Humidity-responsive graphene fiber, fabric and method of making the same
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2026-06-17
- Publication Date
- 2026-07-24
Smart Images
Figure CN122446375A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of functional fibers, and specifically relates to a graphene fiber, fabric and preparation method thereof that can dynamically adjust pressure according to humidity environment. Background Technology
[0002] Sports compression fabrics rely on elastic fibers such as spandex to provide constant static pressure, achieving continuous compression of the leg and foot areas, reducing muscle tremors, delaying muscle fatigue, and promoting exercise recovery. However, the constant high pressure makes them difficult to wear, sometimes requiring specialized dressing aids. Putting them on and taking them off can easily cause skin abrasions, nail snagging, and even material fatigue and pressure loss due to overstretching. Furthermore, the fixed compression force lacks real-time feedback during exercise; the body gradually adapts during activity, resulting in a lower-than-expected pressure effect.
[0003] Existing technologies have attempted to improve wearability and undressability by altering the weaving structure or using lubricating coatings, but this often comes at the cost of sacrificing pressure stability or durability. Furthermore, some research has employed smart materials (such as temperature-sensitive hydrogels) to develop temperature and humidity-responsive smart pressure fabrics, but these still suffer from problems such as slow response, low strength, high cost, and difficulty in large-scale spinning.
[0004] Therefore, there is an urgent need to develop a new type of sports pressure fabric that can have low pressure before wearing for easy wear, and automatically increase local pressure in specific humidity environments after wearing, thereby achieving humidity-responsive pressure regulation function and improving the contradiction between "easy to put on and take off" and "effective support". Summary of the Invention
[0005] This invention aims to provide a humidity-responsive graphene fiber and an adaptive pressure fabric. By utilizing the unique "moisture absorption and volume expansion" property of graphene microspheres, a humidity-responsive pressure fabric is obtained, achieving low resistance during the dressing and doffing stage (low humidity / dry) and high pressure reinforcement during the wearing and working stage (high humidity / sweating). At the same time, gradient design is combined to solve the problem of uneven pressure distribution.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: A humidity-responsive graphene fiber has a core-sheath structure, wherein the core layer is a viscose material containing moisture-absorbing and expanding graphene microspheres, and the sheath layer is a pure viscose material; and the diameter of the core layer is not greater than 2 / 3 of the diameter of the core-sheath structure graphene / viscose fiber, and the mass percentage of moisture-absorbing and expanding graphene microspheres in the core layer is 1% to 5%.
[0007] This fiber employs a core-sheath structure design, combining graphene microspheres and viscose materials. The core layer, formed by spinning a mixture of graphene microspheres and viscose spinning solution, provides the force for moisture absorption and expansion. The sheath layer, composed of viscose materials, serves as a moisture transfer transition layer and, through stretching, forms an orientation structure that restricts the radial expansion of the core layer. This allows more of the moisture absorption and expansion of the core layer to be converted into axial fiber elongation, thereby reducing the impact of radial coarsening on the fabric porosity.
[0008] With the dual control of adding 1%–5% by mass of moisture-expanding graphene microspheres and ensuring the core diameter is no greater than 2 / 3 of the diameter of the core-sheath graphene / viscose fiber, as the relative humidity increases from 30% to 70%, the axial expansion rate of the core-sheath graphene / viscose fiber is 8%–20%, and the radial expansion rate is 1%–5%. Based on these expansion characteristics, the fiber undergoes wavy or arched deformation in a specific relaxed coil structure, causing the fabric to generate pressure changes perpendicular to the fabric direction under moisture, rather than relying primarily on squeezing the mesh to achieve pressure increase.
[0009] Furthermore, the moisture-expanding graphene microspheres have a loose, paper-like structure with high oxygen content inside and low oxygen content outside, which can expand in volume when the ambient humidity increases, thereby driving the fabric to tighten and increase the interfacial pressure on the limbs; the particle size of the moisture-expanding graphene microspheres is 2~10μm, the oxygen content on the outer surface is 2%~5%, and the oxygen content inside is 40%~50%.
[0010] The mechanism of graphene microspheres expanding when exposed to moisture is as follows: In a humid environment, moisture from the environment can penetrate into the interior of the microspheres through microchannels on the surface of the microspheres. This moisture is adsorbed by oxygen-containing groups such as hydroxyl and carboxyl groups on the graphene oxide, resulting in swelling. The loose, paper-like internal structure provides space for the expansion of the sheets. The accumulated internal expansion pressure eventually breaks through the constraint of the low-oxygen-content outer "shell," macroscopically manifesting as a significant increase in the volume of the microspheres. During the drying process, the internal moisture is gradually removed from the microchannels. The elastic recovery force of the sheets themselves, as well as the residual van der Waals forces and π-π interactions between the sheets, act like a compressed spring, driving the sheets to shrink back. Macroscopically, this results in the microspheres shrinking back to their initial structure. Therefore, these graphene microspheres can achieve a reversible cycle of moisture expansion and drying recovery.
[0011] An adaptive pressure fabric for forming wrap-around wearable devices; it is composed of a blend of humidity-responsive graphene fibers, unidirectional moisture-wicking fibers, and spandex. The base structure is formed by the unidirectional moisture-wicking fibers and spandex, with core-sheath graphene / viscose fibers woven onto the base structure. The ratio of the loop span L to the loop span L0 in the base structure is between 1.2 and 2.5. The core-sheath graphene / viscose fibers form a loop structure with a specific degree of relaxation. In this invention, "relaxation" specifically refers to the relaxed knitting area where the loop length is artificially extended, which can be quantitatively measured by the ratio of the relaxed loop span L to the base knitting loop span L0. For example, when L / L0 = 2, ... Figure 3 As shown, the coil representing the humidity-responsive graphene fiber in this structure spans two adjacent basic braided coils, and the humidity-responsive graphene fiber forms a suspended arc on the knitting needle without slipping off the loop.
[0012] This invention achieves a dynamic pressure regulation mechanism for fabrics by designing moisture-absorbing and expanding fibers with a core-sheath structure: when the relative humidity is <30% and the fabric is dry, the graphene microspheres are in a relatively contracted state, and the overall tension of the fabric is low; when the humidity of the body surface rises to >70% after wearing or when it comes into contact with sweat, the graphene microspheres absorb moisture and expand, the fibers undergo axial elongation and out-of-plane buckling in the coil structure, which increases the local interfacial pressure.
[0013] A method for preparing an adaptive pressure fabric based on humidity-responsive graphene fibers includes the following steps: (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method, and ammonia was added to adjust the pH to 8-10. Then H2O2 was added and stirred at 35-50℃ for 5-20 min. The mixture was then spray-dried to obtain moisture-expanded graphene microspheres. The moisture-expanded graphene microspheres were then reduced at low temperature to form a structure in which the carbon-oxygen ratio of the outer layer is higher than that of the inner layer. (2) 1-5 parts by mass of the reduced, moisture-expanded graphene microspheres are added to a viscose spinning solution containing 100 parts by mass of cellulose A. After mixing evenly, the viscose spinning solution containing cellulose A is introduced through the inner and outer needles of a coaxial spinning head for coaxial spinning. The ratio of the inner needle diameter to the outer needle diameter is no greater than 2:3. The fibers are then shaped, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain a core-sheath structure graphene / viscose fiber. The drawing process employs multi-stage drawing, with the drawing ratio gradually increasing from 1.5 to 4.5, resulting in a final fiber orientation degree of 0.8-0.9. Multi-stage drawing is a commonly used technique in this field to improve the orientation degree. For example, the first-stage drawing ratio is 1.5; the second-stage drawing ratio is 2.0; the third-stage drawing ratio is 3.0; and the fourth-stage drawing ratio is 4.5.
[0014] (3) According to the pressure distribution requirements, spandex, unidirectional moisture-wicking fibers, and core-sheath graphene / viscose fibers are woven together, and finally subjected to wet heat setting treatment to form an adaptive pressure fabric. Those skilled in the art can use a computerized flat knitting machine, circular knitting machine, or warp knitting machine to weave the fabric, and adjust the fiber type, weaving density, and loop span in different weaving areas according to the curvature of the human limbs and the pressure distribution requirements. When weaving the core-sheath graphene / viscose fibers, a loop-and-arc structure or an extended loop structure is adopted, so that the loop span containing the fiber is 1.2 to 2.5 times the loop span of the base structure.
[0015] Taking compression stockings as an example, the following pressure zone design can be adopted: The pressure-enhancing zone, located in the ankle, instep, and sole, is formed by a base structure woven from unidirectional moisture-wicking fibers and spandex. A core-sheath structure of graphene / viscose fibers is woven onto this base structure, with the ratio of the coil span L to the coil span L0 in the base structure ranging from 1.2 to 2.5. This core-sheath structure of graphene / viscose fibers creates a coil structure with a specific degree of relaxation, providing pressure to the ankle. Low-pressure zone: Located at the junction of the calf and ankle, it is made of one-way moisture-wicking fibers and spandex to provide continuous low pressure; Breathable zones: Located at the heel and toes, these zones are woven with one-way moisture-wicking fibers and spandex to form a mesh structure that facilitates moisture wicking.
[0016] Based on the compression stockings of this invention, humidity-responsive pressure is achieved at the ankle, instep, and sole. In a dry state with relative humidity below 30%, the applied pressure to the limb is P. dry When the relative humidity is above 70% or the object is wet from contact with sweat, the applied pressure automatically increases to P. wet , where P wet =P dry +ΔP, where ΔP ranges from 5 to 15 mmHg.
[0017] Furthermore, the mass ratio of H2O2 to graphene oxide in step (1) is 0.5~5:1. Adding hydrogen peroxide can further react with the carbon atoms on the surface of graphene oxide, introducing more oxygen-containing functional groups and improving hydrophilicity.
[0018] Furthermore, the spray drying temperature in step (1) is controlled between 130℃ and 180℃. If the temperature is too low, the moisture cannot be fully removed, and if the temperature is too high, a large amount of oxygen-containing groups will be removed, making it difficult to achieve moisture absorption and expansion. The low-temperature reduction is carried out at a reduction temperature of 250℃ to 300℃ for 1 to 4 hours.
[0019] Furthermore, the graphene composite fiber can also impart additional properties to the socks, such as antibacterial properties and far-infrared emission; these properties are confirmed through antibacterial rate testing and far-infrared emissivity testing.
[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. An out-of-plane buckling pressurization mechanism is proposed to achieve humidity-responsive pressure regulation: This invention utilizes a specific relaxation coil structure (the ratio of L to L0 ranges from 1.2 to 2.5) to reserve deformation space for the core-sheath structure of graphene / viscose fibers. Examples show that fibers that expand axially by 8% to 20% after moisture absorption can generate out-of-plane buckling inside the coil, driving the fabric to arch perpendicular to the plane, increasing the local contact pressure by 5 to 15 mmHg in the wet state.
[0021] 2. The "dry wear, wet tightness" design based on structural parameters balances ease of wearing and removal with support during exercise: The core-sheath structure of graphene / viscose fiber is relatively loose in a dry state, keeping the sock body under low pressure during the wearing and removal process; in high humidity or sweating environments, the fiber axial expansion fills the preset looseness, and with the geometric constraints of the coiled arc structure or extended coil structure, the fabric changes from a relatively loose state to a tight state.
[0022] 3. Improving the balance between breathability and pressure: This invention utilizes the anisotropic expansion characteristics of core-sheath structure fibers (axial expansion rate 8%–20%, radial expansion rate 1%–5%) in conjunction with a specific coil structure. This allows the fibers to primarily undergo axial elongation and out-of-plane buckling during moisture absorption and expansion, reducing the compression of the mesh by radial coarsening. Therefore, while providing a pressure-boosting effect, the fabric mesh structure still maintains channels for moisture expulsion.
[0023] 4. Additional functions: The introduced graphene component can provide additional properties such as antibacterial and far-infrared emission. Under the conditions of the example, the antibacterial rate of the socks is 95% to 97%, and the far-infrared emissivity is 0.88 to 0.93.
[0024] 5. Strong process compatibility: Based on mature core-sheath spinning and knitting processes, it does not require expensive electronic equipment or complex finishing, making it easy to scale up industrial production and controllable costs. Attached Figure Description
[0025] Figure 1 A schematic diagram of the cross-section of a core-skin structure graphene / viscose fiber, where 1 is a moisture-expanded graphene microsphere, 2 is the core layer, and 3 is the skin layer.
[0026] Figure 2 Microscopic morphology of moisture-expanded graphene microspheres.
[0027] Figure 3 Schematic diagram of the sock's knitting structure.
[0028] Figure 4 The compression stockings obtained in Example 1 are divided into the following sections: 1—the connection between the lower leg and the ankle, 2—the ankle, 3—the sole of the foot, 4—the instep, 5—the heel, and 6—the toes.
[0029] Figure 5 A schematic diagram of the pressure change curves of the ankle area of the compression socks obtained in Example 1 under different humidity environments. Detailed Implementation
[0030] This invention utilizes the unique "moisture absorption and volume expansion" property of graphene microspheres to prepare a novel viscose fiber that can expand axially in humid environments. Pressure fabrics made from this fiber are indistinguishable from conventional sportswear in a dry state; however, when in a humid / high-humidity or sweaty exercise environment, the fibers stretch along their length, forming a wavy, raised structure that exerts pressure on the limbs or torso contact area. During this process, the radial dimension of the fiber remains essentially unchanged, ensuring the interfiber spacing maintains moisture-wicking and breathability. After exercise and leaving the high-humidity environment, the fabric pressure releases, reducing pressure on the body surface and making the fabric easier to put on and take off.
[0031] The present invention will be further described below with reference to embodiments.
[0032] In the following embodiments, the core testing equipment used to test the adaptive pressure of the fabric includes a standard adult foot mold (one set for men and one set for women, made of hard plastic, completely replicating the foot contour), no less than 9 flexible thin-film pressure sensors with an accuracy of ±1mmHg, a data acquisition instrument with no less than 9 channels and supporting data export, as well as 3 pairs of pressure socks to be tested from the same batch and auxiliary tools such as a constant temperature and humidity chamber; the sensors are distributed as follows: 3 each for the ankle (inner side, outer side, front), the instep (inner side, middle, outer side), and the sole (forefoot, arch, heel), to correspond to different knitting structure areas of the pressure socks.
[0033] Before testing, wipe the mold clean, mark and fix sensor positions on the ankle, instep, and sole, and calibrate the data acquisition instrument. Place the mold and the pressure socks to be tested in a constant temperature and humidity chamber, setting two humidity gradients: low humidity 30±5%RH and high humidity 70±5%RH. Let the socks stand for 2 hours under each humidity condition, then smoothly put them on the mold and let them stand for another 5 minutes under the corresponding humidity condition to stabilize the elasticity and pressure. Then, collect pressure data for 10 minutes at a frequency of 10Hz. Repeat three parallel tests on the same batch of socks at the same humidity, and take the average value. Pdry is the average pressure at the same position after equilibration at 30±5%RH, and Pwet is the average pressure at the same position after equilibration at 70±5%RH. ΔP = Pwet - Pdry.
[0034] The antibacterial rate can be determined according to GB / T 20944 or equivalent test methods for antibacterial properties of textiles; the far-infrared emissivity can be determined according to GB / T 30127 or equivalent test methods for far-infrared textiles.
[0035] Fiber axial and radial expansion rate tests: After equilibrating the fiber samples in an environment of 25±2℃ and 30±5%RH for 2 hours, the initial length and diameter were measured. Then, after equilibrating the samples in an environment of 70±5%RH for 2 hours, the wet length and diameter were measured. Each group consisted of no less than 5 fibers, and the average value of the results was taken. The axial expansion rate was calculated as (L wet state - L dry state) / L dry state × 100%, and the radial expansion rate was calculated as (D wet state - D dry state) / D dry state × 100%.
[0036] The particle size and morphology of the moisture-expanded graphene microspheres were observed using scanning electron microscopy. Particle size was statistically analyzed using acetone as solvent and measured by a laser particle size analyzer. The oxygen atom content on the outer surface was measured using XPS, and the oxygen atom content inside was measured using cross-sectional samples or XPS / EDS after ion etching. The results were taken as the average value of multiple test areas.
[0037] Example 1 (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method, and ammonia was added to adjust the pH to 10. Then H2O2 was added, and the mass ratio of H2O2 to graphene oxide was 0.5. The mixture was stirred at 35℃ for 20 min and spray-dried to obtain moisture-expanded graphene microspheres. The spray drying temperature was controlled at 150℃. The moisture-expanded graphene microspheres were placed in an environment of 300℃ and reduced for 1.5 hours. The resulting microspheres had a particle size of 2~10 μm, an internal oxygen content of 40%, and an external oxygen content of 3%. (2) Add 3 parts by weight of moisture-expanded graphene microspheres to a viscose spinning solution containing 100 parts by weight of cellulose A, mix evenly, and then pass the viscose spinning solution containing cellulose A through the inner and outer needles of the coaxial spinning head; the cellulose A content in the aforementioned viscose spinning solution containing cellulose A is 9 wt%, and the solvent is sodium hydroxide solution. Coaxial spinning was performed with an inner needle diameter to outer needle diameter ratio of 1:2, ensuring the core diameter was half the diameter of the core-sheath graphene / viscose fiber. The fiber was then formed, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain the core-sheath graphene / viscose fiber. Multi-stage drawing was employed, with the draw ratio gradually increasing from 1.5 to 4.5, ultimately achieving a fiber orientation degree of 0.9. During the process of increasing relative humidity from 30% to 70%, the fiber exhibited an axial expansion rate of 12% and a radial expansion rate of 2.3%. (3) According to the pressure distribution requirements, spandex, unidirectional moisture-wicking fibers, and core-sheath structured graphene / viscose fibers are woven together, and finally subjected to wet heat setting treatment to form an adaptive pressure fabric. The specific weaving method is as follows: Using a warp knitting machine, spandex, ordinary viscose fiber, and core-sheath graphene / viscose fiber are knitted into socks through synchronous feeding; The pressure-boosting zones, located at the ankle (2), sole (3), and instep (4), consist of a base structure woven from unidirectional moisture-wicking fibers and spandex. A core-sheath structure of graphene / viscose fibers is woven onto this base structure, with the ratio of the coil span L to the coil span L0 in the base structure ranging from 1.5 to 2. In ankle (2), L / L0 is 2, providing greater pressure. In sole (3) and instep (4), L / L0 is 1.5. Mesh tissue is added to instep (4) to enhance perspiration. Low-pressure zone: Located at the junction of the calf and ankle 1, it is made of one-way moisture-wicking fibers and spandex to provide continuous low pressure; Breathable zones: Located at the heel (5) and toe (6), these zones are woven with one-way moisture-wicking fibers and spandex to form a mesh structure that facilitates moisture expulsion.
[0038] Pressure tests were conducted using foot molds under different humidity levels. The measured pressures (Pdry) for the ankle, instep, and sole areas in a dry state were 15.2 mmHg, 11.8 mmHg, and 7.7 mmHg, respectively. When the relative humidity rose above 70%, the graphene / viscose fiber core-sheath structure expanded and experienced out-of-plane buckling within the coil structure, causing the pressures in the three areas to increase to 24 mmHg, 19.1 mmHg, and 15.5 mmHg (Pwet), respectively. Furthermore, the socks exhibited an antibacterial rate of 97% and a far-infrared emissivity of 0.92.
[0039] Example 2 (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method, and ammonia was added to adjust the pH to 8. Then H2O2 was added, and the mass ratio of H2O2 to graphene oxide was 5. The mixture was stirred at 50℃ for 20 min and spray-dried to obtain moisture-expanded graphene microspheres. The spray drying temperature was controlled at 130℃. The moisture-expanded graphene microspheres were placed in an environment of 250℃ and reduced for 1 hour. The resulting microspheres had a particle size of 2~10μm, an internal oxygen content of 50%, and an external oxygen content of 5%. (2) Add 5 parts by weight of moisture-expanded graphene microspheres to a viscose spinning solution containing 100 parts by weight of cellulose A, mix evenly, and then pass the viscose spinning solution containing cellulose A through the inner and outer needles of the coaxial spinning head; the cellulose A content in the aforementioned viscose spinning solution containing cellulose A is 10 wt%, and the solvent is sodium hydroxide solution. Coaxial spinning was performed with an inner needle diameter to outer needle diameter ratio of 2:3. The fibers were then shaped, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain a core-sheath structured graphene / viscose fiber. Multi-stage drawing was employed, with the draw ratio gradually increasing from 1.5 to 4.5, ultimately achieving a fiber orientation degree of 0.85. During the process of increasing relative humidity from 30% to 70%, the fiber's axial expansion rate was 20%, and its radial expansion rate was 5%. (3) According to the pressure distribution requirements, spandex, unidirectional moisture-wicking fibers and core-sheath structure graphene / viscose fibers are woven together, and finally subjected to wet heat setting treatment to form an adaptive pressure fabric. The specific weaving method is the same as in Example 1.
[0040] Pressure tests were conducted using foot molds under different humidity levels. The measured pressures (Pdry) for the ankle, instep, and sole areas in a dry state were 14.6 mmHg, 11.9 mmHg, and 7.4 mmHg, respectively. When the relative humidity rose above 70%, the graphene / viscose fiber core-sheath structure expanded and experienced out-of-plane buckling within the coil structure, causing the pressures in the three areas to increase to 29.3 mmHg, 26.9 mmHg, and 21.1 mmHg (Pwet), respectively. Furthermore, the socks achieved an antibacterial rate of 97% and a far-infrared emissivity of 0.93.
[0041] Example 3 (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method. Ammonia was added to adjust the pH to 10, and then H2O2 was added. The mass ratio of H2O2 to graphene oxide was 1. The mixture was stirred at 50℃ for 5 min and then spray-dried to obtain moisture-expanded graphene microspheres. The spray drying temperature was controlled at 180℃. The moisture-expanded graphene microspheres were placed in an environment of 260℃ and reduced for 4 hours. The resulting microspheres had a particle size of 2~10μm, an internal oxygen content of 40%, and an external oxygen content of 2%. (2) Add 1 part by mass of moisture-expanded graphene microspheres to a viscose spinning solution containing 100 parts by mass of cellulose A, mix evenly, and then pass the viscose spinning solution containing cellulose A through the inner and outer needles of the coaxial spinning head; the cellulose A content in the aforementioned viscose spinning solution containing cellulose A is 12 wt%, and the solvent is sodium hydroxide solution. Coaxial spinning was performed with an inner needle diameter to outer needle diameter ratio of 2:3. The fibers were then shaped, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain a core-sheath structured graphene / viscose fiber. Multi-stage drawing was employed, with the draw ratio gradually increasing from 1.5 to 4.5, ultimately achieving a fiber orientation degree of 0.8. During the process of increasing relative humidity from 30% to 70%, the fiber's axial expansion rate was 8%, and its radial expansion rate was 1%. (3) According to the pressure distribution requirements, spandex, unidirectional moisture-wicking fibers, and core-sheath structured graphene / viscose fibers are woven together, and finally subjected to wet heat setting treatment to form an adaptive pressure fabric. The specific weaving method is as follows: Using a warp knitting machine, spandex, ordinary viscose fiber, and core-sheath graphene / viscose fiber are knitted into socks through synchronous feeding; The pressure-boosting zone, located in the ankle, sole, and instep, is formed by a base structure woven from unidirectional moisture-wicking fibers and spandex. A core-sheath structure of graphene / viscose fibers is woven onto this base structure, with the ratio of the coil span L to the coil span L0 in the base structure being 2-2.5. In the ankle (zone 2), L / L0 is 2.5, providing greater pressure; in the sole and instep, L / L0 is 2; and in the instep, additional mesh tissue enhances perspiration. Low-pressure zone: Located at the junction of the calf and ankle, it is made of one-way moisture-wicking fibers and spandex to provide continuous low pressure; Breathable zones: Located at the heel and toes, these zones are woven with one-way moisture-wicking fibers and spandex to form a mesh structure that facilitates moisture wicking.
[0042] Pressure tests were conducted using foot molds under different humidity levels. The measured pressures (Pdry) for the ankle, instep, and sole areas in a dry state were 13.4 mmHg, 10.6 mmHg, and 7.5 mmHg, respectively. When the relative humidity rose above 70%, the graphene / viscose fiber core-sheath structure expanded and experienced out-of-plane buckling within the coil structure, causing the pressures in the three areas to increase to 19.8 mmHg, 16.7 mmHg, and 12.5 mmHg (Pwet), respectively. Furthermore, the socks exhibited an antibacterial rate of 95% and a far-infrared emissivity of 0.88.
[0043] Example 4 (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method. Ammonia was added to adjust the pH to 8, and then H2O2 was added. The mass ratio of H2O2 to graphene oxide was 2.5. The mixture was stirred at 35℃ for 20 min and then spray-dried to obtain moisture-expanded graphene microspheres. The spray drying temperature was controlled at 150℃. The moisture-expanded graphene microspheres were placed in an environment of 300℃ and reduced for 2 hours. The resulting microspheres had a particle size of 2~10 μm, an internal oxygen content of 42%, and an external oxygen content of 3.6%. (2) Add 4 parts by weight of moisture-expanded graphene microspheres to a viscose spinning solution containing 100 parts by weight of cellulose A, mix evenly, and then pass the viscose spinning solution containing cellulose A through the inner and outer needles of the coaxial spinning head; the cellulose A content in the aforementioned viscose spinning solution containing cellulose A is 9 wt%, and the solvent is sodium hydroxide solution. Coaxial spinning was performed with an inner needle diameter to outer needle diameter ratio of 1:2. The fibers were then shaped, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain a core-sheath structured graphene / viscose fiber. Multi-stage drawing was employed, with the draw ratio gradually increasing from 1.5 to 4.5, ultimately achieving a fiber orientation degree of 0.9. During the process of increasing relative humidity from 30% to 70%, the fiber's axial expansion rate was 16%, and its radial expansion rate was 3.4%. (3) According to the pressure distribution requirements, spandex, unidirectional moisture-wicking fibers, and core-sheath structured graphene / viscose fibers are woven together, and finally subjected to wet heat setting treatment to form an adaptive pressure fabric. The specific weaving method is as follows: Using a warp knitting machine, spandex, ordinary viscose fiber, and core-sheath graphene / viscose fiber are knitted into socks through synchronous feeding; The pressure-boosting zone, located in the ankle, sole, and instep, is formed by a base structure woven from unidirectional moisture-wicking fibers and spandex. A core-sheath structure of graphene / viscose fibers is woven onto this base structure, with the ratio of the coil span L to the coil span L0 in the base structure ranging from 1.2 to 1.8. The L / L0 ratio in the ankle is 1.8, providing greater pressure; the L / L0 ratio in the sole and instep is 1.2; and the addition of mesh tissue in the instep enhances perspiration. Low-pressure zone: Located at the junction of the calf and ankle, it is made of one-way moisture-wicking fibers and spandex to provide continuous low pressure; Breathable zones: Located at the heel and toes, these zones are woven with one-way moisture-wicking fibers and spandex to form a mesh structure that facilitates moisture wicking.
[0044] Pressure tests were conducted using foot molds under different humidity levels. The measured pressures (Pdry) for the ankle, instep, and sole areas in a dry state were 15 mmHg, 12.3 mmHg, and 10.6 mmHg, respectively. When the relative humidity rose above 70%, the graphene / viscose fiber core-sheath structure expanded and experienced out-of-plane buckling within the coil structure, causing the pressures in the three areas to increase to 23.2 mmHg, 20.4 mmHg, and 15.5 mmHg (Pwet), respectively. Furthermore, the socks exhibited an antibacterial rate of 96% and a far-infrared emissivity of 0.91.
[0045] Comparative Example 1: Ordinary socks with the same fabric structure The socks were woven using unidirectional moisture-wicking fibers, spandex, and ordinary viscose fibers, following step (3) of Example 1.
[0046] Pressure tests were conducted using foot molds under different humidity levels. The measured pressures (Pdry) for the ankle, instep, and sole areas in dry conditions were 15.3 mmHg, 11.7 mmHg, and 7.5 mmHg, respectively. When the relative humidity rose above 70%, the pressures in the three areas decreased to 11.1 mmHg, 9.2 mmHg, and 5.4 mmHg (Pwet) due to the relaxation of the fibers in the wet state.
[0047] Comparative Example 2: Blended fiber socks without a core-sheath structure Prepared using the following method: (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method, and ammonia was added to adjust the pH to 10. Then H2O2 was added, and the mass ratio of H2O2 to graphene oxide was 0.5. The mixture was stirred at 35℃ for 20 min and spray-dried to obtain moisture-expanded graphene microspheres. The spray drying temperature was controlled at 150℃. The moisture-expanded graphene microspheres were placed in an environment of 300℃ and reduced for 1.5 hours. The resulting microspheres had a particle size of 2~10 μm, an internal oxygen content of 40%, and an external oxygen content of 3%. (2) Three parts by weight of moisture-expanded graphene microspheres were added to a viscose spinning solution containing 100 parts by weight of cellulose A (the cellulose A content in the viscose spinning solution was 9 wt%, and the solvent was sodium hydroxide solution). After mixing evenly, the solution was directly spun, shaped, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain graphene / viscose fiber. The drawing was multi-stage drawing, with the draw ratio gradually increasing from 1.5 to 4.5, and the final fiber orientation was 0.9. During the process of increasing the relative humidity from 30% to 70%, the axial expansion rate of the fiber was 11%, and the radial expansion rate was 10%. (3) The socks are knitted using step (3) of Example 1.
[0048] Pressure tests were conducted using foot molds under different humidity levels. The measured pressures (Pdry) for the ankle, instep, and sole areas in dry conditions were 14.9 mmHg, 11.2 mmHg, and 7.3 mmHg, respectively. When the relative humidity rose above 70%, the graphene / viscose fibers underwent simultaneous axial and radial expansion, causing the pressure in the three areas to drop to 31.6 mmHg, 27.4 mmHg, and 21.8 mmHg (Pwet), respectively. However, due to the reduced mesh size, moisture escape was restricted, resulting in stuffiness and sweating observed in actual wearers, making the comfort level lower than in Example 1.
Claims
1. A humidity-responsive graphene fiber, characterized in that, It has a core-skin structure, with the core layer being an adhesive material containing moisture-absorbing and expanding graphene microspheres, and the skin layer being an adhesive material; the diameter of the core layer is no greater than 2 / 3 of the diameter of the graphene / adhesive fiber in the core-skin structure, and the mass percentage of moisture-absorbing and expanding graphene microspheres in the core layer is 1% to 5%.
2. The humidity-responsive graphene fiber according to claim 1, characterized in that, The moisture-expanded graphene microspheres have a paper-like structure and a higher carbon-oxygen ratio on the outer layer than on the inner layer. The oxygen atom content on the outer surface of the moisture-expanded graphene microspheres is 2% to 5%, the oxygen atom content on the inner surface is 40% to 50%, and the particle size is 2 to 10 μm.
3. The fiber according to claim 1, characterized in that, During the process of increasing relative humidity from 30% to 70%, the axial expansion rate of the core-sheath structure graphene / viscose fiber is 8% to 20%, and the radial expansion rate is 1% to 5%.
4. An adaptive pressure fabric for forming a wrap-around wearable device; characterized in that it is made of a blend of humidity-responsive graphene fibers as described in claim 1, unidirectional moisture-wicking fibers, and spandex, and is further characterized in that... The base structure is formed by unidirectional moisture-wicking fibers and spandex, with core-sheath graphene / viscose fibers woven on the base structure, and the ratio of the coil span L to the coil span L0 in the base structure is 1.2 to 2.
5.
5. A method for preparing an adaptive pressure fabric, characterized in that, Includes the following steps: (1) Preparation of moisture-expanded graphene microspheres: Aqueous dispersion of graphene oxide was prepared by Hummers method, and ammonia was added to adjust the pH to 8-10. Then H2O2 was added and stirred at 35-50℃ for 5-20 min. The mixture was then spray-dried to obtain moisture-expanded graphene microspheres. The moisture-expanded graphene microspheres were then reduced at low temperature to form a structure in which the carbon-oxygen ratio of the outer layer is higher than that of the inner layer. (2) Add 1-5 parts by mass of the reduced moisture-expanded graphene microspheres to a viscose spinning solution containing 100 parts by mass of cellulose A. After mixing evenly, pass the viscose spinning solution containing cellulose A through the inner and outer needles of the coaxial spinning head for coaxial spinning. The ratio of the inner needle diameter to the outer needle diameter is not greater than 2:
3. The fibers are shaped, drawn, washed, desulfurized, oiled, and dried in a coagulation bath to obtain a core-sheath structure graphene / viscose fiber. The drawing process is multi-stage drawing, with the drawing ratio gradually increasing from 1.5 to 4.5, and the final fiber orientation is 0.8-0.
9. (3) According to the pressure distribution requirements, spandex, unidirectional moisture-wicking fiber and core-sheath structure graphene / viscose fiber are woven together, and finally subjected to wet heat setting treatment to form an adaptive pressure fabric.
6. The preparation method according to claim 5, characterized in that, The mass ratio of H2O2 to graphene oxide in step (1) is 0.5~5:
1.
7. The preparation method according to claim 5, characterized in that, The low-temperature reduction is carried out at a reduction temperature of 250℃~300℃ for 1~4 hours.
8. The preparation method according to claim 5, characterized in that, The spray drying temperature in step (1) is 130℃~180℃.
9. The use of the adaptive pressure fabric as described in claim 4 in the manufacture of sports pressure socks, leg warmers, ankle supports, knee braces or other wrap-around pressure wearables.