CN118390197A - Method for macro spinning of aramid nanofiber - Google Patents
Method for macro spinning of aramid nanofiber Download PDFInfo
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- CN118390197A CN118390197A CN202410664767.8A CN202410664767A CN118390197A CN 118390197 A CN118390197 A CN 118390197A CN 202410664767 A CN202410664767 A CN 202410664767A CN 118390197 A CN118390197 A CN 118390197A
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- potassium hydroxide
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- 239000004760 aramid Substances 0.000 title claims abstract description 123
- 229920003235 aromatic polyamide Polymers 0.000 title claims abstract description 122
- 239000002121 nanofiber Substances 0.000 title claims abstract description 115
- 238000009987 spinning Methods 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 34
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims abstract description 71
- 239000012530 fluid Substances 0.000 claims abstract description 44
- 238000004804 winding Methods 0.000 claims abstract description 44
- 239000006185 dispersion Substances 0.000 claims abstract description 31
- 238000001035 drying Methods 0.000 claims abstract description 27
- 229920006231 aramid fiber Polymers 0.000 claims abstract description 21
- 238000002156 mixing Methods 0.000 claims abstract description 21
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- 230000001112 coagulating effect Effects 0.000 claims abstract description 15
- 239000007788 liquid Substances 0.000 claims abstract description 14
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 238000002166 wet spinning Methods 0.000 claims abstract description 10
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 44
- 230000015271 coagulation Effects 0.000 claims description 31
- 238000005345 coagulation Methods 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000008367 deionised water Substances 0.000 claims description 20
- 229910021641 deionized water Inorganic materials 0.000 claims description 20
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 230000002378 acidificating effect Effects 0.000 claims description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 238000004108 freeze drying Methods 0.000 claims description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- 239000012445 acidic reagent Substances 0.000 claims description 4
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 claims description 4
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 4
- MFRIHAYPQRLWNB-UHFFFAOYSA-N sodium tert-butoxide Chemical compound [Na+].CC(C)(C)[O-] MFRIHAYPQRLWNB-UHFFFAOYSA-N 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 3
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 239000005711 Benzoic acid Substances 0.000 claims description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 2
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 claims description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 2
- 239000003513 alkali Substances 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- 239000000908 ammonium hydroxide Substances 0.000 claims description 2
- 235000010233 benzoic acid Nutrition 0.000 claims description 2
- 238000001125 extrusion Methods 0.000 claims description 2
- 235000019253 formic acid Nutrition 0.000 claims description 2
- 239000004310 lactic acid Substances 0.000 claims description 2
- 235000014655 lactic acid Nutrition 0.000 claims description 2
- 229910017604 nitric acid Inorganic materials 0.000 claims description 2
- 235000011007 phosphoric acid Nutrition 0.000 claims description 2
- 229910000105 potassium hydride Inorganic materials 0.000 claims description 2
- NTTOTNSKUYCDAV-UHFFFAOYSA-N potassium hydride Chemical compound [KH] NTTOTNSKUYCDAV-UHFFFAOYSA-N 0.000 claims description 2
- LPNYRYFBWFDTMA-UHFFFAOYSA-N potassium tert-butoxide Chemical compound [K+].CC(C)(C)[O-] LPNYRYFBWFDTMA-UHFFFAOYSA-N 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 239000012312 sodium hydride Substances 0.000 claims description 2
- 229910000104 sodium hydride Inorganic materials 0.000 claims description 2
- 239000001488 sodium phosphate Substances 0.000 claims description 2
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 2
- POWFTOSLLWLEBN-UHFFFAOYSA-N tetrasodium;silicate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-][Si]([O-])([O-])[O-] POWFTOSLLWLEBN-UHFFFAOYSA-N 0.000 claims description 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 2
- 239000003153 chemical reaction reagent Substances 0.000 claims 2
- 239000000835 fiber Substances 0.000 abstract description 29
- 239000004372 Polyvinyl alcohol Substances 0.000 description 59
- 229920002451 polyvinyl alcohol Polymers 0.000 description 59
- 238000001879 gelation Methods 0.000 description 8
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- 238000002360 preparation method Methods 0.000 description 7
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- Artificial Filaments (AREA)
Abstract
The invention discloses a macro spinning method of aramid nanofibers, which comprises the following steps: s1: adding aramid fiber into potassium hydroxide solution, heating and stirring to obtain ANF dispersion; s2: mixing the ANF dispersion liquid prepared in the step S1 with the PVA solution, and heating and stirring uniformly to prepare an ANF/PVA spinning fluid; s3: carrying out wet spinning on the ANF/PVA spinning fluid to obtain aramid nanofiber gel filaments; s4: and drying the aramid nanofiber gel filaments to obtain the aramid nanofiber filaments. The invention respectively regulates and controls the spinning fluid and the coagulating bath, improves the strength and the spinning speed of the gel fiber, and can solve the problems of difficult drawing and winding, non-ideal mechanical property and the like of the aramid nanofiber scale spinning in the prior art.
Description
Technical Field
The invention relates to the technical field of fiber spinning, in particular to a macro spinning method for aramid nanofibers.
Background
The recycling of the waste textiles has important significance for environmental protection, energy conservation and emission reduction, and is a necessary requirement for the sustainable development of the textile industry. The aramid fiber is widely applied to the fields of national defense and military industry, aerospace, special protection and the like due to the characteristics of light weight, high strength, high wear resistance, flame retardance and the like. However, a large amount of aramid fibers are disposed of in an incineration and filling manner each year, resulting in a waste of a large amount of resources. At present, macroscopic aramid filaments can be converted into nano-scale fibers by using a chemical splitting method, and the nano-scale fibers have higher specific surface area and better mechanical properties, so that the nano-scale fibers have important application value for improving the properties of composite materials, such as strength, rigidity, toughness and the like. The method for nanocrystallizing the aramid fiber and preparing the regenerated aramid fiber in a recombination mode is one of important ways for endowing the aramid fiber with new generation. The prepared aramid nanofiber filament yarn by wet spinning has the characteristics of similar appearance and performance to those of original aramid fiber, high softness, excellent mechanical properties, flame retardance and the like. In addition, the aramid nanofiber with a one-dimensional linear structure can be compounded with other nano functional materials to prepare a composite material with multiple functions of conductivity, antibiosis, heat insulation, energy storage and the like, and has wide application prospects in various industries, so that the aramid nanofiber is widely focused by scientific research.
The preparation of the aramid nanofiber filament by adopting the wet spinning method requires that an aramid nanofiber spinning fluid is firstly prepared, and the spinning fluid is extruded into a coagulation bath to form an aramid nanofiber gel filament, and the aramid nanofiber filament is obtained through drying. However, the transformation of the aramid nanofiber spinning fluid into gel fiber is a slow process, and the aramid nanofiber gel fiber only has a single hydrogen bond network constructed by amide groups, so that the mechanical property is poor, and the requirements of rapid and continuous spinning mass production are difficult to meet.
Therefore, the development of the macro spinning method for the aramid nanofiber can not only meet the requirement of the macro preparation of the rapid spinning, but also improve the mechanical properties of the aramid nanofiber filaments, and is an important research direction of the current aramid nanofiber preparation technology.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a macro spinning method for aramid nanofibers. The invention respectively regulates and controls the spinning fluid and the coagulating bath, improves the strength and the spinning speed of the gel fiber, and can solve the problems of difficult drawing and winding, non-ideal mechanical property and the like of the aramid nanofiber scale spinning in the prior art.
The technical scheme of the invention is as follows:
The invention aims to provide a macro spinning method for aramid nanofibers, which comprises the following steps:
s1: adding aramid fiber into potassium hydroxide solution, heating and stirring to obtain ANF dispersion;
s2: mixing the ANF dispersion liquid prepared in the step S1 with the PVA solution, and heating and stirring uniformly to prepare an ANF/PVA spinning fluid;
S3: carrying out wet spinning on the ANF/PVA spinning fluid to obtain aramid nanofiber gel filaments;
s4: and drying the aramid nanofiber gel filaments to obtain the aramid nanofiber filaments.
In one embodiment of the present invention, in step S1, the potassium hydroxide solution consists of potassium hydroxide, water and dimethyl sulfoxide; the concentration of potassium hydroxide in the potassium hydroxide solution is 7.5-150g/L; the volume ratio of dimethyl sulfoxide to water in the potassium hydroxide solution is 25-100:1.
In one embodiment of the present invention, in step S1, the mass ratio of the aramid fiber to potassium hydroxide in the potassium hydroxide solution is 1:0.5-1.5.
In one embodiment of the present invention, in step S1, conditions of heating and stirring: the temperature is 65-95 ℃, the time is 6-24 hours, and the stirring speed is 500-1500 rpm.
In one embodiment of the invention, in step S1, the ANF dispersion has a concentration of 0.5-10%.
In one embodiment of the present invention, in step S2, the concentration of the PVA solution is 0.5 to 15%; the volume ratio of the ANF dispersion liquid to the PVA solution is 2:0.1-2.
When the ANF dispersion concentration or PVA concentration increases, the viscosity of the spinning solution increases, and the spinning solution is too viscous to be smoothly extruded through the spinneret orifice, and thus continuous spinning is difficult.
In one embodiment of the present invention, in step S2, the temperature of the heating and stirring is 60 to 95 ℃.
In one embodiment of the present invention, in step S3, during wet spinning, the spinning fluid is extruded by a propeller and then sequentially passed through a spinneret, a coagulation bath, and a winding drum.
Wherein the temperature of the spinning fluid is 20-80 ℃, and the temperature of the coagulating bath is 20-60 ℃.
In one embodiment of the invention, the coagulation bath is an acidic coagulation bath, an alkaline coagulation bath, or a deionized water coagulation bath.
In one embodiment of the invention, the acid reagent in the acidic coagulation bath is one or more of sulfuric acid, hydrochloric acid, nitric acid, formic acid, acetic acid, sulfurous acid, phosphoric acid, lactic acid, benzoic acid, acrylic acid.
In one embodiment of the invention, the concentration of the acid reagent in the acid coagulation bath is 0.05-5 mol/L.
In one embodiment of the invention, the alkaline agent in the alkaline coagulation bath is one or more of sodium hydroxide, sodium carbonate, sodium phosphate, sodium orthosilicate, potassium tert-butoxide, sodium tert-butoxide, potassium hydride, sodium hydride, potassium hydroxide, ammonium hydroxide.
In one embodiment of the invention, the concentration of the alkaline agent in the alkaline coagulation bath is 0.05-5 mol/L.
In one embodiment of the invention, the spinneret is 8-30G in specification and the propeller is 0.3-30 ml/min in extrusion speed when the spinning fluid is extruded; the winding speed of the winding drum is 0.2-14 m/min; by changing the winding speed of the winding drum, a draft of-0.8 to 1.5 times can be achieved.
In one embodiment of the present invention, in step S4, the drying treatment is freeze-drying or heat-drying.
In one embodiment of the invention, the conditions of freeze-drying are: the temperature is-35 ℃, the vacuum degree is 10-20Pa, and the time is 12-24 hours; the conditions of the heating and drying are as follows: the temperature is 80-150 ℃ and the time is 6-12 hours.
The beneficial technical effects of the invention are as follows:
(1) According to the invention, in the process of deprotonating the aramid fiber, the polyvinyl alcohol is uniformly coated on the surface of the aramid nanofiber in the ANF solution added with the polyvinyl alcohol solution, a hydrogen bond crosslinking network is constructed, a good interface interaction is formed, the strength and the toughness of the ANF/PVA gel fiber filament are synchronously improved, and the spinning speed of the ANF gel fiber filament is effectively improved.
(2) According to the method for controlling the sol-gel transition speed of the aramid nanofiber by using the coagulation bath, the gelation speed of the fiber is controlled and controlled by changing the type and the concentration of a proton donor, so that the skin-core structure of the gel fiber is controlled and controlled, the ordered arrangement of the aramid nanofiber in the gel filament is influenced, the microstructure inside the gel fiber is controlled and controlled, and the obtained aramid nanofiber filament has high orientation degree, mechanical strength, chemical corrosion resistance and high temperature resistance, and has wide application prospect in the field of preparing high-performance regenerated chemical fibers.
(3) The aramid nanofiber gel filament provided by the invention can be adopted to obtain the aramid nanofiber filament with different forms and the aramid nanofiber aerogel filament with different forms by adopting different drying spinning, and has high mechanical strength and orientation degree, and can be woven into various fabrics such as woven fabrics, knitted fabrics and the like by a textile processing method.
(4) Compared with the preparation method in the prior art, the preparation method provided by the invention has the advantages of simple process, low energy consumption of production cost, less environmental pollution and capability of meeting the requirement of large-scale production in the spinning industry of mass preparation.
Drawings
FIG. 1 is a schematic diagram of the equipment composition for wet spinning in the present invention;
FIG. 2 is an optical photograph of an ANF dispersion, PVA solution, and ANF/PVA spinning fluid of example 1 of the present invention;
FIG. 3 is an optical photograph of an aramid nanofiber gel filament of example 2 of the present invention;
FIG. 4 is a scanning electron micrograph of an aramid nanofiber filament of example 3 of the present invention;
FIG. 5 is an optical photograph of an aramid nanofiber filament of example 4 of the present invention;
FIG. 6 is an optical photograph of an aramid nano aerogel fiber of example 8 of the present invention and a corresponding scanning electron microscope photograph;
FIG. 7 is a tensile stress-strain curve of the aramid nanofiber gel filaments of example 2 and comparative example 1 of the present invention;
FIG. 8 is a tensile stress-strain curve of the aramid nanofiber gel filaments of examples 1-5 of the present invention;
FIG. 9 is a tensile stress-strain curve of the aramid nanofiber filaments of examples 1-5 of the present invention;
FIG. 10 is a tensile stress-strain curve of the aramid nanofiber gel filaments obtained from different coagulation baths of examples 2,6 and 7 of the present invention;
FIG. 11 is a graph showing tensile stress-strain curves of aramid nanofiber filaments obtained from different coagulation baths of examples 2, 6 and 7 of the present invention;
FIG. 12 is a schematic diagram of a method of calculating gelation time;
FIG. 13 shows the gelation time of various coagulation bath spin fluids of examples 2, 6 and 7 of the present invention;
fig. 14 shows the fastest spin winding speeds for the different coagulation bath spin fluids of examples 2, 6 and 7 of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the drawings and examples.
FIG. 1 is a schematic diagram of the equipment composition for wet spinning in the present invention, consisting of a propeller, a spinneret, a coagulation bath and a winding drum, respectively.
Example 1
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 0.375g of polyvinyl alcohol was added to 25mL of dimethyl sulfoxide and stirred at 95℃for 4 hours to give a 1.5% by weight solution of transparent polyvinyl alcohol;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 1.5wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Fig. 2 is an optical photograph of an ANF dispersion, a PVA solution, and an ANF/PVA spinning fluid in this example, and it can be seen from the figure that the spinning fluid is uniform and stable, and still has good dispersibility after 180 days of storage, and no nanofiber deposition in the solution can be used for wet spinning.
Example 2
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 0.75g of polyvinyl alcohol is added into 25mL of dimethyl sulfoxide and stirred for 4 hours at 95 ℃ to obtain a 3wt% transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 3wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Fig. 3 is an optical photograph of an aramid nanofiber gel filament in this example, and it can be seen from the figure that the ANF/PVA spinning fluid obtained the gel filament, a hydrogen bond cross-linked network was formed between the ANF and PVA molecules, so that the mechanical properties of the gel filament were greatly enhanced, and the gel filament could be smoothly and continuously wound into a bobbin without breaking.
Example 3
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 1.5g of polyvinyl alcohol was added to 25mL of dimethyl sulfoxide and stirred at 95℃for 4 hours to give a 6% by weight transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 6wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
FIG. 4 is a scanning electron micrograph of the aramid nanofiber filament of the present example, which shows that the diameter of the prepared aramid nanofiber filament is about 125 μm, and the surface is smooth and free of impurities.
Example 4
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 2.25g of polyvinyl alcohol was added to 25mL of dimethyl sulfoxide and stirred at 95℃for 4 hours to give a 9% by weight transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 9wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Fig. 5 is an optical photograph of the aramid nanofiber filament of the present example, and it can be seen that the prepared aramid nanofiber filament has orange color, and the fiber can be tightly and continuously wound into a bobbin without breakage due to good flexibility and strength.
Example 5
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 3.75g of polyvinyl alcohol was added to 25mL of dimethyl sulfoxide and stirred at 95℃for 4 hours to give a 9% by weight transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 12wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Example 6
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 0.75g of polyvinyl alcohol is added into 25mL of dimethyl sulfoxide and stirred for 4 hours at 95 ℃ to obtain a 3wt% transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 3wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a 21G spinneret, enters a coagulating bath (100G sodium hydroxide is dissolved in 5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Example 7
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 0.75g of polyvinyl alcohol is added into 25mL of dimethyl sulfoxide and stirred for 4 hours at 95 ℃ to obtain a 3wt% transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 3wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a 21G spinneret, enters a coagulating bath (420 mL of concentrated hydrochloric acid with the concentration of 37% is dissolved in 4580mL of deionized water) at the speed of 4mL/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at the speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Example 8
A method for macro-spinning of aramid nanofibers, comprising the steps of:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) 0.75g of polyvinyl alcohol is added into 25mL of dimethyl sulfoxide and stirred for 4 hours at 95 ℃ to obtain a 3wt% transparent polyvinyl alcohol solution;
(3) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with the 3wt% transparent polyvinyl alcohol solution prepared in the step (2) according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF/PVA spinning fluid;
(4) The ANF/PVA spinning fluid prepared in the step (3) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(5) Winding the aramid nanofiber gel filaments prepared in the step (4) from a winding roller to a yarn drum, and freeze-drying at-40 ℃ for 8 hours to obtain the aramid nanofiber aerogel filaments.
Fig. 6 is an optical photograph of an aramid nano aerogel filament and a corresponding scanning electron microscope photograph in the present embodiment, and it can be seen from the figure that the prepared aramid nano aerogel fiber is light yellow, has a rich porous structure inside, shows obvious aerogel structural characteristics, and has potential for application in the field of heat preservation and heat insulation.
Comparative example 1
The preparation method of the aramid nanofiber comprises the following steps:
(1) 1.5g of aramid fiber is added into a potassium hydroxide solution (composed of 2.25g of potassium hydroxide, 50mL of dimethyl sulfoxide and 2mL of deionized water), and stirred at 95 ℃ for 24 hours to obtain 3wt% dark red aramid nanofiber dispersion;
(2) Mixing the 3wt% aramid nanofiber dispersion liquid prepared in the step (1) with dimethyl sulfoxide according to the volume ratio of 2:1, and stirring and mixing for 4 hours at the temperature of 85 ℃ to obtain an ANF spinning fluid;
(3) The ANF spinning fluid prepared in the step (2) passes through a propeller, passes through a spinneret of 21G, enters a coagulating bath (5L deionized water) at a speed of 4ml/min, is solidified into aramid nanofiber gel filaments, and is collected by a winding roller at a speed of 6 m/min;
(4) Winding the aramid nanofiber gel filaments prepared in the step (3) from a winding roller to a yarn drum, and drying the yarn drum in a drying oven at 100 ℃ for 8 hours to obtain the aramid nanofiber filaments.
Test example:
(1) Mechanical properties
The method for testing the fiber strength is carried out by referring to the national standard GB/T14344-2022 chemical fiber filament tensile property test method, the cut fiber filament is 300mm and is clamped in a fiber strength tester, the clamping distance is adjusted to 250mm, and the tensile speed is adjusted to 250mm/min; the results of mechanical property tests of the aramid nanogel fiber filaments obtained in examples 1 to 7 and comparative example 1 are shown in tables 1 and 2, respectively.
TABLE 1 mechanical Properties of aramid nanogel fiber filaments
TABLE 2 mechanical Properties of aramid nanofiber filaments
| Sample of | Strain (%) | Stress (MPa) |
| Example 1 | 5.0 | 314.76 |
| Example 2 | 6.0 | 346.99 |
| Example 3 | 7.8 | 297.15 |
| Example 4 | 10.3 | 252.79 |
| Example 5 | 13.2 | 208.33 |
| Example 6 | 5.4 | 384.63 |
| Example 7 | 6.9 | 333.54 |
| Comparative example 1 | 3.65 | 289.04 |
FIG. 7 shows tensile stress-strain curves of the aramid nanofiber gel filaments of the example 2 and the comparative example 1 of the present invention, wherein the maximum stress and strain of the comparative example 1 are 0.03Mpa and 3.2% respectively, and the PVA is present in the example 2, and a hydrogen bond cross-linked network is formed with the ANF, wherein the example 2 has 0.16Mpa stress and 14.1% strain, and the mechanical properties are significantly improved, thus providing mechanical guarantee for rapid spinning.
FIG. 8 is a tensile stress-strain curve of the aramid nanofiber gel filaments of examples 1-5 of the present invention, showing that the degree of crosslinking of the gel fibers increases with increasing PVA concentration, and the mechanical properties of the gel fibers increase with increasing PVA content.
Fig. 9 is a tensile stress-strain curve of the aramid nanofiber filament of examples 1-5 according to the present invention, and it can be seen from the graph that the mechanical properties of the dried aramid nanofiber filament are different from the change rule of the mechanical properties of the gel fiber, the stress of the filament is increased and then decreased, wherein the highest stress is about 325.6Mpa when the mass ratio of ANF to PVA is 2:1.
Fig. 10 shows tensile stress-strain curves of the aramid nanofiber gel filaments obtained from different coagulation baths of examples 2, 6 and 7 according to the present invention, and it is known that the mechanical properties of the aramid nanofiber gel filaments prepared from the acid agent are best among the three, and it is verified from the side that the proton donor affects the arrangement of the aramid nanofibers, thereby affecting the mechanical properties of the gel fibers.
Fig. 11 shows the tensile stress-strain curves of the aramid nanofiber filaments obtained by different coagulation baths in examples 2, 6 and 7 of the present invention, and it is known from the figure that the alkali agent has high stress among the three, and it is verified from the side that the proton donor affects the arrangement of the aramid nanofiber and thus the mechanical properties of the filaments.
(2) Gelation time
As shown in fig. 12, the spinning fluid extruded from the spinneret orifice showed a deep yellow color, and the color of the gelled fiber was gradually changed to show a pale yellow color, and the time required for the spinning fluid to change from the deep yellow color to the pale yellow color was recorded as the gelation time.
FIG. 13 shows the gelation time of various coagulation bath spinning fluids according to examples 2, 6 and 7 of the present invention, and the results are shown in Table 3; as can be seen from fig. 13 and table 3, the gelation time was 5.23s at the minimum and 13.2s in the alkaline coagulation bath because of more proton donors in the acidic coagulation bath.
TABLE 3 gelation time under different coagulation baths
| Sample of | Average gel time(s) |
| Example 2 | 9.52 |
| Example 6 | 13.2 |
| Example 7 | 5.23 |
FIG. 14 shows the fastest spinning winding speed of the different coagulation bath spinning fluids according to examples 2,6 and 7 of the present invention, wherein the winding speed is gradually increased during the spinning process, and when the gel fiber breaks, the winding speed is recorded, and the obtained aramid nanogel filament in the acidic coagulation bath has the fastest winding speed of 12.4m/min, which is the better mechanical property of the obtained aramid nanogel filament in the acidic coagulation bath and can bear the centrifugal force generated by the faster winding speed.
The above examples are not intended to limit the scope of the invention nor the order of execution of the steps described. The present invention is obviously modified by a person skilled in the art in combination with the prior common general knowledge, and falls within the scope of protection defined by the claims of the present invention.
Claims (10)
1. A method for macro-spinning of aramid nanofibers, comprising the steps of:
s1: adding aramid fiber into potassium hydroxide solution, heating and stirring to obtain ANF dispersion;
s2: mixing the ANF dispersion liquid prepared in the step S1 with the PVA solution, and heating and stirring uniformly to prepare an ANF/PVA spinning fluid;
S3: carrying out wet spinning on the ANF/PVA spinning fluid to obtain aramid nanofiber gel filaments;
s4: and drying the aramid nanofiber gel filaments to obtain the aramid nanofiber filaments.
2. The method according to claim 1, wherein in step S1, the potassium hydroxide solution consists of potassium hydroxide, water and dimethyl sulfoxide; the concentration of potassium hydroxide in the potassium hydroxide solution is 7.5-150g/L; the volume ratio of dimethyl sulfoxide to water in the potassium hydroxide solution is 25-100:1.
3. The method according to claim 1, wherein in step S1, the mass ratio of the aramid fiber to potassium hydroxide in the potassium hydroxide solution is 1:0.5-1.5.
4. The method according to claim 1, wherein in step S1, the concentration of the ANF dispersion is 0.5-10%.
5. The method according to claim 1, wherein in step S2, the concentration of the PVA solution is 0.5 to 15%; the volume ratio of the ANF dispersion liquid to the PVA solution is 2:0.1-2.
6. The method according to claim 1, wherein in step S3, the spinning fluid is extruded by a propeller and then sequentially passed through a spinneret, a coagulation bath, and a winding drum during wet spinning.
7. The method of claim 6, wherein the coagulation bath is an acidic coagulation bath, an alkaline coagulation bath, or a deionized water coagulation bath;
The acid reagent in the acidic coagulating bath is one or more of sulfuric acid, hydrochloric acid, nitric acid, formic acid, acetic acid, sulfurous acid, phosphoric acid, lactic acid, benzoic acid and acrylic acid; the concentration of the acid reagent in the acid coagulation bath is 0.05-5mol/L;
The alkaline reagent in the alkaline coagulating bath is one or more of sodium hydroxide, sodium carbonate, sodium phosphate, sodium orthosilicate, potassium tert-butoxide, sodium tert-butoxide, potassium hydride, sodium hydride, potassium hydroxide and ammonium hydroxide; the concentration of the alkali reagent in the alkaline coagulating bath is 0.05-5mol/L.
8. The method according to claim 6, wherein the spinneret has a size of 8-30G and the propeller has an extrusion speed of 0.3-30ml/min when the spinning fluid is extruded; the winding speed of the winding drum is 0.2-14m/min.
9. The method according to claim 1, wherein in step S4, the drying treatment is freeze-drying or heat-drying.
10. The method according to claim 9, wherein the conditions of freeze-drying are: the temperature is-35 ℃, the vacuum degree is 10-20Pa, and the time is 12-24 hours; the conditions of the heating and drying are as follows: the temperature is 80-150 ℃ and the time is 6-12 hours.
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