阅读说明：本技术 一种碳纤维表面聚合改性的方法 (Method for polymerization modification of carbon fiber surface ) 是由 敖玉辉 张孟杰 刘浏 尚垒 鄢飞 金琳 于 2019-11-20 设计创作，主要内容包括：本发明提供一种碳纤维表面聚合改性的方法,属于碳纤维改性方法技术领域。该方法包括：将碳纤维浸入pH为7～10的溶有多酚和多胺基分子的缓冲溶液中,在0～90℃下处理0.5～24h,表面形成共聚物层,洗涤、烘干后得到改性后的碳纤维。本发明所采用的多酚原料多来源于植物,同时采用一步溶液浸渍法且溶剂是水,反应条件温和、工艺简单、环保；本发明可直接用于碳纤维的处理,不需要强酸、电化学氧化等预处理,不损害纤维本身的强度；另外,通过在碳纤维表面引入大量的氨基、羟基等活性官能团,能有效提高纤维与树脂的浸润性,增加纤维与树脂之间的物理、化学相互作用,从而提高复合材料的性能。(The invention provides a method for polymerization modification of the surface of carbon fiber, belonging to the technical field of carbon fiber modification methods. The method comprises the following steps: immersing the carbon fiber into a buffer solution with pH of 7-10 and dissolved with polyphenol and polyamino molecules, treating for 0.5-24 h at 0-90 ℃, forming a copolymer layer on the surface, washing and drying to obtain the modified carbon fiber. The polyphenol raw materials adopted by the invention are mostly from plants, and meanwhile, a one-step solution impregnation method is adopted, and the solvent is water, so that the reaction condition is mild, the process is simple, and the environment is protected; the method can be directly used for treating the carbon fiber, does not need pretreatment such as strong acid, electrochemical oxidation and the like, and does not damage the strength of the fiber; in addition, a large number of active functional groups such as amino groups, hydroxyl groups and the like are introduced to the surface of the carbon fiber, so that the wettability of the fiber and resin can be effectively improved, and the physical and chemical interactions between the fiber and the resin are increased, so that the performance of the composite material is improved.)

1. A method for modifying the surface of carbon fiber by polymerization is characterized by comprising the following steps:

immersing the carbon fiber into a buffer solution with pH of 7-10 and dissolved with polyphenol and polyamino molecules, treating for 0.5-24 h at 0-90 ℃, forming a copolymer layer on the surface, washing and drying to obtain the modified carbon fiber.

2. The method for polymerization modification of the surface of carbon fiber according to claim 1, wherein the carbon fiber is polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, viscose-based carbon fiber or graphite fiber.

3. The method for modifying the surface polymerization of carbon fibers according to claim 1, wherein the pH is 8.5.

4. The method for polymerization modification of the surface of carbon fiber according to claim 1, wherein the polyphenol is a molecule containing catechol or pyrogallol structure: one or more of catechol, pyrogallol, 1,2, 4-benzenetriol, gallic acid, ellagic acid, tannic acid, catechin, epicatechin gallate, epigallocatechin gallate, quercetin, morin, naringenin, naringin or rutin.

5. The method for polymerization modification of the surface of carbon fiber according to claim 1, wherein the concentration of the polyphenol is 0.1mg/mL to 10 mg/mL.

6. The method for polymerization modification of the surface of carbon fiber according to claim 1, wherein the polyamine-based molecule is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, polyethylenepolyamine, polyethyleneimine, polyamidoamine, and chitosan.

7. The method for polymerization modification of the surface of carbon fiber according to claim 1, wherein the mass ratio of the polyamine-based molecule to the polyphenol is (0.1-10): 1.

8. the method for polymerization modification of the surface of carbon fiber according to claim 1, wherein the mass ratio of the polyamino molecules to the polyphenol is (0.3-2): 1.

9. the method for modifying the surface polymerization of carbon fiber according to claim 1, wherein the buffer solution is an aqueous solution of tris (hydroxymethyl) aminomethane.

10. The method for polymerizing and modifying the surface of carbon fiber according to claim 1, wherein the washing and drying are performed by washing with deionized water to neutrality and vacuum drying at 40-80 ℃ for 12-48 h.

Technical Field

The invention belongs to the technical field of carbon fiber modification methods, and particularly relates to a method for polymerization modification of the surface of carbon fiber.

Background

Carbon fibers have excellent specific strength and stiffness, low thermal expansion, high modulus, high abrasion resistance, corrosion resistance, and can withstand high temperature loads of up to 3000 ℃ in an inert atmosphere, making them advanced engineering materials suitable for use in the fields of aerospace, transportation, sensors, fuel cells, radar absorbing materials, wind turbine blades, electromagnetic interference shielding, and expensive sporting goods.

The properties of carbon fiber reinforced resin matrix composites are determined by the bulk properties of the fiber and matrix and the interfacial properties between the fiber and the matrix. The good interface phase promotes the stress transfer from the matrix to the reinforcing fibers. However, since the surface of the carbon fiber is chemically inert, amphiphobic and smooth, the impregnation with the resin matrix is poor and the firm interaction is difficult to form, so that the interface performance of the composite material is not ideal, and finally, the overall performance of the composite material cannot be expected, and the application of the carbon fiber composite material is greatly limited. Therefore, it is necessary to treat the surface of the carbon fiber to increase the roughness and activity of the surface of the carbon fiber, improve the wettability of the fiber and the resin, and increase the physical and chemical actions between the carbon fiber and the resin, thereby improving the interface bonding strength of the composite material.

The surface treatment methods of carbon fibers are various and mainly comprise chemical grafting (CN107142730A, CN106192366A, CN104195824A), electrochemical treatment (CN105484012A, CN106319933A), coating methods (CN103572591A, CN105113260A), plasma treatment (CN103437143A, CN101413210A), high-energy radiation, chemical vapor deposition and the like (CN1064095A, CN 105818476A). The methods can increase the surface polarity and the surface roughness of the carbon fiber to different degrees and improve the interface performance between the carbon fiber and resin. However, the above methods have obvious advantages and disadvantages, such as the chemical grafting method can effectively increase the number of active functional groups on the surface of the carbon fiber and increase the chemical action sites between the carbon fiber and the resin, but the method has complicated steps, needs special reagents or catalysts and has the damage to the strength of the fiber. Electrochemical treatment usually does not use complicated treatment steps, but consumes a large amount of electric energy, and has high pollution of electrolyte and difficult treatment. The coating method is simple to implement, can protect the fibers and prevent the fibers from branching and fluffing, but has weak enhancement on the mechanical property of the composite material. Although the treatment methods such as plasma and high-energy radiation have little pollution, the treatment methods have high requirements on equipment and high energy consumption.

Disclosure of Invention

The invention aims to provide a method for polymerization modification of the surface of carbon fiber, which improves the surface polarity, increases active groups and enhances the interface performance of a carbon fiber composite material on the premise of not damaging the strength of the carbon fiber.

The invention provides a carbon fiber surface polymerization modification method, which comprises the following steps:

immersing the carbon fiber into a buffer solution with pH of 7-10 and dissolved with polyphenol and polyamino molecules, treating for 0.5-24 h at 0-90 ℃, forming a copolymer layer on the surface, washing and drying to obtain the modified carbon fiber.

Preferably, the carbon fiber is polyacrylonitrile-based carbon fiber, pitch-based carbon fiber, viscose-based carbon fiber or graphite fiber.

Preferably, the pH is 8.5.

Preferably, the polyphenol is a molecule containing a catechol or pyrogallol structure: one or more of catechol, pyrogallol, 1,2, 4-benzenetriol, gallic acid, ellagic acid, tannic acid, catechin, epicatechin gallate, epigallocatechin gallate, quercetin, morin, naringenin, naringin or rutin.

Preferably, the concentration of the polyphenol is 0.1mg/mL to 10 mg/mL.

Preferably, the polyamino molecules are one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, polyethylene polyamine, polyethyleneimine, polyamidoamine or chitosan.

Preferably, the mass ratio of the polyamine-based molecules to the polyphenol is (0.1-10): 1.

preferably, the mass ratio of the polyamino molecules to the polyphenol is (0.3-2): 1.

preferably, the buffer solution is an aqueous tris solution.

Preferably, the washing and drying are carried out by washing with deionized water to neutrality and vacuum drying at 40-80 ℃ for 12-48 h.

Principle of the invention

The invention relates to a carbon fiber surface polymerization modification method, wherein molecules containing catechol and pyrogallol structures can be oxidized into quinone structures by oxygen in the air under the alkaline or heating condition, and then, Michael addition or Schiff base reaction is carried out on the quinone structures and amino groups in the polyamine group molecules to obtain a cross-linked polymer layer with good adhesion capability, and the polymer layer is adhered to the surface of carbon fibers. The polyamine-based molecules not only participate in the crosslinking reaction to generate a coating layer, but also introduce a large amount of active functional groups such as amino groups and the like into the surface of the carbon fiber, so that the wettability of the carbon fiber and the combination between the carbon fiber and resin are improved.

The invention has the advantages of

The invention relates to a carbon fiber surface polymerization modification method, which adopts a one-step solution impregnation method, uses polyphenol containing catechol and pyrogallol structures as a modifier, reacts with polyamine-based molecules under certain conditions, and coats the surfaces of carbon fibers to further modify the carbon fibers, compared with the prior art, the polyphenol raw materials adopted by the invention are mostly derived from plants, and simultaneously, the one-step solution impregnation method is adopted, and the solvent is water, so that the reaction conditions are mild, the process is simple, and the environment is protected; the method can be directly used for treating the carbon fiber, does not need pretreatment such as strong acid, electrochemical oxidation and the like, and does not damage the strength of the fiber; in addition, a large number of active functional groups such as amino, hydroxyl and the like are introduced to the surface of the carbon fiber, so that the wettability of the fiber and resin can be effectively improved, and the physical and chemical interactions between the fiber and the resin are increased, so that the performance of the composite material is improved, and experimental results show that: compared with untreated carbon fibers, the carbon fiber reinforcement composite material prepared by the invention is obviously improved, and the interlaminar shear strength is improved from 52.8MPa to 65.2-85.7 MPa.

Drawings

FIG. 1 is a scanning electron micrograph of untreated CF;

FIG. 2 is a scanning electron micrograph of a copolymerization modified CF of catechol and polyethyleneimine prepared in example 1 of the present invention;

FIG. 3 is an XPS survey of untreated carbon fibers;

FIG. 4 is a graph of the C1s peak separation in untreated carbon fiber XPS;

FIG. 5 is an XPS survey of a copolymerized modified CF of catechol and polyethyleneimine prepared according to example 1 of the present invention;

FIG. 6 is a chart of the C1s peak in XPS of the copolymerized modified CF of catechol and polyethyleneimine prepared in example 1 of the present invention;

FIG. 7 is a histogram of interlaminar shear.

Detailed Description

The invention provides a carbon fiber surface polymerization modification method, which comprises the following steps:

the method comprises the steps of firstly immersing carbon fibers into a buffer solution with pH of 7-10, preferably pH of 8.5 and dissolved with polyphenol and polyamine group molecules, treating at 0-90 ℃ for 0.5-24 h to form a copolymer layer on the surface, washing and drying to obtain the modified carbon fibers.

According to the present invention, the carbon fiber is preferably a polyacrylonitrile-based carbon fiber, a pitch-based carbon fiber, a viscose-based carbon fiber, or a graphite fiber.

According to the invention, the polyphenol is a molecule containing a catechol or pyrogallol structure, and preferably one or more of catechol, pyrogallol, 1,2, 4-benzenetriol, gallic acid, ellagic acid, tannic acid, catechin, epicatechin gallate, epigallocatechin gallate, quercetin, morin, naringenin, naringin and rutin. The concentration of the polyphenol is preferably 0.1-10 mg/mL, more preferably 0.5-5 mg/mL, the concentration of the polyphenol is strictly controlled, and when the concentration of the polyphenol is lower than 0.1mg/mL, a complete coating layer is difficult to form on the surface of the carbon fiber, and the interface combination is poor; when the concentration of polyphenol is more than 10mg/mL, the coating layer on the surface of the carbon fiber is too thick and uneven, and defects can be formed at the interface of the composite material to influence the stress transfer.

According to the invention, the polyamino molecules are preferably one or more of ethylenediamine, diethylenetriamine, triethylene tetramine, polyethylene polyamine, polyethyleneimine, polyamidoamine or chitosan, and more preferably polyethyleneimine, and the polyamino molecules have high amino content and good solubility.

According to the invention, the mass ratio of the polyamino molecules to the polyphenols is preferably (0.1-10): 1, more preferably (0.3 to 2): 1, the proportion relationship between the two is strictly controlled, because the mass ratio of the polyamine-based molecules and the polyphenol in the copolymerization reaction is less than 0.1: 1, a large amount of amino functional groups are consumed in the reaction, so that the number of the modified carbon fiber surface amino active functional groups is small, and the interface performance is influenced; the mass ratio of polyamine-based molecules to polyphenols is higher than 10: 1, this results in too rapid a reaction, too large a polymer size to form, agglomeration, and adhesion of the copolymer to the fibers, which ultimately affects the interfacial properties.

According to the invention, the buffer solution is an aqueous tris solution.

According to the invention, the washing and drying are preferably carried out by washing with deionized water to neutrality and vacuum drying at 40-80 ℃ for 12-48 h.

The patent is further illustrated below by means of specific examples and comparative examples. It should be noted that the raw materials mentioned in the examples are all commercially available.