A flexible evaporative cooling composite material and its preparation method and application

Abstract

The application provides a flexible sweating cooling composite material and a preparation method and application thereof, and belongs to the technical field of active thermal protection. The flexible sweating cooling composite material comprises, from outside to inside, a sweating function layer, a working medium conveying layer and an elastic substrate layer. The sweating function layer is a composite material comprising a flexible porous material and a hydrogel. The flexible sweating cooling composite material can realize macroscopic and microscopic double precise controllable distribution of the cooling working medium, improve the uniformity of the cooling working medium, has higher cooling efficiency, and meanwhile, each function layer is a flexible material, can be stretched and deformed, and has a thin thickness, good covering effect, can be attached to the surface of each part of an aircraft, good sealing performance, and can adapt to the complex surface requirements of different aircraft surface parts.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of active thermal protection, in particular to a flexible sweat cooling composite material and a preparation method and application thereof. BACKGROUND

[0002] With the demand of long time, high Mach, variable orbit and even reusability of the new generation of high-speed aircraft, the aircraft faces more severe aerodynamic heating and complex mechanical environment. Its unique flight environment and flight characteristics bring great challenges to the design of thermal protection system. Higher requirements are put forward for the flame-retardant and heat-insulating performance of thermal protection and sealing materials with dynamic, deformation requirements and complex connection structure. The traditional rigid ablation-resistant and heat-insulating materials cannot completely meet the application requirements.

[0003] Chinese patent CN113276509A discloses a heat-insulating and flame-erosion-resistant flexible thermal protection material and a preparation method thereof. Under the condition of high-temperature gas at 1500℃-2000℃ and aerodynamic heat flow erosion, the surface of the material is ceramicized under the catalysis of rare earth oxides, and the material has good heat-insulating effect and can realize the protection of the internal structure. The mechanical properties of the material can be improved by more than 30% compared with the commonly used silicone rubber material added with flame-retardant powder, and the material has good heat-insulating and flame-erosion-resistant properties. However, the heat-resistant temperature and time of the material are limited, and the thickness of the material is large, so the material cannot be reused.

[0004] Sweat cooling is inspired by the way of biological sweat cooling. The cooling medium such as sweat slowly overflows from the heated surface, and a relatively uniform film is naturally formed on the surface of the material. The cooling medium can not only absorb heat and dissipate it, but also can raise the boundary layer to form a heat-insulating barrier and reduce aerodynamic heating. The base structure of sweat cooling is generally a structure with a layer plate and a porous material as a skeleton, and the material is generally metal or ceramic. However, there are problems such as complex structure, difficulty in deformation, poor cooling uniformity, etc. CN110696440A discloses a flexible skin for thermal protection of a high-speed aircraft beyond the limit and a method thereof based on a porous foam. The cooling liquid is controlled through the difference in pore diameter of the surface microstructure and the middle porous foam layer. However, due to the large pore diameter and pore spacing and low porosity, the cooling liquid is not uniformly distributed, the cooling efficiency is low, and the heat transfer is deteriorated, which leads to local ablation and other problems.

[0005] Therefore, there is an urgent need to provide a flexible thermal protection material with good heat-insulating uniformity, good sealing effect and deformability to meet the demand of the new generation of high-speed aircraft for thermal protection materials. SUMMARY

[0006] In view of one or more technical problems in the prior art, the present application provides a flexible sweating cooling composite material, a preparation method and application thereof, the flexible sweating cooling composite material provided by the present application can realize macroscopic and microscopic double precise controllable distribution of a cooling working medium, improve the uniformity of the cooling working medium, has higher cooling efficiency, and meanwhile each functional layer is a flexible material, can be stretched and deformed, and has a thin thickness, has a good covering effect, is attached to each part surface of an aircraft, has good sealing performance, and can adapt to complex profile requirements of different aircraft surface parts.

[0007] The present application provides, in a first aspect, a flexible sweating cooling composite material, which comprises, from outside to inside, a sweating functional layer, a working medium conveying layer and an elastic substrate layer;

[0008] The sweating functional layer is a composite material comprising a flexible porous material and a hydrogel.

[0009] The working medium conveying layer is made of a flexible material.

[0010] Preferably, the porosity of the flexible porous material is 45-99%; and / or

[0011] The thickness of the flexible porous material is 0.5-3.0 mm.

[0012] Preferably, the thickness of the elastic substrate layer is 1-4 mm.

[0013] The elastic modulus of the elastic substrate layer is 0.5-100 MPa; and / or

[0014] The elongation at break of the elastic substrate layer is >50%.

[0015] Preferably, the flexible porous material is at least one of a foam and a fiber fabric.

[0016] Preferably, the foam is melamine foam.

[0017] Preferably, the fiber fabric is one or more of a glass fiber fabric, an aramid fiber fabric, a quartz fiber fabric, a basalt fiber fabric and a carbon fiber fabric.

[0018] Preferably, the elastic substrate layer is at least one of a thermoplastic elastomer and a rubber.

[0019] Preferably, the thermoplastic elastomer is at least one of a thermoplastic polyurethane elastomer and a thermoplastic polyolefin elastomer.

[0020] Preferably, the rubber is at least one of silicone rubber and ethylene-propylene-diene rubber.

[0021] The application provides a preparation method of the flexible sweat cooling composite material in the second aspect, and the preparation method comprises the following steps:

[0022] S1. generating a hydrogel in-situ in the flexible porous material to obtain a sweat function layer;

[0023] S2. compounding the working medium conveying layer, the elastic substrate layer and the sweat function layer to obtain the flexible sweat cooling composite material.

[0024] Preferably, the step S1 comprises the following steps:

[0025] immersing the flexible porous material in an initiator solution, and drying to obtain a modified flexible porous material;

[0026] introducing a hydrogel precursor into the modified flexible porous material, and performing vacuum in-situ polymerization and drying to obtain the sweat function layer.

[0027] Preferably, the introducing is performed by a vacuum introduction process; and / or

[0028] the vacuum in-situ polymerization is performed at 20-95 DEG C.

[0029] Preferably, the step S2 comprises the following steps:

[0030] integrating the working medium conveying layer and the elastic substrate layer into an integrated structure by die forming;

[0031] compounding the integrated structure and the sweat function layer to obtain the flexible sweat cooling composite material.

[0032] The application provides an application of the flexible sweat cooling composite material in the third aspect, which is used for a thermal protection system of a high-speed aircraft.

[0033] Compared with the prior art, the application has at least the following beneficial effects:

[0034] The sweat function layer of the flexible sweat cooling composite material is a composite material comprising a flexible porous material and a hydrogel, which has good hydrophilicity on one hand, and is beneficial to the uniform distribution of the cooling working medium; on the other hand, when in a non-heated state or at a low heating temperature, the hydrogel expands after absorbing the cooling working medium, so that the porosity of the flexible porous material is reduced, the sweat function layer presents a water locking state, and the waste of the cooling working medium is reduced; with the increase of the heating temperature, according to the difference of the local heating temperature, the hydrogel in the high-temperature region shrinks after losing water, so that the porosity of the sweat function layer can be adjusted, and the distribution of the cooling working medium is optimized, which is beneficial to solving the problem of local ablation caused by heat transfer deterioration.

[0035] The flexible sweating cooling composite material of the application firstly performs primary distribution of the cooling working medium through the working medium conveying layer, realizes quantitative and accurate controllable distribution of the cooling working medium in a macro region, then realizes micro and macroscopic distribution of the cooling working medium through effective wetting of the sweating functional layer, adjusts the porosity of the sweating functional layer through the water absorption and water loss state of the hydrogel, further optimizes the distribution of the cooling working medium, and improves the uniformity and cooling efficiency of the cooling working medium. The flexible sweating cooling composite material of the application can realize double accurate controllable distribution of the cooling working medium in a macro and micro region, improve the uniformity of the cooling working medium, has higher cooling efficiency, and solves the problems of limited heat resistance temperature and time of the existing passive flexible thermal protection material, poor controllability of the delivery and distribution of the cooling working medium of the sweating cooling material with a hard metal and ceramic structure, easy heat transfer deterioration, and local ablation.

[0036] The sweating cooling composite material of the application is flexible, can be stretched and deformed, and has a thin thickness, has a good covering effect, is attached to the surface of each part of the aircraft, has good sealing performance, can adapt to the complex surface requirements of different surface parts of the aircraft, and overcomes the problems of large thickness of the existing passive flexible thermal protection material, inability to be reused, and difficulty in meeting the deformation and sealing requirements of the sweating cooling material with a hard metal and ceramic structure. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0038] Figure 1 is a structural schematic diagram of a flexible sweating cooling composite material provided by the application;

[0039] Figure 2 is a preparation flowchart of a flexible sweating cooling composite material provided by the application;

[0040] The drawings show that: 11 is a sweating functional layer; 12 is a working medium conveying layer; and 13 is an elastic base layer. DETAILED DESCRIPTION

[0041] In order to make the objects, technical solutions and advantages of the embodiments of the application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the application. Obviously, the described embodiments are some of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the application.

[0042] The present application provides a flexible sweat cooling composite material in the first aspect, the flexible sweat cooling composite material includes sweat function layer, working medium transport layer and elastic substrate layer arranged from outside to inside in sequence;

[0043] The sweat function layer is a composite material including flexible porous material and hydrogel;

[0044] The working medium transport layer is made of flexible material.

[0045] It should be noted that the working medium transport layer is used for transporting cooling working medium, which is made of flexible material (for example, it can be one or more of silicone rubber, PVC and PTFE, or it can be consistent with the material of the elastic substrate layer), including a plurality of cooling working medium transport pipelines, which can realize quantitative and accurate controllable distribution of cooling working medium in a macroscopic region.

[0046] The drawings of the present application are only provided for illustrative purposes, and the proportions of the components in the drawings may not be consistent with the actual product. In the present application, Figure 1 In the present application, the layers of the structure are peeled off from each other, which is to clearly show the positional relationship between the layers of the structure, and it should be understood that the layers of the structure are actually closely attached and / or partially attached.

[0047] The sweat function layer of the flexible sweat cooling composite material of the present application is a composite material including flexible porous material and hydrogel, which has good hydrophilicity on the one hand, and is beneficial to the uniform distribution of cooling working medium, and on the other hand, when in a non-heated state or at a low heated temperature, the hydrogel expands after absorbing the cooling working medium, which can reduce the porosity of the flexible porous material, so that the sweat function layer presents a water locking state to reduce the waste of cooling working medium; with the increase of the heated temperature, according to the difference of the local heated temperature, the hydrogel in the high temperature region shrinks after losing water, which can adjust the porosity of the sweat function layer, and then realize the distribution optimization of the cooling working medium, which is beneficial to solve the problem of local ablation caused by heat transfer deterioration.

[0048] The flexible sweat cooling composite material of the present application firstly realizes the quantitative and accurate controllable distribution of cooling working medium in a macroscopic region through the initial distribution of the cooling working medium by the working medium transport layer; then realizes the microcosmic and microscopic distribution of the cooling working medium through the effective infiltration of the sweat function layer, adjusts the porosity of the sweat function layer through the water absorption and water loss state of the hydrogel, further optimizes the distribution of the cooling working medium, and improves the uniformity and cooling efficiency of the cooling working medium. The flexible sweat cooling composite material of the present application can realize the double accurate controllable distribution of cooling working medium in a macroscopic and microscopic region, improve the uniformity of the cooling working medium, has higher cooling efficiency, and solves the problems of limited heat resistance temperature and time of the existing passive flexible thermal protection material, poor controllability of the distribution and transportation of cooling working medium of the sweat cooling material with hard metal and ceramic structure, and local ablation caused by heat transfer deterioration.

[0049] The sweat cooling composite material of the present application is flexible, stretchable and thin, and has good covering effect, and can be attached to the surface of each part of the aircraft, has good sealing performance, and can adapt to the complex surface requirements of different aircraft surface parts, and overcomes the problems of the existing passive flexible thermal protection material, such as large thickness and non-reusability, and the sweat cooling material of the existing hard metal and ceramic structure, which is difficult to meet the deformation and sealing requirements.

[0050] According to some preferred embodiments, the porosity of the flexible porous material is 45-99% (for example, it can be 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 99%); and / or

[0051] The thickness of the flexible porous material is 0.5-3.0 mm (for example, it can be 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm or 3 mm).

[0052] According to some preferred embodiments, the thickness of the elastic base layer is 1-4 mm (for example, it can be 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm or 4 mm);

[0053] The elastic modulus of the elastic base layer is 0.5-100 MPa (for example, it can be 0.5 MPa, 0.8 MPa, 1 MPa, 1.2 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa); and / or

[0054] The elongation at break of the elastic base layer is >50%.

[0055] According to some preferred embodiments, the flexible porous material is at least one of a foam and a fiber fabric;

[0056] Preferably, the foam is a melamine foam;

[0057] Preferably, the fiber fabric is one or more of a glass fiber fabric, an aramid fiber fabric, a quartz fiber fabric, a basalt fiber fabric and a carbon fiber fabric.

[0058] It should be noted that the flexible porous material of the present application is not limited to foams and fiber fabrics, and other materials meeting the requirements can also be used; the types of the foams and fiber fabrics described above are not limited to the above-mentioned range, and the above examples are only for better illustrating the technical solutions of the present application and are not limiting.

[0059] According to some preferred embodiments, the elastic base layer is at least one of a thermoplastic elastomer, a rubber;

[0060] Preferably, the thermoplastic elastomer is at least one of a thermoplastic polyurethane elastomer (TPU), a thermoplastic polyolefin elastomer (TPO), and a thermoplastic vulcanized rubber (TPV).

[0061] Preferably, the rubber is at least one of a silicone rubber and an ethylene propylene diene rubber (EPDM).

[0062] It should be noted that the elastic base layer of the present application is not limited to thermoplastic elastomers and rubbers, and other materials meeting the requirements can also be used; the types of the thermoplastic elastomers and rubbers described above are not limited to the above-mentioned range, and the above examples are only for better illustrating the technical solutions of the present application and are not limiting.

[0063] The present application provides in a second aspect a preparation method of the flexible sweat cooling composite material of the first aspect, and the preparation method comprises:

[0064] S1. generating a hydrogel in situ in a flexible porous material to obtain a sweat function layer;

[0065] S2. combining a working medium transport layer, an elastic base layer, and the sweat function layer to obtain the flexible sweat cooling composite material.

[0066] The present application selects a flexible porous material, generates a hydrogel in situ in the pores of the flexible porous material in an in-situ preparation manner to obtain a sweat function layer, then combines the sweat function layer, a working medium transport layer, and an elastic base layer, and performs solidification molding to obtain the flexible sweat cooling composite material. The preparation method of the flexible sweat cooling composite material of the present application is simple, the prepared flexible sweat cooling composite material can realize macroscopic and microscopic dual precise controllable distribution of the cooling working medium, improve the uniformity of the cooling working medium, has higher cooling efficiency, and meanwhile, each function layer is a flexible material, can be stretched and deformed, and has a thin thickness, has a good covering effect, can be attached to the surfaces of each part of an aircraft, has good sealing performance, and can adapt to the complex profile requirements of different aircraft surface parts.

[0067] According to some preferred embodiments, step S1 comprises:

[0068] immersing the flexible porous material in an initiator solution, and drying to obtain a modified flexible porous material;

[0069] The hydrogel precursor is introduced into the modified flexible porous material, vacuum in-situ polymerization, drying, to obtain a perspiration functional layer.

[0070] The present application first fully immerses the flexible porous material in an initiator solution, and after drying, a flexible porous material containing an initiator (modified flexible porous material) is obtained. Then the hydrogel precursor is introduced into the internal pores of the flexible porous material containing the initiator (modified flexible porous material), and vacuum in-situ polymerization is carried out to generate hydrogel in-situ in the flexible porous material, to obtain a composite material including flexible porous material and hydrogel, i.e. a perspiration functional layer. The present application first immerses the flexible porous material in an initiator solution to ensure that the initiator can be more uniformly dispersed in the internal pores of the flexible porous material, and then vacuum in-situ polymerization is carried out with the hydrogel precursor, so that the hydrogel can be more uniformly dispersed in the internal pores of the flexible porous material.

[0071] In some specific embodiments of the present application, the initiator is one or more of ammonium persulfate, sodium persulfate, and sodium thiosulfate.

[0072] In some specific embodiments of the present application, the hydrogel precursor includes a hydrogel monomer, a crosslinking agent, and water; wherein the hydrogel monomer is preferably at least one of acrylamide and sodium acrylate; and the crosslinking agent is preferably N,N'-methylenebisacrylamide (MBA).

[0073] In some specific embodiments of the present application, the hydrogel precursor includes a hydrogel monomer, a crosslinking agent, a catalyst, and water; wherein the hydrogel monomer is preferably at least one of acrylamide and sodium acrylate; the crosslinking agent is preferably N,N'-methylenebisacrylamide (MBA); and the catalyst is preferably tetramethyl ethylenediamine (TEMED).

[0074] It should be noted that the types of initiators and the compositions of hydrogel precursors are not limited to the above ranges, and the types and amounts of hydrogel monomers, crosslinking agents, and catalysts can be adjusted according to the specific type of hydrogel. The types of hydrogel monomers, crosslinking agents, and catalysts described above are also not limited to the above ranges, and the above examples are only for better illustrating the technical solutions of the present application and are not limiting.

[0075] According to some preferred embodiments, the introduction is carried out using a vacuum introduction process; and / or

[0076] The vacuum in-situ polymerization is carried out at 20-95°C (for example, it can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C).

[0077] According to some preferred embodiments, step S2 comprises:

[0078] The working medium transport layer and the elastic substrate layer are compounded into an integrated structure by mold pressing;

[0079] The integrated structure is compounded with the sweating functional layer to obtain the flexible sweating cooling composite material.

[0080] The present application first prepares an integrated structure of the elastic substrate layer and the working medium transport layer by mold pressing, and then compounds the sweating functional layer on the side of the integrated structure close to the working medium transport layer to obtain the flexible sweating cooling composite material. It should be noted that the surface of the elastic substrate layer is provided with a groove matching the shape of the working medium transport layer, and the working medium transport layer can be embedded into the elastic substrate layer by mold pressing to obtain the integrated structure of the working medium transport layer and the elastic substrate layer.

[0081] In some preferred embodiments of the present application, compounding the sweating functional layer with the integrated structure comprises: adhering a binder layer on the surface of the working medium transport layer of the integrated structure, then adhering the sweating functional layer on the surface of the binder layer, and then curing and forming by heating and pressing to obtain the flexible sweating cooling composite material.

[0082] It should be noted that the temperature and pressure of the heating and pressing curing are not specifically limited in the present application, and can be adjusted according to the type of the selected binder. The specific type of the binder is also not specifically limited, and can be selected according to actual needs, as long as it can ensure that the sweating functional layer is tightly bonded with the integrated structure.

[0083] In some preferred embodiments of the present application, the temperature of the heating and pressing curing is room temperature to 200℃; and / or, the pressure of the heating and pressing curing is 0.01-0.2MPa (for example, it can be 0.01MPa, 0.02MPa, 0.04MPa, 0.05MPa, 0.06MPa, 0.08MPa, 0.1MPa, 0.12MPa, 0.15MPa, 0.16MPa, 0.18MPa or 0.2MPa).

[0084] The present application provides, in a third aspect, an application of the flexible sweating cooling composite material of the first aspect, for the thermal protection system of a high-speed aircraft.

[0085] The flexible sweating cooling composite material provided by the present application can realize macroscopic and microscopic double precise controllable distribution of the cooling working medium, improve the uniformity of the cooling working medium, has higher cooling efficiency, and at the same time, each functional layer is a flexible material, which can be stretched and deformed and has a thin thickness, has a good covering effect, can be adhered to the surface of each part of the aircraft, has good sealing performance, can adapt to the complex profile requirements of different aircraft surface parts, and is used for the thermal protection system of a high-speed aircraft.

[0086] In actual use, the flexible sweating cooling composite material of the present application first delivers the cooling working medium to the sweating functional layer through the working medium delivery layer, so that the initial distribution of the cooling working medium in the sweating functional layer can be realized. Due to the presence of the hydrogel, the sweating functional layer has good hydrophilicity, so that the effective wetting of the cooling working medium can be realized, and the micro and macro distribution of the cooling working medium is further realized, which is more conducive to the uniform distribution of the cooling working medium in the sweating functional layer. When in a non-heated state or at a low heating temperature, the hydrogel expands after absorbing the cooling working medium, which can reduce the porosity of the flexible porous material, so that the sweating functional layer presents a water locking state, and the waste of the cooling working medium can be reduced. With the increase of the heating temperature, according to the different local heating temperatures, the hydrogel in the high temperature region shrinks due to water loss, and the porosity of the sweating functional layer changes, so that the porosity of each region of the sweating functional layer can be adjusted according to the temperature of each region, and then the amount of the cooling working medium distributed to each region can be adjusted, so as to improve the uniformity of the distribution of the cooling working medium and the cooling efficiency. In the relatively high temperature region, the water loss of the hydrogel is more serious, and the porosity of the flexible porous material is larger, so that more cooling working medium can enter the sweating cooling layer to perform sweating cooling; in the relatively low temperature region, the water loss of the hydrogel is less, and the porosity of the flexible porous material is smaller, so that less cooling working medium enters the sweating cooling layer to perform sweating cooling. In this way, the distribution of the cooling working medium can be optimized, the uniformity of the distribution of the cooling working medium and the cooling efficiency can be improved, the local ablation problem caused by heat transfer deterioration can be solved, and the waste of the cooling working medium can be avoided.

[0087] In order to more clearly illustrate the technical solutions and advantages of the present application, the present application will be further described below with reference to the embodiments.

[0088] The source of each reagent used in the examples and comparative examples of the present application is not specifically limited, and can be directly purchased or synthesized by the applicant.

[0089] Example 1

[0090] A flexible sweating cooling composite material, comprising a sweating functional layer, a working medium delivery layer and an elastic substrate layer arranged in sequence from outside to inside; the sweating functional layer is a composite material comprising melamine foam and hydrogel; the working medium delivery layer is made of flexible material and comprises a plurality of cooling working medium delivery pipelines for delivering cooling working medium; and the elastic substrate layer is a TPU material (thermoplastic polyurethane elastomer).

[0091] The preparation method of the flexible sweating cooling composite material comprises the following steps:

[0092] S1. The melamine foam (thickness of 2 mm, porosity of 90%) is fully immersed in an ammonium persulfate solution (wherein the mass fraction of ammonium persulfate is 1%), dried, to obtain modified melamine foam; and the hydrogel precursor is introduced into the modified melamine foam, vacuum in-situ polymerization, drying, to obtain the sweating functional layer; wherein the hydrogel precursor is obtained by mixing acrylamide, tetramethyl ethylenediamine (TEMED), N,N'-methylene bisacrylamide (MBA) and deionized water in a mass ratio of 100:3:0.25:1000;

[0093] S2. The TPU material (thickness of 2 mm, elastic modulus of 10 MPa, elongation at break of 80%) and the working medium conveying layer are compounded by mold forming to form an integrated structure;

[0094] S3. The adhesive layer is attached to the surface of the working medium conveying and distributing layer, and the sweating functional layer is attached to the surface of the adhesive layer, and is cured by heating and pressing to form a flexible sweating cooling composite material.

[0095] Example 2

[0096] A flexible sweating cooling composite material, comprising, from the outside to the inside, a sweating functional layer, a working medium conveying layer and an elastic substrate layer; the sweating functional layer is a composite material comprising glass fiber fabric and hydrogel; the working medium conveying layer is made of flexible material and comprises a plurality of cooling working medium conveying pipelines for conveying cooling working medium; the elastic substrate layer is a silicone rubber material.

[0097] The preparation method of the flexible sweating cooling composite material comprises the following steps:

[0098] S1. The glass fiber fabric (thickness of 1.5 mm, porosity of 75%) is fully immersed in an ammonium persulfate solution (wherein the mass fraction of ammonium persulfate is 0.8%), dried, to obtain modified glass fiber fabric; and the hydrogel precursor is introduced into the pores of the modified glass fiber fabric, vacuum in-situ polymerization, drying, to obtain the sweating functional layer; wherein the hydrogel precursor is obtained by mixing acrylamide, tetramethyl ethylenediamine (TEMED), N,N'-methylene bisacrylamide (MBA) and deionized water in a mass ratio of 100:3:0.25:1000;

[0099] S2. The silicone rubber material (thickness of 1.5 mm, elastic modulus of 2 MPa, elongation at break of 240%) and the working medium conveying layer are compounded by mold forming to form an integrated structure;

[0100] S3. The adhesive layer is attached to the surface of the working medium conveying and distributing layer, and the sweating functional layer is attached to the surface of the adhesive layer, and is cured by heating and pressing to form a flexible sweating cooling composite material.

[0101] Example 3

[0102] A flexible sweating cooling composite material, comprising, from outside to inside, a sweating functional layer, a working medium conveying layer and an elastic substrate layer; the sweating functional layer is a composite material comprising aramid fabric and hydrogel; the working medium conveying layer is made of flexible material and comprises a plurality of cooling working medium conveying pipelines for conveying cooling working medium; and the elastic substrate layer is EPDM (ethylene propylene diene rubber).

[0103] S1. Aramid fabric (thickness of 3 mm, porosity of 65%) is fully immersed in a solution containing sodium persulfate and sodium thiosulfate, dried to obtain modified aramid fabric; a hydrogel precursor is introduced into the pores of the modified aramid fabric, vacuum in-situ polymerization, drying to obtain a sweating functional layer; wherein the hydrogel precursor is obtained by mixing sodium acrylate, N,N'-methylene bisacrylamide (MBA) and deionized water; wherein the total amount of sodium persulfate and sodium thiosulfate is 0.25% of the mass of sodium acrylate, and the amount of N,N'-methylene bisacrylamide is 0.4% of the mass of sodium acrylate;

[0104] S2. The ethylene propylene diene rubber (thickness of 2 mm, elastic modulus of 6 MPa, elongation at break of 180%) and the working medium conveying layer are compounded by mold forming to form an integrated structure;

[0105] S3. The surface of the working medium conveying distribution layer is bonded with an adhesive layer, and the surface of the adhesive layer is bonded with the sweating functional layer, and the flexible sweating cooling composite material is obtained by heating and pressing curing forming.

[0106] Example 4

[0107] A flexible sweating cooling composite material, comprising, from outside to inside, a sweating functional layer, a working medium conveying layer and an elastic substrate layer; the sweating functional layer is a composite material comprising basalt fiber fabric and hydrogel; the working medium conveying layer is made of flexible material and comprises a plurality of cooling working medium conveying pipelines for conveying cooling working medium; and the elastic substrate layer is TPV material (thermoplastic vulcanized rubber).

[0108] The preparation method of the flexible sweating cooling composite material, comprising the following steps:

[0109] S1. Aramid fabric (thickness of 3 mm, porosity of 65%) is fully immersed in a solution containing sodium persulfate and sodium thiosulfate, dried to obtain modified aramid fabric; a hydrogel precursor is introduced into the pores of the modified aramid fabric, vacuum in-situ polymerization, drying to obtain a sweating functional layer; wherein the hydrogel precursor is obtained by mixing sodium acrylate, N,N'-methylene bisacrylamide (MBA) and deionized water; wherein the total amount of sodium persulfate and sodium thiosulfate is 0.25% of the mass of sodium acrylate, and the amount of N,N'-methylene bisacrylamide is 0.4% of the mass of sodium acrylate;

[0110] S2. Adopting mold pressing to composite the TPV material (thickness is 2mm, elastic modulus is 10MPa, breaking elongation is 80%) and the working medium transport layer to form integrated structure;

[0111] S3. Pasting the adhesive layer on the surface of the working medium transport distribution layer, and pasting the sweating functional layer on the surface of the adhesive layer, and curing and forming by heating and pressing to obtain the flexible sweating cooling composite material.

[0112] Example 5

[0113] A flexible sweating cooling composite material, comprising a sweating functional layer, a working medium transport layer and an elastic substrate layer arranged in sequence from outside to inside; the sweating functional layer is a composite material comprising carbon fiber fabric and hydrogel; the working medium transport layer is made of flexible material and comprises a plurality of cooling working medium transport pipelines for transporting cooling working medium; the elastic substrate layer is TPO material (thermoplastic polyolefin elastomer).

[0114] The preparation method of the flexible sweating cooling composite material comprises the following steps:

[0115] S1. Impregnating carbon fiber fabric (thickness is 0.5mm, porosity is 65%) in ammonium persulfate solution (wherein the mass fraction of ammonium persulfate is 2%), and drying to obtain modified carbon fiber fabric; introducing hydrogel precursor into the pores of the modified carbon fiber fabric, and performing vacuum in-situ polymerization and drying to obtain the sweating functional layer; wherein the hydrogel precursor is obtained by mixing acrylamide, tetramethyl ethylenediamine (TEMED), N,N'-methylene bisacrylamide (MBA) and deionized water in a mass ratio of 100:3:0.25:1000;

[0116] S2. Adopting mold pressing to composite the TPO material (thickness is 4mm, elastic modulus is 0.8MPa, breaking elongation is 120%) and the working medium transport layer to form integrated structure;

[0117] S3. Pasting the adhesive layer on the surface of the working medium transport distribution layer, and pasting the sweating functional layer on the surface of the adhesive layer, and curing and forming by heating and pressing to obtain the flexible sweating cooling composite material.

[0118] Comparative Example 1

[0119] The same as Example 1, the only difference is that the sweating functional layer is melamine foam (thickness is 2mm, porosity is 90%) and is not compounded with hydrogel.

[0120] Comparative Example 1 has no hydrogel, and under the same test, the surface temperature and the back temperature are obviously higher than those of Example 1, and a large area of heat transfer deterioration high temperature area appears, and local ablation phenomenon appears on the surface.

[0121] Comparative Example 2

[0122] The same as Example 1, except that the melamine foam was replaced by a copper foam (2 mm in thickness and 90% in porosity).

[0123] Comparative Example 3

[0124] The same as Example 3, except that the aramid fabric was replaced by a porous ceramic material (3 mm in thickness and 65% in porosity).

[0125] Comparative Example 4

[0126] The same as Example 3, except that the aramid fabric was replaced by a porous ceramic material (3 mm in thickness and 65% in porosity).

[0127] Comparative Example 5

[0128] The same as Example 3, except that the aramid fabric was replaced by a porous ceramic material (3 mm in thickness and 65% in porosity).

[0129] Comparative Example 6

[0130] A flexible fiber was used as a skeleton, and a ceramicized silicone rubber was used as a matrix to prepare a flame erosion resistant material layer, and a high reflectivity heatproof coating was applied to the surface. The thickness was 3 mm, 7 mm aerogel was used for filling as a thermal insulation material, and the overall thickness was 10 mm to prepare a passive heat-resistant and high-temperature-resistant composite material with reusability.

[0131] Table 1. Performance test conditions and performance data of the composite materials prepared in the examples and comparative examples of the present application

[0132]

[0133] It should be noted that the thickness in the table is the total thickness of the composite material; the maximum surface temperature and the maximum back temperature are measured by an infrared thermal imager and a thermocouple, respectively, at the corresponding heat flux density; and the deformation amount is measured by stretching the composite material with a clamp. As can be seen from Table 1, the flexible sweating cooling composite material prepared in the examples of the present application has higher cooling efficiency, and each functional layer is a flexible material, which can be stretched and deformed and has a thin thickness, good covering effect, and can be attached to the surface of each part of the aircraft, good sealing, and can adapt to the complex profile requirements of different aircraft surface parts.

[0134] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A flexible, evaporative cooling composite material, characterized in that, The flexible sweat cooling composite material is sequentially provided from outside to inside with a sweat function layer, a working medium conveying layer and an elastic substrate layer. The sweat function layer is a composite material comprising a flexible porous material and a hydrogel. The porosity of the flexible porous material is 45-99%; the flexible porous material is at least one of a foam and a fiber fabric; the foam is melamine foam; the fiber fabric is one or more of glass fiber fabric, aramid fiber fabric, quartz fiber fabric, basalt fiber fabric and carbon fiber fabric; the sweat function layer is prepared by impregnating the flexible porous material in an initiator solution, drying to obtain a modified flexible porous material, introducing a hydrogel precursor into the modified flexible porous material, vacuum in-situ polymerization and drying to obtain the sweat function layer; the hydrogel precursor comprises a hydrogel monomer, a crosslinking agent, a catalyst and water; the hydrogel monomer is at least one of acrylamide and sodium acrylate; in a non-heated state or at a low heating temperature, the hydrogel expands after absorbing the cooling working medium, reducing the porosity of the flexible porous material, so that the sweat function layer presents a water locking state; as the heating temperature increases, according to the difference in local heating temperature, the hydrogel in the high temperature region shrinks after losing water, adjusting the porosity of the sweat function layer, and then optimizing the distribution of the cooling working medium; in the relatively high temperature region, the hydrogel loses more water, the porosity of the flexible porous material is larger, and more cooling working medium can enter the sweat function layer for sweat cooling; in the relatively low temperature region, the hydrogel loses less water, the porosity of the flexible porous material is smaller, and less cooling working medium enters the sweat function layer for sweat cooling. The working medium conveying layer is made of a flexible material.

2. The flexible transpiration cooling composite of claim 1, wherein, The thickness of the flexible porous material is 0.5-3.0 mm.

3. The flexible transpiration cooling composite of claim 1, wherein, The thickness of the elastic substrate layer is 1-4 mm; The elastic modulus of the elastic substrate layer is 0.5-100 MPa; and / or The elongation at break of the elastic substrate layer is >50%.

4. The flexible transpiration cooling composite of claim 1, wherein, The elastic substrate layer is at least one of thermoplastic polyurethane elastomer, thermoplastic polyolefin elastomer, thermoplastic vulcanized rubber, silicone rubber and ethylene-propylene-diene rubber.

5. A method of making the flexible transpiration cooling composite of any one of claims 1-4, characterized in that, The preparation method comprises: S1. generating a hydrogel in the flexible porous material in-situ to obtain a sweat function layer; step S1 comprises: impregnating the flexible porous material in an initiator solution, drying to obtain a modified flexible porous material, introducing a hydrogel precursor into the modified flexible porous material, vacuum in-situ polymerization and drying to obtain the sweat function layer; the hydrogel precursor comprises a hydrogel monomer, a crosslinking agent, a catalyst and water; the hydrogel monomer is at least one of acrylamide and sodium acrylate; S2. compounding the working medium conveying layer, the elastic substrate layer and the sweat function layer to obtain a flexible sweat cooling composite material.

6. The preparation method according to claim 5, characterized in that, The introduction adopts a vacuum introduction process; and / or The vacuum in-situ polymerization is performed at 20-95℃.

7. The preparation method according to claim 5, characterized in that, Step S2 comprises: integrating the working medium conveying layer and the elastic substrate layer into an integrated structure by mold pressing; The integrated structure is compounded with the perspiration function layer to obtain a flexible perspiration cooling composite material.

8. Use of a flexible transpiration cooling composite material according to any one of claims 1 to 4, characterized in that, Thermal protection system for high speed vehicles.

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