Preparation method of modified silica aerogel, and modified silica aerogel

Abstract

The invention belongs to the field of aerogel, relates to the technical field of silica aerogels, and concretely relates to a preparation method of modified silica aerogel, and the silica aerogel. A sulfydryl modified fiber is used as a reinforcing material, and when the silica aerogel is prepared, a modifier containing carbon-carbon unsaturated double bonds is used for modification, and the sulfydryl group and the carbon-carbon unsaturated double bonds are subjected to a sulfydryl-alkene click chemical reaction under ultraviolet irradiation to obtain the fiber reinforced silica aerogel. The silica aerogel has good mechanical properties at a low fiber content, and the properties of low density, low heat conductivity coefficient and the like of the silica aerogel are maintained to a large extent.

Description

technical field

[0001] The invention belongs to the technical field of airgel, and relates to a preparation method of modified silica airgel and the modified silica airgel. Background technique

[0002] Silica airgel is a new type of nanoporous material, more than 95% of its volume is filled with air, so it has the characteristics of low density, low thermal conductivity, high porosity, and large specific surface area. Large new material, but it also has the disadvantage of low strength, and supercritical drying or freeze drying is required in the preparation process, which has high cost, long cycle and low production capacity. Therefore, the use of modification means to improve the mechanical strength of silica, which can be dried under normal pressure, is the development direction of silica airgel, and one of the means is to use fiber reinforcement modification. CN110127706A adopted glass fibers, CN110256101A adopted PI chopped fibers, CN108640643A adopted reinforcing fib...

Examples

Embodiment 1

[0024] Ultrasonic dispersion of 1 part of mercapto-modified chopped glass fiber into 150 parts of absolute ethanol, adding 20 parts of tetraethyl orthosilicate and stirring evenly, adding 15 parts of water and stirring evenly, then adding 1mol / L hydrochloric acid solution to adjust the pH to 3, stirring Hydrolyze for 3 hours, add ammonia water to adjust the pH to 9, stir and condense to obtain a wet gel; the wet gel is placed in an environment of 45°C for 40 hours, replaced with absolute ethanol twice, and soaked at a concentration of 90g / L of dimethylvinylchlorosilane n-hexane solution for 15 hours, take it out, soak it in benzoin dimethyl ether absolute ethanol solution with a concentration of 2g / L for 15 hours, and irradiate with ultraviolet light with a dominant wavelength of 365nm and a light intensity of 6mW / cm After 7 minutes, take it out, and dry at 40°C for 2 hours, 80°C for 3 hours, and 120°C for 2 hours under normal pressure to obtain glass fiber-modified silica air...

Embodiment 2

[0026] Ultrasonic dispersion of 1 part of mercapto-modified chopped polyester fiber into 400 parts of absolute ethanol, adding 50 parts of tetraethyl orthosilicate and stirring evenly, adding 30 parts of water and stirring evenly, then adding 1mol / L hydrochloric acid solution to adjust the pH to 3, Stir well for hydrolysis for 2.5 hours, add ammonia water to adjust the pH to 9, stir well and condense to obtain a wet gel; the wet gel is placed in a 45°C environment for 45 hours of airtight aging, replaced with absolute ethanol twice, and soaked at a concentration of 60g / L of dimethylvinylchlorosilane n-hexane solution for 20 hours, take it out, soak it in benzoin ethyl ether absolute ethanol solution with a concentration of 4g / L for 20 hours, and irradiate it with ultraviolet light with a dominant wavelength of 365nm and a light intensity of 6mW / cm for 3 Minutes, take it out, and dry at 40°C for 2 hours, 80°C for 2 hours, and 120°C for 2.5 hours under normal pressure to obtain ...

Embodiment 3

[0028] Ultrasonic dispersion of 1 part of mercapto-modified chopped polyamide fiber into 800 parts of absolute ethanol, adding 90 parts of tetraethyl orthosilicate and stirring evenly, adding 60 parts of water and stirring evenly, then adding oxalic acid to adjust the pH to 3, stirring well for hydrolysis After 3 hours, add sodium carbonate to adjust the pH to 9, stir well to condense, and obtain a wet gel; place the wet gel in a 45°C environment for 40 hours of airtight aging, replace it with absolute ethanol twice, and soak it in a concentration of 150g / L Tetramethyldivinyldisilazane n-hexane solution for 25 hours, take it out, soak in benzoin butyl ether absolute ethanol solution with a concentration of 3g / L for 18 hours, and irradiate with ultraviolet light with a dominant wavelength of 365nm and a light intensity of 6mW / cm After 5 minutes, take it out, and dry at 40°C for 3 hours, 80°C for 3 hours, and 120°C for 2 hours under normal pressure to obtain polyamide fiber-modif...

technical field

[0001] The invention belongs to the technical field of airgel, and relates to a preparation method of modified silica airgel and the modified silica airgel. Background technique

[0002] Silica airgel is a new type of nanoporous material, more than 95% of its volume is filled with air, so it has the characteristics of low density, low thermal conductivity, high porosity, and large specific surface area. Large new material, but it also has the disadvantage of low strength, and supercritical drying or freeze drying is required in the preparation process, which has high cost, long cycle and low production capacity. Therefore, the use of modification means to improve the mechanical strength of silica, which can be dried under normal pressure, is the development direction of silica airgel, and one of the means is to use fiber reinforcement modification. CN110127706A adopted glass fibers, CN110256101A adopted PI chopped fibers, CN108640643A adopted reinforcing fib...

Examples

Embodiment 1

[0024] Ultrasonic dispersion of 1 part of mercapto-modified chopped glass fiber into 150 parts of absolute ethanol, adding 20 parts of tetraethyl orthosilicate and stirring evenly, adding 15 parts of water and stirring evenly, then adding 1mol / L hydrochloric acid solution to adjust the pH to 3, stirring Hydrolyze for 3 hours, add ammonia water to adjust the pH to 9, stir and condense to obtain a wet gel; the wet gel is placed in an environment of 45°C for 40 hours, replaced with absolute ethanol twice, and soaked at a concentration of 90g / L of dimethylvinylchlorosilane n-hexane solution for 15 hours, take it out, soak it in benzoin dimethyl ether absolute ethanol solution with a concentration of 2g / L for 15 hours, and irradiate with ultraviolet light with a dominant wavelength of 365nm and a light intensity of 6mW / cm After 7 minutes, take it out, and dry at 40°C for 2 hours, 80°C for 3 hours, and 120°C for 2 hours under normal pressure to obtain glass fiber-modified silica air...

Embodiment 2

[0026] Ultrasonic dispersion of 1 part of mercapto-modified chopped polyester fiber into 400 parts of absolute ethanol, adding 50 parts of tetraethyl orthosilicate and stirring evenly, adding 30 parts of water and stirring evenly, then adding 1mol / L hydrochloric acid solution to adjust the pH to 3, Stir well for hydrolysis for 2.5 hours, add ammonia water to adjust the pH to 9, stir well and condense to obtain a wet gel; the wet gel is placed in a 45°C environment for 45 hours of airtight aging, replaced with absolute ethanol twice, and soaked at a concentration of 60g / L of dimethylvinylchlorosilane n-hexane solution for 20 hours, take it out, soak it in benzoin ethyl ether absolute ethanol solution with a concentration of 4g / L for 20 hours, and irradiate it with ultraviolet light with a dominant wavelength of 365nm and a light intensity of 6mW / cm for 3 Minutes, take it out, and dry at 40°C for 2 hours, 80°C for 2 hours, and 120°C for 2.5 hours under normal pressure to obtain ...

Embodiment 3

[0028] Ultrasonic dispersion of 1 part of mercapto-modified chopped polyamide fiber into 800 parts of absolute ethanol, adding 90 parts of tetraethyl orthosilicate and stirring evenly, adding 60 parts of water and stirring evenly, then adding oxalic acid to adjust the pH to 3, stirring well for hydrolysis After 3 hours, add sodium carbonate to adjust the pH to 9, stir well to condense, and obtain a wet gel; place the wet gel in a 45°C environment for 40 hours of airtight aging, replace it with absolute ethanol twice, and soak it in a concentration of 150g / L Tetramethyldivinyldisilazane n-hexane solution for 25 hours, take it out, soak in benzoin butyl ether absolute ethanol solution with a concentration of 3g / L for 18 hours, and irradiate with ultraviolet light with a dominant wavelength of 365nm and a light intensity of 6mW / cm After 5 minutes, take it out, and dry at 40°C for 3 hours, 80°C for 3 hours, and 120°C for 2 hours under normal pressure to obtain polyamide fiber-modif...