阅读说明：本技术 二氧化硅微球改性多尺度杂化碳纤维及其制备方法和应用 (Silica microsphere modified multi-scale hybrid carbon fiber and preparation method and application thereof ) 是由 徐海兵 祝颖丹 邢开 马芸芸 颜春 刘�东 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种二氧化硅微球改性多尺度杂化碳纤维及其制备方法和在制备复合材料中的应用,所述制备方法包括步骤：(1)对碳纤维表面进行氧化处理,得到表面氧化的碳纤维；(2)将六氯环三磷腈接枝到所述的表面氧化的碳纤维表面,得到六氯环三磷腈接枝改性的碳纤维；(3)将六氯环三磷腈与聚乙烯亚胺在六氯环三磷腈接枝改性的碳纤维表面进行原位聚合反应,得到表面带有正电荷的聚磷腈涂层改性碳纤维；(4)将带有正电荷的聚磷腈涂层改性碳纤维浸渍于纳米二氧化硅微球胶体溶液中,带负电荷的纳米二氧化硅微球通过静电吸附作用附着于聚磷腈涂层改性碳纤维表面,得到二氧化硅微球改性多尺度杂化碳纤维。(The invention discloses a silicon dioxide microsphere modified multi-scale hybrid carbon fiber, a preparation method thereof and application thereof in preparing composite materials, wherein the preparation method comprises the following steps: (1) carrying out oxidation treatment on the surface of the carbon fiber to obtain the carbon fiber with oxidized surface; (2) grafting hexachlorocyclotriphosphazene to the surface of the carbon fiber with the oxidized surface to obtain hexachlorocyclotriphosphazene graft modified carbon fiber; (3) in-situ polymerization reaction is carried out on hexachlorocyclotriphosphazene and polyethyleneimine on the surface of carbon fiber grafted and modified by hexachlorocyclotriphosphazene to obtain polyphosphazene coating modified carbon fiber with positive charges on the surface; (4) and (3) soaking the polyphosphazene coating modified carbon fiber with positive charges into a nano-silica microsphere colloidal solution, and attaching the nano-silica microspheres with negative charges to the surface of the polyphosphazene coating modified carbon fiber through electrostatic adsorption to obtain the silica microsphere modified multi-scale hybrid carbon fiber.)

1. A preparation method of silica microsphere modified multi-scale hybrid carbon fiber is characterized by comprising the following steps:

(1) carrying out oxidation treatment on the surface of the carbon fiber to obtain the carbon fiber with oxidized surface;

(2) grafting hexachlorocyclotriphosphazene to the surface of the carbon fiber with the oxidized surface to obtain hexachlorocyclotriphosphazene graft modified carbon fiber;

(3) in-situ polymerization reaction is carried out on hexachlorocyclotriphosphazene and polyethyleneimine on the surface of carbon fiber grafted and modified by hexachlorocyclotriphosphazene to obtain polyphosphazene coating modified carbon fiber with positive charges on the surface;

(4) and (3) soaking the polyphosphazene coating modified carbon fiber in a nano-silica microsphere colloidal solution, and attaching the nano-silica microsphere with negative charge to the surface of the polyphosphazene coating modified carbon fiber through electrostatic adsorption to obtain the silica microsphere modified multi-scale hybrid carbon fiber.

2. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 1, wherein the weight ratio of the surface oxidized carbon fiber to the hexachlorocyclotriphosphazene is 100: 25-250;

the molecular weight range of the polyethyleneimine is 600-70000 g/mol, and the weight ratio of the polyethyleneimine to the hexachlorocyclotriphosphazene is 100: 25-250.

3. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 1, wherein the specific steps of the step (2) comprise: putting hexachlorocyclotriphosphazene and the carbon fiber with oxidized surface into a solvent to form a mixed solution, adding an acid-binding agent into the mixed solution, and reacting to obtain the hexachlorocyclotriphosphazene graft modified carbon fiber.

4. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 3, wherein the molar ratio of hexachlorocyclotriphosphazene to acid-binding agent is 1: 1-10;

the acid-binding agent is selected from one or more of triethylamine, sodium hydroxide, potassium carbonate and sodium carbonate.

5. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 1 or 3, wherein the reaction in the step (2) is carried out for 1-24 hours under the conditions of constant-temperature stirring at 20-80 ℃ or water bath ultrasound.

6. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 3, wherein the specific steps of the step (3) comprise: and (3) adding polyethyleneimine into the mixed solution obtained after the reaction in the step (2), and introducing the polyphosphazene coating with positive charges and a flexible chain segment to the surface of the carbon fiber through in-situ polymerization of the polyethyleneimine and hexachlorocyclotriphosphazene on the surface of the carbon fiber to obtain the polyphosphazene coating modified carbon fiber with positive charges on the surface.

7. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 1 or 6, wherein the reaction in the step (3) is carried out for 1-24 hours under the conditions of constant-temperature stirring at 20-80 ℃ or water bath ultrasound.

8. The preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 1, wherein in the step (4), the solvent in the nano silica microsphere colloidal solution is at least one of water, ethanol, propanol and ethyl acetate, the mass percent of the nano silica microsphere is 0.01-10%, and the particle size of the nano silica microsphere is 1-1000 nm;

and the dipping time of the polyphosphazene coating modified carbon fiber in the nano silicon dioxide microsphere colloidal solution is 0.5-60 min.

9. The silica microsphere modified multi-scale hybrid carbon fiber prepared by the preparation method of the silica microsphere modified multi-scale hybrid carbon fiber according to any one of claims 1 to 8.

10. Use of the silica microsphere modified multi-scale hybrid carbon fiber according to claim 9 in the preparation of composite materials.

Technical Field

The invention relates to the technical field of carbon fiber surface modification, in particular to a silica microsphere modified multi-scale hybrid carbon fiber and a preparation method and application thereof.

Background

The carbon fiber reinforced resin-based advanced composite material has a series of advantages of light weight, high strength, strong designability, excellent fatigue resistance and the like. In addition, the carbon fiber reinforced resin-based advanced composite material has a series of excellent performances such as high specific strength, high specific modulus, strong designability and the like, and is widely applied to the fields of aerospace, transportation, sports and leisure.

The carbon fiber has poor matching with a resin matrix due to factors such as smooth surface, chemical inertness and the like, so that the interfacial property of the composite material is not ideal. The carbon fiber is usually subjected to surface treatment and then compounded with a resin matrix to obtain a composite material with excellent interface performance. At present, a plurality of methods are developed to carry out surface modification treatment on carbon fibers, and the interface performance of the carbon fiber reinforced resin matrix composite material is obviously improved.

However, it is often the case that the interlaminar toughness of the composite is reduced while the interfacial properties are greatly improved, and in practical applications, the interlaminar fracture toughness is critical to the overall mechanical properties of the composite.

In order to improve the interlayer toughness of the composite material, nano-fillers such as nanotubes and graphene are introduced to the surface of carbon fibers to construct a micro-nano multi-scale hybrid carbon fiber reinforced material, so that the interface phase of the carbon fiber composite material is strengthened and strengthened.

At present, nano reinforced particles such as nanotubes and graphene are grafted to the surface of carbon fibers through chemical grafting, the process is complicated, the reaction conditions are harsh, and the strength of the carbon fiber body is affected to a certain degree.

Therefore, there is still a need in the art to develop a simple and efficient method for surface modification of multi-scale hybrid carbon fibers, so as to improve the interfacial bond strength of the further prepared composite material and simultaneously improve the interfacial fracture toughness.

Disclosure of Invention

Aiming at the defects in the field, the invention provides a preparation method of a silica microsphere modified multi-scale hybrid carbon fiber, in particular to a modification method for modifying a carbon fiber surface interface through electrostatic adsorption after a polyphosphazene coating with positive charges and a flexible chain segment is subjected to in-situ polymerization.

A preparation method of silica microsphere modified multi-scale hybrid carbon fiber is characterized by comprising the following steps:

(1) carrying out oxidation treatment on the surface of the carbon fiber to obtain the carbon fiber with oxidized surface;

(2) grafting hexachlorocyclotriphosphazene to the surface of the carbon fiber with the oxidized surface to obtain hexachlorocyclotriphosphazene graft modified carbon fiber;

(3) in-situ polymerization reaction is carried out on hexachlorocyclotriphosphazene and polyethyleneimine on the surface of carbon fiber grafted and modified by hexachlorocyclotriphosphazene to obtain polyphosphazene coating modified carbon fiber with positive charges on the surface;

(4) and (3) soaking the polyphosphazene coating modified carbon fiber in a nano-silica microsphere colloidal solution, and attaching the nano-silica microsphere with negative charge to the surface of the polyphosphazene coating modified carbon fiber through electrostatic adsorption to obtain the silica microsphere modified multi-scale hybrid carbon fiber.

According to the invention, hexachlorocyclotriphosphazene and Polyethyleneimine (PEI) are used as comonomers, and a polyphosphazene coating with positive charges and a flexible chain segment is introduced to the surface of carbon fiber through simple in-situ copolymerization reaction, so that the positive charges on the surface of the carbon fiber are more firmly attached and more uniformly distributed, and the adsorption of nano silica microspheres through electrostatic adsorption is further facilitated, and the interface bonding strength and the fracture toughness of the subsequently prepared composite material are better enhanced and improved.

The molecular formula of the hexachlorocyclotriphosphazene is shown as the following formula (I):

the molecular formula of the polyethyleneimine is shown as the following formula (II):

in the step (1), preferably, the oxidation treatment is a mixing reaction of the carbon fiber and an oxidizing strong acid, or an anodic electrooxidation treatment.

Preferably, the weight ratio of the carbon fiber to the strong oxidizing acid is 1-20: 100.

The strong oxidizing acid may be selected from concentrated nitric acid, concentrated sulfuric acid, or a combination thereof.

The concentrated nitric acid is nitric acid with the mass concentration of more than or equal to 60 percent.

The concentrated sulfuric acid is sulfuric acid with the mass concentration of more than or equal to 98 percent.

Preferably, the strong oxidizing acid is a mixed acid prepared by mixing nitric acid with a mass concentration of 60% and sulfuric acid with a mass concentration of 98% in a volume ratio of 1: 4.

Preferably, the reaction temperature of the mixing reaction of the carbon fiber and the strong oxidizing acid is 50-150 ℃, and the reaction time is 1-4 hours.

Preferably, after the surface of the carbon fiber is subjected to oxidation treatment, the carbon fiber is washed to be neutral and dried to obtain the carbon fiber with the oxidized surface.

Preferably, the drying temperature is 50-100 ℃.

In the step (2), the weight ratio of the surface-oxidized carbon fibers to the hexachlorocyclotriphosphazene is 100: 25-250.

Preferably, the specific steps of step (2) include: putting hexachlorocyclotriphosphazene and the carbon fiber with oxidized surface into a solvent to form a mixed solution, adding an acid-binding agent into the mixed solution, and reacting to obtain the hexachlorocyclotriphosphazene graft modified carbon fiber.

Preferably, the molar ratio of the hexachlorocyclotriphosphazene to the acid-binding agent is 1: 1-10.

The solvent may be selected from: tetrahydrofuran, toluene, anhydrous acetonitrile, acetone, or combinations thereof.

The acid-binding agent can be one or more of triethylamine, sodium hydroxide, potassium carbonate and sodium carbonate.

Preferably, the reaction in the step (2) is carried out for 1-24 hours under the conditions of constant-temperature stirring at 20-80 ℃ or water bath ultrasound.

Preferably, the specific steps of step (3) include: and (3) adding polyethyleneimine into the mixed solution obtained after the reaction in the step (2), and introducing a polyphosphazene coating with positive charges and a flexible chain segment to the surface of the carbon fiber through in-situ polymerization of the polyethyleneimine and hexachlorocyclotriphosphazene on the surface of the carbon fiber to obtain the polyphosphazene coating modified carbon fiber.

Preferably, the weight ratio of the polyethyleneimine to the hexachlorocyclotriphosphazene is 100: 25-250.

Preferably, the reaction in the step (3) is carried out for 1-24 hours under the conditions of constant-temperature stirring at 20-80 ℃ or water bath ultrasound.

Preferably, the polyphosphazene coating modified carbon fiber obtained is washed by solvent or/and water in an ultrasonic mode and dried in vacuum.

Preferably, the temperature of the vacuum drying is 50-100 ℃.

Preferably, the molecular weight of the polyethyleneimine is 600-70000 g/mol.

Preferably, in the step (4), the solvent in the colloidal solution of the nano-silica microspheres is at least one of water, ethanol, propanol and ethyl acetate, the mass percentage of the nano-silica microspheres is 0.01-10%, and the particle size of the nano-silica microspheres is 1-1000 nm;

and the dipping time of the polyphosphazene coating modified carbon fiber in the nano silicon dioxide microsphere colloidal solution is 0.5-60 min.

Further preferably, the particle size of the nano silicon dioxide microspheres is 1-200 nm, so that electrostatic adsorption can be performed more favorably, and the mechanical property of the material can be improved.

Preferably, the obtained silica microsphere modified multi-scale hybrid carbon fiber is washed by a solvent or/and water and dried in vacuum.

Preferably, the temperature of the vacuum drying is 50-100 ℃.

The invention also provides the silica microsphere modified multi-scale hybrid carbon fiber prepared by the preparation method of the silica microsphere modified multi-scale hybrid carbon fiber.

The invention also provides application of the silica microsphere modified multi-scale hybrid carbon fiber in preparation of composite materials.

Preferably, the composite material is a carbon fiber reinforced resin matrix composite material.

Compared with the prior art, the invention has the main advantages that: according to the invention, the cyclic polyphosphazene coating with positive charges and a flexible chain segment is introduced to the surface of the carbon fiber through in-situ polymerization, so that on one hand, the modified carbon fiber with a large number of positive charges on the surface is obtained, the electrostatic adsorption capacity of the carbon fiber is increased, and on the other hand, a flexible macromolecule layer is introduced to the surface of the carbon fiber. Further, the nano silicon dioxide microspheres are attached to the surface of the carbon fiber through simple electrostatic adsorption, so that the micro-nano multi-scale hybrid modified carbon fiber with a rigid-flexible modified layer is constructed, and the interface bonding strength and the interface toughness of the carbon fiber reinforced resin matrix composite are improved.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) photograph of a polyphosphazene coating modified carbon fiber of example 1;

fig. 2 and 3 are SEM photographs of the silica microsphere-modified multi-scale hybrid carbon fiber of example 1.

Detailed Description

The invention is further described with reference to the following drawings and specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The following examples are conducted under conditions not specified, usually according to conventional conditions, or according to conditions recommended by the manufacturer.

Example 1

(1) Carbon fiber surface oxidation treatment: removing a sizing agent on the surface of a commercially available carbon fiber by using acetone, carrying out oxidation treatment for 2 hours by using concentrated nitric acid, washing by using deionized water, and carrying out vacuum drying to obtain a Carbon Fiber (CFO) with an oxidized surface;

(2) preparing phosphazene modified carbon fibers: adding 15g of Hexachlorocyclotriphosphazene (HCCP) into 2500mL of anhydrous acetonitrile, and stirring for dissolving; adding about 30g of a bundle of oxidized Carbon Fibers (CFO) into the HCCP/acetonitrile solution, dripping 100mL of triethylamine, and stirring at 50 ℃ for reaction for 2h to obtain the HCCP grafted carbon fibers CFO-HCCP.

(3) And (3) adding 26.5g of polyethyleneimine (1800g/mol) into the solution reacted in the step (2), stirring and dissolving, continuing to react for 6 hours, taking out the modified carbon fiber, and washing for 3 times by using anhydrous acetonitrile to obtain the polyphosphazene coating modified carbon fiber, wherein the morphology is shown in figure 1.

(4) And (3) soaking the polyphosphazene coating modified carbon fiber into a nano silica microsphere colloidal aqueous solution with the mass fraction of 1% and the particle size of about 25nm for 20 minutes, taking out, and washing with deionized water for 3 times to obtain the silica microsphere modified multi-scale hybrid carbon fiber, wherein the morphology is shown in fig. 2 and 3.

(5) The above process may be repeated in order to obtain more modified carbon fibers to make a composite laminate.

In this example, the oxidized carbon fiber of step (1), the polyphosphazene coating modified carbon fiber of step (3), and the silica microsphere modified multi-scale hybrid carbon fiber of step (4) are respectively mixed with the same epoxy resin to prepare a composite material according to the same method, and the corresponding interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and I-type interlaminar fracture toughness (GIC) are measured, and the results are shown in table 1.

TABLE 1

Example 2

(1) Carbon fiber surface oxidation treatment: removing a sizing agent on the surface of a commercially available carbon fiber by using acetone, carrying out oxidation treatment for 1h by using concentrated nitric acid, washing by using deionized water, and carrying out vacuum drying to obtain a Carbon Fiber (CFO) with an oxidized surface;

(2) preparing phosphazene modified carbon fibers: adding 10g of Hexachlorocyclotriphosphazene (HCCP) into 2000mL of anhydrous acetonitrile, and stirring for dissolving; adding about 20g of a bundle of oxidized Carbon Fibers (CFO) into the HCCP/acetonitrile solution, dripping 65mL of triethylamine, and stirring at 50 ℃ for reaction for 2h to obtain the HCCP grafted carbon fibers CFO-HCCP.

(3) And (3) adding 17.6g of polyethyleneimine (1800g/mol) into the solution obtained after the reaction in the step (2), stirring and dissolving, continuing to react for 5 hours, taking out the modified carbon fiber, and washing for 3 times by using anhydrous acetonitrile to obtain the polyphosphazene coating modified carbon fiber.

(4) And (3) soaking the polyphosphazene coating modified carbon fiber into a nano silica microsphere colloidal aqueous solution with the mass fraction of 3% and the particle size of about 50nm for 10 minutes, taking out, and washing for 3 times by using deionized water to obtain the silica microsphere modified multi-scale hybrid carbon fiber.

(5) The above process may be repeated in order to obtain more modified carbon fibers to make a composite laminate.

In this example, the oxidized carbon fiber of step (1), the polyphosphazene coating modified carbon fiber of step (3), and the silica microsphere modified multi-scale hybrid carbon fiber of step (4) are respectively mixed with the same epoxy resin to prepare a composite material according to the same method, and the corresponding interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and I-type interlaminar fracture toughness (GIC) are measured, and the results are shown in table 2.

TABLE 2

Example 3

(1) Carbon fiber surface oxidation treatment: removing a sizing agent on the surface of a commercially available carbon fiber by using acetone, carrying out oxidation treatment for 1h by using concentrated nitric acid, washing by using deionized water, and carrying out vacuum drying to obtain a Carbon Fiber (CFO) with an oxidized surface;

(2) preparing phosphazene modified carbon fibers: adding 15g of Hexachlorocyclotriphosphazene (HCCP) into 3000mL of anhydrous acetonitrile, and stirring for dissolving; adding about 20g of a bundle of oxidized Carbon Fibers (CFO) into the HCCP/acetonitrile solution, dripping 5mL of triethylamine, and stirring at 50 ℃ for reaction for 5 hours to obtain the HCCP grafted carbon fibers CFO-HCCP.

(3) And (3) adding 37.5g of polyethyleneimine (600g/mol) into the solution obtained after the reaction in the step (2), stirring and dissolving, continuing to react for 8 hours, taking out the modified carbon fiber, and washing for 3 times by using anhydrous acetonitrile to obtain the polyphosphazene coating modified carbon fiber.

(4) And (3) soaking the polyphosphazene coating modified carbon fiber into a nano silica microsphere colloidal aqueous solution with the mass fraction of 5% and the particle size of about 50nm for 10 minutes, taking out, and washing for 3 times by using deionized water to obtain the silica microsphere modified multi-scale hybrid carbon fiber.

(5) The above process may be repeated in order to obtain more modified carbon fibers to make a composite laminate.

In this example, the oxidized carbon fiber of step (1), the polyphosphazene coating modified carbon fiber of step (3), and the silica microsphere modified multi-scale hybrid carbon fiber of step (4) were respectively mixed with the same epoxy resin to prepare a composite material according to the same method, and the corresponding interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and I-type interlaminar fracture toughness (GIC) were measured, and the results are shown in table 3.

TABLE 3

Furthermore, it should be understood that various changes and modifications can be made by one skilled in the art after reading the above description of the present invention, and equivalents also fall within the scope of the invention as defined by the appended claims.