the phytic acid-doped polypyrrole fire-retardant conductive layer is constructed on the surface of the cellulose hydrogel fiber by in-situ chemical oxidation polymerization using phytic acid as a dopant, pyrrole as a monomer, ammonium persulfate as an initiator and a low-molecular-weight alcohol as a displacement solvent.

[0050] Further, the fire warning layer is composed of the ZnO@MXene nanohybrid material.

[0051] Further, the preparation method of the ZnO@MXene nanohybrid material is as follows: lithium fluoride is added to an aqueous hydrochloric acid solution to react, then Ti3AlC2 is added to continue the reaction, then the reaction solution is centrifuged, the precipitate is reserved and washed with water until the pH of the precipitate is neutral, then the water-washed precipitate is mixed with water and ultrasonicated, the upper suspension is collected and freeze-dried to obtain MXene powder; a zinc source, sodium hydroxide and the MXene powder are weighed and added to water, stirred and then subjected to hydrothermal reaction, then the obtained reaction product is washed with water and dried to obtain the ZnO@MXene nanohybrid material.

[0052] Further, the concentration of the aqueous hydrochloric acid solution is 5-10 M.

[0053] Further, the mass ratio of lithium fluoride to the volume of the aqueous hydrochloric acid solution is 1 g : 10-30 mL.

[0054] Further, the mass ratio of lithium fluoride to Ti3AlC2 is 1-1.5 : 1.

[0055] Further, the temperature of the reaction before the addition of Ti3AlC2 is 20-30℃, and the time is 20-60 min.

[0056] Further, the temperature of the reaction after adding Ti3AlC2 is 30-40 ℃, and the time is 20-24 h.

[0057] Further, the zinc source includes one or more of zinc acetate, zinc nitrate, and zinc chloride.

[0058] Further, the mass ratio of the zinc source to sodium hydroxide is 1-3 : 3-8.

[0059] Further, the mass ratio of the zinc source to MXene powder is 1-3 : 1-5.

[0060] Further, the temperature of the hydrothermal reaction is 120-170 ℃, and the time is 10-20 h.

[0061] The application provides application of the above-mentioned flame-retardant fire warning bacterial cellulose aerogel fiber in the fields of textiles, clothing, furniture or ornaments.

[0062] Advantages

[0063] (1) The application adopts an environmentally friendly strategy, uses bacterial cellulose as a core raw material, has a wide source, a green and pollution-free production process, and environmental degradability, and effectively promotes the concept of green environmental protection and sustainable development.

[0064] (2) Compared with a traditional "dipping-baking" flame-retardant finishing method, the application uses a solvent replacement method to penetrate the phytic acid-doped polypyrrole flame-retardant conductive layer into the fiber, and further improves the flame-retardant effect and washing resistance. The obtained flame-retardant fire warning bacterial cellulose aerogel fiber shows a synergistic flame-retardant system integrating an acid source, a gas source and a carbon source, and can effectively catalyze the aerogel fiber to form a dense carbonized layer at high temperature, and significantly enhances the flame-retardant performance of the aerogel fiber.

[0065] (3) The flame-retardant fire warning bacterial cellulose aerogel fiber prepared by the application effectively plays the catalytic carbonization of phytic acid and the gas-phase flame-retardant effect of polypyrrole, improves the flame-retardant performance of the aerogel fiber, and the total heat release and the peak value of the heat release rate are reduced by more than 85% and 80%, respectively, compared with ordinary bacterial cellulose aerogel fiber.

[0066] (4) The flame-retardant fire warning bacterial cellulose aerogel fiber prepared by the application effectively plays the synergistic fire warning effect of ZnO and MXene, and the flame response intensity reaches 89.3% within 1.3 s of contacting the fire.

[0067] (5) The method is simple, efficient, controllable and repeatable, the component of the aerogel fiber is green and environmentally friendly, the flame retardant performance and fire warning performance of the bacterial cellulose aerogel fiber are improved, functional aerogel fiber textiles with flame retardant and fire warning functions are developed, the flammability problem of the bacterial cellulose aerogel fiber is solved, and the bacterial cellulose aerogel fiber has a wide application scene in the fields of vehicle interiors, clothing and furniture. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 Preparation flow chart of the flame-retardant and fire-warning bacterial cellulose aerogel fiber prepared in Example 1;

[0069] Figure 2 Digital photo of the flame-retardant and fire-warning bacterial cellulose aerogel fiber prepared in Example 1;

[0070] Figure 3 Combustion digital photo of the woven fabric of the flame-retardant and fire-warning bacterial cellulose aerogel fiber prepared in Example 1;

[0071] Figure 4 Fourier infrared (FTIR) diagram of the flame-retardant and fire-warning bacterial cellulose aerogel fiber prepared in Example 1;

[0072] Figure 5 Scanning electron microscope (SEM) diagrams of the flame-retardant and fire-warning bacterial cellulose aerogel fiber and the bacterial cellulose aerogel fiber prepared in Example 1;

[0073] Figure 6 Thermogravimetric (TG) and thermogravimetric rate (DTG) curves of the flame-retardant and fire-warning bacterial cellulose aerogel fiber and the ordinary bacterial cellulose aerogel fiber prepared in Example 1;

[0074] Figure 7 Heat release rate (HRR) diagram of the flame-retardant and fire-warning bacterial cellulose aerogel fiber and the ordinary bacterial cellulose aerogel fiber prepared in Example 1;

[0075] Figure 8 Total heat release (THR) diagram of the flame-retardant and fire-warning bacterial cellulose aerogel fiber and the ordinary bacterial cellulose aerogel fiber prepared in Example 1;

[0076] Figure 9 Fire warning diagram of the flame-retardant and fire-warning bacterial cellulose aerogel fiber prepared in Example 1;

[0077] Figure 10 Infrared thermal imaging diagram of the flame-retardant and fire-warning bacterial cellulose aerogel fiber woven fabric prepared in Example 1 placed on a human palm. DETAILED DESCRIPTION

[0078] Raw material sources

[0079] Bacterial cellulose powder (BC) was prepared by freeze-drying and crushing the water dispersion purchased from Guilin Qihong Technology; phytic acid, pyrrole, zinc oxide, lithium fluoride, and hydrochloric acid were purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.; Ti3AlC2 was purchased from Jilin Province Yi Yi Technology Co., Ltd., and other raw materials used were ordinary commercially available products unless otherwise specified.

[0080] Test method

[0081] In the present application, Fourier infrared instrument is used to determine the molecular bond structure of the fire-retardant fire warning bacterial cellulose aerogel fiber.

[0082] In the present application, scanning electron microscope is used to observe the surface morphology of the bacterial cellulose aerogel fiber and the fire-retardant fire warning bacterial cellulose aerogel fiber.

[0083] In the present application, micro-thermal instrument is used to measure the heat release rate and total heat release of the bacterial cellulose aerogel fiber and the fire-retardant fire warning bacterial cellulose aerogel fiber; the sample mass is 5-10 mg, the heating rate is set to 1℃ / s, and the test temperature range is 100-800℃.

[0084] In the present application, thermal gravimetric analyzer is used to determine the thermal stability of the bacterial cellulose aerogel fiber and the fire-retardant fire warning bacterial cellulose aerogel fiber; the heating rate is set to 10℃ / min, the test temperature range is 30-900℃, the gas atmosphere is nitrogen, and the gas flow is 50 mL / min.

[0085] In the present application, DMM5100 resistance meter is used to determine the response performance of the fire-retardant fire warning bacterial cellulose aerogel fiber to flame; the flame source is an alcohol lamp, and the aerogel fiber is woven into a 2 cm × 2 cm fabric for testing.

[0086] In the present application, infrared thermal imager is used to determine the heat insulation performance of the fire-retardant fire warning bacterial cellulose aerogel fiber.

[0087] Example 1

[0088] Preparation of fire-retardant fire warning bacterial cellulose aerogel fiber:

[0089] (1) Preparation of bacterial cellulose hydrogel fiber: 1 g of bacterial cellulose powder was dissolved in 19 g of 7% LiCl solution (solvent is N, NThe bacterial cellulose spinning solution was prepared by ultrasonic stirring for 5 h in dimethylacetamide; the spinning solution was placed in a wet spinning device for spinning, the inner diameter of the spinning needle was 0.7 mm, the extrusion rate was 80 μL / min, and after 1.2 times drawing in a deionized water coagulation bath, the bacterial cellulose hydrogel fiber was obtained;

[0090] (2) Preparation of the PA@PPy flame-retardant conductive layer: 2.468 g (0.036 mol) of pyrrole and 4.052 g (0.006 mol) of phytic acid were mixed with 20 g of isopropyl alcohol to obtain a mixed solution, and the bacterial cellulose hydrogel fiber obtained in step (1) was placed in the mixed solution and soaked for 5 min; 3.68 g of ammonium persulfate was dissolved in 20 mL of water to obtain an ammonium persulfate solution, which was then quickly added to the mixed solution, and the mixture was left to stand for another 5 min; finally, the soaked bacterial cellulose hydrogel fiber was taken out and washed with deionized water for 2-3 times to remove the excess poly-pyrrole on the surface, and the conductive cellulose hydrogel fiber was obtained;

[0091] (3) Preparation of ZnO@MXene nanohybrid material: 2 g of lithium fluoride was added to 40 mL of 9 M hydrochloric acid aqueous solution, and the reaction was carried out at 25 °C for 30 min, then the temperature was raised to 35 °C, and then 2 g of Ti3AlC2 was added and the reaction was continued for 24 h; the reaction solution was then centrifuged, and the lower layer precipitate was retained and washed with water until the pH of the precipitate was 7±0.5; then the water-washed precipitate was mixed with water again and ultrasonicated for 60 min; the upper layer suspension was collected and freeze-dried to obtain 2D Ti3C2T x nanosheet (MXene powder); 1.04 g of zinc nitrate hexahydrate, 1.6 g of sodium hydroxide, and 0.665 g of MXene powder were added to 50 mL of deionized water, ultrasonically stirred for 30 min, and then transferred to an autoclave for hydrothermal reaction at 120 °C for 12 h; finally, the reaction product was washed with water and dried to obtain the ZnO@MXene nanohybrid material;

[0092] (4) Preparation of the fire warning layer: the ZnO@MXene nanohybrid material obtained in step (3) was added to water and ultrasonically stirred for 1 h to prepare a dispersion liquid with a concentration of 5 mg / mL; the conductive cellulose hydrogel fiber obtained in step (2) was soaked in the dispersion liquid for 20 min, and then the soaked conductive cellulose hydrogel fiber was freeze-dried (the freeze-drying temperature was -40 °C, and the freeze-drying time was 48 h) to obtain the flame-retardant fire warning bacterial cellulose aerogel fiber.

[0093] The preparation process of the flame-retardant fire warning bacterial cellulose aerogel fiber is shown in Figure 1 .

[0094] A digital photo of the flame-retardant fire warning bacterial cellulose aerogel fiber prepared in Example 1 is shown in FIG. 1. Figure 2

[0095] A digital photo of the flame-retardant fire warning bacterial cellulose aerogel fiber fabric prepared in Example 1 exposed to an alcohol lamp flame is shown in FIG. 2. Figure 3

[0096] The flame-retardant fire warning bacterial cellulose aerogel fiber prepared in Example 1 was subjected to Fourier infrared spectrum test, and the results are shown in FIG. 3. Figure 4 The N-H characteristic peak at 3445 cm-1, the hydroxyl absorption peak at 3334 cm-1, the C-N bond absorption peak at 1557 cm-1, the P-O characteristic peak at 1255 cm-1, the C-O-C stretching vibration absorption peak at 1034 cm-1, and the like can be observed. -1 -1 -1 -1 -1 -1

[0097] The flame-retardant fire warning bacterial cellulose aerogel fiber prepared in Example 1 and the bacterial cellulose hydrogel fiber were subjected to scanning electron microscope, thermal stability, heat release rate (HRR), total heat release (THR), fire warning, and heat insulation performance tests, and the results are shown in FIG. 4, and the specific performance results are shown in Table 1. Figures 5 to 10

[0098] Table 1 Performance data of the flame-retardant fire warning bacterial cellulose aerogel fiber

[0099]

[0100] Compared with the unmodified bacterial cellulose aerogel fiber, the peak heat release rate of the flame-retardant fire warning bacterial cellulose aerogel fiber prepared in Example 1 is reduced by 80.6%, the total heat release is reduced by 88.4%, the flame-retardant performance is significantly increased, the carbon residue at 800 ℃ is increased by 19.5%, which indicates that the flame-retardant fire warning bacterial cellulose aerogel fiber prepared in Example 1 has superior thermal stability; the flame response sensitivity and flame response intensity data show that Example 1 has excellent fire warning function, which expands the application range of the bacterial cellulose fiber; in addition, the temperature difference at 90 ℃ background is slightly higher than that of the pure bacterial cellulose aerogel fiber, reaching 45.1 ℃, which shows superior heat insulation performance.

[0101] The preparation method of the present application is simple and controllable, the aerogel fiber substrate used is green and environmentally friendly, and the flame-retardant fire warning aerogel fiber prepared has excellent flame-retardant effect and high flame sensitivity. ​​​​​​​​​

[0102] Example 2

[0103] In this example, different amounts of phytic acid were used to prepare the fire-retardant fire warning bacterial cellulose aerogel fibers.

[0104] Single factor control: refer to the steps of Example 1, wherein only the amount of phytic acid added in step (2) is replaced by 0.002 mol, 0.004 mol, 0.008 mol, and 0.01 mol, respectively, and other conditions remain unchanged, to prepare a series of fire-retardant fire warning bacterial cellulose aerogel fibers.

[0105] The performance of the obtained fire-retardant fire warning bacterial cellulose aerogel fibers was determined, and the results are shown in Table 2.

[0106] Table 2 Performance data of fire-retardant fire warning bacterial cellulose aerogel fibers prepared with different amounts of phytic acid

[0107]

[0108] It can be seen that, with other conditions unchanged, the addition of phytic acid increases, the fire-retardant effect improves, the flame sensitivity changes little, and the heat insulation performance decreases. However, when the amount of phytic acid added is increased to 0.008 mol, the heat insulation performance decreases significantly, which is due to the destruction of the internal skeleton structure of the bacterial cellulose aerogel fibers caused by the excessive addition of phytic acid, resulting in the collapse of the internal structure. This defect will significantly reduce the application of the prepared bacterial cellulose aerogel fibers in the direction of high-efficiency heat-insulating fire-retardant fire warning textiles, and therefore, the optimal amount of phytic acid is 0.006 mol.

[0109] Example 3

[0110] In this example, different zinc sources were used to prepare fire-retardant fire warning bacterial cellulose aerogel fibers.

[0111] Single factor control: refer to the steps of Example 1, wherein only the zinc source in the hydrothermal reaction in step (3) is replaced by equimolar amounts of zinc chloride (0.46 g) and zinc acetate (0.62 g), respectively, and other conditions remain unchanged, to prepare a series of fire-retardant fire warning bacterial cellulose aerogel fibers.

[0112] The performance of the obtained fire-retardant fire warning bacterial cellulose aerogel fibers was determined, and the results are shown in Table 3.

[0113] Table 3 Performance data of fire-retardant fire warning bacterial cellulose aerogel fibers prepared with different zinc sources

[0114]

[0115] It can be seen that, under the same conditions, the performance of the flame-retardant fire warning bacterial cellulose aerogel fiber does not change significantly when the zinc source in the hydrothermal reaction is replaced by zinc chloride and zinc acetate instead of zinc nitrate hexahydrate.

[0116] Example 4

[0117] In this example, flame-retardant fire warning bacterial cellulose aerogel fibers were prepared using different concentrations of ZnO@MXene dispersion liquid.

[0118] Single factor control: referring to Example 1, only the concentration of ZnO@MXene dispersion liquid in step (4) was replaced from 5 mg / mL to 1 mg / mL, 3 mg / mL, 7 mg / mL and 9 mg / mL respectively, and other conditions remained unchanged, a series of flame-retardant fire warning bacterial cellulose aerogel fibers were prepared.

[0119] The performance of the obtained flame-retardant fire warning bacterial cellulose aerogel fibers was determined, and the results are shown in Table 4.

[0120] Table 4 Performance data of flame-retardant fire warning bacterial cellulose aerogel fibers with different concentrations of ZnO@MXene dispersion liquid

[0121]

[0122] It can be seen that, under the same conditions, the performance of the flame-retardant fire warning bacterial cellulose aerogel fiber does not change significantly when the zinc source in the hydrothermal reaction is replaced by zinc chloride and zinc acetate instead of zinc nitrate hexahydrate.

[0123] Example 5

[0124] In this example, flame-retardant fire warning bacterial cellulose aerogel fibers were prepared using different sensing nanomaterials@MXene nanocomposites.

[0125] Single factor control: referring to Example 1, only the ZnO generated on the surface of MXene in the hydrothermal reaction in step (3) was replaced by CuO and SnO2, and other conditions remained unchanged, to prepare flame-retardant fire warning bacterial cellulose aerogel fibers. The specific operation is as follows:

[0126] Preparation of CuO@MXene nanohybrid material: 2 g of lithium fluoride was added to 40 mL of 9 M hydrochloric acid solution, and after reaction at room temperature for 30 min, the temperature was raised to 35 °C, and 2 g of Ti3AlC2was added, and reacted for 24 h. After centrifugation, the lower precipitate was washed with water to pH = 7 ± 0.5, and then ultrasonic treatment was performed for 60 min. The upper suspension was collected, and freeze-drying was performed to obtain 2D Ti3C2T x Monolayer nanosheet (MXene powder). 31.7 mg of copper acetate, 120 mg of sodium hydroxide, and 21.6 mg of Ti3C2T x The monolayer nanosheet was mixed with 30 mL of water and magnetically stirred for 30 min, and then transferred into a hydrothermal reactor, and reacted at 140 °C for 24 h. After cooling to room temperature, it was taken out, washed with water, and vacuum dried to obtain the CuO@MXene nanohybrid material.

[0127] Preparation of SnO2@MXene nanohybrid material: 2 g of lithium fluoride was added to 40 mL of 9 M hydrochloric acid solution, and after reaction at room temperature for 30 min, the temperature was raised to 35 °C, and 2 g of Ti3AlC2was added, and reacted for 24 h. After centrifugation, the lower precipitate was washed with water to pH = 7 ± 0.5, and then ultrasonic treatment was performed for 60 min. The upper suspension was collected, and freeze-drying was performed to obtain 2D Ti3C2T x Monolayer nanosheet (MXene powder). 90 mg of stannous chloride dihydrate, 294 mg of sodium hydroxide, and 105 mg of Ti3C2T x The monolayer nanosheet was mixed with 30 mL of water and magnetically stirred for 30 min, and then transferred into a hydrothermal reactor, and reacted at 140 °C for 24 h. After cooling to room temperature, it was taken out, washed with water, and vacuum dried to obtain the CuO@MXene nanohybrid material.

[0128] Preparation of SnO2@MXene nanohybrid material: 2 g of lithium fluoride was added to 40 mL of 9 M hydrochloric acid solution, and after reaction at room temperature for 30 min, the temperature was raised to 35 °C, and 2 g of Ti3AlC2was added, and reacted for 24 h. After centrifugation, the lower precipitate was washed with water to pH = 7 ± 0.5, and then ultrasonic treatment was performed for 60 min. The upper suspension was collected, and freeze-drying was performed to obtain 2D Ti3C2T x Monolayer nanosheet (MXene powder). 90 mg of stannous chloride dihydrate, 294 mg of sodium hydroxide, and 105 mg of Ti3C2T x The monolayer nanosheet was mixed with 30 mL of water and magnetically stirred for 30 min, and then transferred into a hydrothermal reactor, and reacted at 140 °C for 24 h. After cooling to room temperature, it was taken out, washed with water, and vacuum dried to obtain the CuO@MXene nanohybrid material.

[0129] The performance of the obtained flame-retardant fire warning bacterial cellulose aerogel fiber was determined, and the results are shown in Table 5.

[0130] Table 5 Performance data of flame-retardant fire warning bacterial cellulose aerogel fibers prepared by different sensing nanomaterials

[0131]

[0132] It can be seen that, with other conditions unchanged, after replacing ZnO generated on the surface of MXene by CuO and SnO2 in the hydrothermal reaction, the flame sensitivity and flame response intensity of the obtained flame-retardant fire warning bacterial cellulose aerogel fiber are reduced. After replacing ZnO by MoS2, the flame-retardant performance is improved, but the flame sensitivity and flame response intensity are reduced. Therefore, ZnO achieves the best effect in the flame-retardant fire warning bacterial cellulose aerogel fiber.

[0133] Example 6

[0134] This example is to prepare flame-retardant fire warning bacterial cellulose aerogel fibers using different two-dimensional materials.

[0135] Single factor control: with reference to Example 1, only the two-dimensional material participating in the hydrothermal reaction in step (3) is replaced by equal mass of graphene oxide and boron nitride instead of MXene, and other conditions remain unchanged, to prepare flame-retardant fire warning bacterial cellulose aerogel fibers.

[0136] The performance of the obtained flame-retardant fire warning bacterial cellulose aerogel fiber was determined, and the results are shown in Table 6.

[0137] Table 6 Performance data of flame-retardant fire warning bacterial cellulose aerogel fibers prepared by different sensing nanomaterials

[0138]

[0139] It can be seen that, with other conditions unchanged, after replacing the two-dimensional material participating in the hydrothermal reaction by graphene oxide and boron nitride instead of MXene, the flame sensitivity and flame response intensity of the flame-retardant fire warning bacterial cellulose aerogel fiber are reduced. Therefore, it is best to use MXene as the two-dimensional material in the flame-retardant fire warning bacterial cellulose aerogel fiber.

[0140] Although the present application has been disclosed with reference to the preferred embodiments above, it is not intended to limit the present application, and any person skilled in the art can make various modifications and modifications without departing from the spirit and scope of the present application, therefore the protection scope of the present application should be defined by the claims.

Claims

1. A method for preparing flame-retardant fire early warning bacterial cellulose aerogel fiber, characterized in that, The preparation method includes the following steps: (1) Preparation of bacterial cellulose hydrogel fibers: Bacterial cellulose powder was placed in an organic solvent and stirred to prepare a spinning solution. The spinning solution was then wet-spun to obtain bacterial cellulose hydrogel fibers. (2) Preparation of PA@PPy flame-retardant conductive layer: Phytic acid, pyrrole and low molecular weight alcohol are mixed to prepare a mixture, and then the cellulose hydrogel fiber obtained in step (1) is immersed in the mixture. Ammonium persulfate solution is added, and after standing, the cellulose hydrogel fiber is taken out and washed to obtain conductive cellulose hydrogel fiber; the concentration of phytic acid in the mixture is 0.2-0.3 g / mL, and the concentration of pyrrole is 0.1-0.2 g / mL; (3) Preparation of fire warning layer: ZnO@MXene nano-hybrid material is added to water and stirred to form a dispersion. The conductive cellulose hydrogel fiber obtained in step (2) is immersed in the dispersion. Then the conductive cellulose hydrogel fiber is taken out and freeze-dried to obtain flame-retardant fire warning bacterial cellulose aerogel fiber. The preparation method of the ZnO@MXene nanohybrid material is as follows: lithium fluoride is added to hydrochloric acid aqueous solution for reaction, and then Ti3AlC2 is added to continue the reaction. After that, the reaction solution is centrifuged, the precipitate is retained and washed with water until its pH is neutral. Then, the washed precipitate is mixed with water and sonicated. The upper suspension is collected and freeze-dried to obtain MXene powder. Zinc source, sodium hydroxide and MXene powder are weighed and added to water. After stirring, a hydrothermal reaction is carried out. Then, the obtained reaction product is washed with water and dried to obtain ZnO@MXene nanohybrid material.

2. The preparation method according to claim 1, characterized in that, In step (1), the organic solvent includes one or more of N,N-dimethylacetamide, N-methylpyrrolidone, acetone, dimethyl sulfoxide, toluene, tetrahydrofuran, acetonitrile, cyclohexanone, cyclohexane, and ethyl acetate; the concentration of bacterial cellulose in the spinning solution is 5-15 wt%.

3. The preparation method according to claim 1, characterized in that, In step (1), the wet spinning is carried out using a wet spinning device with a spinning needle inner diameter of 0.5 to 1 mm and an extrusion rate of 50 to 100 μL / min.

4. The preparation method according to claim 1, characterized in that, In step (2), the concentration of phytic acid in the mixture is 0.25 to 0.28 g / mL.

5. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the ammonium persulfate solution is 0.1-0.2 g / mL; the mass ratio of phytic acid to ammonium persulfate is 1-1.5:

1.

6. The preparation method according to claim 1, characterized in that, In the preparation method of ZnO@MXene nanohybrid materials, the concentration of hydrochloric acid aqueous solution is 5-10M, the mass ratio of lithium fluoride to the volume of hydrochloric acid aqueous solution is 1g:10-30mL, and the mass ratio of lithium fluoride to Ti3AlC2 is 1-1.5:

1.

7. The preparation method according to claim 1, characterized in that, In the preparation method of ZnO@MXene nanohybrid materials, the mass ratio of zinc source to sodium hydroxide is 1-3:3-8, the mass ratio of zinc source to MXene powder is 1-3:1-5, the hydrothermal reaction temperature is 120-170℃, and the time is 10-20h.

8. The preparation method according to claim 1, characterized in that, In step (3), the concentration of ZnO@MXene nano-hybrid material in the dispersion is 3-10 mg / mL; the soaking time is 10 min-60 min, and the soaking temperature is 15-30℃.

9. A flame-retardant fire warning bacterial cellulose aerogel fiber, characterized in that, The flame-retardant fire early warning bacterial cellulose aerogel fiber consists of the following components from the inside out: a fiber layer, a phytic acid-doped polypyrrole flame-retardant conductive layer, and a ZnO@MXene nano-hybrid flame-sensing layer. The fiber layer is obtained by wet spinning of a spinning solution made from bacterial cellulose powder; The phytic acid-doped polypyrrole flame-retardant conductive layer is constructed on the surface of cellulose hydrogel fibers by using phytic acid as a dopant, pyrrole as a monomer, ammonium persulfate as an initiator, and low molecular weight alcohols as a displacement solvent through in-situ chemical oxidation polymerization. The fire warning layer is composed of ZnO@MXene nano-hybrid material. The preparation method of ZnO@MXene nano-hybrid material is as follows: lithium fluoride is added to hydrochloric acid aqueous solution for reaction, and then Ti3AlC2 is added to continue the reaction. After that, the reaction solution is centrifuged, the precipitate is retained and washed with water until its pH is neutral. Then the washed precipitate is mixed with water and sonicated. The upper suspension is collected and freeze-dried to obtain MXene powder. Zinc source, sodium hydroxide and MXene powder are weighed and added to water. After stirring, a hydrothermal reaction is carried out. Then the obtained reaction product is washed with water and dried to obtain ZnO@MXene nano-hybrid material.

10. The application of the flame-retardant fire warning bacterial cellulose aerogel fiber obtained by the preparation method according to any one of claims 1 to 8, or the flame-retardant fire warning bacterial cellulose aerogel fiber according to claim 9, in the fields of textiles, clothing, furniture, or decorations.

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