CN111575815A

CN111575815A - Method for preparing spiral nano material fiber by electrostatic spinning method

Info

Publication number: CN111575815A
Application number: CN202010461360.7A
Authority: CN
Inventors: 任朋成
Original assignee: Yantai Hengnuo New Material Co ltd
Current assignee: Yantai Hengnuo New Material Co ltd
Priority date: 2020-05-27
Filing date: 2020-05-27
Publication date: 2020-08-25

Abstract

The invention discloses a method for preparing a spiral nano material fiber by an electrostatic spinning method, which comprises the following steps: immersing the ground nano functional material in mixed acid of nitric acid and sulfuric acid, soaking for 1-2h at 0 ℃, cooling to-15 ℃, adding hydrogen peroxide, potassium permanganate and hypochlorous acid, reacting for 0.5-24h at-10-60 ℃, performing centrifugal separation, drying a filter cake, and then adding NaBH₄And CaCl₂Soaking the fiber in the solution, filtering, drying the filter cake to obtain a nano functional material containing hydroxyl and carboxyl, dissolving the nano functional material in a solvent to prepare a spinning solution, carrying out electrostatic spinning, wherein the spinneret orifice of a spinneret is wedge-shaped, and collecting the obtained fiber on a receiving device. The invention carries out electrostatic spinning processing on the modified nano functional material, adopts wedge-shaped spinneret orifices to form defects on the surface of the fiber to form self-curled thread-shaped nano fiber, has high elasticity, can restore the curled state after external force disappears, and can be used as a composite materialThe continuous phase ensures that the composite material has better elasticity and tensile resistance.

Description

Method for preparing spiral nano material fiber by electrostatic spinning method

Technical Field

The invention relates to preparation of a composite material, in particular to a method for preparing a spiral nano material fiber by an electrostatic spinning method.

Background

Electrostatic spinning is a special fiber manufacturing process, and the principle is that an electric field is applied to a polymer solution or a melt, the force of the electric field is gradually increased along with the increase of voltage, so that Taylor cone-shaped liquid drops are formed at a jet hole, and charges and the electric field are gathered at the tip of the cone. When the critical voltage is exceeded, the electric field force overcomes the surface tension, and the liquid forms a jet flow and accelerates to fly towards the collecting substrate of the negative pole. In the process, the solvent is continuously volatilized, the jet flow gradually becomes unstable, violent shaking, bending and stretching are carried out under the action of a high-voltage electric field, the diameter is continuously reduced, and finally the micro-nano fiber is solidified.

The electrostatic spinning is the simplest and feasible method for preparing nano-to micron-sized fibers and is the technology with the greatest prospect, and the nano-fibers prepared by the method have larger length-diameter ratio and specific surface area and are suitable for preparing functionalized composite material fibers.

The spiral fiber formed by the spinning solution of electrostatic spinning after passing through the spinneret is caused by the interference of an electric field, the spiral structure has insufficient energy storage, is easy to extend under the action of external force, and has poor elasticity.

Disclosure of Invention

The invention provides a method for preparing a spiral nano material fiber by an electrostatic spinning method, aiming at the problem that the elastic property of the fiber prepared by the existing electrostatic spinning method is insufficient.

The invention adopts a solution electrostatic spinning process, a spinning solution is a solution prepared by dissolving a modified nano-functional material in an organic solvent, the nano-functional material which can be used for modification is carbon materials such as carbon nano tubes, graphene, multilayer graphite micro-sheets, chopped carbon fibers and the like, active groups on the surface of the nano-functional material are oxidized by adopting a mixed oxidant, and then the oxidized groups are partially reduced, so that the nano-functional material has hydroxyl and carboxyl, and the specific modification steps are as follows: immersing the ground nano functional material in mixed acid of nitric acid and sulfuric acid, soaking for 1-2h at 0 ℃, cooling to-15 ℃, adding hydrogen peroxide, potassium permanganate and hypochlorous acid, reacting for 0.5-24h at-10-60 ℃, then performing centrifugal separation, washing a filter cake with deionized water until the pH of the washing liquid is 6-7, placing the filter cake in a vacuum drying oven, drying for 4-6h at 60-70 ℃, and drying the obtained powder containing NaBH₄And CaCl₂The solution is soaked for 8 to 10 hours and then filtered, and filter cakes are washed by deionized water and then dried for 6 hours in a drying oven at 60 ℃ to obtain the nano functional material containing hydroxyl and carboxyl.

The mixed oxidant of hydrogen peroxide, potassium permanganate and hypochlorous acid is adopted to fully and thoroughly oxidize active groups on the surface of the nano functional material, and the compatibility of the modified nano functional material and an organic solvent is improved. The molar ratio of the three oxidants of the invention is 1 (0.25-0.5) to (0.25-1).

The modified nanometer functional material has hydroxyl and carboxyl, and can be dissolved in an organic solvent to form a stable spinning solution for electrostatic spinning. According to the requirements of the electrostatic spinning process, the voltage of a direct current power supply loaded by a spinning nozzle and a high-voltage ionization coil below the spinning nozzle is 12-15kV, an organic solvent is selected from one of ethyl acetate, PMA, DMAc, DMF, butyl acetate or DBE, the concentration of a spinning solution is controlled to be 20-50 wt%, and in the electrostatic spinning process, fibers are gradually thinned, the solvent is volatilized, and the solid content of the fibers is increased.

The electrostatic spinning process is characterized in that the spinneret orifices of the spinneret are wedge-shaped, when stable fiber tows are formed, irregular flow of spinning stock solution is more obvious when the spinning stock solution continuously passes through the wedge-shaped spinneret orifices, the narrow end of the wedge-shaped spinneret orifices can cause the surface of solution fluid to generate defects, the fibers can bend to one side of the defects after solvent volatilization, self-curling thread-shaped fibers are formed under the ionization action, and the length-diameter ratio is larger.

The invention carries out the eccentric electrostatic spinning method on the nano functional material with modified surface, the smooth fiber surface generates groove scratch or concave-convex defect through a wedge-shaped alloy nozzle, the stress is not uniform, the nano rod/tube fiber with the defect on the surface is electrostatically charged through a middle high-voltage ionization coil, the nano material generates stress, the large-caliber nano material generates stress orientation in the one-dimensional direction, the self-curling nano fiber with large length-diameter ratio is formed, the nano fiber has high elasticity, the curling state can be recovered after the external force disappears, and the nano fiber can be used as the continuous phase of the composite material, so that the composite material has better elasticity and tensile resistance.

Drawings

FIG. 1 is an electron micrograph of a fiber obtained in example 1; FIG. 2 is an electron micrograph of the fiber obtained in comparative example 1; FIG. 3 is an electron micrograph of the fiber obtained in example 2; FIG. 4 is an electron micrograph of the fiber obtained in comparative example 2.

Detailed Description

The present invention is described below with reference to examples, which are provided for illustration only and are not intended to limit the scope of the present invention.

Example 1

A method for preparing spiral nano material fiber by an electrostatic spinning method comprises the following steps: immersing the ground carbon nano tube in mixed acid of nitric acid and sulfuric acid, immersing for 1h at 0 ℃, cooling to-15 ℃, adding 10mol of hydrogen peroxide, 2.5mol of potassium permanganate and 10mol of hypochlorous acid, reacting for 24h at-10 ℃, then centrifugally separating, washing a filter cake with deionized water until the pH of a washing liquid is 6-7, placing the filter cake in a vacuum drying oven, drying for 4h at 70 ℃, and drying the obtained powder containing NaBH₄And CaCl₂Soaking the solution for 10h, filtering, washing the filter cake with deionized water, drying in a drying oven at 60 ℃ for 6h to obtain a nano functional material containing hydroxyl and carboxyl, dissolving the nano functional material in ethyl acetate to obtain 20 wt% of spinning stock solution, carrying out direct current electrostatic spinning on the spinning stock solution, arranging a high-voltage ionization coil under a spinneret, wherein the voltage between the spinneret and the high-voltage ionization coil is 12kV, and collecting the obtained fibers on a receiving device.

Example 2

A method for preparing spiral nano material fiber by an electrostatic spinning method comprises the following steps: immersing the ground multilayer graphite microchip in mixed acid of nitric acid and sulfuric acid, soaking for 1.5h at 0 ℃, cooling to-15 ℃, adding 10mol of hydrogen peroxide, 3mol of potassium permanganate and 7.5mol of hypochlorous acid, reacting for 12h at 25 ℃, then performing centrifugal separation, washing a filter cake with deionized water until the pH value of a washing solution is 6-7, placing the filter cake in a vacuum drying oven, drying for 5h at 65 ℃, and drying the obtained powder containing NaBH₄And CaCl₂Soaking the solution for 8-10h, filtering, washing the filter cake with deionized water, drying in a drying oven at 60 deg.C for 6h to obtain nanometer functional material containing hydroxyl and carboxyl, dissolving in DMF to obtain 35 wt% spinning solution, and performing electrostatic spinning with the spinneret orifice of the spinneret being wedge-shaped, and high-voltage ionizing coil arranged under the spinneret and having voltage of 13.5kV between the spinneret and the high-voltage ionizing coilThe resulting fibers are collected at a receiving device.

Example 3

A method for preparing spiral nano material fiber by an electrostatic spinning method comprises the following steps: immersing the ground short carbon fiber into mixed acid of nitric acid and sulfuric acid, immersing for 2h at 0 ℃, cooling to-15 ℃, adding 10mol of hydrogen peroxide, 2.5mol of potassium permanganate and 2.5mol of hypochlorous acid, reacting for 0.5h at 60 ℃, then performing centrifugal separation, washing a filter cake with deionized water until the pH value of washing liquor is 6-7, placing the filter cake in a vacuum drying oven, drying for 6h at 60 ℃, and drying the obtained powder containing NaBH₄And CaCl₂Soaking the solution for 8-10h, filtering, washing the filter cake with deionized water, drying in a drying oven at 60 ℃ for 6h to obtain a nano functional material containing hydroxyl and carboxyl, dissolving the nano functional material in a PMA solvent to obtain 50 wt% of spinning stock solution, carrying out electrostatic spinning on the spinning stock solution, arranging a high-voltage ionization coil under the spinning head, wherein the voltage between the spinning head and the high-voltage ionization coil is 15kV, and collecting the obtained fibers on a receiving device.

Comparative examples 1 to 3 are fibers obtained by replacing the wedge-shaped spinneret holes used in examples 1 to 3 with circular spinneret holes, respectively. The fibers obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to the relevant property tests, respectively, as shown in Table 1.

As can be seen from the test results in Table 1, the fibers obtained in examples 1-3 have higher elongation at break and lower elastic modulus than the corresponding fibers obtained in comparative examples due to the presence of self-curling, which indicates that the fibers obtained in examples 1-3 have better elastic properties, but have reduced mechanical properties due to the presence of defects on the fiber surface.

TABLE 1 testing of the properties of the fibers obtained in the examples and comparative examples

FIGS. 1 to 4 are electron micrographs of the fibers obtained in examples 1 and 2 and comparative examples 1 and 2, respectively, and it can be seen that the fibers obtained using the circular spinneret had no self-curled shape and poor elasticity, as directly confirmed by the test data in Table 1.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A method for preparing spiral nano material fiber by an electrostatic spinning method is characterized by comprising the following steps:

1) preparation of the spinning dope

Immersing the ground nano functional material in mixed acid of nitric acid and sulfuric acid, soaking for 1-2h at 0 ℃, cooling to-15 ℃, adding hydrogen peroxide, potassium permanganate and hypochlorous acid, reacting for 0.5-24h at-10-60 ℃, then performing centrifugal separation, washing a filter cake with deionized water until the pH of the washing liquid is 6-7, placing the filter cake in a vacuum drying oven, drying for 4-6h at 60-70 ℃, and drying the obtained powder containing NaBH₄And CaCl₂Soaking the solution for 8-10h, filtering, washing the filter cake with deionized water, drying in a drying oven at 60 ℃ for 6h to obtain a nano functional material containing hydroxyl and carboxyl, and dissolving the nano functional material in a solvent to prepare a spinning solution;

2) electrostatic spinning

Carrying out electrostatic spinning on the spinning solution obtained in the step 1), wherein the spinneret orifice of a spinneret is wedge-shaped, a high-voltage ionization coil is arranged right below the spinneret, and the obtained fibers are collected on a receiving device.

2. The method of claim 1, wherein in step 1), the nano-functional material is one of carbon nanotubes, graphene, multi-layered graphite micro-sheets, or chopped carbon fibers.

3. The method as claimed in claim 1, wherein in step 1), the molar ratio of hydrogen peroxide to potassium permanganate to hypochlorous acid is 1 (0.25-0.5) to (0.25-1).

4. The method of claim 1, wherein in step 1), the solvent is one of ethyl acetate, PMA, DMAc, DMF, butyl acetate, or DBE.

5. The method of claim 4, wherein the concentration of the dope obtained in step 1) is 20 to 50 wt%.

6. The method of claim 1, wherein in step 2), the spinneret and the high voltage ionizing coil are applied with a dc power supply at a voltage of 12-15 kV.