阅读说明：本技术 一种提高沥青基石墨碳纤维表面活性的方法 (Method for improving surface activity of asphalt-based graphite carbon fiber ) 是由 姜海涛 李文泉 孙海成 迟伟东 周玉柱 于 2021-08-30 设计创作，主要内容包括：本发明公开一种提高沥青基石墨碳纤维表面活性的方法,在沥青基石墨碳纤维进行阳极氧化刻蚀之前或之后进行氧化增氧,得到表面活性高的沥青基石墨碳纤维,本申请通过氧化增氧提高沥青基石墨化碳纤维表面的氧含量,处理后氧含量增加在5.0％以上,外表面活性明显增强并且氧化增氧的表面处理方法,简单高效、易操作、对环境无污染、便于工业化应用。(The invention discloses a method for improving the surface activity of asphalt-based graphite carbon fibers, which is a surface treatment method for improving the surface oxygen content of asphalt-based graphite carbon fibers by oxidizing and oxygenating before or after anodic oxidation etching of the asphalt-based graphite carbon fibers to obtain the asphalt-based graphite carbon fibers with high surface activity, wherein the oxygen content of the surfaces of the asphalt-based graphite carbon fibers is improved by oxidizing and oxygenating, the oxygen content is increased by more than 5.0 percent after treatment, the surface activity is obviously enhanced, and the oxidizing and oxygenating method is simple, efficient, easy to operate, free of pollution to the environment and convenient for industrial application.)

1. A method for improving the surface activity of asphalt-based graphite carbon fibers is characterized in that the asphalt-based graphite carbon fibers with high surface activity are obtained by oxidizing and oxygenating at 400-600 ℃ for 60-300 s before or after anodic oxidation etching.

2. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 1, wherein the oxidation oxygenation adopts an oxidation atmosphere with a flow rate of 0.5L/min to 5.0L/min.

3. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 2, wherein the oxidizing atmosphere is oxygen, and the oxygen content is 20-50%.

4. The method for increasing the surface activity of the pitch-based graphite carbon fiber according to claim 1, wherein the oxidizing oxygen increasing is performed in an oxidizing furnace.

5. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 1, wherein the anodic oxidation etching is performed in a strong electrolyte at 30 to 60 ℃ by using the asphalt-based graphite carbon fiber as an anode and a graphite plate as a cathode.

6. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 5, wherein the strong electrolyte is a nitric acid aqueous solution with a mass concentration of 0.5-4.0%.

7. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 1, wherein the asphalt-based graphite carbon fiber is subjected to anodic oxidation etching for 60-180 s under the current intensity condition of 100-1000 mA.

8. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 1, wherein the asphalt-based graphite carbon fiber after anodic oxidation etching is dried at 100 ℃ to 130 ℃.

9. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 1, wherein the obtained asphalt-based graphite carbon fiber with high surface activity has a surface oxygen content of not less than 5.09%.

10. The method for improving the surface activity of the asphalt-based graphite carbon fiber according to claim 1, wherein the obtained asphalt-based graphite carbon fiber with high surface activity has an increase in interlaminar shear strength of not less than 6.49 MPa.

Technical Field

The invention belongs to the technical field of high polymer carbon fiber materials, and relates to a method for improving the surface activity of asphalt-based graphite carbon fibers.

Background

The carbon fiber is a high-performance fiber with low density, high specific modulus, excellent ablation resistance, high specific strength, excellent fatigue resistance, low thermal expansion coefficient and high temperature resistance. The composite material is widely applied to a plurality of fields such as aerospace, sports equipment, wind power manufacturing industry, automobile manufacturing industry and the like as a reinforcement of an advanced composite material. Compared with polyacrylonitrile carbon fiber, the mesophase pitch-based carbon fiber has higher modulus, higher thermal conductivity and smaller deformation, and has unique application scenes in subdivided fields, so that the mesophase pitch-based carbon fiber is a research hotspot in the field of carbon fiber, and the production process is unique, therefore, the production and application research of the mesophase pitch-based carbon fiber is urgent.

The carbon fiber is mainly used as a reinforcement of the composite material, and the interfacial adhesion performance of the composite material is directly influenced by the surface activity of the carbon fiber. After the carbon fiber is subjected to carbonization or graphitization heat treatment, particularly after the asphalt-based carbon fiber is subjected to graphitization treatment, a compact carbon sheet layer is formed on the surface, the number of active points is small (the surface carbon content is more than 98%), a certain amount of active functional groups need to be introduced to the surface of the graphite fiber through a surface treatment process, the inert surface activation is realized, and the bonding strength with a matrix is improved conveniently.

At present, the surface treatment method basically used in the carbon fiber industry is an electrochemical anodic oxidation method, the oxidation reaction is mild and easy to control, and the treatment effect is obvious. However, the anodic oxidation treatment is mainly a treatment method for polyacrylonitrile carbon fibers (which are not graphitized), the carbon content on the surfaces of the polyacrylonitrile carbon fibers is 90-95%, because the surface has certain activity and the effect of combining with anodic oxidation treatment is obvious, but because of the strong inertia of the surface of the asphalt-based graphitized carbon fiber, the carbon content is more than 99 percent, the surface activation points are less, when the dry tows enter the electrolytic bath, the dry tows cannot be quickly and uniformly wetted by the electrolyte, and the surfaces of the dry tows have extremely strong inertia, so that the electrochemical oxidation treatment is not ideal, after single anodic oxidation etching treatment, the introduction amount of functional groups on the surface is still small, so that the interface bonding performance of the carbon fiber and the sizing agent is poor, therefore, the activity of the carbon fiber surface treatment is improved, and the method has important significance for improving the composite performance of the asphalt-based graphite carbon fiber.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a method for improving the surface activity of the asphalt-based graphite carbon fiber, which improves the surface oxygen content of the asphalt-based graphite carbon fiber, greatly improves the surface activity, strengthens the bonding of an epoxy component in a sizing agent and improves the interlaminar shear strength of the asphalt-based graphite carbon fiber.

In order to achieve the purpose, the invention provides the following technical scheme: a method for improving the surface activity of asphalt-based graphite carbon fibers comprises oxidizing and oxygenating the asphalt-based graphite carbon fibers at 400-600 ℃ for 60-300 s before or after anodic oxidation etching is carried out on the asphalt-based graphite carbon fibers to obtain the asphalt-based graphite carbon fibers with high surface activity.

Furthermore, the oxidation oxygenation adopts an oxidation atmosphere with the flow of 0.5L/min to 5.0L/min.

Further, the oxidizing atmosphere is oxygen, and the content of the oxygen is 20% -50%.

Further, the oxidation oxygenation is carried out in an oxidation furnace.

Further, when anodic oxidation etching is carried out, the asphalt-based graphite carbon fiber is used as an anode, the graphite plate is used as a cathode, and the anodic oxidation etching is carried out in strong electrolyte at the temperature of 30-60 ℃.

Further, the strong electrolyte is a nitric acid aqueous solution with the mass concentration of 0.5% -4.0%.

Further, the asphalt-based graphite carbon fiber is subjected to anodic oxidation etching for 60-180 s under the current intensity condition of 100-1000 mA.

Further, the pitch-based graphite carbon fiber after anodic oxidation etching is dried at 100-130 ℃.

Further, the surface oxygen content of the obtained pitch-based graphite carbon fiber with high surface activity is not less than 5.09%.

Furthermore, the interlaminar shear strength increment of the obtained asphalt-based graphite carbon fiber with high surface activity is not less than 6.49 MPa.

Compared with the prior art, the invention has at least the following beneficial effects:

the invention provides a method for improving the surface activity of pitch-based graphitized carbon fibers, wherein the pitch-based graphitized carbon fibers are subjected to oxidation oxygenation treatment before or after oxidation etching, the oxygen content of the surfaces of the treated pitch-based graphitized carbon fibers is obviously improved, the oxygen content is increased by more than 5.09%, and the surface activity is enhanced;

due to the increase of the oxygen content on the surface of the pitch-based graphitized carbon fiber, the pitch-based graphitized carbon fiber and epoxy resin in a sizing agent system are subjected to chemical bonding to form a firmly-bonded surface layer and then are bonded with matrix resin, so that the bonding strength of a resin-based composite material is improved; the surface treatment method for oxygenation is simple, efficient, easy to operate, free of environmental pollution and convenient for industrial application.

Drawings

FIG. 1 is a flow chart of the treatment method of the present invention.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

As shown in fig. 1, a method for improving the surface activity of pitch-based graphite carbon fiber comprises the following steps:

the first step is as follows: preparation of anodic oxidation etched pitch-based graphite carbon fiber

The asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) is taken as an anode, a graphite plate is taken as a cathode, nitric acid aqueous solution with the mass concentration of 0.5-4.0% is taken as strong electrolyte to carry out electrochemical anodic oxidation, the applied current intensity is 100 mA-1000 mA, the temperature of the electrolyte is 30-60 ℃, the electrolytic treatment time is 60-180 s, and the asphalt-based graphite carbon fiber after anodic oxidation etching treatment is obtained by drying at 100-130 ℃.

Preferably, the asphalt-based graphite carbon fiber with the surface carbon content of more than or equal to 99 percent is adopted, is highly graphitized, and has excellent heat conductivity and high modulus.

The second step is that: oxidation oxygenation of anodically oxidized and etched pitch-based graphite carbon fibers

And placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, setting the oxidation temperature to be 400-600 ℃, the oxidation time to be 60-300 s, the oxygen content of the oxidation atmosphere to be 20-50% and the flow of the oxidation atmosphere to be 0.5-5.0L/min, and obtaining the pitch-based graphite carbon fiber subjected to oxygenation.

Preferably, the pitch-based graphite carbon fiber of the present invention is subjected to oxidation oxygenation treatment before anodic oxidation etching.

And thirdly, sizing and drying the pitch-based graphite carbon fiber after the oxidation oxygenation treatment to obtain the pitch-based graphite carbon fiber with high surface activity.

Example 1

Firstly, taking asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode, taking nitric acid aqueous solution with the mass concentration of 0.5% as electrolyte, carrying out electrochemical anodic oxidation, wherein the applied current intensity is 100mA, the electrolyte temperature is 30 ℃, the electrolytic treatment time is 60s, and drying at 130 ℃ to obtain the asphalt-based graphite carbon fiber after anodic oxidation etching treatment.

And then placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, setting the oxidation temperature at 600 ℃, the oxidation time at 60s, the oxygen content of the oxidation atmosphere at 20% and the flow of the oxidation atmosphere at 5.0L/min for treatment, and obtaining the pitch-based graphite carbon fiber subjected to surface treatment.

Analyzing the surface chemical components by adopting a Thermo VG ESCALAB250 type X photoelectron spectrometer; and (3) carrying out interlaminar shear strength test on the asphalt-based graphite carbon fiber after surface treatment, testing the interlaminar shear strength by adopting an INSTRON-1121 universal material testing machine according to an operation method of GB30969-2014 test methods for the shear strength of the short beam of the polymer-based composite material, and recording data.

Example 2

Firstly, taking asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode, taking nitric acid aqueous solution with the mass concentration of 0.5% as electrolyte, carrying out electrochemical anodic oxidation, wherein the applied current intensity is 1000mA, the electrolyte temperature is 60 ℃, the electrolytic treatment time is 180s, and drying at 100 ℃ to obtain the asphalt-based graphite carbon fiber after anodic oxidation etching treatment.

And then placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, setting the oxidation temperature to be 400 ℃, the oxidation time to be 300s, the oxygen content of the oxidation atmosphere to be 50 percent and the flow of the oxidation atmosphere to be 0.5L/min for treatment, and obtaining the pitch-based graphite carbon fiber subjected to surface treatment. The test method was the same as in example 1.

Example 3

Firstly, taking asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode, taking nitric acid aqueous solution with the mass concentration of 4.0% as electrolyte, carrying out electrochemical anodic oxidation, wherein the applied current intensity is 100mA, the electrolyte temperature is 30 ℃, the electrolytic treatment time is 60s, and drying at 130 ℃ to obtain the asphalt-based graphite carbon fiber after anodic oxidation etching treatment. And then placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, setting the oxidation temperature at 600 ℃, the oxidation time at 60s, the oxygen content of the oxidation atmosphere at 50% and the flow of the oxidation atmosphere at 5.0L/min for treatment, and obtaining the pitch-based graphite carbon fiber subjected to surface treatment. The test method was the same as in example 1.

Example 4

Firstly, taking asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode, taking nitric acid aqueous solution with the mass concentration of 4.0% as electrolyte, carrying out electrochemical anodic oxidation, wherein the applied current intensity is 1000mA, the electrolyte temperature is 60 ℃, the electrolytic treatment time is 180s, and drying at 100 ℃ to obtain the asphalt-based graphite carbon fiber after anodic oxidation etching treatment. And then placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, setting the oxidation temperature to be 400 ℃, the oxidation time to be 300s, the oxygen content of the oxidation atmosphere to be 20% and the flow of the oxidation atmosphere to be 0.5L/min for treatment, and obtaining the pitch-based graphite carbon fiber subjected to surface treatment. The test method was the same as in example 1.

Example 5

Firstly, taking asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode, taking nitric acid aqueous solution with the mass concentration of 2.0% as electrolyte, carrying out electrochemical anodic oxidation, wherein the applied current intensity is 500mA, the electrolyte temperature is 50 ℃, the electrolytic treatment time is 90s, and drying at 120 ℃ to obtain the asphalt-based graphite carbon fiber after anodic oxidation etching treatment. And then placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, and setting the oxidation temperature to be 500 ℃, the oxidation time to be 180s, the oxygen content of the oxidation atmosphere to be 35% and the flow of the oxidation atmosphere to be 2.5L/min for treatment to obtain the pitch-based graphite carbon fiber subjected to surface treatment. The test method was the same as in example 1.

Example 6

Firstly, taking asphalt-based graphite carbon fiber (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode, taking nitric acid aqueous solution with the mass concentration of 3.0% as electrolyte, carrying out electrochemical anodic oxidation, wherein the applied current intensity is 700mA, the electrolyte temperature is 50 ℃, the electrolytic treatment time is 120s, and drying at 110 ℃ to obtain the asphalt-based graphite carbon fiber after anodic oxidation etching treatment. And then placing the pitch-based graphite carbon fiber subjected to anodic oxidation etching in an oxidation furnace, and setting the oxidation temperature to be 550 ℃, the oxidation time to be 200s, the oxygen content of the oxidation atmosphere to be 30% and the flow of the oxidation atmosphere to be 3.5L/min for treatment to obtain the pitch-based graphite carbon fiber subjected to surface treatment. The test method was the same as in example 1.

Example 7

Firstly, putting asphalt-based graphite carbon fibers (the surface carbon content is more than or equal to 99%) into an oxidation furnace, and treating at the oxidation temperature of 500 ℃, the oxidation time of 180s, the oxygen content of the oxidation atmosphere of 35% and the flow of the oxidation atmosphere of 2.5L/min to obtain the asphalt-based graphite carbon fibers after oxygenation treatment. And (2) carrying out electrochemical anodic oxidation by taking the asphalt-based graphite carbon fiber subjected to oxygenation treatment as an anode, a graphite plate as a cathode and a nitric acid aqueous solution with the mass concentration of 2.0% as an electrolyte, wherein the applied current intensity is 500mA, the electrolyte temperature is 50 ℃, the electrolysis treatment time is 90s, and the asphalt-based graphite carbon fiber subjected to anodic oxidation etching treatment is obtained by drying at 120 ℃. The anodized etched pitch-based graphite carbon fiber was then tested as in example 1.

Example 8

Firstly, asphalt-based graphite carbon fibers (the surface carbon content is more than or equal to 99%) are placed in an oxidation furnace, the oxidation temperature is set to be 400 ℃, the oxidation time is set to be 300s, the oxygen content of the oxidation atmosphere is 50%, and the flow of the oxidation atmosphere is 0.5L/min for treatment, so that the asphalt-based graphite carbon fibers after oxygenation treatment are obtained. And (2) carrying out electrochemical anodic oxidation by taking the asphalt-based graphite carbon fiber subjected to oxygenation treatment as an anode, a graphite plate as a cathode and a nitric acid aqueous solution with the mass concentration of 1.0% as an electrolyte, wherein the applied current intensity is 1000mA, the electrolyte temperature is 30 ℃, the electrolysis treatment time is 120s, and the asphalt-based graphite carbon fiber subjected to anodic oxidation etching treatment is obtained by drying at 120 ℃. The anodized etched pitch-based graphite carbon fiber was then tested as in example 1.

Example 9

Firstly, putting asphalt-based graphite carbon fibers (the surface carbon content is more than or equal to 99%) into an oxidation furnace, and treating the asphalt-based graphite carbon fibers by setting the oxidation temperature to be 600 ℃, the oxidation time to be 60s, the oxygen content of the oxidation atmosphere to be 20% and the flow of the oxidation atmosphere to be 5L/min to obtain the asphalt-based graphite carbon fibers after oxygenation treatment. And (2) carrying out electrochemical anodic oxidation by taking the asphalt-based graphite carbon fiber subjected to oxygenation treatment as an anode, a graphite plate as a cathode and a nitric acid aqueous solution with the mass concentration of 4.0% as an electrolyte, wherein the applied current intensity is 100mA, the temperature of the electrolyte is 60 ℃, the electrolysis treatment time is 180s, and drying is carried out at 100 ℃ to obtain the asphalt-based graphite carbon fiber subjected to anodic oxidation etching treatment. The anodized etched pitch-based graphite carbon fiber was then tested as in example 1.

Comparative example 1

And (2) carrying out electrochemical anodic oxidation etching by taking asphalt-based graphite carbon fibers (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode and taking nitric acid aqueous solution with the mass concentration of 0.5% as electrolyte, wherein the applied current intensity is 100mA, the electrolyte temperature is 30 ℃, the electrolytic treatment time is 60s, and drying is carried out at 130 ℃ to obtain the asphalt-based graphite carbon fibers subjected to anodic oxidation etching treatment. The test method was the same as in example 1.

Comparative example 2

And (2) carrying out electrochemical anodic oxidation etching by taking asphalt-based graphite carbon fibers (the surface carbon content is more than or equal to 99%) as an anode, taking a graphite plate as a cathode and taking a nitric acid aqueous solution with the mass concentration of 4.0% as an electrolyte, wherein the applied current intensity is 1000mA, the electrolyte temperature is 60 ℃, the electrolytic treatment time is 180s, and drying is carried out at 100 ℃ to obtain the asphalt-based graphite carbon fibers subjected to anodic oxidation etching treatment. The test method was the same as in example 1.

Comparative example 3

An unsurfaced pitch-based graphitic carbon fiber. The test method was the same as in example 1.

The test data are shown in table 1:

TABLE 1 statistical table of element contents and interlaminar shear strengths

Through comparison between examples 1 to 9 and comparative examples 1 to 3, it can be found that, after anodic oxidation etching and oxidation oxygen increasing treatment, compared with the samples in comparative examples 1 and 2, the interlaminar shear strength of the pitch-based graphite carbon fiber of the present invention is significantly improved, the interlaminar shear strength increment is not less than 6.49MPa, and the oxygen content is not less than 5.09.

The same results as in examples 7-9 show that the same oxygen enrichment effect can be achieved by performing the pitch-based graphite carbon fiber oxidation oxygen enrichment treatment before anodic oxidation etching. The increase of the oxygen content is beneficial to generating more chemical bonding effects with epoxy resin in a sizing agent system, oxygen-containing groups (hydroxyl and carboxyl) can generate certain chemical bonding with an epoxy resin matrix, so that the increase of the hydroxyl and carboxyl contents is beneficial to improving the interface shear strength of carbon fibers and the epoxy resin matrix, a firmly combined surface layer is formed, the bonding strength of a resin matrix composite material is favorably improved, the higher the surface activity is, the higher the interlayer shear strength is, the interlayer shear strength is obviously improved compared with that without peroxide oxygen enrichment treatment, the maximum increase of the interlayer shear strength reaches 86.36 percent, the promotion effect on the performance improvement of the resin matrix composite material is greatly achieved, and the popularization and application of the asphalt-based graphite carbon fibers are facilitated.

The invention is not limited to the embodiments, and any equivalent changes to the technical solution of the invention by a person skilled in the art after reading the description of the invention are covered by the claims of the invention.