Preparation method of thermal insulation aerogel material

Abstract

The invention discloses a preparation method of a heat-insulating aerogel material, which comprises the following steps: preparing modified halloysite, preparing aramid nanofiber dispersion liquid, mixing methyl triethoxysilane, tetraethoxysilane, hexadecyl trimethyl ammonium bromide, modified halloysite and aramid nanofiber dispersion liquid to prepare hydrogel, and drying to obtain the aerogel material. According to the invention, the preparation process and composition of the aerogel are improved, and the addition of the modified halloysite and the aramid nanofiber is matched with the improvement of the double silicon sources, so that the thermal insulation performance of the aerogel is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and specifically to a method for preparing thermal insulation aerogel materials. Background Technology

[0002] Silica aerogel is a porous solid material with extremely low density, high porosity, and high specific surface area. These properties make it promising for applications in thermal insulation, wastewater treatment, and filtration. Taking thermal insulation as an example, with the rapid development of aerospace, military, and agricultural production, the demand for new thermal insulation and protection materials for various instruments and pipelines is increasing. However, existing silica aerogel materials cannot meet the requirements in terms of thermal insulation performance and strength, and improvements are needed. Summary of the Invention

[0003] To address at least one of the aforementioned technical deficiencies, the present invention provides the following technical solution:

[0004] This application discloses a method for preparing thermal insulation aerogel materials, including the following steps:

[0005] Preparation of modified halloysite: Methyl myristate was mixed with lauric acid, methyl methacrylate and halloysite and dried to obtain modified halloysite;

[0006] Preparation of aramid nanofiber dispersion: The gel formed by dissolving aramid nanofibers is mixed with water and homogenized to form an aramid nanofiber dispersion.

[0007] Methyltriethoxysilane, tetraethyl orthosilicate, hexadecyltrimethylammonium bromide, modified halloysite, aramid nanofiber dispersion, and polyethylene glycol were mixed and placed into a mold to prepare a hydrogel of the desired shape. After drying, an aerogel material was obtained.

[0008] Aramid nanofibers can support the internal pores of aerogels, improving their porosity and toughness. By loading phase change materials with halloysite, a large amount of heat is absorbed or released during the phase change process. Combined with methyltriethoxysilane and tetraethyl orthosilicate dual silicon sources, a complex network structure is formed, which helps to significantly improve the thermal insulation performance of aerogels. The addition of halloysite helps to improve the strength of aerogels.

[0009] Furthermore, the preparation of modified halloysite involves mixing methyl laurate with molten methyl myristate, then adding methyl methacrylate to the mixture to form a loading component. The loading component is then mixed with halloysite, ultrasonically treated, transferred to a vacuum chamber, dried, and extracted to remove the loading component from the halloysite surface, thus forming modified halloysite. This process simplifies the preparation process and facilitates operation.

[0010] Furthermore, the methyl lauryl, methyl myristate, and methyl methacrylate are mixed in a molar ratio of 1-2:1-3:0.8-1.2, and the ratio of halloysite to the total mass of methyl lauryl, methyl myristate, and methyl methacrylate is 200:0.6-1.5. This preferred composition ratio helps to improve the performance of the aerogel.

[0011] Further, the preparation of aramid nanofiber dispersion: Aramid nanofibers and alkaline components are added to a mixture of dimethyl sulfoxide and water, and stirred at 45-55°C until the aramid nanofibers are dissolved. The resulting mixture is then added to water to displace the nanofibers and obtain a hydrogel. The hydrogel is then homogenized with water to obtain the aramid nanofiber dispersion. The state of the aramid nanofiber dispersion makes it easier to mix with silicon sources and other materials to form a gel, and facilitates the entry of nanofibers into the interior of the aerogel to improve the distribution of pores.

[0012] Further, hexadecyltrimethylammonium bromide, methyltriethoxysilane, and tetraethyl orthosilicate are added to the solution and stirred until homogeneous. Hydrochloric acid is added to hydrolyze the silicon source. Then, ammonia, modified halloysite, and aramid nanofiber dispersion are added and injected into the mold.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] 1. This invention improves the preparation process and composition of aerogel. The addition of modified halloysite and aramid nanofibers, combined with the improvement of dual silicon sources, helps to significantly improve the thermal insulation performance and strength of aerogel. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments.

[0016] Example 1

[0017] The preparation method of thermal insulation aerogel material includes the following steps:

[0018] Preparation of modified halloysite:

[0019] Methyl myristate was heated to a molten state, methyl laurate was added to the molten methyl myristate and mixed evenly, and then methyl methacrylate was added to the mixture and stirred for 1.5 h to form a loaded component, wherein the molar ratio of methyl laurate, methyl myristate and methyl methacrylate was 1:1:1.

[0020] The obtained supported component was mixed with halloysite at a mass ratio of 1:200. The mixture was stirred at room temperature for 2 hours and then sonicated for 30 minutes. The resulting suspension was then transferred to a vacuum tank with a vacuum degree of 10. -1Pa, let stand for 2 hours to allow the loaded components to enter the lumen of halloysite, dry for 24 hours, then remove the loaded components from the surface of halloysite by Soxhlet extraction, and finally dry for 24 hours to form modified halloysite.

[0021] Preparation of aramid nanofiber dispersion: Aramid nanofibers and potassium hydroxide were added to a mixture of dimethyl sulfoxide and water. The aramid nanofibers were short para-aramid fibers with a length of 3 nm. The mass ratio of aramid nanofibers to potassium hydroxide was 1:1, the volume-to-mass ratio of the mixture to aramid nanofibers was 100 ml: 1 g, and the mass ratio of dimethyl sulfoxide to water was 20:1. The mixture was stirred at 50 °C until the aramid nanofibers were dissolved. The resulting mixture was then added to water to displace and remove dimethyl sulfoxide and potassium hydroxide, resulting in a hydrogel. The hydrogel was then homogenized with water to obtain an aramid nanofiber dispersion (mass fraction of 1.5%).

[0022] Hexadecyltrimethylammonium bromide, methyltriethoxysilane, and tetraethyl orthosilicate were added to a solution and stirred until homogeneous. The mass ratio of hexadecyltrimethylammonium bromide to tetraethyl orthosilicate was 1:100. Hydrochloric acid (36%) was added to adjust the pH to 5 to hydrolyze the silicon source. Then, ammonia (26%) with 4 times the volume of hydrochloric acid was added to make the solution alkaline. At the same time, the modified halloysite and aramid nanofiber dispersion prepared above were added and stirred for 10 min. The mixture was then poured into a mold to form a hydrogel of a predetermined shape and dried to obtain a thermal insulation aerogel material.

[0023] Example 2

[0024] The preparation method of thermal insulation aerogel material includes the following steps:

[0025] Preparation of modified halloysite:

[0026] Methyl myristate was heated to a molten state, methyl laurate was added to the molten methyl myristate and mixed evenly, and then methyl methacrylate was added to the mixture and stirred for 1.5 h to form a loaded component. The molar ratio of methyl laurate, methyl myristate and methyl methacrylate was 1:2:1.

[0027] The obtained supported component was mixed with halloysite at a mass ratio of 1.5:200. The mixture was stirred at room temperature for 2 hours and then sonicated for 40 minutes. The resulting suspension was then transferred to a vacuum tank with a vacuum degree of 10. -1 Pa, let stand for 3 hours to allow the loaded components to enter the lumen of halloysite, dry for 30 hours, then remove the loaded components from the surface of halloysite by Soxhlet extraction, and finally dry for 24 hours to form modified halloysite.

[0028] Preparation of aramid nanofiber dispersion: Aramid nanofibers and potassium hydroxide were added to a mixture of dimethyl sulfoxide and water. The aramid nanofibers were short para-aramid fibers with a length of 3 nm. The mass ratio of aramid nanofibers to potassium hydroxide was 1:1, the volume-to-mass ratio of the mixture to aramid nanofibers was 120 ml: 1 g, and the mass ratio of dimethyl sulfoxide to water was 24:1. The mixture was stirred at 50 °C until the aramid nanofibers were dissolved. The resulting mixture was then added to water to displace and remove dimethyl sulfoxide and potassium hydroxide, resulting in a hydrogel. The hydrogel was then homogenized with water to obtain an aramid nanofiber dispersion (mass fraction of 1.5%).

[0029] Hexadecyltrimethylammonium bromide, methyltriethoxysilane, and tetraethyl orthosilicate were added to a solution and stirred until homogeneous. The mass ratio of hexadecyltrimethylammonium bromide to tetraethyl orthosilicate was 1:105. Hydrochloric acid (36%) was added to adjust the pH to 5 to hydrolyze the silicon source. Then, ammonia (26%) with 4 times the volume of hydrochloric acid was added to make the solution alkaline. At the same time, the modified halloysite and aramid nanofiber dispersion prepared above were added and stirred for 15 minutes. The mixture was then poured into a mold to form a hydrogel of a predetermined shape and dried to obtain a thermal insulation aerogel material.

[0030] Example 3

[0031] The preparation method of thermal insulation aerogel material includes the following steps:

[0032] Preparation of modified halloysite:

[0033] Methyl myristate was heated to a molten state, methyl laurate was added to the molten methyl myristate and mixed evenly, and then methyl methacrylate was added to the mixture and stirred for 1 hour to form a loaded component. The molar ratio of methyl laurate, methyl myristate and methyl methacrylate was 1.2:1:1.

[0034] The obtained supported component was mixed with halloysite at a mass ratio of 1.1:200. The mixture was stirred at room temperature for 2 hours and then sonicated for 40 minutes. The resulting suspension was then transferred to a vacuum tank with a vacuum degree of 10. -1 Pa, let stand for 1.5 h to allow the loaded components to enter the lumen of halloysite, dry for 24 h, then remove the loaded components from the surface of halloysite by Soxhlet extraction, and finally dry for 24 h to form modified halloysite.

[0035] Preparation of aramid nanofiber dispersion: Aramid nanofibers and potassium hydroxide were added to a mixture of dimethyl sulfoxide and water. The aramid nanofibers were short para-aramid fibers with a length of 3 nm. The mass ratio of aramid nanofibers to potassium hydroxide was 1:0.8, the volume-to-mass ratio of the mixture to aramid nanofibers was 110 ml:1 g, and the mass ratio of dimethyl sulfoxide to water was 22:1. The mixture was stirred at 50 °C until the aramid nanofibers were dissolved. The resulting mixture was then added to water to displace and remove dimethyl sulfoxide and potassium hydroxide, resulting in a hydrogel. The hydrogel was then homogenized with water to obtain an aramid nanofiber dispersion (mass fraction of 1.5%).

[0036] Hexadecyltrimethylammonium bromide, methyltriethoxysilane, and tetraethyl orthosilicate were added to a solution and stirred until homogeneous. The mass ratio of hexadecyltrimethylammonium bromide to tetraethyl orthosilicate was 1:103. Hydrochloric acid (36%) was added to adjust the pH to 5 to hydrolyze the silicon source. Then, ammonia (26%) with 4 times the volume of hydrochloric acid was added to make the solution alkaline. At the same time, the modified halloysite and aramid nanofiber dispersion prepared above were added and stirred for 10 min. The mixture was then poured into a mold to form a hydrogel of a predetermined shape and dried to obtain a thermal insulation aerogel material.

[0037] Comparative Example 1

[0038] The difference compared to Example 1 is that no aramid nanofiber dispersion was added.

[0039] The performance of the thermal insulation aerogel material prepared above was tested, as shown in Table 1.

[0040] Table 1

[0041] Stress (KPa) Temperature difference (°C) Example 1 37.2 55.5 Example 2 43.5 60.7 Example 3 40.6 57.2 Comparative Example 1 30.1 46.8

[0042] The stress test was conducted under 60% compression conditions.

[0043] Temperature difference test: The thermal insulation aerogel material is placed on a heating plate, the heating plate is heated to 100°C, and the temperature difference between the upper surface of the aerogel and the surface of the heating plate is calculated within a predetermined time, i.e., the temperature difference shown in Table 1.

[0044] As can be seen from Table 1, the complex structure aerogel with halloysite-loaded phase change components and subsequent infiltration of phase change polyethylene glycol combined with aramid fibers and dual silicon sources exhibits excellent thermal insulation and strength.

[0045] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a thermal insulation aerogel material, characterized in that, Includes the following steps: Preparation of modified halloysite: Modified halloysite was obtained by mixing silane coupling agent KH-560, methyl methacrylate and halloysite and then drying. Preparation of aramid nanofiber dispersion: The gel formed by dissolving aramid nanofibers is mixed with water and homogenized to form an aramid nanofiber dispersion. Methyltriethoxysilane, tetraethyl orthosilicate, hexadecyltrimethylammonium bromide, modified halloysite, aramid nanofiber dispersion, and polyethylene glycol were mixed and placed into a mold to prepare a hydrogel of the desired shape. After drying, an aerogel material was obtained.

2. The method for preparing the thermal insulation aerogel material as described in claim 1, characterized in that: Preparation of modified halloysite: Methyl laurate was added to molten methyl myristate and mixed, and then methyl methacrylate was added to the mixture to form a loading component. The loading component was mixed with halloysite, and after ultrasonic treatment, it was transferred to a vacuum tank, dried and extracted to remove the loading component on the surface of halloysite to form modified halloysite.

3. The method for preparing the thermal insulation aerogel material as described in claim 2, characterized in that: The methyl lauryl, methyl myristate, and methyl methacrylate are mixed in a molar ratio of 1-2:1-3:0.8-1.2, and the mass ratio of halloysite to the total mass of methyl lauryl, methyl myristate, and methyl methacrylate is 200:0.6-1.

5.

4. The method for preparing the thermal insulation aerogel material as described in claim 1, characterized in that: Preparation of aramid nanofiber dispersion: Aramid nanofibers and alkaline components were added to a mixture of dimethyl sulfoxide and water, and stirred at 45-55℃ until the aramid nanofibers were dissolved. The resulting mixture was then added to water to displace the aramid nanofibers and obtain a hydrogel. The hydrogel was then homogenized with water to obtain the aramid nanofiber dispersion.

5. The method for preparing the thermal insulation aerogel material as described in claim 1, characterized in that: Hexadecyltrimethylammonium bromide, methyltriethoxysilane, and tetraethyl orthosilicate were added to the solution and stirred until homogeneous. Hydrochloric acid was added to hydrolyze the silicon source. Then, ammonia, modified halloysite, and aramid nanofiber dispersion were added and injected into a mold.