Preparation method of a straw ash filled cellulose-based composite material and aerogel

Abstract

A preparation method of a grass ash filled cellulose-based composite material and an aerogel, by quaternary ammonium salt modification treatment of cellulose and addition of grass ash, the roughness of the fiber surface in the aerogel is increased, the material structure is more compact, the quaternary ammonium salt modification improves the crystallinity and surface charge density, the calcium and potassium ions in the grass ash are complexed with the cellulose to enhance the interface polarization, the dielectric properties of the material are effectively improved, the triboelectric output is enhanced, at the same time, the multi-scale fiber entanglement of the quaternary ammonium salt modified cellulose and the microfibrillated cellulose is used as the skeleton, the mechanical stability of the composite material is enhanced, the composite material has good high humidity durability, is environmentally friendly and sustainable, the preparation method does not need special equipment, greatly shortens the drying time, has low energy consumption, simple operation, and is easy to carry out large-scale production, the prepared aerogel also has the characteristics of light weight, low apparent density, high plasticity and good flexibility.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cellulose composites, and particularly relates to a preparation method of a straw ash filled cellulose-based composite material and aerogel. BACKGROUND

[0002] The rapid development of the Internet of Things has promoted the demand for intelligent sensing technology in the fields of smart home and smart agriculture, and non-contact sensing has become a hot topic in the industry due to its real-time, wide-area, and low-intrusiveness. However, current mainstream sensors generally rely on external power sources, and large-scale deployment faces severe energy challenges.

[0003] Triboelectric nanogenerators are based on triboelectric charging and electrostatic induction effects, and can simultaneously achieve energy harvesting and sensing functions, providing a new approach to solving energy problems. Non-contact triboelectric nanogenerators also expand the detection dimension.

[0004] However, traditional triboelectric materials (such as polyamide and polyethylene terephthalate) are non-renewable and difficult to degrade, and large-scale application can easily cause pollution and health risks. In addition, the environmental stability of triboelectric nanogenerators is insufficient, and water molecules in high humidity environments can transfer, neutralize and dissipate the charge at the sensing interface, leading to a decrease in sensitivity and a decrease in energy harvesting efficiency. Furthermore, the signal output intensity of non-contact sensing is several to dozens of times weaker than that of contact sensing, and the charge retention time is very short.

[0005] Cellulose is an ideal candidate material due to its renewable, biodegradable, and low-cost advantages. The molecular structure of cellulose endows it with certain triboelectric potential, but the low charge density of natural cellulose and its high hydrophilicity result in fast charge dissipation and poor structural stability in high humidity. Existing optimization schemes (such as composite modification and hydrophobic integration) have improved performance to some extent, but still have problems such as limited biocompatibility, insufficient long-term stability, and high cost.

[0006] Therefore, in order to solve the above problems, the application provides a preparation method of a straw ash filled cellulose-based composite material and aerogel. SUMMARY

[0007] The application aims to solve the comprehensive problems of insufficient humidity adaptability of existing triboelectric nanogenerators, insufficient triboelectric output of cellulose-based aerogels, high cost, and non-renewable materials, and provides a preparation method of a straw ash filled cellulose-based composite material, which includes the following steps:

[0008] S10: configuring an aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, adding a strong base, and performing first stirring to form a quaternary ammonium salt solution;

[0009] S20: Take the needle leaf wood pulp to carry out homogenization treatment to form cellulose fibers, add the quaternary ammonium salt solution, carry out second stirring while heating, then wash with water to form quaternary ammonium salt modified cellulose;

[0010] S30: Take the microfibrillated cellulose, wood ash and deionized water, mix with the quaternary ammonium salt modified cellulose, carry out third stirring to obtain the composite material.

[0011] Further, the microfibrillated cellulose has a fiber width of 50nm to 200nm and a fiber length of 20μm to 500μm.

[0012] Further, the volume of the aqueous solution is 80mL to 140mL, and the mass of the (3-chloro-2-hydroxypropyl) trimethylammonium chloride contained therein is 1.4g to 6.0g.

[0013] Further, the mass ratio of the strong base to the cellulose fibers in the quaternary ammonium salt modified cellulose is 1.0g to 1.2g: 1.8g to 3.0g.

[0014] Further, the strong base is sodium hydroxide or potassium hydroxide.

[0015] Further, when the volume of the deionized water used is 200mL to 400mL, the mass of the microfibrillated cellulose used is 0.6g to 1.8g, and the mass of the wood ash used is 0.36g to 1.08g.

[0016] Further, the wood ash is obtained by washing, drying, and grinding the ash after burning the fallen leaves, and the fallen leaves are one of the fallen leaves of Ilex purpurea, Broussonetia papyrifera, Eriobotrya japonica, Sabal, Ficus microcarpa or Cinnamomum camphora.

[0017] Further, the second stirring while heating is stirring at a speed of 40r / min to 50r / min at a temperature of 65℃ to 75℃ for 50min to 70min.

[0018] An aerogel of a wood ash filled cellulose based composite material, the preparation process of the aerogel being: loading the composite material prepared by the above preparation method into a leaching solvent tool to leach out the solvent, then drying to obtain the aerogel.

[0019] Further, the drying is freezing at a temperature of -18℃ to -5℃ for 2.0h to 4.5h, then drying at a temperature of 55℃ to 65℃ for 20min to 35min, then extruding, and finally drying at 55℃ to 65℃ for 6h to 8h.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] By using the quaternary ammonium salt containing epoxy groups and adding wood ash, the roughness of the fiber surface in the aerogel is increased, the material structure is more compact, the introduction of microfibrillated cellulose can effectively improve the multi-scale crosslinking effect, the modification of quaternary ammonium salt can increase the crystallinity of aerogel, and the calcium and magnesium ions rich in wood ash can restructure the multi-crosslinking structure of the aerogel system. The mechanical properties of the aerogel are enhanced by multiple factors, and the tensile strength, elastic modulus, compressive strength and compressive modulus are improved; at the same time, after the combination of quaternary ammonium salt and cellulose skeleton, the polarization ability and activity of the molecule are improved, the dielectric properties and surface charge density are improved, the calcium and potassium ions in the wood ash are complexed with cellulose to enhance ion polarization, and the existence of calcium carbonate and magnesium carbonate crystals further enhances the interface polarization, thereby effectively improving the triboelectric output of the aerogel.

[0022] And the material has excellent performance in high humidity environment, when the relative humidity is 30% to 80%, the voltage and current increase with the increase of humidity, the humidity sensitivity is high, and the humidity response is reversible, the output voltage remains stable after 14000 cycles at a relative humidity of 83%RH, the high humidity durability is good, and the self-power process energy efficiency can be maintained in high humidity environment.

[0023] The application uses quaternary ammonium salt modified cellulose and microfibrillated cellulose fibers as the base material, and combines wood ash after leaf burning, which is environmentally friendly and sustainable, and the preparation process does not require special equipment, so it is easy to produce on a large scale, the preparation process greatly shortens the drying time, has low energy consumption and simple operation, and the prepared aerogel also has the characteristics of light weight, low apparent density, high plasticity and good flexibility. At the same time, the wood ash made from different varieties of fallen leaves has good applicability, strong scheme expandability and universality.

[0024] The application overturns the use of only simple raw material components through a simple preparation process to form a triboelectric composite material and aerogel with good performance. Compared with the cellulose-based triboelectric composite material of the prior art, which uses dozens or even hundreds of raw materials for preparation, and it is difficult to ensure that the raw materials have high standard environmental performance, and the preparation process has dozens of steps, the application uses raw materials that are not only common but also have high standard environmental properties. The main raw materials (cellulose fibers and wood ash) are widely sourced and have very low cost. The overall preparation process does not exceed ten steps (even less than five steps), so from the use of raw materials to the preparation process, it has the characteristics of convenience, low cost and easy operation. The performance of the formed material is good, suitable for large-scale production, and the material has strong applicability. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1A photograph of moldability of the aerogel prepared in Example 1 of the present application, Figure 1 Fig. 1 is an aerogel of various shapes, Fig. 2 is an aerogel in different bending states, and Fig. 3 is an aerogel in different twisting states;

[0026] Figure 2 SEM photographs of the surface of the aerogels prepared in Comparative Examples 1 to 4 of the present application and SEM photographs and EDS photographs of the cross section of the aerogel prepared in Example 1 of the present application; Figure 2 (a) to (h) of Fig. 1 are SEM photographs of the surface of the aerogels prepared in Comparative Examples 1 to 4 of the present application; Figure 2 (i) and (j) of Fig. 1 are SEM photographs of the cross section of the aerogel prepared in Example 1 of the present application; Figure 2 (k) and (l) of Fig. 1 are EDS photographs of the cross section of the aerogel prepared in Example 1 of the present application;

[0027] Figure 3 EDS spectrograms of samples of CF, C2M1, C2M1S 10 , A 10 C2M1, A 12 C2M1S 10 , A 40 C2M1S 20 ; Figure 3 (a) to Figure 3 (f) of Fig. 1;

[0028] Figure 4 Infrared spectrograms of the aerogels prepared in Example 1 of the present application and Comparative Examples 1 to 4;

[0029] Figure 5 X-ray diffraction patterns of the aerogels prepared in Example 1 of the present application and Comparative Examples 1 to 4;

[0030] Figure 6 Tensile stress-strain diagrams, maximum tensile strength diagrams and elastic modulus diagrams of the aerogels prepared in Example 1 of the present application and Comparative Examples 1 to 4;

[0031] Figure 7 Compression stress-strain diagrams and compression modulus diagrams of the aerogels prepared in Example 1 of the present application and Comparative Examples 1 to 4;

[0032] Figure 8 Working principle diagrams of the aerogels prepared in Example 1 of the present application and Comparative Examples 1 to 4 assembled into a vertical contact-separation mode triboelectric nanogenerator;

[0033] Figure 9 Short-circuit current signal diagrams of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present application in one cycle;

[0034] Figure 10 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;

[0035] Figure 11 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;

[0036] Figure 12 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;

[0037] Figure 13 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;

[0038] Figure 14 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N; Figure 14

[0039] Figure 15 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N; Figure 15 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N; Figure 15 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N; Figure 15 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N; Figure 15 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N; Figure 15 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;

[0040] Figure 16 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;

[0041] Figure 17 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared for Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N;​Figure 17 (a) of FIG. 1 is a graph of open-circuit voltage of the aerogel-based triboelectric nanogenerator prepared in Example 1 under different humidity environments, Figure 17 (b) of FIG. 1 is a graph of short-circuit current of the aerogel-based triboelectric nanogenerator prepared in Example 1 under different humidity environments;

[0042] Figure 18 FIG. 2 is a schematic diagram of the interface of the aerogel-based triboelectric nanogenerator prepared in Example 1 improving the electrical output by forming bound water and ion channels through hydrogen bonding during operation in a humid environment;

[0043] Figure 19 FIG. 3 is a graph of the humidity sensing sensitivity of the aerogel-based triboelectric nanogenerator prepared in Example 1; Figure 19 (a) of FIG. 4 is a graph of the fitting curves of the open-circuit voltage and short-circuit current of the aerogel-based triboelectric nanogenerator prepared in Example 1 varying with humidity in the range of 30% to 80% relative humidity; Figure 19 (b) of FIG. 4 is a graph of the open-circuit voltage response of the aerogel-based triboelectric nanogenerator prepared in Example 1 during humidification or dehumidification;

[0044] Figure 20 FIG. 5 is a graph of the open-circuit voltage of the aerogel-based triboelectric nanogenerator prepared in Example 1 under 83% relative humidity for 14,000 cycles of contact-separation;

[0045] Figure 21 FIG. 6 is a graph of the real-time output open-circuit voltage of the aerogel-based triboelectric nanogenerator prepared in Example 1 intermittently exhaling to the friction layer during operation using a commercial exciter;

[0046] Figure 22 FIG. 7 is a product application diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1, Figure 22 (a) of FIG. 8 is a schematic diagram of powering 632 LEDs, Figure 22 (b) of FIG. 8 is a graph of charging curves to commercial capacitors of 0.22 μF to 10 μF, Figure 22 (c) of FIG. 8 is a schematic diagram of powering an electronic stopwatch requiring a 3 V power supply;

[0047] Figure 23 FIG. 9 is an output voltage diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 as a sensor detecting human motion, Figure 23 (a) of FIG. 10 is an output voltage diagram of detecting human motion as a contact sensor, Figure 23 (b) of FIG. 10 is an output voltage diagram of detecting human motion as a non-contact sensor;

[0048] Figure 24The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared by using the process of the embodiment 1 of the present application for the ash made of different varieties of fallen leaves, Figure 24 The (a) graph in FIG. 1 is a schematic diagram of the aerogel-based triboelectric nanogenerator prepared by the embodiment 1 as a burglar alarm, Figure 24 The (b) graph in FIG. 1 is a schematic diagram of the simulated alarm working,

[0049] Figure 25 The open circuit voltage graph of the aerogel-based triboelectric nanogenerator prepared by using the process of the embodiment 1 of the present application for the ash made of different varieties of fallen leaves,

[0050] Figure 26 The aerogel degradation process graph prepared by the embodiment 1 of the present application,

[0051] Figure 27 The electrical output performance comparison graph of the aerogel-based triboelectric nanogenerator prepared by recycling the aerogel prepared by the embodiment 1 of the present application for multiple times, Figure 27 The (a) graph in FIG. 1 is an open circuit voltage comparison graph, Figure 27 The (b) graph in FIG. 1 is a short circuit current comparison graph, Figure 27 The (c) graph in FIG. 1 is a charge transfer amount comparison graph. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0053] It should be noted that the professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present application can be purchased from the market or prepared by the existing method.

[0054] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0055] The weight of the related components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the embodiment description of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the embodiment description of the present application. Specifically, the weight mentioned in the embodiment description of the present application can be μg, mg, g, kg, nm, μm, cm, mm, wt%, mPa, L, mL and other mass units commonly known in the chemical industry.

[0056] The following is further illustrated by specific examples.

[0057] The preparation method of the wood ash filled cellulose-based composite material of the present embodiment comprises the following steps:

[0058] S10: configuring an aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, adding a strong base, and stirring for the first time to form a quaternary ammonium salt solution;

[0059] S20: taking coniferous wood pulp for homogenization treatment to form cellulose fibers, adding the quaternary ammonium salt solution, and stirring for the second time while heating, and then washing with water to form quaternary ammonium salt modified cellulose;

[0060] S30: taking microfibrillated cellulose, wood ash and deionized water, mixing with the quaternary ammonium salt modified cellulose, and stirring for the third time to obtain the composite material.

[0061] It is worth noting that the above S10 step is actually a cyclization reaction of a quaternary ammonium salt without an epoxy group under alkaline conditions to obtain a quaternary ammonium salt containing an epoxy group.

[0062] The preparation method of the wood ash filled cellulose-based composite material of the present embodiment is as follows:

[0063] The composite material comprises the following formulation:

[0064] Aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride: 80 mL to 140 mL, preferably 120 mL, wherein the mass of (3-chloro-2-hydroxypropyl) trimethylammonium chloride contained therein is 1.4 g to 6.0 g;

[0065] Sodium hydroxide or potassium hydroxide: 1.0 g to 1.2 g;

[0066] Cellulose fibers: 1.8 to 3.0 g;

[0067] Microfibrillated cellulose: 0.6 to 1.8 g, with a fiber width of 50 nm to 200 nm and a fiber length of 20 μm to 500 μm;

[0068] Wood ash: 0.36 to 1.08 g;

[0069] Deionized water: 200 mL to 400 mL, preferably 300 mL is used.

[0070] The preparation steps are as follows:

[0071] Step S10: Add sodium hydroxide or potassium hydroxide to the aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution, and stir for the first time to obtain a quaternary ammonium salt solution.

[0072] Step S20: Take coniferous pulp for homogenization treatment to form cellulose fibers, and add to the quaternary ammonium salt solution, stir at a speed of 40 r / min to 50 r / min at a temperature of 65℃ to 75℃ for 50 min to 70 min, and then wash with water to form quaternary ammonium salt modified cellulose.

[0073] Step S30: Take deciduous leaves, wash, dry, and grind into wood ash after burning into ashes, then take microfibrillated cellulose, deionized water, and mix with the quaternary ammonium salt modified cellulose, and stir for the third time to obtain a composite material.

[0074] The application also provides an aerogel made of the wood ash filled cellulose-based composite material, which is prepared by placing the prepared composite material in a leaching solvent tool provided with a screen at the bottom to leach out the solvent. The leaching solvent tool is a mold with a geometric three-dimensional hollow structure, at least one side of the mold is made of a screen, and the screen is optionally one of gauze, PTFE mesh, nylon mesh, PVC mesh, PET mesh or PP mesh, steel mesh, or aluminum mesh. The mesh size of the screen is 80 to 120 mesh. Then freeze at a temperature of -18℃ to -5℃ for 2.0 h to 4.5 h, and then dry at a temperature of 55℃ to 65℃ for 20 min to 35 min, then extrude, and finally dry at 55℃ to 65℃ for 6 h to 8 h to obtain the aerogel of the cellulose composite wood ash system.

[0075] The embodiment first removes hydrogen chloride under the action of strong alkali on (3-chloro-2-hydroxypropyl) trimethylammonium chloride to generate 2,3-epoxypropyl trimethylammonium chloride, forming a quaternary ammonium salt containing an epoxy group, and then reacting with the hydroxyl group in the homogenized cellulose fibers to connect the quaternary ammonium salt to the molecules of the cellulose fibers, forming a cationic cellulose ether, and obtaining quaternary ammonium salt modified cellulose.

[0076] Then, the quaternary ammonium salt modified cellulose and microfibrillated cellulose are mixed by high-speed stirring and form a multi-scale fiber entanglement, and then wood ash is added. The rich magnesium, calcium and other metal ions in the wood ash can form chelate bonds with the active groups in the cellulose fibers, thus forming a triple network structure composed of chemical crosslinking, ion complexation and hydrogen bond crosslinking, making the material structure more stable.

[0077] Then, the mixed sample is poured into a leaching solvent tool to leach out the excess solvent, and then placed in a refrigerator to freeze at a temperature of -18℃ to -5℃. The low temperature causes the cellulose chains to be more closely aggregated laterally due to hydrogen bonding, and the water molecules are further compressed into the skeleton structure of the material when frozen into ice crystals, so that the layers are formed between the fibers.

[0078] After freezing, the sample is quickly pressed between glass plates after drying in an oven for 20min to 35min to remove most of the solvent, and then completely dried to obtain the aerogel of the cellulose composite plant ash system.

[0079] Please refer to Figure 1 , Figure 1 the physical figure of the moldability of the aerogel prepared in Example 1 of the present application, Figure 1 Fig. 1 is an aerogel of various shapes, Fig. 2 is an aerogel of different bending states, and Fig. 3 is an aerogel of different twisting states.

[0080] This preparation method has no special and difficult preparation process, so it does not require special equipment, greatly shortening the drying time. This process not only has low energy consumption, simple operation, green environmental protection, easy to scale production, but also the aerogel made of composite material has the excellent characteristics of light weight and low apparent density, and high plasticity and good flexibility.

[0081] To further illustrate the influence of the amount of each key component on the performance of the composite material, the cellulose-based aerogels prepared in Example 1 and Comparative Examples 1 to 4 are provided in the following table and tested.

[0082] Table 1 - Formula scheme table of the embodiment:

[0083]

[0084] It should be noted that the aerogel prepared in Comparative Example 1 of the present application is referred to as CF in the specific embodiment and the drawing, the aerogel prepared in Comparative Example 2 is referred to as C2M1 in the specific embodiment and the drawing, the aerogel prepared in Comparative Example 3 is referred to as C2M1S in the specific embodiment and the drawing 10 , and the aerogel prepared in Comparative Example 4 is referred to as A in the specific embodiment and the drawing. 10 C2M1.

[0085] Wherein, A represents: (3-chloro-2-hydroxypropyl) trimethylammonium chloride, C represents: cellulose fiber, M represents: microfibrillated cellulose, and S represents: plant ash.

[0086] The aerogel prepared in Example 1 of the present application is A x Cy M1S z , the variables of different components in the formula of Example 1 were detected and analyzed in subsequent detection, wherein "x" represents the concentration of the aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride (preferably: 12 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, of which 12 g / L is comparatively illustrated in the drawings of the specification, specifically, in the comparative illustrations of Figs. 7, 11), "y" represents the relative ratio of the amount of cellulose fibers and microfibrillated cellulose (preferably: 1, 2, 3, 4 and 5), and "z" represents the proportion of wood ash in the total amount of fibers (preferably: 10wt%, 15wt%, 20wt%, 25wt% and 30wt%). Figure 3 、 6 , 7, 11 comparatively illustrate).

[0087] It should be noted that CF in the specific embodiments and the drawings of the specification represents cellulose fiber aerogel, MCF represents microfibrillated cellulose, and PLSH represents wood ash.

[0088] Please refer to Figure 2 and Figure 3 , Figure 2 the surface SEM images of the aerogels prepared in Comparative Examples 1 to 4 and the SEM images and EDS images of the cross sections of the aerogel prepared in Example 1; Figure 2 Figs. (a) to (h) in the drawings are the surface SEM images of the aerogels prepared in Comparative Examples 1 to 4; Figure 2 Figs. (i) and (j) in the drawings are the SEM images of the cross sections of the aerogel prepared in Example 1; Figure 2 Figs. (k) and (l) in the drawings are the EDS images of the cross sections of the aerogel prepared in Example 1; Figure 3 are the EDS spectrograms of the samples of CF, C2M1, C2M1S 10 , A 10 C2M1, A 12 C2M1S 10 , A 40 C2M1S 20 . Figure 3 Figs. (a) to Figure 3 Figs. (f) in the drawings.

[0089] The fibers on the surface of the aerogel of Comparative Example 1 are thick and flat, the fibers in the aerogel of Comparative Example 2 are more closely arranged, and large pieces of thick and thin fibers appear to be adhered on the surface, the fibers on the surface of the aerogel of Comparative Example 4 are more rough, and a small amount of holes appear on the surface, while the fibers on the surface of the aerogel of Comparative Example 3 have more obvious damage and more holes appear.

[0090] From Figure 2The (a) figure in the figure can be seen that the surface of the rough fiber of the aerogel of embodiment 1 is interwoven, and the pore is obvious, Figure 2 The (j) figure in the figure can be obviously seen that the size of the wood ash particles distributed on the fiber is different, and the combination Figure 2 The (d) figure in the figure can be seen that the roughness of the fiber surface of the aerogel is obviously increased after the modification treatment of the quaternary ammonium salt and the addition of wood ash, Figure 2 The (k) figure in the figure is the cross-sectional electron microscope of embodiment 4, and the fiber is obviously seen to be distributed in layers, showing obvious order, and the structure makes the overall structure of the aerogel more compact, finally, the (l) figure in the figure and Figure 2 The EDS result of Figure 3 can prove that the addition of wood ash introduces Ca, Si, Mg and K elements.

[0091] Table 2-corresponds to Figure 3 EDS test data table:

[0092]

[0093] Please refer to Figure 4 , Figure 4 The infrared spectrum of the aerogel prepared in embodiment 1 and comparative examples 1 to 4 of the application.

[0094] As Figure 4 shown, comparative example 1 has characteristic peaks of cellulose macromolecular structure at 1030cm -1 , 897cm -1 and 1156cm -1 ; comparative example 2 has a broadened absorption band near 3200cm -1 because of the introduction of a large number of hydroxyl groups by containing microfibrillated cellulose; comparative example 3 has enhanced absorption bands near 1430cm and 860cm -1 because of the introduction of carbonate by containing wood ash; comparative example 4 has increased peak intensity near 3300cm -1 , 2900cm -1 , 1472cm -1 and 1030cm -1 because of the change of the number of hydrogen bonds, the number of alkyl groups, the introduction of quaternary ammonium salt group and the stretching strength of C-O-C pyranose ring caused by the introduction of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, thereby proving the successful grafting of (3-chloro-2-hydroxypropyl) trimethylammonium chloride; and the quaternary ammonium salt peak and the carbonate peak in embodiment 1 are stronger than those in comparative example 2, thereby verifying the successful modification of cellulose fibers.

[0095] Please refer to Figure 5 , Figure 5 The X-ray diffraction pattern of the aerogel prepared in embodiment 1 and comparative examples 1 to 4 of the application.

[0096] See Figure 5 The aerogels in Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Example 1 all have typical diffraction peaks of cellulose I at 15.1°, 16.5°, 22.5° and 34.5° (corresponding to (1-10), (110), (200) and (004) crystal planes), indicating that the treatment of ammonium salt and the introduction of wood ash do not change the cellulose crystal structure.

[0097] However, the significant difference is that Comparative Example 3 has characteristic peaks of calcium carbonate and magnesium carbonate near 2θ = 30° and 36° (confirming the successful introduction of wood ash), and the intensity of the cellulose diffraction peaks (especially at (200)) is significantly reduced, which is due to the complexation of wood ash and cellulose reducing the crystallinity; the intensity of the cellulose diffraction peaks of Comparative Example 4 is significantly enhanced, because the molecules of (3-chloro-2-hydroxypropyl) trimethylammonium chloride are grafted to the cellulose chain, increasing the crystallinity; and the crystallinity of the cellulose molecules in Example 1 is reduced under the competitive action of quaternary ammonium salt modification and wood ash, proving the successful introduction of both.

[0098] See Figure 6 , Figure 6 The tensile stress-strain diagram, maximum tensile strength diagram and elastic modulus diagram of the aerogels prepared in Example 1 and Comparative Examples 1 to 4 are shown in Figures a and b, which include A 12 C2M1S 10 , A 12 C2M1S 20 , A 12 C2M1S 30 and Comparative Examples 1 to 4, and Figures c and d include A 30 C2M1S 20 , A 40 C2M1S 20 , A 50 C2M1S 20 , A 40 C1M1S 20 , A 40 C3M1S 20 .

[0099] As Figure 6 shown, the tensile strength and elastic modulus of the aerogel in Comparative Example 1 are 0.4 MPa and 10.8 MPa, respectively; and the tensile strengths of Comparative Examples 2, 3 and 4 are 5.9 MPa, 8.5 MPa and 12.9 MPa, respectively, and the elastic moduli are 243.9 MPa, 356.1 MPa and 611.8 MPa, respectively, proving that the addition of microfibrillated cellulose, (3-chloro-2-hydroxypropyl) trimethylammonium chloride and wood ash can effectively improve the tensile strength and modulus in the aerogel.

[0100] It is worth mentioning that the tensile strength and modulus of Example 1 decreases with the increase of the amount of wood ash, which is due to the enhancement of multi-scale cross-linking of microfibrillated cellulose, the increase of crystallinity of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, and the improvement of tensile properties. Although the crystallinity of the aerogel decreases after adding wood ash, the ions introduced can restructure the multi-crosslinking network structure of the aerogel system, so that the tensile properties of the aerogel are improved after adding a small amount of wood ash. If too much wood ash is added, it will aggregate on the surface of the fiber, thereby negatively affecting the tensile properties.

[0101] Further, from the change of the tensile strength and modulus of Comparative Examples 1 to 4, the concentration of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, the amount of cellulose fiber and microfibrillated fiber, and the influence of the amount of cellulose fiber and microfibrillated fiber on the tensile properties of the aerogel are not obvious.

[0102] Please refer to Figure 7 , Figure 7 The compression stress-strain diagram and compression modulus diagram of the aerogel prepared in Example 1 and Comparative Examples 1 to 4 (wherein: Figure a and Figure b include A 12 C2M1S 10 , A 12 C2M1S 20 , A 12 C2M1S 30 and Comparative Examples 1 to 4, Figure c and Figure d include A 30 C2M1S 20 , A 40 C2M1S 20 , A 50 C2M1S 20 , A 40 C1M1S 20 , A 40 C3M1S 20 ).

[0103] As shown in (a) of Figure 7 , the addition of microfibrillated cellulose, (3-chloro-2-hydroxypropyl) trimethylammonium chloride and wood ash can improve the compressive strength and compression modulus of the aerogel. Especially, the compressive strength of the aerogel of Comparative Example 2 at 30% strain is 3.4 MPa, which is greatly improved compared with Comparative Example 1. Although the addition of (3-chloro-2-hydroxypropyl) trimethylammonium chloride and wood ash reduces the compressive strength of the aerogel, by adjusting the relative amount of the two, the compressive strength of the aerogel can still be similar to that of Comparative Example 2 (as shown in (c) of Figure 7 and (d) of Figure 7 ), and A 30 C2M1S 20The compressive strength of the aerogel (prepared by the process of Example 1: the concentration of the (3-chloro-2-hydroxypropyl) trimethylammonium chloride aqueous solution is 30 g / L, the relative ratio of the amount of cellulose fibers to the amount of microfibrillated cellulose is 2, and the proportion of wood ash in the total amount of fibers is 20 wt%) is the highest, which is 3.5 MPa.

[0104] Referring to Figure 8 , Figure 8 The working principle diagram of the vertical contact-separation mode triboelectric nanogenerator assembled by the aerogel prepared in Example 1 and Comparative Examples 1 to 4 of the present application is shown in FIG. a in Figure 8 FIG. a in Figure 8 FIG. b in

[0105] As shown in (a) in Figure 8 , the aerogel of the present example is used as the triboelectric positive electrode, the polytetrafluoroethylene film is used as the negative electrode, the copper sheet is used as the back electrode and connected to the external circuit, the ethylene-vinyl acetate sponge is used as the spacer, and the vertical contact-separation mode triboelectric nanogenerator is assembled, and the triboelectric performance is evaluated by measuring the electrical output; at the same time, the aerogel-based triboelectric nanogenerator of Comparative Example 1, Comparative Example 2 and Comparative Example 3 is assembled in the same way for comparison.

[0106] As shown in (b) in Figure 8 , the working principle diagram of the triboelectric device of the triboelectric nanogenerator is shown, which includes processes (I) to (V), specifically: (I) in the initial state, the positive and negative electrodes are separated, no charge is generated, and the potential difference between the two ends is zero; (II) under the action of external force, the aerogel contacts the polytetrafluoroethylene film, which causes the surface charge transfer in the contact area, the aerogel surface and the inside induce positive charges, and the polytetrafluoroethylene film surface induces negative charges, since the triboelectric charges only exist in the contact surface, the charges with opposite signs almost coincide in the same plane, and there is almost no potential difference between the two electrodes; (III) when the applied external force is removed, the potential difference between the two ends is formed by the positive and negative charges, and the charge transfer occurs between the electrodes in the external circuit; (IV) with the charge transfer, the potential difference between the two ends gradually tends to be equal, and finally reaches the electrostatic equilibrium; (V) when the triboelectric nanogenerator is applied with force again, the aerogel and the polytetrafluoroethylene film gradually approach each other, a reverse potential difference is generated between the two, and then a negative signal is formed.

[0107] The repeated contact and separation of the triboelectric material make the two end electrodes continuously accumulate charges, forming a stable electrical output signal.

[0108] Referring to Figure 9 , Figure 9 The short-circuit current signal diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present application under one cycle is shown in FIG.

[0109] As Figure 9 shown, in the repeated vertical contact and separation process driven by external force, the current signal characteristics of the Example 1-based triboelectric nanogenerator verified the above-mentioned mechanism.

[0110] Referring to Figure 10 , Figure 10 The open-circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared in accordance with the Comparative Example 1 to Comparative Example 4 of the present application under the condition of an action frequency of 5 Hz and an action force of 10 N.

[0111] As Figure 10 shown, under the condition of an action frequency of 5 Hz and an action force of 10 N, the open-circuit voltage of the aerogel-based triboelectric nanogenerator prepared in accordance with the Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 (corresponding to CF, C2M1, C2M1S 10 , A 10 C2M1 in the diagram, respectively) was 35.2 V, 74.4 V, 111.5 V and 116.4 V, respectively, and the aerogel-based triboelectric nanogenerator of Comparative Example 2, Comparative Example 3 and Comparative Example 4 was improved by 211.3%, 316.7% and 330.6% compared with that of Comparative Example 1, respectively. Therefore, it can be known that the microfibrillated cellulose, (3-chloro-2-hydroxypropyl) trimethylammonium chloride and wood ash all have an improving effect on the open-circuit voltage.

[0112] Referring to Figure 11 , Figure 11 The open-circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared in accordance with the process of Example 1 of the present application with different amounts of wood ash (wherein the aerogel of Example 1 includes A 12 C2M1S z , and “z” represents the proportion of wood ash in the total amount of fibers, which is 10wt%, 15wt%, 20wt%, 25wt% and 30wt%, respectively).

[0113] As Figure 11 shown, the open-circuit voltage of the triboelectric nanogenerator first increases and then decreases with the amount of wood ash, and thus it can be known that the complexation of calcium and potassium ions in the wood ash with cellulose increases the ion polarization, the existence of calcium carbonate and magnesium carbonate crystals increases the boundary between the crystalline region and the amorphous region in the system, and enhances the interface polarization. The open-circuit voltage of A12C2M1S20 (aerogel prepared using the process of Example 1: the concentration of (3-chloro-2-hydroxypropyl) trimethylammonium chloride aqueous solution is 12 g / L, the relative ratio of the amount of cellulose fibers to microfibrillated cellulose is 2, and the proportion of wood ash in the total amount of fibers is 20wt%) is the largest, which is 170.9 V. If the amount of wood ash is excessive, it is easy to agglomerate and disperse unevenly, resulting in a decrease in output.

[0114] Referring to Figure 12The open circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared by using different concentrations of (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution in the process of Example 1 of the present application (wherein the aerogel of Example 1 comprises A x C2M1S 20 , and "x" represents the concentration of the aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, which is 30 g / L, 35 g / L, 40 g / L, 45 g / L, and 50 g / L, respectively).

[0115] As shown in Figure 12 , the electrical output of the triboelectric nanogenerator increases with the increase of the concentration of (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution, and when the concentration of (3-chloro-2-hydroxypropyl) trimethylammonium chloride reaches 40 g / L, the open circuit voltage of the triboelectric nanogenerator almost no longer changes and tends to be stable.

[0116] The open circuit voltage of the aerogel-based triboelectric nanogenerator of Example 1 can reach 307.3 V, because after (3-chloro-2-hydroxypropyl) trimethylammonium chloride is combined with the cellulose skeleton, the nitrogen atoms therein become part of the positive charge center, changing the electron density of the adjacent carbon atoms, enhancing the polarization ability of the molecule, and because there is no hydrogen bond between nitrogen and oxygen, the activity of the molecule is more flexible. The movement of the positive and negative charge centers changes the dipole moment, thereby increasing the dielectric properties of the modified cellulose, and the crystallinity of the aerogel is improved, increasing the amount of polarized charge in the contact charging process, and the introduced cationic groups further increase the charge density on the surface of the material.

[0117] However, because the reaction of (3-chloro-2-hydroxypropyl) trimethylammonium chloride with cellulose is limited, when its amount increases to a certain extent, the open circuit voltage of the triboelectric nanogenerator almost no longer increases.

[0118] Referring to Figure 13 , Figure 13 , the open circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared by using the process of Example 1 of the present application.

[0119] As shown in Figure 13 , the figure shows the effect of the ratio of cellulose fibers to microfibrillated cellulose after modification by ammonium salt on the open circuit voltage, indicating that the ratio of the aerogel of Example 1 is optimal.

[0120] Referring to Figure 14 , Figure 14 , the open circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared by using the process of Example 1 of the present application. Figure 14Figure (b) in the figure is the open circuit voltage diagram of the aerogel-based triboelectric nanogenerator with different thicknesses prepared in Example 1 of the present application.

[0121] As shown in Figure 14 , by analyzing the effect of the interfacial distance of the positive and negative friction surfaces and the thickness of the aerogel of Example 1 on the output of the triboelectric nanogenerator, it is determined that the interfacial distance of the triboelectric nanogenerator device with the optimal open circuit voltage is 15 mm, and the thickness of the aerogel is 6 mm.

[0122] Referring to Figure 15 , Figure 15 , the pressure sensing diagram and the anti-fatigue characteristic result diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present application are shown; Figure 15 Figure (a) in the figure is the open circuit voltage diagram under different applied forces (1N to 20N), Figure 15 Figure (b) in the figure is the short circuit current diagram under different applied forces (1N to 20N), Figure 15 Figure (c) in the figure is the short circuit current diagram and the charge transfer amount diagram under different applied forces (1N to 20N), Figure 15 Figure (d) in the figure is the linear relationship between the open circuit voltage and the applied force, Figure 15 Figure (e) in the figure is the open circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 during 13000 cycles.

[0123] As shown in Figure 15 , because the increasing force makes the positive and negative friction layers contact more closely and the effective contact area increases, thereby improving the triboelectric output, the open circuit voltage, the short circuit current and the charge transfer amount all increase with the increasing applied force (1N to 20N), and the maximum output values are 442.9V, 4.68μA and 131.2nC, respectively. At the same time, the fiber profile and the concave-convex microstructure on the surface of the aerogel of Example 1 enable it to exhibit good pressure sensitivity within a certain force range, and through fitting calculation, the pressure sensitivity of Example 1 within the range of 1N to 10N is 20.65V / N, which can provide performance guarantee for subsequent sensing applications.

[0124] As shown in Figure 15 Figure (e), after 13000 cycles, the aerogel-based triboelectric nanogenerator prepared in Example 1 still maintains stable electrical output, and has excellent anti-fatigue characteristics.

[0125] Referring to Figure 16 , Figure 16 , the open circuit voltage diagram, the short circuit current diagram and the output power density diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present application under external variable resistance are shown.

[0126] In addition, as shown in Figure 16As shown, it is connected to 10 4 to 10 9 Ω variable resistor, the open circuit voltage is measured to increase with resistance, short-circuit current decreases with resistance, when the resistance is 20MΩ, the peak power density reaches 165.7μW / cm².

[0127] As shown in Figure 17 , Figure 17 The figure (a) in FIG. shows the triboelectric output performance of the aerogel-based triboelectric nanogenerator prepared in Example 1 under different relative humidity environments, Figure 17 The figure (b) in FIG. shows the short-circuit current of the aerogel-based triboelectric nanogenerator prepared in Example 1 under different humidity environments. Figure 17

[0128] As shown in Figure 17 , the aerogel of Example 1 with a surface of 5cm²×5cm² is used as the triboelectric positive electrode material, and a polytetrafluoroethylene film is used as the negative electrode material to assemble the aerogel-based triboelectric nanogenerator of Example 1, which is sealed in a container to control the change of humidity inside, and the triboelectric output performance under different humidity environments is tested under the condition of 1.9Hz and 8N, as shown in the figure (a) in FIG. and the figure (b) in FIG. Figure 17 Figure 18

[0129] As shown in Figure 18 , Figure 18 The figure shows that the interface of the aerogel-based triboelectric nanogenerator prepared in Example 1 forms bound water and ion channels through hydrogen bonds to improve the electrical output during operation in a humid environment.

[0130] Figure 17 As shown in the figure, due to the rich hydrophilic groups such as hydroxyl groups in the aerogel and its porous structure, a large number of water molecules form bound water on the surface and inside of the aerogel in the low humidity and medium humidity range, and cations and metal ions further promote the charge transfer, thus increasing the electrical output of the triboelectric nanogenerator, as shown in the figure (a) in FIG. and the figure (b) in FIG. Figure 17 Figure 19

[0131] As shown in​​​​​Figure 19 , Figure 19 This is a wet sensing sensitivity diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present invention; Figure 19 Figure (a) in the figure is a fitting curve of the open circuit voltage and short circuit current of the aerogel-based triboelectric nanogenerator prepared in Example 1 as a function of humidity in the range of relative humidity from 30% to 80%. Figure 19 Figure (b) shows the open-circuit voltage response of the aerogel-based triboelectric nanogenerator prepared in Example 1 during humidification or dehumidification.

[0132] Depend on Figure 19 As shown in Figure (a), the humidity sensitivity of open-circuit voltage and short-circuit current in the range of 30%RH to 80%RH is 0.985V / %RH (R 2 =0.984) and 0.005μA / %RH (R 2 =0.996), indicating that it has excellent humidity sensing performance within this humidity range; by Figure 20 As shown in Figure (b), when the ambient humidity decreases from 90%RH to 30%RH, the open-circuit voltage first increases and then decreases, which is opposite to the trend of the ambient humidity increase process. Furthermore, the output voltage changes very little during the moisture absorption and dehumidification processes, indicating that the aerogel-based triboelectric nanogenerator of Example 1 has reversible humidity response.

[0133] Please see Figure 21 and Figure 20 , Figure 21 The open-circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present invention after 14,000 contact-separation cycles at 83% relative humidity. Figure 20 The real-time open-circuit voltage of the aerogel-based triboelectric nanogenerator prepared in Example 1 of this invention is obtained by intermittently exhaling air into the triboelectric layer during the operation driven by a commercial exciter.

[0134] like Figure 21 As shown, after 14,000 contact-separation cycles at 83% RH, the open-circuit voltage remained stable without significant change, demonstrating high humidity durability. When breath was exhaled onto the aerogel-based triboelectric nanogenerator of Example 1, which is driven by a commercial vibrator, the output voltage exhibited a trend of first increasing and then decreasing, with the electrical signal variation amplitude remaining stable (e.g., ...). Figure 22 As shown in the figure, the aerogel of Example 1 has the potential to monitor respiration.

[0135] Please see Figure 22 , Figure 22 This is a product application diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 of the present invention. Figure 22 Figure (a) shows a schematic diagram of powering 632 LEDs.Figure 22 Figure (b) shows the charging curves of commercial capacitors ranging from 0.22 μF to 10 μF. Figure 22 Figure (c) in the diagram is a schematic diagram of the process of powering an electronic stopwatch that requires a 3V power supply.

[0136] The aerogel-based triboelectric nanogenerator of this embodiment can be applied to capacitor charging, electronic stopwatches, wireless sensors for detecting human movement, and burglar alarms due to its energy harvesting and intelligent sensing capabilities.

[0137] like Figure 22 As shown in Figure a, a 5cm²×5cm² device can simultaneously light up 632 LEDs.

[0138] like Figure 22 As shown in b, after the AC power is converted to DC power by the bridge rectifier, it can charge commercial capacitors ranging from 0.22μF to 10μF.

[0139] like Figure 23 As shown in c, it can also drive an electronic stopwatch that requires a 3V power supply, demonstrating its energy harvesting potential.

[0140] Please see Figure 23 , Figure 23 The diagram shows the output voltage of the aerogel-based triboelectric nanogenerator prepared in Example 1 of this invention as a sensor for detecting human motion. Figure 23 Figure (a) shows the output voltage as a contact sensor for detecting human movement. Figure 23 Figure (b) shows the output voltage as a non-contact sensor for detecting human motion.

[0141] In addition to energy harvesting, such as Figure 23 As shown, this triboelectric nanogenerator can be used as a wireless sensor to detect human movement. Its working principle is as follows: when a foot touches a 3.5cm²×3.5cm² triboelectric nanogenerator or passes a 5cm²×5cm² single-electrode triboelectric nanogenerator from 1m away, the output voltage signal is converted into a square wave by the processing circuit. This signal is counted by a microcontroller and transmitted wirelessly. Another microcontroller then triggers a buzzer and a digital display. The signal strength reflects the movement state. Figure 23 In Figure (a), when the sensor is in motion, the output voltages for walking, running, and jumping are 121.8V, 151.1V, and 182.3V, respectively; Figure 24 Figure (b) shows the values ​​of 1.8V, 2.6V, and 3.5V for non-contact sensing, respectively, which verifies the feasibility of human motion monitoring.

[0142] Please see Figure 24 , Figure 24 This diagram shows the application of the aerogel-based triboelectric nanogenerator prepared in Example 1 of this invention in a burglar alarm. Figure 24Fig. (a) in the figure is a schematic diagram of the aerogel-based triboelectric nanogenerator prepared in Example 1 as a theft alarm, Figure 24 Fig. (b) in the figure is a schematic diagram of the simulated alarm working.

[0143] As shown in Figure 25 , the theft alarm developed by the aerogel-based triboelectric nanogenerator can be placed under the door mat, when someone steps on or approaches, the triboelectric nanogenerator triggers the voltage signal, activates the buzzer and the nixie tube, and the voice alarm and the position display.

[0144] Referring to Figure 26 , Figure 26 , the figure is the open-circuit voltage diagram of the aerogel-based triboelectric nanogenerator prepared by the process of Example 1 of the present application using different types of leaf litter made into wood ash.

[0145] The leaf litter of the present embodiment is one of ilex wintergreen leaf litter, broussonetia papyrifera leaf litter, loquat leaf litter, sedge leaf litter, plane tree leaf litter and camphor tree leaf litter.

[0146] Specifically, the leaf litter of ilex wintergreen, broussonetia papyrifera, loquat, sedge and camphor tree is made into wood ash, and aerogels of different wood ash sources are prepared by using the same component ratio and process route as Example 1 and assembled into vertical contact separation mode triboelectric nanogenerator, the output voltage is measured, the results show that the voltage output is different due to the difference of leaf species but has good output performance, which proves that the manufacturing method of the present application has expansibility and universality.

[0147] Referring to Figure 26 , Figure 27 , the figure is the degradation process diagram of the aerogel prepared in Example 1 of the present application.

[0148] As shown in Figure 27 , Example 1 is buried in outdoor soil, after one month, the aerogel prepared in Example 1 is dry but the structure is intact, after 5 months, the aerogel is split into small pieces, after 6 months, many small holes appear on the small pieces, and some small pieces observed before have disappeared, which shows that the aerogel has been partially degraded and the degradation behavior is still continuing, so it can be known that the aerogel has good biodegradability and high standard environmental protection characteristics.

[0149] Referring to Figure 27 , Figure 27 , the figure is the electrical output performance comparison diagram of the aerogel-based triboelectric nanogenerator prepared by recycling the aerogel prepared in Example 1 of the present application for multiple times, Figure 27 Fig. (a) in the figure is an open-circuit voltage comparison diagram, Figure 27 Fig. (b) in the figure is a short-circuit current comparison diagram, ​ Fig. (c) in the figure is a charge transfer amount comparison diagram.

[0150] As ​ shown, the aerogel and the remaining aerogel scraps in the used Example 1 aerogel-based triboelectric nanogenerator were normally placed for 60 days, and the aerogel sample was prepared by remixing, and assembled into a vertical contact-separated triboelectric nanogenerator, which had an output voltage of 438.2 V, an output current of 3.81 μA and a charge transfer amount of 122.8 nC; the voltage of the triboelectric nanogenerator assembled by the Example 1 aerogel after three cycles of preparation only decreased by 5.9%, the current decreased by 39.7%, and the transferred charge decreased by 27.0%.

[0151] In summary, by modifying cellulose with quaternary ammonium salt and multi-scale fiber entanglement of microfibrillated cellulose as the skeleton, adding wood ash after leaf burning, and through rapid dehydration, freezing and normal temperature drying, an aerogel with excellent mechanical properties, recyclability and biodegradability is prepared, realizing the processing of cellulose aerogel with high humidity adaptability, high output, recyclability and biodegradability.

[0152] The present application needs to be explained that, in the present application, when referring to a numerical range, it should be understood that each numerical range of two endpoints and any one numerical value between the two endpoints can be selected, since the same steps and examples are adopted, in order to prevent repetition, the present application describes the preferred examples; although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept; therefore, the appended claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0153] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the idea and scope of the present application; if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing a wood ash filled cellulose based composite material, characterized by, The method comprises the following steps: S10: preparing an aqueous solution of (3-chloro-2-hydroxypropyl) trimethylammonium chloride, adding a strong base, and stirring for the first time to form a quaternary ammonium salt solution; S20: taking coniferous wood pulp for homogenization treatment to form cellulose fibers, adding the quaternary ammonium salt solution, and stirring for the second time while heating, and then washing with water to form quaternary ammonium salt modified cellulose; S30: taking microfibrillated cellulose, wood ash, and deionized water, mixing with the quaternary ammonium salt modified cellulose, and stirring for the third time to obtain the composite material.

2. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1, characterized in that, The microfibrillated cellulose has a fiber width of 50 nm to 200 nm and a fiber length of 20 μm to 500 μm.

3. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1, characterized in that, The aqueous solution has a volume of 80 mL to 140 mL, and the (3-chloro-2-hydroxypropyl) trimethylammonium chloride contained therein has a mass of 1.4 g to 6.0 g.

4. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1, characterized in that, The mass ratio of the strong base to the cellulose fibers in the quaternary ammonium salt modified cellulose is 1.0 g to 1.2 g: 1.8 g to 3.0 g.

5. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1 or 4, characterized in that, The strong base is sodium hydroxide or potassium hydroxide.

6. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1, characterized in that, The deionized water has a volume of 200 mL to 400 mL, and the microfibrillated cellulose has a mass of 0.6 g to 1.8 g, and the wood ash has a mass of 0.36 g to 1.08 g.

7. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1, characterized in that, The wood ash is obtained by washing, drying, and grinding the ash obtained by burning fallen leaves, wherein the fallen leaves are at least one of fallen leaves of Ilex purpurea, Broussonetia papyrifera, Eriobotrya japonica, Sabal, Ficus superba, or Cinnamomum camphora.

8. The method for preparing the cellulose-based composite material filled with plant ash according to claim 1, characterized in that, The stirring for the second time while heating is stirring at a temperature of 65°C to 75°C and a rotation speed of 40 r / min to 50 r / min for 50 min to 70 min.

9. Aerogel of a wood ash filled cellulose based composite, characterized in that, The preparation process of the aerogel is as follows: the composite material prepared by the preparation method of any one of claims 1 to 8 is placed in a solvent leaching tool to leach out the solvent, and then dried to obtain the aerogel.

10. The aerogel of grasswood ash filled cellulose based composite material as claimed in claim 9, wherein, The drying is freezing at a temperature of -18°C to -5°C for 2.0 h to 4.5 h, drying at a temperature of 55°C to 65°C for 20 min to 35 min, then pressing, and finally drying at a temperature of 55°C to 65°C for 6 h to 8 h.

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