A kind of aerogel composite material and its application

Abstract

An aerogel composite material is disclosed, which is prepared by hydrolyzing methyltriethoxysilane, dimethyldimethoxysilane and ethyl orthosilicate under the catalysis of hydrochloric acid to obtain a precursor solution, then adding urea for gelation, and finally drying at normal pressure; butanetetracarboxylic acid and carboxylated cellulose nanofibers are added to the precursor solution. Also disclosed is the application of the aerogel composite material in heat insulation and flame retardancy. The aerogel composite material not only has strong compressive resistance, but is also not prone to rupture, and has greatly improved mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of aerogels and relates to an aerogel composite material and application thereof. Background Art

[0002] Aerogel is a highly dispersed solid nanomaterial with a nanoporous network structure, which is composed of polymer or colloidal particles aggregated together. The gaseous dispersion medium filled in its nanopores gives aerogel many advantages and is widely used in many fields such as military, construction, energy and environmental protection.

[0003] Among aerogels, the most studied aerogels are silica aerogels. This type of aerogel has low thermal conductivity, high specific surface area, high porosity, low density and low refractive index. These physical properties determine the application of silica aerogel in thermal insulation. Silica aerogel has extremely low thermal conductivity, and its spatial network structure is mainly composed of Si-O-Si bonds. It has good flame retardant properties and can be used directly as an inorganic flame retardant material. However, direct use has problems such as poor mechanical properties and high brittleness. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, an object of the present invention is to provide an aerogel composite material with better mechanical properties and its application.

[0005] In order to achieve the above-mentioned purpose, on the one hand, the technical scheme adopted by the present invention is as follows: an aerogel composite material, which is prepared by hydrolyzing methyltriethoxysilane, dimethyldimethoxysilane and ethyl orthosilicate under the catalysis of hydrochloric acid to obtain a precursor solution, then adding urea for gelation, and finally drying at normal pressure; wherein, butanetetracarboxylic acid and carboxylated cellulose nanofibers are added to the precursor solution.

[0006] According to the aerogel composite material of the present invention, the molar ratio of methyltriethoxysilane, dimethyldimethoxysilane and tetraethyl orthosilicate is 1: (0.16-0.20): (0.04-0.08).

[0007] In a specific embodiment, the molar ratio of methyltriethoxysilane, dimethyldimethoxysilane and ethyl orthosilicate is 1:0.18:0.06.

[0008] According to the aerogel composite material of the present invention, the molar ratio of methyltriethoxysilane to water is 1:(18-22).

[0009] In one specific embodiment, the molar ratio of methyltriethoxysilane to water is 1:20.

[0010] According to the aerogel composite material of the present invention, the precursor solution is added with (2-4) wt % of hexadecyltrimethylammonium bromide, calculated based on the total weight of the precursor solution.

[0011] In one embodiment, the precursor solution is added with (3.3) wt % hexadecyltrimethylammonium bromide, based on the total weight of the precursor solution.

[0012] According to the aerogel composite material of the present invention, the added amount of butanetetracarboxylic acid is (0.5-1.5) wt%, calculated based on the total weight of the precursor solution.

[0013] In a specific embodiment, the amount of butanetetracarboxylic acid added is 1 wt %, based on the total weight of the precursor solution.

[0014] According to the aerogel composite material of the present invention, the added amount of the carboxylated cellulose nanofibers is (6-10) wt%, calculated based on the total weight of the precursor solution.

[0015] In a specific embodiment, the amount of carboxylated cellulose nanofibers added is 7.9 wt %, based on the total weight of the precursor solution.

[0016] According to the aerogel composite material of the present invention, the average diameter of the carboxylated cellulose nanofibers is 2-10 nm, the length is 50-500 nm, and the carboxyl content is 2.0-4.0 mmol / g.

[0017] In a specific embodiment, the carboxylated cellulose nanofibers have an average diameter of 6 nm, a length of 200 nm, and a carboxyl content of 3.0 mmol / g.

[0018] According to the aerogel composite material of the present invention, the gelation temperature is 70-90°C; and the normal pressure drying temperature is 50-70°C.

[0019] In a specific embodiment, the gelation temperature is 80°C; and the normal pressure drying temperature is 60°C.

[0020] On the other hand, the technical solution adopted by the present invention is as follows: an application of the aerogel composite material according to the present invention in thermal insulation.

[0021] In another aspect, the technical solution adopted by the present invention is as follows: an application of the aerogel composite material according to the present invention in flame retardancy.

[0022] Compared with the prior art, the aerogel composite material according to the present invention not only has stronger compressive resistance, but is also less likely to break, and its mechanical properties are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a SEM picture of the aerogel composite material of Example 1.

[0024] Figure 2 This is the adsorption-desorption VS partial pressure curve of the aerogel composite material in Example 1.

[0025] Figure 3 is the pore width distribution curve of the aerogel composite material of Example 1. DETAILED DESCRIPTION

[0026] It must be noted that, as used in this specification and the appended claims, the singular forms "a", "an", and "the" may include both one and plural referents (i.e., more than two, including two), unless the context clearly dictates otherwise.

[0027] Unless otherwise indicated, the numerical range in the present invention is approximately, and therefore may include values ​​outside the range. The numerical range can be expressed in the present invention as from "about" a specific value and / or to "about" another specific value. When expressing such a range, another aspect includes from the specific value and / or to another specific value. Similarly, when a value is expressed as an approximation by using the antecedent "about", it should be understood that the specific value forms another aspect. It should also be understood that the endpoint of each in the numerical range is important and independent of the other endpoint in the relationship with the other endpoint.

[0028] References in the specification and the appended claims to parts by weight of a particular element or component in a composition or article refer to the weight relationship between that element or component and any other elements or components in the composition or article expressed in parts by weight.

[0029] In the present invention, unless otherwise specifically indicated, or implied by the context or the customary manner in the technical field, the solutions mentioned in the present invention are all aqueous solutions; when the solute of the aqueous solution is a liquid, all fractions and percentages are calculated by volume, and the volume percentage of the component is based on the total volume of the composition or product containing the component; when the solute of the aqueous solution is a solid, all fractions and percentages are calculated by weight, and the weight percentage of the component is based on the total weight of the composition or product containing the component.

[0030] The terms "comprising", "including", "having" and the like mentioned in the present invention are not intended to exclude the existence of any optional components, steps or procedures, regardless of whether any optional components, steps or procedures are specifically disclosed. For the avoidance of any doubt, all methods claimed by using the term "comprising" may include one or more additional steps, equipment parts or components and / or substances unless otherwise stated. In contrast, the term "consisting of" excludes any components, steps or procedures that are not specifically described or listed. Unless otherwise stated, the term "or" refers to the members listed individually and in any combination.

[0031] Furthermore, the contents of any patent or non-patent document referenced in this invention are hereby incorporated by reference in their entirety, particularly with respect to definitions published in the art (to the extent not inconsistent with any definitions specifically provided herein) and common knowledge.

[0032] In the present invention, unless otherwise indicated, parts are by weight, temperatures are expressed in ° C or at ambient temperature, and pressures are atmospheric or near atmospheric. Room temperature means 20-30 ° C. There are many variations and combinations of reaction conditions (e.g., component concentrations, desired solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the product purity and yield obtained by the method. Only reasonable routine experiments will be required to optimize such process conditions.

[0033] Example 1

[0034] Add 2g CTAB to 36.8mL 1M hydrochloric acid solution and stir continuously until completely dissolved. Then, add 17.8g methyltriethoxysilane, 2.16g dimethyldimethoxysilane, and 1.25g ethyl orthosilicate (converted to a molar ratio of 1:0.18:0.06) to the above solution and stir to fully hydrolyze the precursor solution. Add 0.6g butanetetracarboxylic acid and stir to fully dissolve it; then add 4.8g carboxylated cellulose nanofibers (average diameter 6nm, length 200nm, carboxyl content 3.0mmol / g) and continue stirring to mix the components evenly. Add 4g urea and pour it into the mold after it is fully dissolved. Place it in an oven at a temperature of 80℃ for gelation for 6h; age it under heat preservation conditions for 18h to obtain an aged wet gel. Soak and wash the wet gel with anhydrous ethanol 3 times, place it in an oven at a temperature of 60℃ and dry it at normal pressure for 12h to finally obtain an aerogel composite material.

[0035] SEM images of aerogel composites can be found at Figure 1 The IR spectrum of the aerogel composite material shows that the product has a peak at 3342 cm -1 、2980cm -1 、1724cm -1 、1228cm -1 、1415cm -1 、1036cm -1 and 776cm -1 It has a characteristic absorption peak.

[0036] The adsorption and pore width distribution curves of the aerogel composite material were tested by the specific surface area and porosity analyzer. The adsorption-desorption VS partial pressure curve and pore width distribution curve of the aerogel composite material are shown in Figure 2. Figure 2 and 3The BET surface area, total pore volume and average pore width were calculated according to the adsorption curve, as shown in Table 1.

[0037] The mechanical properties of the aerogel composite material were tested using a universal material testing machine with a loading speed of 2 mm / min and a sample size of Φ10 mm×20 mm. The Young's modulus E of the aerogel composite material was calculated through the linear region of the first 20% strain of the stress-strain curve, and the rupture stress σ* and strain S* were calculated at the same time, as shown in Table 2.

[0038] Comparative Example 1

[0039] The other steps were the same as in Example 1 except that butanetetracarboxylic acid was not added.

[0040] Comparative Example 2

[0041] The carboxylated cellulose nanofibers were replaced with cellulose nanofibers (average diameter 6 nm, length 200 nm), and the rest was the same as in Example 1.

[0042] According to the same test method, the BET surface area, total pore volume and average pore width of each sample were calculated according to the adsorption curves of Example 1 and Comparative Examples 1-2, as shown in Table 1; and the Young's modulus E, rupture stress σ* and strain S* of each sample were calculated, as shown in Table 2.

[0043] Table 1

[0044]

[0045] Table 2

[0046]

[0047] It can be seen from Table 1-2 that, compared with Comparative Examples 1-2, the aerogel composite material of Example 1 of the present application not only has stronger compressive resistance, but is also less likely to break, and its mechanical properties are greatly improved.

[0048] In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes, substitutions, deletions, corrections or adjustments to the technical solutions of the present invention, and these equivalent technical solutions also fall within the scope defined by the claims of the present invention.

Claims

1. An aerogel composite material, which is prepared by hydrolyzing methyltriethoxysilane, dimethyldimethoxysilane and ethyl orthosilicate under the catalysis of hydrochloric acid to obtain a precursor solution, then adding urea to gelate, and finally drying at normal pressure; characterized in that: The precursor solution is added with butane tetracarboxylic acid and carboxylated cellulose nanofibers; The molar ratio of methyltriethoxysilane, dimethyldimethoxysilane and ethyl orthosilicate is 1:(0.16-0.20):(0.04-0.08); the molar ratio of methyltriethoxysilane to water is 1:(18-22); The precursor solution is added with (2-4) wt% hexadecyltrimethylammonium bromide, calculated based on the total weight of the precursor solution; The amount of butanetetracarboxylic acid added is (0.5-1.5) wt%, and the amount of carboxylated cellulose nanofibers added is (6-10) wt%, based on the total weight of the precursor solution; The average diameter of the carboxylated cellulose nanofibers is 2-10 nm, the length is 50-500 nm, and the carboxyl content is 2.0-4.0 mmol / g.

2. The aerogel composite material according to claim 1, characterized in that: The gelation temperature is 70-90°C; the normal pressure drying temperature is 50-70°C.

3. Use of the aerogel composite material according to claim 1 or 2 in thermal insulation.

4. Use of the aerogel composite material according to claim 1 or 2 in flame retardancy.

Images