CN114574977A

CN114574977A - Self-early-warning coaxial electrostatic spinning fiber and preparation method and application thereof

Info

Publication number: CN114574977A
Application number: CN202210170246.8A
Authority: CN
Inventors: 王巍; 曹琳; 秦绪德; 王通; 朴金明; 陈守刚
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2022-02-24
Filing date: 2022-02-24
Publication date: 2022-06-03

Abstract

The invention provides a preparation method and application of a self-warning coaxial electrostatic spinning fiber. The method comprises the following steps: respectively adding chitosan and polyvinyl alcohol into a solvent to dissolve to obtain two solutions; mixing the two solutions according to a certain proportion to obtain a shell solution, and preparing the thin film by using an indicator solution as a core solution and adopting a coaxial electrostatic spinning method. And loading the self-early-warning fiber into resin to obtain the self-repairing coating with the self-early-warning function. The invention can effectively improve the load stability and uniformity of the indicator in the coaxial fiber. Q235 steel is used as a research substrate, when a coating is damaged, the indicator in the coaxial fiber is released and combined with iron ions on the surface of metal to generate obvious color change, and the early warning function of damage is realized. Meanwhile, indicator molecules can form a dense film on the surface of steel to prevent corrosion of the substrate. The composite coating based on the self-warning coaxial fiber has the functions of indicating and repairing damage, and has great potential in the practical application of material protection.

Description

Self-early-warning coaxial electrostatic spinning fiber and preparation method and application thereof

Technical Field

The invention relates to the technical field of preparation of coaxial electrostatic spinning fibers, in particular to a self-warning coaxial electrostatic spinning fiber and a preparation method and application thereof, and belongs to the field of self-repairing anticorrosive coatings.

Background

In the marine environment, the corrosion problem of engineering materials becomes one of the technical bottlenecks which severely restrict the development of major marine engineering technology and equipment, and the failure problem of the corrosion problem seriously affects the reliability and the service life of the marine engineering equipment. Organic coatings are widely used to protect engineering equipment operating in various environments from corrosion. Such coatings can provide good protection over a period of time, but most fail prematurely due to corrosion, with serious consequences and high cost losses. Therefore, early detection of the occurrence of corrosion so that necessary maintenance activities can be planned is an important way that integrity can be maintained over a long period of time. Various instrumental techniques have been reported for detecting corrosion under coatings. These corrosion detection techniques are only effective when physically embedded in the coating system or located at/near the corrosion site, even requiring physical scanning of the coating surface, and another method of sensing corrosion is to convert passive organic coatings into active or smart coatings by adding certain chemicals to the coating formulation. However, man-made materials are susceptible to damage, particularly on a microscopic scale, which can severely compromise their overall performance, shorten their useful life and ultimately lead to catastrophic failure of the material. The detection of small damages inside the material is performed by special equipment, while the commonly used coatings themselves cannot report the presence of defects. Therefore, it is of great interest to develop smart coatings with the ability to automatically detect and repair damage.

The coaxial nanofiber prepared by the electrostatic spinning technology has the advantages of simple experimental process, stable appearance, uniform structure, high load rate and the like. Has great potential in loading indicators and repairing agents. When the coaxial fibers are scratched, the indicator loaded in the fibers can be released, and the corrosion early warning and repairing effects are achieved.

Therefore, the self-repairing anti-corrosion coating based on the electrostatic spinning material with simple process, high load and self-warning function is urgent.

Disclosure of Invention

The invention aims at overcoming the defects of the prior art, provides a self-warning coaxial electrostatic spinning fiber, a preparation method and application thereof, improves the mechanical property of a self-repairing coating, and has the functions of corrosion warning and protection.

The innovation points of the invention are mainly as follows:

1. the coaxial electrostatic spinning fiber is used as the nano container, and the indicator with corrosion early warning and protection repair functions is loaded, so that the material is uniformly dispersed in the organic resin, and the corrosion prevention effect is improved.

2. The coaxial electrostatic spinning fiber is used as the filler to form the composite coating, so that the damaged coating can be quickly indicated to play a warning role, the corrosion resistance of the coating is enhanced, and the service life of the composite coating is prolonged.

3. By introducing the coaxial electrostatic spinning fiber, the breaking strength of the coating is improved, and the mechanical property of the composite coating is improved.

4. The multifunctional nano-fiber is added into the alkyd resin coating, so that the anti-corrosion performance of the alkyd resin is improved.

The technical scheme adopted by the invention for solving the technical problems is as follows:

1. the invention provides a self-warning coaxial electrostatic spinning fiber, which comprises a coaxial shell structure component A, a coaxial core structure component B coated in the shell structure, and an organic resin component C:

wherein the coaxial shell component solution is prepared by mixing a polymer 1, a polymer 2, a solvent 1 and a solvent 2 according to the mass ratio of 0.2-1:0.5-5:9-15: 9-15;

wherein the coaxial core component solution is prepared by indicator and solvent according to the mass ratio of 1: 5-20;

and respectively injecting the shell component solution and the core component solution into two solution channels of a coaxial electrostatic spinning device, and carrying out electrostatic spinning preparation to obtain the self-early-warning electrostatic spinning fiber with the coaxial structure.

2. The invention also provides a preparation method of the self-warning coaxial electrostatic spinning fiber, which comprises the following concrete steps:

1) preparation of component A coaxial shell solution: the preparation method comprises the following steps of mixing a polymer 1, a polymer 2, a solvent 1 and a solvent 2 according to a mass ratio of 0.2-1:0.5-5:9-15:9-15, wherein the adding sequence of the medicines is as follows:

1.1) mixing the polymer 1 and the solvent 1, and stirring for 12-24 hours at the rotation speed of 200-8000rmp within the temperature range of 20-35 ℃;

1.2) mixing the polymer 2 with the solvent 2, and stirring for 14-36 hours at the rotating speed of 300-800rmp within the temperature range of 50-100 ℃;

1.3) mixing the two solutions according to the proportion of 6:1-4, and stirring for 2-10 hours at the temperature of 20-35 ℃;

2) preparing a component B coaxial core solution: weighing the indicator and the solvent according to the mass ratio of 1:5-20, and stirring for 2-10 hours at the rotating speed of 200-;

3) preparing coaxial electrostatic spinning fibers: fixing a receiver, installing a coaxial needle injector of the shell-core component solution, switching on a power supply, and carrying out electrostatic spinning preparation, specifically:

3.1) the capacity of the injector is used by 5-20mL, the positive voltage is set to be 20-30KV, the negative voltage is set to be-2-5 KV, the component A of the injection rate is 0.1-3mm/min, the component B is 0.01-1mm/min, the receiving rate is 50-150 r/min, and the receiving distance is 10-30 cm;

3.2) after spinning for 2-5 hours, a self-warning coaxial electrostatic spinning fiber mat can be obtained.

Optionally, the polymer is one of polyvinyl alcohol, chitosan, polyvinylpyrrolidone and methyl cellulose, or a mixture of the above polymers.

Optionally, the shell component solvent 1 is one of acetic acid, oxalic acid, lactic acid and dilute hydrochloric acid, or an aqueous solution mixture of the above solvents.

Optionally, the indicator is any one or more of phenanthroline, phenolphthalein, tannic acid and gallic acid.

The prepared electrostatic spinning material and the organic coating are mixed according to the thickness ratio of 1:1-20, coated on the surface of a metal matrix, and dried at room temperature for 72 hours to obtain the self-repairing anticorrosive coating which is applied to the field of matrix anticorrosion.

Optionally, the organic resin is any one of alkyd resin, epoxy resin, polyurethane paint and acrylic resin.

3. The invention also provides an application of the self-warning coaxial electrostatic spinning fiber, which is characterized in that the prepared coaxial electrostatic spinning fiber and organic resin are mixed and proportioned according to the thickness ratio of 1:1-10, coated on the surface of Q235 steel, and cured for 72-85 hours at room temperature to obtain the self-repairing anticorrosive coating with the self-warning function.

The base material to be protected is metal, can be steel material with wide application, and can also be other metal materials such as iron, copper, aluminum and the like.

Compared with the prior art, the self-warning coaxial electrostatic spinning fiber and the preparation method and the application thereof have the following beneficial effects:

1. the invention provides a preparation method of a self-warning coaxial electrostatic spinning fiber and a preparation method of a self-repairing coating. The prepared coaxial electrostatic spinning fiber is used as a container, and the indicator with the corrosion early warning function is uniformly loaded in the coaxial fiber core layer, so that the problems that the nano container is not uniformly dispersed in the coating and is easy to agglomerate are solved.

2. Experiments show that the self-warning coaxial electrostatic spinning material prepared by the invention is added into an organic coating to improve the breaking strength of the coating and improve the mechanical property of the composite coating.

3. The self-warning coaxial electrostatic spinning material can be added into organic coating, is designed and developed into a self-repairing coating with a self-warning function, can quickly indicate a damaged coating to play a warning role, can realize the visualization of the warning effect after the coating is damaged, and has a wide application prospect in future marine anticorrosion application.

Drawings

FIG. 1 is a scanning electron microscope photograph of a PVA-CS @ Phen coaxial electrospun fiber prepared in the first embodiment of the invention;

FIG. 2 is a projection electron microscope photograph of the PVA-CS @ Phen coaxial electrospun fiber prepared in the first embodiment of the invention;

FIG. 3 is a scanning electron micrograph of MC-CS @ Phen co-axial electrospinning prepared according to example two of the present invention;

FIG. 4 is a scanning electron micrograph of PVP-CS @ TA coaxial electrospinning prepared in example three of the present invention;

FIG. 5 is a scanning electron micrograph of PVA-CS @ TA coaxial electrospinning prepared according to example four of the present invention;

FIG. 6 is a stress-strain curve of a composite coating and a blank coating prepared in accordance with example five of the present invention;

FIG. 7 is an optical photograph of the composite coating prepared in the fifth example of the present invention and a blank coating before and after a salt spray experiment when the composite coating and the blank coating are damaged;

FIG. 8 is a stress-strain curve for a composite coating and a blank coating prepared in accordance with a sixth embodiment of the present invention;

FIG. 9 is a graph comparing electrochemical impedance spectra of a composite coating prepared according to example six of the present invention and a blank coating in a 3.5% NaCl solution.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a self-warning coaxial electrostatic spinning fiber, which comprises a coaxial shell structure component A, a coaxial core structure component B coated in the shell structure, and an organic resin component C:

wherein the coaxial core component solution is prepared by an indicator and a solvent according to the mass ratio of 1: 5-20;

The invention also provides a preparation method of the self-warning coaxial electrostatic spinning fiber, which comprises the following concrete steps:

1) the preparation of the component A coaxial shell solution comprises the following steps of mixing a polymer 1, a polymer 2, a solvent 1 and a solvent 2 according to the mass ratio of 0.2-1:0.5-5:9-15:9-15, wherein the adding sequence of the medicines is as follows:

1.1) mixing the polymer 1 and the solvent 1, and stirring at the rotating speed of 200-8000rmp within the temperature range of 20-35 ℃ for 12-24 hours;

Wherein the polymer in the step 1) is one of polyvinyl alcohol, chitosan, polyvinylpyrrolidone and methyl cellulose, or a mixture of the polymers.

Wherein the shell component solvent 1 in the step 1) is one of acetic acid, oxalic acid, lactic acid and dilute hydrochloric acid, or an aqueous solution mixture of the above solvents.

Wherein the indicator in the step 2) is any one or more of phenanthroline, phenolphthalein, tannic acid and gallic acid.

Wherein the organic resin is any one of alkyd resin, epoxy resin, polyurethane coating and acrylic resin.

Example one

The invention provides a self-warning coaxial electrostatic spinning fiber, which comprises an A component shell structure and a B component core structure loaded in the shell structure,

the method comprises the following specific steps:

1) preparing a component A coaxial shell solution: the polymer 1, the polymer 2, the solvent 1 and the solvent 2 are mixed according to the mass ratio of 0.3:1:15:10, and the adding sequence of the medicine is as follows:

1.1) 3g of Chitin (CS) was dissolved in 150mL of 2% aqueous acetic acid and magnetically stirred for 14 hours until uniformly dissolved;

1.2) dissolving 1g of polyvinyl alcohol (PVA) in 10mL of deionized water, heating in a water bath at 95 ℃, and magnetically stirring for 16 hours until complete dissolution;

1.3) mixing the two solutions according to the proportion of 6:4, and stirring for 3 hours at 25 ℃;

2) preparing a component B coaxial core solution: 1g of phenanthroline (Phen) is added into 10mL of deionized water, and the mixture is stirred for 5 hours at the temperature of 25 ℃ and the rotating speed of 500 rmp;

3) preparing electrostatic spinning: the coaxial needle injector of the shell-core component solution is installed, then a power supply is switched on, and electrostatic spinning preparation is carried out, specifically:

3.1) the capacity of the injector is 5mL, the positive voltage is 21KV, the negative voltage is-3 KV, the component A of the injection rate is 0.1mm/min, the component B of the injection rate is 0.03mm/min, the receiving rate is 100 r/min, and the receiving distance is 20 cm;

3.2) spinning for 3h, obtaining a PVA-CS @ Phen coaxial electrostatic spinning fiber mat sample.

The coaxial electrospun fiber obtained above is subjected to characterization test:

the scanning electron microscope photo of the PVA-CS @ Phen coaxial electrospun fiber is shown in figure 1, the coaxial fiber has a smooth surface and uniform appearance, and the average diameter is about 396 nm.

A projection electron micrograph of the PVA-CS @ Phen coaxial electrospun fiber is shown in FIG. 2 and is in an obvious coaxial structure, and TEM shows that the indicator is successfully loaded in the fiber.

Example two

the method comprises the following specific steps:

1) preparation of component A coaxial shell solution: the preparation method comprises the following steps of mixing a polymer 1, a polymer 2, a solvent 1 and a solvent 2 according to a mass ratio of 0.3:1:15:10, wherein the adding sequence of the medicine is as follows:

1.2) dissolving 1g of Methylcellulose (MC) in 10mL of deionized water, heating in a water bath at 80 ℃, and magnetically stirring for 16 hours until complete dissolution;

1.3) mixing the two solutions according to the ratio of 6:2, and stirring for 5 hours at 25 ℃;

3.1) the capacity of the injector is 5mL, the positive voltage is 25KV, the negative voltage is-3 KV, the component A of the injection rate is 0.1mm/min, the component B of the injection rate is 0.02mm/min, the receiving rate is 100 r/min, and the receiving distance is 20 cm;

3.2) after spinning for 3h, a MC-CS @ Phen coaxial electrospun fiber mat sample can be obtained.

the scanning electron microscope photo of the MC-CS @ Phen coaxial electrospun fiber is shown in figure 3, the coaxial fiber has smooth surface and uniform appearance, and the average diameter is about 420 nm.

EXAMPLE III

the method comprises the following specific steps:

1) preparation of component A coaxial shell solution: the preparation method comprises the following steps of mixing a polymer 1, a polymer 2, a solvent 1 and a solvent 2 according to a mass ratio of 0.2:1:15:10, wherein the adding sequence of the medicine is as follows:

1.1) 0.2g of Chitin (CS) was dissolved in 15mL of 2% aqueous acetic acid and magnetically stirred for 14 hours until uniformly dissolved;

1.2) dissolving 0.8g of polyvinyl alcohol (PVP) in 10mL of deionized water, heating in a water bath at 80 ℃, and magnetically stirring for 16 hours until complete dissolution;

2) preparing a component B coaxial core solution: 0.5g of Tannic Acid (TA) was added to 10mL of deionized water and stirred at 25 ℃ at 500rmp for 5 hours;

3.1) the capacity of the injector is 5mL, the positive voltage is 25KV, the negative voltage is-3 KV, the component A of the injection rate is 0.1mm/min, the component B of the injection rate is 0.05mm/min, the receiving rate is 100 r/min, and the receiving distance is 20 cm;

3.2) spinning for 3h to obtain a PVP-CS @ TA coaxial electrostatic spinning fiber mat sample.

the scanning electron micrograph of the PVP-CS @ TA coaxial electrostatic spinning fiber is shown in figure 4, the coaxial fiber has a smooth surface and uniform appearance, and the average diameter is about 330 nm.

Example four

the method comprises the following specific steps:

1.1) 0.3g of Chitin (CS) was dissolved in 15mL of 2% aqueous acetic acid and magnetically stirred for 14 hours until uniformly dissolved;

3.1) the capacity of the injector is 5mL, the positive voltage is 22KV, the negative voltage is-3 KV, the component A of the injection rate is 0.1mm/min, the component B of the injection rate is 0.04mm/min, the receiving rate is 100 r/min, and the receiving distance is 20 cm;

3.2) spinning for 3 hours to obtain a PVA-CS @ TA coaxial electrostatic spinning fiber mat sample.

And (3) performing characterization test on the coaxial electrospun fiber obtained by the step:

the scanning electron microscope photo of the PVA-CS @ TA coaxial electrostatic spinning fiber is shown in FIG. 5, the coaxial fiber has a smooth surface and uniform appearance, and the average diameter is about 280 nm.

EXAMPLE five

The invention provides a preparation method of a self-warning coaxial electrostatic spinning fiber and a self-repairing coating, which comprises a coaxial shell structure component A, a core structure component B loaded in the shell structure, and an organic resin component C;

the method comprises the following specific steps:

3.2) spinning for 3h, a PVA-CS @ Phen coaxial electrospun fiber mat sample can be obtained.

4) After the Q235 steel sheet is ground on sand paper, the steel sheet is coated with ethanol to prevent corrosion.

5) The prepared electrostatic spinning material and the organic resin C component epoxy resin are mixed according to the thickness ratio of 1:3 to prepare the composite coating, and the total thickness of the composite coating is about 120 mu m.

6) And coating the composite coating on the processed Q235 steel sheet, and drying at room temperature for 72 hours to prepare the self-repairing coating with the self-warning function.

And (3) carrying out performance test on the obtained composite coating:

the stress-strain curves of the prepared composite coating and the blank coating are compared as shown in fig. 6. Compared with the blank epoxy coating, the fracture strain of the composite coating is increased to 139%, and the fracture stress of the composite coating is 1.6MPa which is twice of that of the blank coating. The mechanical properties of the coating can be improved by adding a suitable amount of nanofibers to the epoxy coating.

And scratching the surfaces of the prepared composite coating and the prepared blank epoxy coating by using a scalpel to form a scratch with the width of 40 mu m, and performing a salt spray test. FIG. 7 is a graph of color change before and after salt spray for composite and blank coating failures. After the salt spray experiment is carried out on the damaged part of the composite coating, red particles appear at the scratched part, wherein the red particles are phenanthroline and Fe²⁺The color reaction occurred when the scratches were repaired by the red particles formed by the protective film of Phen under microscopic observation. While there was no color change in the blank coating where it was broken.

EXAMPLE six

the method comprises the following specific steps:

3.1) the capacity of the injector is 5mL, the positive voltage is 23KV, the negative voltage is-3 KV, the component A of the injection rate is 0.1mm/min, the component B of the injection rate is 0.03mm/min, the receiving rate is 100 r/min, and the receiving distance is 20 cm;

5) And mixing and proportioning the prepared electrostatic spinning material and the organic resin C component epoxy resin according to the thickness ratio of 1:1 to prepare the composite coating, wherein the total thickness of the composite coating is about 120 mu m.

And (3) carrying out performance test on the obtained composite coating:

the stress-strain curve of the prepared composite coating and the blank coating are shown in fig. 8. Compared with a blank epoxy coating, the fracture strain of the composite coating is increased to 143%, and the fracture stress of the composite coating is 2.5MPa, which is three times that of the blank coating. The addition of the nano-fiber can effectively improve the Young modulus of the coating, so that the coating is more resistant to external impact, and the service life of the coating is prolonged.

Electrochemical impedance analysis testing of electrodes modified with different coatings is shown in figure 9. As can be seen from the Nyquist plot of the blank coating versus the composite coating after scratching in fig. 9, both curves are semicircular above the solid axis. The capacitive reactance arcs in the figure are arranged in size: the blank coating is less than the composite coating. After the composite coating is damaged, the indicator flows out of the nano-fibers to form a complex with the metal substrate, and the water-insoluble reaction products fill the bottom of the crack to form a protective film, so that the service life of the coating is prolonged.

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

In addition to the technical features described in the specification, the technology is known to those skilled in the art.

Claims

1. The preparation method and the application of the self-early-warning coaxial electrostatic spinning fiber are characterized in that the self-early-warning coaxial electrostatic spinning fiber is prepared from the following raw materials: a coaxial shell component, a coaxial core component;

2. A preparation method and application of a self-warning coaxial electrostatic spinning fiber are characterized by comprising the following concrete implementation steps:

1) preparation of component A coaxial shell solution: the polymer 1, the polymer 2, the solvent 1 and the solvent 2 are mixed according to the mass ratio of 0.2-1:0.5-5:9-15:9-15, and the adding sequence of the medicine is as follows:

3. The preparation method and application of the self-warning coaxial electrospun fiber according to claim 2, wherein the polymer in the step 1) is one of polyvinyl alcohol, chitosan, polyvinylpyrrolidone and methyl cellulose, or a mixture of the above polymers.

4. The preparation method of the self-warning coaxial electrospun fiber according to claim 2 or 3, characterized in that the shell component solvent 1 in the step 1) is one of acetic acid, oxalic acid, lactic acid and dilute hydrochloric acid, or an aqueous solution mixture of the above solvents.

5. The preparation method of the self-warning coaxial electrospun fiber according to claim 2 or 3, characterized in that the indicator in step 2) is any one or more of phenanthroline, phenolphthalein, tannic acid and gallic acid.

6. The application of the self-warning coaxial electrostatic spinning fiber is characterized in that the coaxial electrostatic spinning fiber prepared in the claim 1 and organic resin are mixed and proportioned according to the thickness ratio of 1:1-10, coated on the surface of Q235 steel, and cured for 72-85 hours at room temperature, so that the self-repairing anticorrosive coating with the self-warning function is obtained.

7. The application of the self-warning coaxial electrospun fiber according to claim 6, wherein the organic coating is any one of alkyd resin, epoxy resin, polyurethane coating and acrylic resin.