Magnesium-based fly ash porous sound-absorbing material with surface hydrophobically modified and preparation method thereof

Abstract

A magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified, and a preparation method thereof are provided. In the preparation method, a basic magnesium sulfate cement is adopted as a cementing agent and a fly ash is adopted as a mineral admixture to prepare a slurry; foaming is conducted through a physical foaming process in a foaming machine to obtain a foam; and the foam is mixed with the slurry, and a resulting mixture is poured and cured, and then subjected to a surface hydrophobic modification through vapor deposition to obtain the sound-absorbing material. The sound-absorbing material has a density of 251 kg/m.sup.3 to 306 kg/m.sup.3, a noise reduction coefficient (NRC) of 0.65 to 0.7, a compressive strength of 1.8 MPa to 2.2 MPa, and a water contact angle of 129 to 151.

Claims

1. A preparation method of a magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified, comprising the following steps: step 1: thoroughly mixing magnesium oxide, a fly ash, and a fiber to obtain a mixed dry material, wherein a mass of the fly ash is 10% to 30% of a total mass of the mixed dry material; step 2: dissolving magnesium sulfate heptahydrate and an admixture in water, and heating for dissolution to obtain an admixture-containing magnesium sulfate solution; step 3: adding the mixed dry material obtained in step 1 to the admixture-containing magnesium sulfate solution obtained in step 2, and stirring to obtain a cement slurry; step 4: diluting a foaming agent with water, using a foaming machine to prepare a foam, and adding the foam to the cement slurry obtained in step 3 under a low-speed stirring to obtain a foamed slurry, wherein the foaming agent is diluted 50 to 80 times with the water, and the foam has a density of 30 kg/m.sup.3 to 60 kg/m.sup.3; step 5: pouring the foamed slurry obtained in step 4 into a mold, covering with a layer of plastic wrap, curing in air at room temperature for 1 d, demolding, and further curing until a test age to obtain a magnesium-based fly ash porous material; step 6: adding a modifier dropwise around the magnesium-based fly ash porous material obtained in step 5, sealing, and conducting a surface deposition modification at a constant temperature to obtain a modified material, wherein the modifier is added dropwise at an amount of 1 mL to 10 mL per 1 m.sup.2 of the magnesium-based fly ash porous material; and step 7: fully cooling the modified material obtained in step 6 at room temperature, and taking the modified material out to obtain the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified.

2. The preparation method according to claim 1, wherein in step 1, the magnesium oxide is light burned magnesia (LBM), wherein a content of active magnesium oxide is 55 wt % to 70 wt % in the LBM; and a mass of the fiber is 0.3% to 0.8% of the total mass of the mixed dry material.

3. The preparation method according to claim 1, wherein in step 1, the fiber is any one selected from the group consisting of a polyethylene (PE) fiber, a polypropylene (PP) fiber, a polyvinyl alcohol (PVA) fiber, a polyester fiber, and a polyamide (PA) fiber.

4. The preparation method according to claim 2, wherein in step 2, a molar ratio of magnesium sulfate in the magnesium sulfate heptahydrate to the active magnesium oxide is 1:5; a mass of the admixture is 0.5% to 1% of a mass of the active magnesium oxide; the admixture is any one selected from the group consisting of citric acid, a citrate, tartaric acid, a tartrate, phosphoric acid, and a phosphate; and the heating is conducted at 30 C. to 50 C. for dissolution.

5. The preparation method according to claim 1, wherein in step 3, the cement slurry has a water-to-cement ratio of 0.6 to 0.8.

6. The preparation method according to claim 1, wherein in step 3, the stirring is conducted at 600 r/min to 800 r/min for 8 min to 10 min.

7. The preparation method according to claim 1, wherein in step 4, the foaming agent is obtained by mixing at least one selected from the group consisting of tetradecyl dimethyl betaine, sodium dodecylbenzenesulfonate (SDBS), and sodium dodecyl sulfate (SDS) at any ratio; and the low-speed stirring is conducted at 200 r/min to 400 r/min.

8. The preparation method according to claim 1, wherein in step 6, the modifier is any one selected from the group consisting of triethoxymethylsilane, isobutyltriethoxysilane, -aminopropyltriethoxysilane, poly(methyl 3,3,3-trioxopropyl)siloxane, and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES).

9. The preparation method according to claim 1, wherein in step 6, the surface deposition modification is conducted at 55 C. to 70 C. for 2 h to 6 h.

10. A magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified prepared by the preparation method according to claim 1, wherein the magnesium-based fly ash porous sound-absorbing material has a density of 251 kg/m.sup.3 to 306 kg/m.sup.3, a noise reduction coefficient (NRC) of 0.65 to 0.7, a compressive strength of 1.8 MPa to 2.2 MPa, and a water contact angle of 129 to 151.

11. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 1 of the preparation method, the magnesium oxide is light burned magnesia (LBM), wherein a content of active magnesium oxide is 55 wt % to 70 wt % in the LBM; and a mass of the fiber is 0.3% to 0.8% of the total mass of the mixed dry material.

12. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 1 of the preparation method, the fiber is any one selected from the group consisting of a polyethylene (PE) fiber, a polypropylene (PP) fiber, a polyvinyl alcohol (PVA) fiber, a polyester fiber, and a polyamide (PA) fiber.

13. The magnesium-based fly ash porous sound-absorbing material according to claim 11, wherein in step 2 of the preparation method, a molar ratio of magnesium sulfate in the magnesium sulfate heptahydrate to the active magnesium oxide is 1:5; a mass of the admixture is 0.5% to 1% of a mass of the active magnesium oxide; the admixture is any one selected from the group consisting of citric acid, a citrate, tartaric acid, a tartrate, phosphoric acid, and a phosphate; and the heating is conducted at 30 C. to 50 C. for dissolution.

14. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 3 of the preparation method, the cement slurry has a water-to-cement ratio of 0.6 to 0.8.

15. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 3 of the preparation method, the stirring is conducted at 600 r/min to 800 r/min for 8 min to 10 min.

16. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 4 of the preparation method, the foaming agent is obtained by mixing at least one selected from the group consisting of tetradecyl dimethyl betaine, sodium dodecylbenzenesulfonate (SDBS), and sodium dodecyl sulfate (SDS) at any ratio; and the low-speed stirring is conducted at 200 r/min to 400 r/min.

17. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 6 of the preparation method, the modifier is any one selected from the group consisting of triethoxymethylsilane, isobutyltriethoxysilane, -aminopropyltriethoxysilane, poly(methyl 3,3,3-trioxopropyl)siloxane, and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES).

18. The magnesium-based fly ash porous sound-absorbing material according to claim 10, wherein in step 6 of the preparation method, the surface deposition modification is conducted at 55 C. to 70 C. for 2 h to 6 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A-1F show water contact angles of the materials prepared in Comparative Examples 1 and 2 and Examples 1, 2, 3, and 4,

(2) where FIG. 1A is for Comparative Example 1, FIG. 1B is for Comparative Example 2, FIG. 1C is for Example 1, FIG. 1D is for Example 2, FIG. 1E is for Example 3, and FIG. 1F is for Example 3.

(3) FIG. 2 shows a pore structure and a micro-morphology of the magnesium-based fly ash porous sound-absorbing material.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) The technical solutions of the present disclosure will be further described below through specific examples. Those skilled in the art should understand that the specific examples only help understand the present disclosure and should not be regarded as specific limitations to the present disclosure.

Comparative Example 1

(5) A preparation method of a basic magnesium sulfate cement porous sound-absorbing material with a surface hydrophobically modified was provided, including the following steps:

(6) (1) 1,380 g of magnesium oxide with an active magnesium oxide content of 61 wt % and 982.6 g of magnesium sulfate heptahydrate were weighed, where a molar ratio of the active magnesium oxide to magnesium sulfate was 5:1, 6.19 g of a PP fiber and 8.44 g of citric acid were weighed, and the active magnesium oxide was thoroughly mixed with the fiber to obtain a mixed dry material.

(7) (2) 792.4 g of water was weighed; and the magnesium sulfate heptahydrate, the citric acid, and the water were mixed and incubated in a water bath at 45 C. for dissolution to obtain a magnesium sulfate solution.

(8) (3) The mixed dry material obtained in step (1) was added to the magnesium sulfate solution obtained in step (2), and a resulting mixture was thoroughly stirred to obtain a slurry.

(9) (4) Tetradecyl dimethyl betaine was diluted according to 1:60 and then used for foaming in a foaming machine to obtain a foam with a density of 45 kg/m.sup.3, and the foam was added to the slurry obtained in step (3) under stirring at a rotational speed of 300 r/min to obtain a foamed slurry.

(10) (5) The foamed slurry was poured into a mold and wrapped by a film, cured in air at room temperature for 1 d, then demolded, and further cured until a test age to obtain a basic magnesium sulfate cement porous sound-absorbing material.

(11) (6) The porous sound-absorbing material obtained in step (5) was placed in a Petri dish, then 0.2 mL of PFDTES was added dropwise around the material in the Petri dish, the Petri dish was sealed with a lid and then placed in a 55 C. incubator, and a surface deposition modification was conducted at the constant temperature for 2 h.

(12) (7) After the constant-temperature modification, the Petri dish with the lid covered was taken out and cooled to room temperature to obtain the basic magnesium sulfate cement porous sound-absorbing material with a surface hydrophobically modified.

(13) A water contact angle of the basic magnesium sulfate cement porous sound-absorbing material with a surface hydrophobically modified prepared in this comparative example was shown in FIG. 1A, and the mechanical and sound absorption performance indexes of the sound-absorbing material were shown in Table 1.

Comparative Example 2

(14) A preparation method of a magnesium-based fly ash porous sound-absorbing material was provided, including the following steps:

(15) (1) 1,530 g of magnesium oxide with an active magnesium oxide content of 55 wt % and 982.6 g of magnesium sulfate heptahydrate were weighed, where a molar ratio of the active magnesium oxide to magnesium sulfate was 5:1; 502.5 g of a fly ash, 12.6 g of a PVA fiber, and 8.44 g of citric acid were weighed; and the active magnesium oxide, the fly ash, and the fiber were thoroughly mixed to obtain a mixed dry material.

(16) (2) 919.8 g of water was weighed and the magnesium sulfate heptahydrate, the citric acid, and the water were mixed and incubated in a water bath at 45 C. for dissolution to obtain a magnesium sulfate solution.

(17) (3) The mixed dry material obtained in step (1) was added to the magnesium sulfate solution obtained in step (2), and a resulting mixture was thoroughly stirred to obtain a slurry.

(18) (4) Tetradecyl dimethyl betaine was diluted according to 1:50 and then used for foaming in a foaming machine to obtain a foam with a density of 30 kg/m.sup.3, and the foam was added to the slurry obtained in step (3) under stirring at a rotational speed of 200 r/min to obtain a foamed slurry.

(19) (5) The foamed slurry was poured into a mold and wrapped by a film, cured in air at room temperature for 1 d, then demolded, and further cured until a test age to obtain the magnesium-based fly ash porous sound-absorbing material.

(20) A water contact angle of the magnesium-based fly ash porous sound-absorbing material prepared in this comparative example was shown in FIG. 1B, and the mechanical and sound absorption performance indexes of the sound-absorbing material were shown in Table 1.

Example 1

(21) A preparation method of a magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified was provided, including the following steps:

(22) (1) 1,530 g of magnesium oxide with an active magnesium oxide content of 55 wt % and 982.6 g of magnesium sulfate heptahydrate were weighed, where a molar ratio of the active magnesium oxide to magnesium sulfate was 5:1; 502.5 g of a fly ash, 12.6 g of a PVA fiber, and 8.44 g of citric acid were weighed; and the active magnesium oxide, the fly ash, and the fiber were thoroughly mixed to obtain a mixed dry material.

(23) (2) 919.8 g of water was weighed; and the magnesium sulfate heptahydrate, the citric acid, and the water were mixed and incubated in a water bath at 45 C. for dissolution to obtain a magnesium sulfate solution.

(24) (3) The mixed dry material obtained in step (1) was added to the magnesium sulfate solution obtained in step (2), and a resulting mixture was thoroughly stirred to obtain a slurry.

(25) (4) Tetradecyl dimethyl betaine was diluted according to 1:50 and then used for foaming in a foaming machine to obtain a foam with a density of 30 kg/m.sup.3, and the foam was added to the slurry obtained in step (3) under stirring at a rotational speed of 200 r/min to obtain a foamed slurry.

(26) (5) The foamed slurry was poured into a mold and wrapped by a film, cured in air at room temperature for 1 d, then demolded, and further cured until a test age to obtain the magnesium-based fly ash porous sound-absorbing material.

(27) (6) The magnesium-based fly ash porous sound-absorbing material obtained in step (5) was placed in a Petri dish, then 0.1 mL of triethoxymethylsilane was added dropwise around the material in the Petri dish, the Petri dish was sealed with a lid and then placed in a 70 C. incubator, and a surface deposition modification was conducted at the constant temperature for 3 h.

(28) (7) After the constant-temperature modification, the Petri dish with the lid covered was taken out and cooled to room temperature to obtain the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified.

(29) A water contact angle of the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified prepared in this example was shown in FIG. 1C, and the mechanical and sound absorption performance indexes of the sound-absorbing material were shown in Table 1.

Example 2

(30) A preparation method of a magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified was provided, including the following steps:

(31) (1) 1,202 g of magnesium oxide with an active magnesium oxide content of 70 wt % and 982.6 g of magnesium sulfate heptahydrate were weighed, where a molar ratio of the active magnesium oxide to magnesium sulfate was 5:1; 720.8 g of a fly ash, 19.2 g of a PP fiber, and 8.44 g of citric acid were weighed; and the active magnesium oxide, the fly ash, and the fiber were thoroughly mixed to obtain a mixed dry material.

(32) (2) 1418.8 g of water was weighed; and the magnesium sulfate heptahydrate, the citric acid, and the water were mixed and incubated in a water bath at 45 C. for dissolution to obtain a magnesium sulfate solution.

(33) (3) The mixed dry material obtained in step (1) was added to the magnesium sulfate solution obtained in step (2), and a resulting mixture was thoroughly stirred to obtain a slurry.

(34) (4) Tetradecyl dimethyl betaine was diluted according to 1:70 and then used for foaming in a foaming machine to obtain a foam with a density of 50 kg/m.sup.3, and the foam was added to the slurry obtained in step (3) under stirring at a rotational speed of 400 r/min to obtain a foamed slurry.

(35) (5) The foamed slurry was poured into a mold and wrapped by a film, cured in air at room temperature for 1 d, then demolded, and further cured until a test age to obtain the magnesium-based fly ash porous sound-absorbing material.

(36) (6) The magnesium-based fly ash porous sound-absorbing material obtained in step (5) was placed in a Petri dish, then 0.15 mL of isobutyltriethoxysilane was added dropwise around the material in the Petri dish, the Petri dish was sealed with a lid and then placed in a 65 C. incubator, and a surface deposition modification was conducted at the constant temperature for 4 h.

(37) (7) After the constant-temperature modification, the Petri dish with the lid covered was taken out and cooled to room temperature to obtain the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified.

(38) A water contact angle of the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified prepared in this example was shown in FIG. 1D, and the mechanical and sound absorption performance indexes of the sound-absorbing material were shown in Table 1.

Example 3

(39) A preparation method of a magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified was provided, including the following steps:

(40) (1) 1,380 g of magnesium oxide with an active magnesium oxide content of 61 wt % and 982.6 g of magnesium sulfate heptahydrate were weighed, where a molar ratio of the active magnesium oxide to magnesium sulfate was 5:1; 796.8 g of a fly ash, 13.3 g of a PP fiber, and 8.44 g of citric acid were weighed; and the active magnesium oxide, the fly ash, and the fiber were thoroughly mixed to obtain a mixed dry material.

(41) (2) 1,488.8 g of water was weighed; and the magnesium sulfate heptahydrate, the citric acid, and the water were mixed and incubated in a water bath at 45 C. for dissolution to obtain a magnesium sulfate solution.

(42) (3) The mixed dry material obtained in step (1) was added to the magnesium sulfate solution obtained in step (2), and a resulting mixture was thoroughly stirred to obtain a slurry.

(43) (4) Tetradecyl dimethyl betaine was diluted according to 1:80 and then used for foaming in a foaming machine to obtain a foam with a density of 60 kg/m.sup.3, and the foam was added to the slurry obtained in step (3) under stirring at a rotational speed of 400 r/min to obtain a foamed slurry.

(44) (5) The foamed slurry was poured into a mold and wrapped by a film, cured in air at room temperature for 1 d, then demolded, and further cured until a test age to obtain the magnesium-based fly ash porous sound-absorbing material.

(45) (6) The magnesium-based fly ash porous sound-absorbing material obtained in step (5) was placed in a Petri dish, then 0.1 mL of PFDTES was added dropwise around the material in the Petri dish, the Petri dish was sealed with a lid and then placed in a 65 C. incubator, and a surface deposition modification was conducted at the constant temperature for 3 h.

(46) (7) After the constant-temperature modification, the Petri dish with the lid covered was taken out and cooled to room temperature to obtain the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified.

(47) A water contact angle of the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified prepared in this example was shown in FIG. JE, and the mechanical and sound absorption performance indexes of the sound-absorbing material were shown in Table 1.

Example 4

(48) A preparation method of a magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified was provided, including the following steps:

(49) (1) 1,530 g of magnesium oxide with an active magnesium oxide content of 55 wt % and 982.6 g of magnesium sulfate heptahydrate were weighed, where a molar ratio of the active magnesium oxide to magnesium sulfate was 5:1; 223.3 g of a fly ash, 8.9 g of a PVA fiber, and 8.44 g of citric acid were weighed; and the active magnesium oxide, the fly ash, and the fiber were thoroughly mixed to obtain a mixed dry material.

(50) (2) 836.6 g of water was weighed; and the magnesium sulfate heptahydrate and the water were mixed and incubated in a water bath at 45 C. for dissolution to obtain a magnesium sulfate solution.

(51) (3) The mixed dry material obtained in step (1) was added to the magnesium sulfate solution obtained in step (2), and a resulting mixture was thoroughly stirred to obtain a slurry.

(52) (4) Tetradecyl dimethyl betaine was diluted according to 1:50 and then used for foaming in a foaming machine to obtain a foam with a density of 30 kg/m.sup.3, and the foam was added to the slurry obtained in step (3) under stirring at a rotational speed of 200 r/min to obtain a foamed slurry.

(53) (5) The foamed slurry was poured into a mold and wrapped by a film, cured in air at room temperature for 1 d, then demolded, and further cured until a test age to obtain the magnesium-based fly ash porous sound-absorbing material.

(54) (6) The magnesium-based fly ash porous sound-absorbing material obtained in step (5) was placed in a Petri dish, then 0.2 mL of triethoxymethylsilane was added dropwise around the material in the Petri dish, the Petri dish was sealed with a lid and then placed in a 60 C. incubator, and a surface deposition modification was conducted at the constant temperature for 4 h.

(55) (7) After the constant-temperature modification, the Petri dish with the lid covered was taken out and cooled to room temperature to obtain the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified.

(56) A water contact angle of the magnesium-based fly ash porous sound-absorbing material with a surface hydrophobically modified prepared in this example was shown in FIG. 1F, and the performance indexes of the sound-absorbing material were shown in Table 1.

(57) TABLE-US-00001 TABLE 1 Performance of the magnesium-based fly ash porous sound- absorbing materials with a surface hydrophobically modified Density Compressive No. (kg/m.sup.3) strength (MPa) NRC Comparative Example 1 277 2.2 0.73 Comparative Example 2 270 1.9 0.69 Example 1 268 1.9 0.68 Example 2 251 1.8 0.7 Example 3 293 2 0.69 Example 4 306 2. 0.65

(58) It can be seen from Table 1 that, when at a density of 251 kg/m.sup.3 to 306 kg/m.sup.3, the magnesium-based fly ash porous sound-absorbing materials with a surface hydrophobically modified prepared in Examples 1 to 4 have a compressive strength as high as 1.8 MPa to 2.2 MPa and exhibit mechanical performance far better than that of the existing Portland cement porous material and when a fly ash content is 30%, the NRC still can reach 0.65.

(59) FIGS. 1A-1F show water contact angles of the materials prepared in Comparative Examples 1 and 2 and Examples 1 to 4. It can be seen from FIG. 1B that the unmodified sound-absorbing material has a water contact angle almost of 0 and is superhydrophilic, and a surface of each of the modified materials exhibits excellent hydrophobicity. In addition, it can be seen from FIG. 1A and FIG. 1E that, for the same PFDTES modifier, when the modification temperature is increased and the modification time is extended, the surface hydrophobicity of the material of the present disclosure is significantly enhanced, and the water contact angle can reach 151, indicating superhydrophobicity.

(60) FIG. 2 shows a pore structure and a micro-morphology of the magnesium-based fly ash porous sound-absorbing material. It can be seen from the figure that the prepared material has abundant pore structures, and a large number of basic magnesium sulfate needle-like and rod-like crystals grow on an inner pore wall to form a villiform micro-nano rough surface.

(61) The above implementations are only used to explain the present disclosure, not to limit the present disclosure. Without departing from the spirit and scope of the present disclosure, those of ordinary skill in the art can also make various changes and variations. Therefore, all equivalent technical solutions also belong to the scope of the present disclosure, and the patent protection scope of the present disclosure shall be defined by the claims.

(62) The content not described in detail in the description of the present disclosure refers to existing technologies known by those skilled in the art. The illustrative specific implementations of the present disclosure are described above to facilitate those skilled in the art to understand the present disclosure, but it should be noted that the present disclosure is not limited to the scope of the specific implementations. Various obvious changes made by those of ordinary skill in the art within the spirit and scope of the present disclosure defined by the appended claims should fall within the protection scope of the present disclosure.