Fiber membrane with radiation refrigeration regulation and control performance and preparation method thereof

Abstract

The invention relates to a fiber membrane capable of regulating and controlling radiation refrigeration performance and a preparation method thereof, the fiber membrane is composed of micro-nano fibers with tensile capacity, and the thickness of the fiber membrane is 10-500 microns; the fiber diameter of the micro-nano fiber is 0.1 to 25 [mu] m; the micro-nano fibers are high-molecular polymer fibers; the sunlight transmittance regulation and control range of the fiber membrane is not less than 40%, and the mid-infrared transmittance regulation and control range is not less than 50%. Compared with the prior art, the fiber film has the adjustable transmittance in the sunlight and mid-infrared wave bands, and when the fiber film serves as a wind screen to be additionally arranged on the upper portion of any existing radiation refrigeration material, the refrigeration effect of the radiation refrigeration material can be adjusted and controlled by adjusting and controlling the transmittance of the radiation refrigeration material in the sunlight and mid-infrared wave bands.

Description

Technical Field

[0001] The present invention relates to the field of radiation refrigeration technology, and in particular to a fiber membrane with regulated radiation refrigeration performance and a preparation method thereof. Background Art

[0002] In recent years, with global warming, a large amount of greenhouse gases have been emitted in human production and life, and a large amount of waste heat has been generated, which has exacerbated this phenomenon. High temperature weather has occurred frequently, which not only increases the indoor cooling load and the energy consumption of refrigeration equipment, but also seriously threatens human survival. In hot seasons or regions, in order to ensure the comfort and health of the human body, large-scale use of energy-consuming equipment such as air conditioners is required to assist in cooling, which consumes about 15% of the world's electricity and aggravates the environmental and energy crisis. Radiative cooling is a passive cooling technology that emits heat to outer space through thermal radiation to achieve cooling. This cooling process does not consume any earth energy. Typical radiative cooling materials have high solar reflectivity and high mid-infrared emissivity. However, the optical properties of the developed radiative cooling materials are fixed. In low temperature seasons or at night, the continuous cooling of radiative cooling materials leads to the problem of over-cooling, which in turn increases heating energy consumption.

[0003] At present, radiation refrigeration materials already have very excellent refrigeration performance, but it is very difficult to develop dynamic radiation refrigeration materials with variable optical properties, and it will greatly increase the cost and manufacturing difficulty, resulting in the existing dynamic radiation refrigeration materials still facing the huge challenges of insufficient regulation performance and high cost. In order to solve the above problems, a fiber membrane with adjustable transmittance in the sunlight and mid-infrared bands was prepared by electrospinning technology. The fiber membrane has good mechanical properties. When it is installed as a wind screen on the top of any existing radiation refrigeration material, the latter's refrigeration effect can be adjusted. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a fiber membrane with adjustable radiation cooling performance and a preparation method thereof. The fiber membrane has adjustable transmittance in both the sunlight and mid-infrared bands. When installed as a wind screen on the top of any existing radiation cooling material, the cooling effect of the radiation cooling material can be regulated by regulating its transmittance in sunlight and mid-infrared.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The first aspect of the present invention provides a fiber membrane with regulated radiation cooling performance, wherein the fiber membrane is composed of micro-nano fibers with stretchability, and the fiber membrane has a thickness of 10-500 μm;

[0007] The fiber diameter of the micro-nano fiber is 0.1 to 25 μm;

[0008] The micro-nano fibers are thermoplastic elastomer polymer fibers;

[0009] The fiber membrane has a solar light transmittance control range of not less than 40%, and a mid-infrared transmittance control range of not less than 50%.

[0010] Furthermore, the fiber membrane is formed by electrospinning a high molecular polymer and depositing it on a receiver.

[0011] Furthermore, the polymer material in the polymer fiber includes one of polyurethane, ethylene-octene copolymer, butene-styrene thermoplastic elastomer, polyester and polyolefin.

[0012] Furthermore, when the stretching rates are 0%, 200% and 400%, respectively, the average fiber diameters of the fiber membrane are 15-25 μm, 5-15 μm and 0.1-5 μm, respectively.

[0013] Furthermore, within the wavelength range of 200 to 2500 nm of the solar spectrum, when the stretching rate of the radiation cooling fiber membrane varies between 0 and 400%, its average transmittance varies between 20 and 80%.

[0014] Furthermore, within the wavelength range of 3 to 20 μm, when the stretching rate of the radiation cooling fiber membrane varies between 0 and 400%, its average transmittance varies between 20 and 90%.

[0015] A second aspect of the present invention provides a method for preparing a fiber membrane having the ability to regulate radiation cooling as described above, comprising the following steps:

[0016] S1, mixing a high molecular polymer and an organic solvent, and stirring until they are completely dissolved to form a spinning solution;

[0017] S2. Inject the spinning solution into a syringe of an electrospinning machine and spray out to form fibers. The fibers are deposited on a receiver to form the fiber membrane. Dry the fiber membrane under ventilation conditions for 2 to 48 hours to obtain a fiber membrane with regulated radiation refrigeration performance.

[0018] Furthermore, the organic solvent is selected from one or a combination of tetrahydrofuran, chloroform, toluene, cyclohexane, n-hexane, ethyl acetate, butyl acetate, xylene, and carbon tetrachloride.

[0019] Furthermore, in S1, the mass ratio of the high molecular weight polymer to the organic solvent is (0.1-1):1.

[0020] Furthermore, in S2, the voltage used for electrospinning is 5 to 25 kV, the propulsion speed is 0.0005 to 0.1 mm / s, the distance is 5 to 30 cm, and the syringe needle is 17 to 22 gauge.

[0021] Further preferably, in S2, the voltage used for electrospinning is 20-25 kV, the propulsion speed is 0.005-0.1 mm / s, the distance is 20 cm, and the syringe needle is No. 18.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The present invention proposes an effective method for preparing a fiber membrane with regulated radiative cooling performance. Compared with the prior art, the method has the advantages of simplicity, environmental protection, and energy saving and emission reduction. The fabric has a large regulated range of transmittance in both sunlight and mid-infrared bands, and exhibits excellent regulating effect on the refrigeration effect of radiative cooling materials; it makes up for the defect of fixed optical properties of traditional radiative cooling materials, and can effectively reduce the heating energy consumption increased by excessive cooling in cold seasons or at night.

[0024] 2) In addition, the fiber membrane prepared by the present invention also has excellent tensile properties and cyclic stability. The present invention provides a new method for dynamic radiation cooling, which can realize dynamic radiation cooling in a low temperature environment when combined with radiation cooling materials. The technology has potential economic value and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a real picture of the fiber membrane in the present invention;

[0026] Figure 2 Optical photos and SEM images of the fiber membrane of the present invention at different stretching rates;

[0027] Figure 3 This is a test diagram of the fiber membrane breaking and stretching in the present invention;

[0028] Figure 4 This is a graph of the cyclic tensile test of the fiber membrane in the present invention;

[0029] Figure 5 The sunlight and mid-infrared transmittance spectra of the fiber membrane of the present invention at different stretching rates;

[0030] Figure 6 The temperature comparison between the fiber membrane of the present invention in the cooling state and the traditional radiation cooling material during the day;

[0031] Figure 7 The temperature comparison between the fiber membrane of the present invention and the traditional radiation cooling material at night when the fiber membrane is in a non-refrigeration state. DETAILED DESCRIPTION

[0032] The present invention belongs to the field of radiation refrigeration technology, and specifically relates to a fiber membrane with adjustable radiation refrigeration performance and a preparation method thereof. The fiber membrane is assembled from stretchable nanofibers. The fiber membrane has adjustable transmittance in both the sunlight and mid-infrared bands. When installed as a wind screen on the upper part of any existing radiation refrigeration material, the refrigeration effect of the radiation refrigeration material can be regulated by regulating the transmittance of the radiation refrigeration material in sunlight and mid-infrared; the breaking elongation of the fiber membrane is greater than 500%, and the original tensile properties can be maintained after cyclic stretching, and the fiber membrane has high mechanical strength. The fiber membrane can effectively solve the problem of supercooling caused by continuous refrigeration of the radiation refrigeration material at low temperatures. The fiber membrane is combined with the radiation refrigeration material to achieve dynamic regulation of the refrigeration effect. In addition, the preparation method of the fiber membrane is simple and environmentally friendly. In view of the problem of supercooling caused by continuous refrigeration of traditional radiation refrigeration materials at low temperatures, the present invention provides a method for regulating the transmittance of radiation refrigeration materials in sunlight and mid-infrared to achieve dynamic radiation refrigeration.

[0033] The fiber membrane for regulating radiation cooling performance in the present invention is composed of micro-nano fibers with stretchability.

[0034] In a specific implementation, the fiber membrane has a thickness of 10-500 μm and has a large elongation rate.

[0035] In a specific implementation, the fiber membrane has a solar transmittance control range of not less than 40%, and a mid-infrared transmittance control range of not less than 50%.

[0036] In specific implementation, the method for preparing a fiber membrane for regulating radiation cooling performance comprises the following steps:

[0037] a) mixing a high molecular polymer and an organic solvent in a certain mass ratio and stirring until they are completely dissolved to form a spinning solution;

[0038] b) injecting the spinning solution into a syringe of an electrospinning machine and spraying it out under certain conditions to form fibers; the fibers are deposited on a receiver to form the fiber membrane; and the fiber membrane is dried under ventilation conditions for 2 to 48 hours to obtain the fiber membrane.

[0039] In a specific implementation, the mass ratio of the thermoplastic elastomer polymer to the organic solvent in step a) is (0.1-1):1.

[0040] In specific implementation, the thermoplastic elastomer polymer described in step a) is used as a raw material, wherein the polymer can be polyurethane, ethylene-octene copolymer, butene-styrene thermoplastic elastomer, polyester, polyolefin and other materials.

[0041] In specific implementation, the organic solvent in step a) is used to dissolve the high molecular polymer, wherein the organic solvent can be one solvent or a combination of multiple solvents selected from tetrahydrofuran, chloroform, toluene, cyclohexane, n-hexane, ethyl acetate, butyl acetate, xylene, and carbon tetrachloride.

[0042] In specific implementation, the certain conditions in step a) include an electrospinning voltage of 5 to 25 kV, a propulsion speed of 0.0005 to 0.1 mm / s, a distance of 5 to 30 cm, and a syringe needle of No. 17 to 22. Preferably, the electrospinning voltage is 20 to 25 kV, the propulsion speed is 0.005 to 0.1 mm / s, the distance is 20 cm, and the syringe needle is No. 18.

[0043] In a specific implementation, the fiber membrane has a fiber diameter of 0.1 to 25 μm.

[0044] The present invention mainly has the following technical innovations:

[0045] (1) To address the over-cooling problem of existing radiation cooling materials, the present invention combines a fiber membrane with adjustable sunlight and mid-infrared transmittance with a radiation cooling material, which has the advantages of low-cost and scalable manufacturing;

[0046] (2) In view of the high cost and high development difficulty of existing dynamic radiation cooling materials, the present invention proposes a method for preparing a fiber membrane with adjustable radiation cooling performance by a simple electrospinning method;

[0047] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Any features such as preparation means, materials, structures or composition ratios not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0048] Unless otherwise defined, the terms (including technical terms) used herein should be interpreted as having the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It will also be understood that the terms used herein should be interpreted as having the meaning consistent with their meanings in the content of this specification and related technologies, and should not be interpreted in an idealized or excessive form unless specifically defined as such herein.

[0049] Example 1

[0050] This embodiment prepares a fiber membrane 1 for regulating radiative cooling performance, comprising the following steps:

[0051] a), completely dissolving butene-styrene thermoplastic elastomer SEBS in tetrahydrofuran, and stirring for 2 hours to obtain a spinning solution with a concentration of 30wt%;

[0052] b), transferring the spinning solution in step a) into a syringe, and preparing a fiber membrane by electrospinning, wherein the syringe needle is No. 18, the spinning voltage is 25 kV, the propulsion speed is 0.01 mm / s, and the distance is 20 cm; the spinning solution is ejected from under the action of the electric field, and the solvent in the fiber evaporates rapidly in the air and falls on the receiving substrate to form a fiber membrane 1 for regulating the radiation cooling performance. The actual fiber membrane is as shown in Figure 1 shown.

[0053] Example 2

[0054] This embodiment prepares a fiber membrane 2 for regulating radiative cooling performance, comprising the following steps:

[0055] a), adding butene-styrene thermoplastic elastomer SEBS into a mixed solution of tetrahydrofuran and toluene, and stirring for 2 hours to obtain a spinning solution with a concentration of 30wt%;

[0056] b) Transfer the spinning solution in step a) into a syringe and prepare a fiber membrane by electrospinning, wherein the syringe needle is No. 18, the spinning voltage is 20 kV, the propulsion speed is 0.005 mm / s, and the distance is 20 cm; the spinning solution is ejected from under the action of the electric field, and the solvent in the fiber evaporates rapidly in the air and falls on the receiving substrate to form a fiber membrane 2 that regulates the radiation cooling performance.

[0057] Verification Example 1

[0058] This verification example tests the optical properties of the fiber membrane prepared in Example 1 for regulating radiative cooling performance.

[0059] a) Characterization of the microscopic morphology of the fiber membrane 1:

[0060] The microstructure of the fiber membrane at different stretching rates was observed by field emission scanning electron microscopy. Figure 2 As shown, the fiber membrane 1 is composed of a plurality of fibers, and the fiber diameter is related to the stretching rate. When the stretching rates are 0%, 200% and 400%, the average fiber diameters of the fiber membrane 1 are 15.4, 7.1 and 4.7 μm, respectively.

[0061] b) Test the transmittance of the fiber membrane 1 in the sunlight band:

[0062] The transmittance spectrum of the fiber membrane 1 in the wavelength range of 200 to 2500 nm of the solar spectrum was measured using an ultraviolet-visible-near infrared spectrophotometer (Lambda 1050, PerkinElmer). Figure 5 As shown, when the stretching rate of the radiation cooling fiber membrane 1 changes between 0% and 400%, the average transmittance in the sunlight band changes dynamically between 20.5% and 75.3%.

[0063] c) Test the transmittance of fiber membrane 1 in the mid-infrared band:

[0064] The transmittance spectrum of the fiber membrane 1 in the wavelength range of 3 to 20 μm was measured using an integrating sphere Fourier transform infrared spectrometer (Nicolet 6700, Thermo Scientific). Figure 5 As shown, when the stretching rate of the radiation cooling fiber membrane 1 varies between 0% and 400%, the average transmittance in the infrared band varies between 21.2% and 85.6%.

[0065] From the above tests, it can be seen that the transmittance of the fiber membrane for regulating the radiative cooling performance can dynamically change between 20.5-75.3% in the solar band, and the transmittance in the mid-infrared band can change between 21.2-85.6%, indicating that placing the fiber membrane above the radiative cooling material can control the radiative heat transfer of the radiative cooling material by stretching.

[0066] d) Testing the mechanical properties of the fiber membrane 1:

[0067] A thin strip with a width of 2 cm is cut from the fiber membrane 1 for regulating the radiative cooling performance, and the initial length of the thin strip is measured to be 5 cm; the thin strip is stretched to the maximum extent so that it reaches a state of being about to break, such as Figure 3 As shown in FIG. 1 , the breaking elongation of the fiber membrane 1 is 500%. In addition, the fiber membrane was subjected to 100 cycles of tensile testing ( Figure 4 ), the tensile properties of the fiber membrane did not show a significant decrease after cyclic stretching, indicating that the fiber membrane has excellent mechanical properties.

[0068] e) Test the regulating effect of fiber membrane 1 on radiant cooling temperature:

[0069] The temperature test of the radiative cooling material was carried out in two acrylic measuring chambers with dimensions of 40×40×20 cm. The measuring chambers were covered with a sunlight reflecting film and had an 8×8 cm window on the top. Polyethylene film or the prepared fiber membrane 1 was placed in the windows of the two measuring chambers. Polyethylene film was used as a control sample. The radiative cooling material was placed on a polystyrene foam support inside the measuring chamber, with a distance of 2 cm from the window. The top of the measuring chamber was facing the sky. The temperature of the radiative cooling material during the test was recorded using a thermocouple with a temperature uncertainty of 0.1°C. See Figure 6 and Figure 7 The test results show that during the day, the temperature of the radiation cooling material under the window covered by the fiber membrane 1 with a stretch rate of 400% is 0.3℃ lower than that of the control sample; at night, the temperature of the radiation cooling material under the fiber membrane 1 with a stretch rate of 0% is 3.3℃ higher than that of the control sample. This shows that the refrigeration effect of radiation cooling has an excellent regulatory effect.

[0070] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A fiber membrane with regulated radiation cooling performance, characterized in that: The fiber membrane is composed of micro-nano fibers with stretchability, and the fiber membrane has a thickness of 10-500 μm; The fiber diameter of the micro-nano fiber is 0.1 to 25 μm; The micro-nano fibers are thermoplastic elastomer polymer fibers; The fiber membrane has a solar light transmittance control range of not less than 40%, and a mid-infrared transmittance control range of not less than 50%.

2. A fiber membrane with regulated radiation cooling performance according to claim 1, characterized in that: The fiber membrane is formed by electrospinning a high molecular polymer onto a receiver.

3. The fiber membrane with regulated radiation cooling performance according to claim 1, characterized in that: The high molecular material in the high molecular polymer fiber includes one of polyurethane, ethylene-octene copolymer, butene-styrene thermoplastic elastomer, polyester and polyolefin.

4. The fiber membrane with regulated radiation cooling performance according to claim 1, characterized in that: When the stretching rates are 0%, 200% and 400%, respectively, the average fiber diameters of the fiber membrane are 15-25 μm, 5-15 μm and 0.1-5 μm, respectively.

5. The fiber membrane with regulated radiation cooling performance according to claim 1, characterized in that: In the wavelength range of 200-2500nm of the solar spectrum, when the stretching rate of the radiation cooling fiber membrane varies between 0% and 400%, its average transmittance varies between 20% and 80%.

6. The fiber membrane with regulated radiation cooling performance according to claim 1, characterized in that: In the wavelength range of 3 to 20 μm, when the stretching rate of the radiation cooling fiber membrane varies between 0 and 400%, its average transmittance varies between 20 and 90%.

7. A method for preparing a fiber membrane having regulated radiation cooling performance as claimed in claim 1, characterized in that: The following steps are involved: S1, mixing a high molecular polymer and an organic solvent, and stirring until they are completely dissolved to form a spinning solution; S2. Inject the spinning solution into a syringe of an electrospinning machine and spray out to form fibers. The fibers are deposited on a receiver to form the fiber membrane. Dry the fiber membrane under ventilation conditions for 2 to 48 hours to obtain a fiber membrane with regulated radiation refrigeration performance.

8. The method for preparing a fiber membrane having regulated radiation cooling performance according to claim 7, characterized in that: The organic solvent is selected from tetrahydrofuran, chloroform, toluene, cyclohexane, n-hexane, ethyl acetate, butyl acetate, xylene, carbon tetrachloride, or a combination of multiple solvents.

9. The method for preparing a fiber membrane having regulated radiation cooling performance according to claim 7, characterized in that: In S1, the mass ratio of the high molecular weight polymer to the organic solvent is (0.1-1):

1.

10. The method for preparing a fiber membrane having regulated radiation cooling performance according to claim 7, characterized in that: In S2, the voltage used for electrospinning was 5 to 25 kV, the propulsion speed was 0.0005 to 0.1 mm / s, the distance was 5 to 30 cm, and the syringe needle was 17 to 22 gauge.

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