WO2020082738A1 - Method employing aromatic fused ring molecule to modify assembly of carbon fiber surface, and method for preparing resin matrix composite material having carbon fiber reinforced interface - Google Patents

Abstract

The present invention pertains to the technical field of carbon fiber modification, and relates to a method employing an aromatic fused ring molecule to modify assembly of a carbon fiber surface. The method comprises the following steps: conducting an imidization reaction of an aromatic fused ring dihydric anhydride and a diamine to obtain an aromatic fused ring imide molecule assembly liquid; immersing carbon fibers in the aromatic fused ring imide molecule assembly liquid, such that the aromatic fused ring imide molecules adhere to the carbon fibers, so as to obtain carbon fibers having a modified surface assembly. The modification method of the present invention is adopted to improve the chemical activity on the surface of carbon fibers. The present invention further provides a method for preparing a resin matrix composite material having a carbon fiber reinforced interface: after the carbon fibers having the modified assembly surface are obtained, compounding and curing the carbon fibers having the modified surface assembly and a resin, to give a resin matrix composite material having an interface reinforced by a carbon fiber assembly modified with an aromatic fused ring molecule. The interface reinforced resin matrix composite material given by the preparation method has good interfacial bonding strength and interfacial shear strength.

Description

Method for assembling modified carbon fiber surface by aromatic fused ring molecules and preparation method of carbon fiber interface reinforced resin matrix composite material Technical field

The invention relates to the technical field of carbon fiber modification, in particular to a method for assembling a modified carbon fiber surface with aromatic fused ring molecules and a method for preparing a carbon fiber interface reinforced resin matrix composite material.

Background technique

Carbon fiber reinforced resin-based composite materials are widely used in fighter aircraft, large aircraft, space vehicles, satellites, etc. due to the advantages of designable performance, high specific strength and specific rigidity, good fatigue resistance, corrosion resistance, integral molding and multifunctional integration field. In order to meet the overall performance needs of composite materials in the design of aerospace materials, carrying out basic research on high-performance carbon fiber resin-based composite materials is currently a hot and difficult research in the world, and it is also a major national strategic need and has important theoretical research value. And the prospects for engineering applications.

The carbon fiber surface is a graphite-like structure formed by stacking flake graphite crystallites along the fiber axis. The surface roughness is low, the chemical inertness is large, and the adhesion to the resin matrix is poor, which limits the high performance of carbon fiber. At present, although the commercial sizing agent coated on the surface of the carbon fiber has the functions of bundling and lubricant, and improves the wettability with the resin matrix, the limited chemical bond between the sizing agent layer and the surface of the carbon fiber can easily lead to the destruction of the composite Cracks are prone to interface debonding along the fiber axis, so the increase in interface shear strength is limited.

Summary of the invention

The purpose of the present invention is to provide a method for assembling modified carbon fiber surface with aromatic condensed ring molecules to improve the surface roughness and chemical activity of carbon fiber, and then effectively improve the interfacial adhesion of carbon fiber and resin-based composite material when carbon fiber and resin are compounded Junction performance and interface shear strength.

In order to achieve the above object of the invention, the present invention provides the following technical solutions:

The invention provides a method for assembling modified carbon fiber surface with aromatic fused ring molecules, comprising the following steps: performing an imidization reaction of aromatic fused ring dianhydrides and diamines to obtain an aromatic fused ring imide molecular assembly liquid Immersing carbon fibers in the assembly liquid of aromatic fused ring imide molecules, the aromatic fused ring imide molecules are combined with carbon fibers to obtain surface-assembled modified carbon fibers.

Preferably, the molar ratio of the aromatic fused ring dianhydride to the diamine is 1: (1-2).

Preferably, the aromatic fused ring dianhydride is one of pyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and 3,4,9,10-perylenetetracarboxylic dianhydride ; The diamine is one of aliphatic diamine, aromatic diamine and alicyclic diamine.

Preferably, the temperature of the imidization reaction is 60-120 ° C, and the time is 12-24 hours.

Preferably, the imidization reaction is carried out under the action of a catalyst, and the catalyst is one or more of triethylamine, hydroxybenzoic acid, hydroxyphenol and quinoline.

Preferably, the mass of the catalyst is 0.1-0.2% of the mass of the aromatic fused ring dianhydride.

Preferably, the imidization reaction is carried out in a solvent system, and the solvent is one or more of N, N-dimethylformamide, toluene, methanol, acetonitrile and ether.

Preferably, the immersion time is 2-10 minutes.

Preferably, after the dipping, the carbon fiber after dipping is also dried.

The invention also provides a method for preparing a carbon fiber interface-reinforced resin-based composite material, comprising: after obtaining the surface-assembled modified carbon fiber by the method described in the above technical solution, compound-solidifying the surface-assembled modified carbon fiber and the resin, Obtained aromatic fused ring molecular assembly modified carbon fiber interface reinforced resin matrix composite material.

The invention provides a method for assembling modified carbon fiber surface with aromatic fused ring molecules, comprising the following steps: performing an imidization reaction of aromatic fused ring dianhydrides and diamines to obtain an aromatic fused ring imide molecular assembly liquid Immersing carbon fibers in the assembly liquid of aromatic fused ring imide molecules, the aromatic fused ring imide molecules are combined with carbon fibers to obtain surface-assembled modified carbon fibers. In the present invention, an aromatic fused ring dianhydride and a diamine are imidized to obtain an aromatic fused ring imide molecule assembly solution. The assembly solution uses π-π stacking between aromatic fused rings as the dominant force. The aromatic fused ring The hydrogen bond between the amine group on the imide molecule and the hydroxyl group on the surface of the carbon fiber is used as the driving force, and the carbon fiber is immersed in the assembly solution, so that the aromatic fused ring imide forms an amino-carboxyl covalent bond with the surface of the carbon fiber graphite structure And the π-π conjugation effect, forming an active nano-assembled layer structure on the surface of the carbon fiber, improving the roughness and chemical activity of the carbon fiber surface. The results of the examples show that the N / C and O / C ratios of the carbon fiber before modification are 0.04 and 0.34, respectively, the N / C ratio of the modified carbon fiber is increased to 0.11 to 0.13, and the O / C ratio is increased to 0.49 to 0.73. It shows that the chemical activity of carbon fiber surface is greatly improved.

The invention also provides a method for preparing a carbon fiber interface reinforced resin matrix composite material. After obtaining the surface-assembled modified carbon fiber in the present invention, the surface-assembled modified carbon fiber and the resin are compounded and cured to obtain an aromatic fused ring molecular assembly modified carbon fiber interface-reinforced resin-based composite material. The nanostructure of the active assembly layer on the surface of the carbon fiber of the present invention forms a nanometer intermediate phase with the resin matrix, improves the synergistic effect of physical engagement and chemical bonding between the carbon fiber and the resin matrix, and increases the interface bonding strength between the intermediate phase and the resin; At the same time, it can improve the interface failure mode of composite materials, control the propagation of interface cracks, induce crack bifurcation, increase the energy absorbed by interface failure, and ultimately increase the interface shear strength of composite materials. The results of the examples show that the interface shear strength of the composite material obtained by compounding unmodified commercial M40J carbon fiber and resin is 52.6 MPa, while the interface shear strength of the M40J carbon fiber reinforced resin composite material modified by the method of the present invention Achieving 80.80 MPa indicates that the aromatic fused ring molecular assembly modified carbon fiber interface-reinforced resin-based composite material prepared by the present invention has better interface adhesion performance and interface shear strength.

BRIEF DESCRIPTION

FIG. 1 is an SEM image of the carbon fiber after assembly modification in Example 1;

2 is an SEM image of the carbon fiber after modification by assembly in Example 2;

FIG. 3 is an SEM image of the carbon fiber after modification in Example 3;

4 is an SEM image of unmodified carbon fiber of the comparative example;

5 is the interface shear strength force-displacement curve of modified carbon fibers of Examples 1 to 3 and unmodified carbon fibers of Comparative Examples.

detailed description

The invention provides a method for assembling modified carbon fiber surface with aromatic fused ring molecules, comprising the following steps: performing an imidization reaction of aromatic fused ring dianhydrides and diamines to obtain an aromatic fused ring imide molecular assembly liquid Immersing carbon fibers in the assembly liquid of aromatic fused ring imide molecules, the aromatic fused ring imide molecules are combined with carbon fibers to obtain surface-assembled modified carbon fibers.

In the present invention, an aromatic fused ring dianhydride and a diamine are imidized to obtain an aromatic fused ring imide molecular assembly solution. In the present invention, the molar ratio of the aromatic fused ring dianhydride to the diamine is preferably 1: (1-2), and more preferably 1: (1.3-2). In the present invention, the aromatic fused ring dianhydride is preferably pyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride and 3,4,9,10-perylenetetracarboxylic dianhydride The diamine is preferably one of an aliphatic diamine, an aromatic diamine, and an alicyclic diamine, and more preferably an aliphatic diamine. In the present invention, there is no special requirement for the source of the aromatic fused ring dianhydride and diamine, and the aromatic fused ring dianhydride and diamine derived from sources familiar to those skilled in the art may be used. Specific examples include commercially available aromatic fused ring Dihydric anhydride and commercially available diamines.

In the present invention, the temperature of the imidization reaction is preferably 60 to 120 ° C, more preferably 70 to 110 ° C; the time of the imidization reaction is preferably 12 to 24h, further preferably 12 to 20h . The imidization reaction of the present invention is preferably carried out under the action of a catalyst. The catalyst is preferably one or more of triethylamine, hydroxybenzoic acid, hydroxyphenol and quinoline; the quality of the catalyst is preferably aromatic 0.1 to 0.2% of the mass of the fused ring dianhydride, more preferably 0.1 to 0.15%. The imidization reaction of the present invention is preferably carried out in a solvent system, and the solvent is preferably one or more of N, N-dimethylformamide, toluene, methanol, acetonitrile and ether. The present invention has no special requirements on the amount of the solvent, and it is sufficient to dissolve all the aromatic fused ring dianhydride and diamine. In the present invention, there is no special requirement on the source of the catalyst and the solvent, and it is sufficient to use a catalyst and a solvent whose source is well-known to those skilled in the art.

In the present invention, the aromatic fused ring dianhydride and the diamine are preferably dissolved in a solvent, and the amidation reaction is carried out under the action of a catalyst to obtain an aromatic fused ring imide molecular assembly solution. The present invention has no special requirements for the dissolution conditions, and it is sufficient to use room temperature dissolution. In the aromatic fused ring imide molecule assembly solution of the present invention, the mass of the aromatic fused ring imide molecule is preferably 1 to 3% of the mass of the solvent. The present invention controls the mass fraction of aromatic fused ring imide molecules by controlling the amount of solvent added.

After obtaining the aromatic fused ring imide molecule assembly solution, the present invention immerses the carbon fiber in the aromatic fused ring imide molecule assembly solution, and the aromatic fused ring imide molecule is combined with the carbon fiber to obtain a surface assembly modified carbon fiber.

In the present invention, the immersion time is preferably 2 to 10 minutes, and more preferably 5 to 10 minutes. The temperature of the immersion in the present invention is preferably normal temperature. In the present invention, there is no special requirement for the source of the carbon fiber, and it is sufficient to use unsized carbon fiber well known to those skilled in the art. In the impregnation process of the present invention, physical adsorption and molecular assembly occur on the surface of the carbon fiber. The aromatic fused ring imide and the carbon fiber are combined on the surface of the carbon fiber to form a molecular assembly layer, thereby completing the modification of the carbon fiber. The mass of the assembly layer of the present invention is preferably 1 to 2.5% of the mass of the carbon fiber, which does not include the mass of the assembly layer. In the present invention, by selecting different aromatic fused ring dianhydrides and diamines, an assembly layer with different morphologies is formed on the surface of the carbon fiber, especially the choice of diamine has a greater influence on the morphology of the assembly layer. Preferably, when the diamine is biphenyl diamine, the shape of the assembly layer is fibrous; when the diamine is ethylene diamine, the resulting assembly layer is in the form of a sheet. If mono-anhydrides and mono-amines or poly-anhydrides and poly-amines are used as raw materials, the purpose of the present invention to improve the chemical activity of the carbon fiber surface cannot be achieved because they cannot provide sufficient reactive groups or easily form high polymers.

After the impregnation, the present invention preferably further includes drying the impregnated carbon fiber. In the present invention, the drying is preferably normal temperature drying. The present invention has no special requirements on the drying time, and only needs to achieve the purpose of drying.

The invention also provides a method for preparing a carbon fiber interface-reinforced resin-based composite material, comprising: after obtaining the surface-assembled modified carbon fiber by the method described in the above technical solution, compound-solidifying the surface-assembled modified carbon fiber and the resin, Obtained aromatic fused ring molecular assembly modified carbon fiber interface reinforced resin matrix composite material. The present invention has no special requirements on the kind of the resin, preferably epoxy resin, more preferably one or more of glycidyl ether epoxy resin, glycidyl amine epoxy resin and glycidyl ester epoxy resin Species.

The present invention does not have special requirements for the compounding method in the compound curing, and a compounding method well known to those skilled in the art may be used. The present invention has no special requirements for curing conditions, and it is sufficient to use curing conditions well known to those skilled in the art. Specifically, high temperature curing can be used. In the present invention, the temperature of the high-temperature curing is preferably 150 to 200 ° C, and the time of the high-temperature curing is preferably 3 to 5 hours. The present invention has no special requirements on the mixing ratio of the modified carbon fiber and resin assembled by aromatic fused ring molecules in the composite material, and those skilled in the art can freely mix the ratio.

The method for assembling the modified carbon fiber surface of the aromatic fused ring molecules provided by the present invention and the preparation method of the modified carbon fiber reinforced resin matrix composite material provided by the aromatic fused ring molecules for the present invention will be described in detail below with reference to examples, but they cannot be understood as protecting the present invention Limitation of scope.

Example 1

(1) Under the catalytic action of triethylamine, pyromellitic dianhydride and biphenyldiamine are reacted at 90 ° C for 24h in a mixed solvent of N, N-dimethylformamide / ether to obtain aromatic thick Cyclimide molecular assembly liquid, in which the molar ratio of pyromellitic dianhydride to biphenyldiamine is 1: 1.1, the catalyst is 0.1% by weight of pyromellitic dianhydride, aromatic fused ring imide in the assembly liquid The mass fraction of molecules in the solvent is 1%;

(2) The unsized M55J carbon fiber was immersed in the assembly solution for 10 minutes, and dried to obtain the carbon fiber with the nano-fibrous assembly layer on the surface, wherein the surface assembly layer was 2.5 wt% of the carbon fiber mass.

(3) Preparation of interface-reinforced composite material: Glycidyl epoxy resin was added dropwise to M40J carbon fiber with surface assembly layer and cured at 150 ℃ for 5 hours to obtain interface-reinforced composite material.

Example 2

(1) Under the catalysis of hydroxybenzoic acid, in methanol / acetonitrile, 3,4,9,10-perylenetetracarboxylic dianhydride and octanediamine are reacted at 120 ℃ for 18h to obtain aromatic fused ring imide Molecular assembly liquid, in which the molar ratio of 3,4,9,10-perylenetetracarboxylic dianhydride to octanediamine is 1: 1.5, the aromatic fused ring imide molecule in the assembly liquid accounts for 2% of the mass fraction of the solvent, and the catalyst The mass is 3,4,9,10-perylenetetracarboxylic dianhydride 0.15% of the mass;

(2) Immerse the unsized T800 carbon fiber in the assembly solution for 5 minutes, and vacuum dry to obtain the carbon fiber with nano-spherical / sheet-like assembly layer on the surface, where the surface assembly layer is 1.8% by weight of the carbon fiber mass;

(3) Preparation of the interface-reinforced composite material: Glycidyl ether resin was added dropwise to the surface of the T800 carbon fiber containing the surface assembly layer and cured at 180 ° C for 3 hours to obtain an interface-reinforced composite material.

Example 3

(1) Under the catalytic action of hydroxyphenol, 1,4,5,8, -naphthalenetetracarboxylic dianhydride and ethylenediamine are reacted in N, N-dimethylformamide at 60 ℃ for 12h to obtain Aromatic fused ring imide molecule assembly liquid, in which the molar ratio of 1,4,5,8, -naphthalenetetracarboxylic dianhydride to ethylenediamine is 1: 2, and the aryl fused ring imide molecule accounts for the flux in the assembly liquid The mass fraction is 3%, the mass of the catalyst is 0.1% of the mass of 1,4,5,8, -naphthalenetetracarboxylic dianhydride;

(2) Immerse the unsized M40J carbon fiber in the assembly solution for 2 minutes, and vacuum dry to obtain the carbon fiber with the nano-sheet assembly layer on the surface, where the surface assembly layer is 1% by weight of the carbon fiber mass;

(3) Preparation of interface-reinforced composite material: Glycidylamine-type epoxy resin was added dropwise to M40J carbon fiber with surface assembly layer and cured at 200 ℃ for 2 hours to obtain interface-reinforced composite material.

Comparative example

The difference from Example 3 is that the unmodified commercial M40J carbon fiber is used to prepare the interface-reinforced resin matrix composite material, and the other conditions are completely the same as those in Example 3.

The modified carbon fibers of Examples 1 to 3 and the unmodified carbon fibers of Comparative Examples were observed with a scanning electron microscope, and the results are shown in FIGS. 1 to 4. Fig. 1 is an SEM image of carbon fibers after assembly modification in Example 1, Fig. 2 is an SEM image of carbon fibers after assembly modification in Example 2, and Fig. 3 is an SEM image of carbon fibers after assembly modification in Example 3 Fig. 4 is an SEM image of the unmodified carbon fiber of the comparative example. Figures 1 to 4 show that the surface of the unmodified carbon fiber is smooth (Figure 4), while the surface of the modified carbon fiber of Example 1 forms a fibrous assembly layer (Figure 1). A nanosphere-nanosheet composite assembly layer was formed on the surface of the carbon fiber (FIG. 2), and a nanosheet assembly layer was formed on the surface of the modified carbon fiber in Example 3.

The modified carbon fibers of Examples 1 to 3 and the unmodified carbon fibers of Comparative Examples were tested for interfacial shear strength. The test results are shown in FIG. 5. 5 is the interface shear strength force-displacement curve of modified carbon fibers of Examples 1 to 3 and unmodified carbon fibers of Comparative Examples. It can be seen from FIG. 5 that the carbon fiber modified by the method of the present invention has a higher interfacial shear strength.

The surface element content of the carbon fibers of Examples 1 to 3 and Comparative Examples was measured, and the measurement results are shown in Table 1.

Table 1 Carbon fiber surface element distribution table

sample	C (%)	N (%)	O (%)	N / C	O / C
Comparative example	72.34	2.94	24.73	0.04	0.34
Example 1	61.78	7.90	30.32	0.13	0.49
Example 2	53.75	6.31	39.94	0.12	0.74
Example 3	54.44	5.78	39.79	0.11	0.73

It can be seen from Table 1 that the N / C and O / C ratios of the carbon fiber before modification are 0.04 and 0.34, respectively, the N / C ratio of the modified carbon fiber is increased to 0.11 to 0.13, and the O / C ratio is increased to 0.49 to 0.73 It shows that the chemical activity of carbon fiber surface is greatly improved.

The interface-reinforced composite materials obtained in Examples 1 to 3 and the comparative examples were tested for interface shear strength according to the micro-debond test. The test results are shown in Table 2.

Table 2 Interfacial shear strength of carbon fiber interface reinforced composites of Examples 1 to 3 and Comparative Examples

A	Example 1	Example 2	Example 3	Comparative example
Interface shear strength MPa	76.7	96.72	80.80	52.6

It can be seen from Table 2 that the interface-reinforced composite material prepared by the method of the present invention has higher shear strength than the interface-reinforced composite material prepared by using ordinary unmodified carbon fiber, and shows that the carbon fiber interface-reinforced composite prepared by the method of the present invention The material has better interface bonding performance.

It can be seen from the above examples that the present invention provides a method for assembling modified carbon fiber surfaces with aromatic fused ring molecules. Using the method of the present invention to modify carbon fibers can significantly improve the surface activity and interface shear strength of carbon fibers. The invention also provides a method for preparing modified carbon fiber reinforced resin matrix composite material assembled by aromatic fused ring molecules. The carbon fiber interface reinforced composite material prepared by the invention has good interface bonding performance and interface shear strength.

The above is only a preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present invention, several improvements and retouches can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A method for assembling modified carbon fiber surface with aromatic fused ring molecules, comprising the following steps: imidization reaction of aromatic fused ring dianhydride and diamine to obtain aromatic fused ring imide molecular assembly liquid; impregnation of carbon fiber In the aromatic fused ring imide molecule assembly solution, the aromatic fused ring imide molecules are combined with carbon fibers to obtain surface assembled modified carbon fibers.
2. The method for assembling a modified carbon fiber surface with an aromatic fused ring molecule according to claim 1, wherein the molar ratio of the aromatic fused ring dianhydride to the diamine is 1: (1-2).
3. The method for assembling modified carbon fiber surface of aromatic fused ring molecules according to claim 2, wherein the aromatic fused ring dianhydride is pyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid One of dianhydride and 3,4,9,10-perylenetetracarboxylic dianhydride; the diamine is one of aliphatic diamine, aromatic diamine and alicyclic diamine.
4. The method for assembling a modified carbon fiber surface with aromatic fused ring molecules according to claim 1, wherein the temperature of the imidization reaction is 60 to 120 ° C and the time is 12 to 24h.
5. The method for assembling modified carbon fiber surface with aromatic fused ring molecules according to claim 4, characterized in that the imidization reaction is carried out under the action of a catalyst, and the catalyst is triethylamine, hydroxybenzoic acid, hydroxyphenol And one or more of quinoline.
6. The method for assembling a modified carbon fiber surface with aromatic fused ring molecules according to claim 5, wherein the mass of the catalyst is 0.1-0.2% of the mass of the aromatic fused ring dibasic anhydride.
7. The method for assembling modified carbon fiber surface with aromatic fused ring molecules according to claim 4, characterized in that the imidization reaction is carried out in a solvent system, and the solvent is N, N-dimethylformamide, One or more of toluene, methanol, acetonitrile and ether.
8. The method for assembling a modified carbon fiber surface with aromatic fused ring molecules according to claim 1, wherein the immersion time is 2 to 10 minutes.
9. The method for assembling a modified carbon fiber surface with aromatic fused ring molecules according to claim 8, wherein after the impregnation, the method further includes drying the impregnated carbon fiber.
10. A method for preparing a carbon fiber interface-reinforced resin-based composite material, comprising: after obtaining a surface-assembled modified carbon fiber using the method of claim 9, compounding and curing the surface-assembled modified carbon fiber and a resin to obtain aromatic fused ring molecules Assemble modified carbon fiber interface reinforced resin matrix composites.

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