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CN-121976321-A - Phase change fiber with structural damage visualization function and preparation method thereof

CN121976321ACN 121976321 ACN121976321 ACN 121976321ACN-121976321-A

Abstract

The invention belongs to the technical field of phase change fiber structural damage identification, and relates to a phase change fiber with a structural damage visualization function and a preparation method thereof. The phase change fiber has a three-layer coaxial structure, the core layer is composed of solid-liquid phase material and thixotropic agent, the core layer is gel-like in a static state and has fluidity under the action of shear stress, the middle layer is composed of polymer and functional filler, the functional filler is porous adsorbent filler loaded with indicating dye, the outer layer is an optical shielding layer containing transparent colored pigment, and the transparent colored pigment has selective absorption attenuation effect on a background color development output wave band of the indicating dye under the visible light illumination condition. Firstly, preparing a primary fiber formed by compounding a core layer and a middle layer by adopting a coaxial wet spinning process, and then coating the surface of the primary fiber to form an outer layer to prepare the product. The phase change fiber with the structure damage visualization function can realize visual monitoring in a natural light environment, and the preparation method is simple.

Inventors

  • WANG XIANFENG
  • Qu Chengran
  • LIN YANYAN
  • DING BIN
  • YU JIANYONG

Assignees

  • 东华大学

Dates

Publication Date
20260505
Application Date
20260408

Claims (10)

  1. 1. The phase change fiber with the structure damage visualization function is characterized by having a three-layer coaxial structure, and sequentially comprising a core layer, a middle layer and an outer layer from inside to outside; The core layer is composed of solid-liquid phase material and thixotropic agent, is in gel state in static state, and has fluidity under the action of shear stress; The middle layer consists of a polymer and a functional filler, wherein the functional filler is a porous adsorbent filler loaded with an indicating dye; The outer layer is an optical shielding layer containing transparent colored pigment, and the transparent colored pigment has selective absorption and attenuation effects on a background color development output wave band of the indicator dye under the visible light illumination condition.
  2. 2. The phase change fiber with the structure damage visualization function according to claim 1, wherein the solid-liquid phase change material is an alkane phase change material, and the structural formula is C n H 2n+2 , wherein the value range of n is 14-20.
  3. 3. The phase change fiber with the structure damage visualization function according to claim 1, wherein the thixotropic agent is more than one of hydrophobic fumed silica, organic modified bentonite, organic montmorillonite, attapulgite, hydrophobic modified cellulose nanocrystalline and carbon nanotubes, and the thixotropic agent accounts for 5-15% of the core layer by mass.
  4. 4. The phase change fiber with the function of visualizing structural damage according to claim 1, wherein the polymer is one or more of thermoplastic polyurethane, polyacrylonitrile, polyvinylidene fluoride, poly (vinylidene fluoride-hexafluoropropylene), polymethyl methacrylate, polyethersulfone, polysulfone, polyvinyl chloride, and cellulose acetate; The porous adsorbent filler is hydrophilic fumed silica, mesoporous carbon, a metal organic framework material, porous zeolite or porous starch, and the mass fraction of the porous adsorbent filler relative to the polymer is 5-20%; The indicating dye is nile Red, coumarin 6 or Lumogen F Red 305, and the loading amount of the indicating dye relative to the porous adsorbent filler is 0.3-2.0wt%.
  5. 5. The phase change fiber with the structure damage visualization function according to claim 1, wherein the material of the optical shielding layer is aqueous polyurethane, organic silicon rubber or acrylic resin; The thickness of the outer layer is 2-10 mu m, and the average light transmittance in a visible light wave band is 35-70%; the diameter of the core layer is 200-340 mu m, and the radial thickness of the intermediate layer is 15-65 mu m.
  6. 6. The phase change fiber with structural damage visualization function according to claim 1, wherein the indicator dye and the transparent colored pigment satisfy one of the following matching relations: a. the indicating dye is nile red, the transparent colored pigment is purple transparent pigment, and the transparent colored pigment accounts for 1.0-1.5% of the outer layer by mass; b. The indicating dye is coumarin 6, the transparent colored pigment is red or magenta transparent pigment, and the transparent colored pigment accounts for 1.0-2.0% of the outer layer by mass; c. the indicating dye is Lumogen F Red 305, the transparent colored pigment is a green transparent pigment, and the transparent colored pigment accounts for 1.5-3.0% of the outer layer by mass.
  7. 7. The method for preparing the phase-change fiber with the structure damage visualization function according to any one of claims 1to 6, wherein a coaxial wet spinning process is adopted to prepare a primary fiber formed by compounding the core layer and the middle layer, and then the surface of the primary fiber is coated to form the outer layer, so that the phase-change fiber with the structure damage visualization function is prepared.
  8. 8. The method for preparing the phase change fiber with the structure damage visualization function according to claim 7, which is characterized by comprising the following specific steps: S1, heating the solid-liquid phase-change material to a molten state, preserving heat, adding the thixotropic agent, and preparing a core thixotropic fluid through ultrasonic treatment and/or high-speed shearing and dispersing; s2, preparing a uniform mixed solution containing the polymer, the porous adsorbent filler and the indicator dye as an intermediate layer spinning solution; S3, respectively introducing the thixotropic fluid of the core layer and the spinning solution of the middle layer into an inner channel and an outer channel of a coaxial spinneret, extruding into a coagulating bath for curing and forming, and washing and drying in sequence to obtain the nascent fiber; and S4, coating a coating liquid on the surface of the nascent fiber, and curing to form the outer layer, wherein the coating liquid is aqueous polyurethane, organic silicon rubber or acrylic resin solution containing the transparent colored pigment.
  9. 9. The method for preparing the phase change fiber with the structure damage visualization function according to claim 8, wherein the preparation process of the intermediate layer spinning solution in the step S2 comprises the following steps: s21, preparing composite powder, namely dissolving the indicator dye in ethanol to prepare dye solution, carrying out pre-wetting treatment on the dried porous adsorbent filler by utilizing the dye solution to form dye-adsorbent slurry, and then heating and drying to remove the ethanol, so that the indicator dye is adsorbed on the surface or pores of the porous adsorbent filler to obtain composite powder; S22, temporary coating treatment, namely dissolving polyvinyl alcohol and/or sodium alginate in deionized water to obtain coating liquid, adding the composite powder into the coating liquid for mixing and dispersing to enable the polyvinyl alcohol and/or sodium alginate to form coating on the outer surface of the composite powder; S23, spinning solution blending, namely dissolving the polymer in an organic solvent to obtain a uniform solution, and dispersing the coated composite powder in the uniform solution to obtain an intermediate layer spinning solution, wherein the mass fraction of the polymer in the uniform solution is 15-20%, and the organic solvent is more than one of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran and acetone.
  10. 10. The method for preparing a phase change fiber with a structure damage visualization function according to claim 9, wherein in the steps S3 and S4, specific process parameters are as follows: the inner diameter of the outer channel needle is 0.86-1.05 mm, the inner diameter of the inner channel needle is 0.27-0.40 mm, the outer diameter of the inner channel needle head is 0.55-0.70 mm; the extrusion flow rate ratio of the thixotropic fluid of the core layer to the spinning solution of the middle layer is 0.15-1:1; The coagulating bath is deionized water or a mixed solution of deionized water and ethanol, and the coagulating bath temperature is 30-45 ℃; washing the nascent fiber with water in step S3 or after step S3 to dissolve and remove the temporary coating layer formed by the coated composite powder; the solid content of the coating liquid is 40-100%; and the curing mode in the step S4 is room temperature drying curing or 60-100 ℃ heating curing.

Description

Phase change fiber with structural damage visualization function and preparation method thereof Technical Field The invention belongs to the technical field of phase change fiber structural damage identification, and relates to a phase change fiber with a structural damage visualization function and a preparation method thereof. Background The phase change fiber has excellent latent heat energy storage and temperature regulation characteristics, and has great application potential in the fields of intelligent textiles, wearable equipment and device heat management. However, the solid-liquid phase change material is extremely easy to generate the risk of liquid leakage in the endothermic melting stage, so that the latent heat energy storage performance is greatly attenuated, leaked liquid substances even pollute the surrounding environment, and the reliability and the safety of the phase change fiber are seriously restricted. The research of the existing phase change fiber is mainly focused on the aspects of improving the loading capacity of the phase change material of the core layer and the stability of the outer layer encapsulation, such as sheath-core structure fiber prepared by using a coaxial wet spinning technology, and the sheath polymer cladding is used for realizing the high enthalpy value and the leakage resistance. However, when the fibers generate microcracks due to mechanical fatigue in the long-term service process, the fibers are difficult to be found by naked eyes in time, and the problems are often exposed after a large amount of core materials leak or the energy storage function is remarkably attenuated. The traditional sheath-core structure phase-change fibers such as CN202311267840.X and CN202310878877.X disclose a process route for preparing the sheath-core structure phase-change fibers by adopting coaxial wet spinning, and focus is on improving the load capacity, packaging stability, leakage prevention capacity and enthalpy value of core layer phase-change materials (such as paraffin, octadecane and the like), wherein the sheath layer is usually a single polymer (such as polyacrylonitrile, polyurethane and the like), or functional particles are introduced into the sheath layer to realize additional functions such as photo-thermal, electric heating and the like. Although the coaxial phase change fiber is focused on improving the encapsulation rate and the enthalpy value, microcracks generated by mechanical fatigue of the skin layer are invisible to naked eyes in long-term service, and before microcracks are not developed into obvious cracks, a user cannot easily judge whether the core layer has micro leakage or thermal property attenuation in time. In practice, the core material is often not found until a large amount of the core material flows out of polluted clothes or the energy storage function is obviously disabled, so that the safety and the reliability are insufficient. In order to overcome the defects, researchers develop intelligent monitoring technologies, such as grafting aggregation fluorescent groups onto a phase change material molecular chain, and realize a tracing effect by utilizing the characteristic of fluorescence enhancement after leakage. The method relies on ultraviolet light source excitation, signals are weak under natural light, fluorescence intensity is easily influenced by the phase state and distribution of leakage matters, damage cannot be reflected stably and intuitively, meanwhile, fiber structure breakage and internal normal migration are difficult to distinguish, and the visual recognition requirements on the damage position, degree and type in practical application cannot be met. For example, literature 1（Cellulose nanofiber encapsulated PEG phase change composites containing AIE-gen for monitoring leak process[J]. Composites Part A, 2023） grafts aggregation-induced emission (AIE) fluorophor (ZPP) onto a PEG molecular chain by a chemical method to obtain PEG-ZPP, and then physically blends the PEG-ZPP with pure PEG to form a fluorescent phase change composite system, and introduces the fluorescent phase change composite system into a cellulose nanofiber aerogel skeleton by a vacuum impregnation mode to form a composite phase change material. The working principle is that the characteristic that AIE groups are obviously enhanced in fluorescence after leakage, solidification and aggregation is generated is utilized, and the integral fluorescence intensity change is used as a leakage indication signal under the excitation of ultraviolet light (UV 365 nm). However, it has the following disadvantages: (1) The device has strong dependence, can not realize direct visual alarm under natural light, enhances the leakage visibility by a fluorescence mode, has clear effect often built under external conditions such as UV irradiation/dark environment and the like, and has easily weakened or inadequately striking signal under the condition of common natural light or