Disclosure of Invention
The invention aims to provide a method for complexing and modifying the surface of carbon fiber, which can increase active groups, improve the surface polarity and enhance the interface performance of a carbon fiber resin composite material on the premise of not damaging the strength of the carbon fiber.
The technical scheme of the invention is as follows:
a carbon fiber surface complexing modification method preferably comprises the following steps:
soaking carbon fiber in buffer solution with pH value of 7-10 and dissolved with polyphenol, stirring at normal temperature for 12-48h, and repeatedly washing with deionized water for 2-10min to obtain product 1;
adding graphene oxide into a buffer solution with pH value of 7-10 and dissolved with polyphenol, stirring at normal temperature for 12-48h, and taking supernatant to obtain a solution 2;
and immersing the product 1 in a solution containing transition metal ions for 30-60min, then immersing the product in the solution 2 for 30-60min, and washing and drying to obtain the modified carbon fiber.
Preferably, the carbon fibers are large tow carbon fibers or small tow carbon fibers.
Preferably, the carbon fiber is one of polyacrylonitrile-based carbon fiber, pitch-based carbon fiber or graphite carbon fiber.
Preferably, the polyphenol is a molecule containing a catechol or pyrogallol structure.
Preferably, the polyphenol is one or more of catechol, pyrogallol, gallic acid, tannic acid, catechin, morin or rutin which are mixed in any proportion.
Preferably, the mass ratio of the carbon fibers to the graphene oxide is 1: 0.5-1.
Preferably, the buffer is a tris aqueous solution, and the concentration of the polyphenol in the buffer is 0.5mg/mL-10 mg/mL.
Preferably, the pH of the buffer in which the polyphenol is dissolved is 8.5.
Preferably, the transition metal ion is one of ferric ion, cobalt ion or nickel ion, and the concentration of the transition metal ion is 10mg/mL-50 mg/mL.
Preferably, the specific operation flow of washing and drying includes: washing the mixture to be neutral by using deionized water, and then drying the mixture in vacuum for 12 to 24 hours at the temperature of between 40 and 80 ℃.
The invention has the beneficial effects that:
1. the raw material o-phenyl polyphenol used in the invention has good adhesion capability in a plurality of matrixes, a stable five-membered ring complex is quickly formed by the complexation of the carbon fiber and the o-phenyl polyphenol coated on the surface of the graphene oxide and transition metal ions, the graphene oxide is grafted to the surface of the carbon fiber to modify the surface of the inert carbon fiber, and a large number of oxygen-containing groups can be introduced to the surface of the carbon fiber to improve the wettability and the associativity of resin and the surface of the carbon fiber, so that the interface strength between the carbon fiber and the resin matrix is improved, and the introduction of the graphene oxide also enhances the conductivity of the modified carbon fiber;
2. the method has the advantages of simple treatment process, short reaction time, environmental friendliness, no need of harsh conditions such as strong acid, strong alkali, high temperature and the like, and no damage to the strength of the fiber body.
Detailed Description
The following specific examples are further illustrative of the technical solutions of the present invention, but should not be construed as limiting the invention, and the raw materials in the practice process are all commercially available.
Example 1:
0.625g of small tow polyacrylonitrile-based carbon fiber is immersed in 500ml of trimethylolpropane aminomethane water solution with pH of 8.5 and 2.5g of tannic acid dissolved in the solution, the solution is stirred for 12 hours at normal temperature, and then the solution is repeatedly washed for 2 minutes by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of trihydroxymethyl aminomethane buffer aqueous solution with pH of 8.5 and dissolved with 2.5g of tannic acid, stirring at normal temperature for 12h, and taking supernatant to obtain solution 2;
and immersing the product 1 in 500ml of nickel ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.
Scanning electron microscope analysis is respectively carried out on the untreated carbon fiber and the modified carbon fiber, wherein fig. 1 is a scanning electron microscope picture of the untreated carbon fiber, fig. 2 is a scanning electron microscope picture of the modified carbon fiber, and a comparison shows that the surface of the modified carbon fiber is grafted with a uniform graphene oxide coating.
Fourier infrared spectrum analysis is respectively carried out on the untreated carbon fiber, the product 1 and the modified carbon fiber, the results respectively correspond to curves a, b and c in figure 3, and it can be seen that the untreated carbon fiber and the product 1 are all in the range of 3420cm-1A strong stretching vibration peak appears, which corresponds to-OH, 1203cm in the spectrogram of the product 1-1、761cm-1The positions respectively correspond to the stretching vibration of-OH in catechol/pyrogallol in tannic acid and the characteristic peak of TA, and 1726cm in a spectrogram of the modified carbon fiber-1、1226cm-1And 1100cm-1Respectively correspond to graphene oxideC ═ O stretching vibration peak, epoxy stretching vibration peak, and alkoxy stretching vibration peak on (d).
The X-ray photoelectron spectroscopy analysis is respectively carried out on the untreated carbon fiber and the modified carbon fiber to respectively obtain spectrograms shown in fig. 4 and fig. 5, and the comparison shows that in the spectrogram of the modified carbon fiber, a characteristic peak added with Ni2p can be observed at the position of 870eV of binding energy, and the characteristic peak of corresponding elements is changed due to the fact that the graphene oxide layer is deposited on the surface of the carbon fiber, and the C1s peak at the position of 290eV is relatively enhanced.
The peak separation of Ni2p to obtain FIG. 6 shows that the Ni2p peak is composed of Ni-O group with binding energy of about 861eV, which is derived from polyphenol-metal ion complex layer on the surface of carbon fiber, and Ni-OH group with binding energy of about 856eV, which is derived from polyphenol-metal ion complex layer on the surface of carbon fiber2+Hydrogen bonding by coordinated water molecules. Fig. 7 is a characteristic peak narrow spectrum of Ni2p, and it can be seen that a main peak appears at a binding energy of 855eV, which is consistent with that of a normal nickel ion spectrum. The above characterization results all confirm that the complex has been successfully deposited on the carbon fiber surface.
Uniformly mixing epoxy resin and 3, 3' -diethyl-4, 4-diaminodiphenylmethane in a mass ratio of 10:3, degassing, placing a unidirectional fiber fabric made of the modified carbon fiber prepared in the embodiment on a mold, covering a flow guide net, sealing the mold by using a vacuum bag, sucking resin glue into the fiber fabric by using a vacuum pump, and then curing the mold at 90 ℃ for 2h, 120 ℃ for 2h and 150 ℃ for 3h by using vacuum to obtain the carbon fiber epoxy resin composite material.
The prepared composite material is subjected to an interlaminar shear strength test to obtain a shear strength columnar comparison graph shown in figure 8, a and b respectively represent the untreated carbon fiber epoxy resin composite material and the modified carbon fiber epoxy resin composite material, the interlaminar shear strength value of the untreated carbon fiber epoxy resin composite material is only 46.21MPa, but the interlaminar shear strength value of the modified carbon fiber composite material is increased to 57.37MPa and is increased by 24.15%.
Example 2:
0.625g of small tow polyacrylonitrile-based carbon fiber is immersed in 500ml of trimethylolpropane aminomethane water solution with pH of 8.5 and 2.5g of tannic acid dissolved in the solution, the solution is stirred for 12 hours at normal temperature, and then the solution is repeatedly washed for 2 minutes by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of trimethylolpropane aminomethane buffer aqueous solution with pH of 8.5 and dissolved with 2.5g of catechol, stirring at normal temperature for 12h, and taking supernatant to obtain solution 2;
and immersing the product 1 in 500ml of ferric ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.
Example 3:
0.625g of small tow polyacrylonitrile-based carbon fiber is immersed in 500ml of trihydroxymethyl aminomethane water solution with pH of 7.5 and 2.5g of tannic acid dissolved in the water solution, stirred for 12 hours at normal temperature, and repeatedly washed for 2 minutes by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of 7.5 pH trihydroxymethyl aminomethane buffer aqueous solution dissolved with 2.5g of catechol, stirring at normal temperature for 12h, and taking supernatant to obtain solution 2;
and immersing the product 1 in 500ml of nickel ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.
Example 4:
0.625g of small tow polyacrylonitrile-based carbon fiber is immersed in 500ml of trihydroxymethyl aminomethane water solution with pH of 9.5 and dissolved with 2.5g of tannic acid, stirred for 12 hours at normal temperature, and repeatedly washed for 2 minutes by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of a trimethylolpropane aminomethane buffer aqueous solution with pH of 9.5 and dissolved with 2.5g of catechol, stirring at normal temperature for 12h, and taking supernatant to obtain a solution 2;
and immersing the product 1 in 500ml of nickel ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.
Example 5:
0.625g of small tow polyacrylonitrile-based carbon fiber is immersed in 500ml of trimethylolpropane buffer aqueous solution with pH of 8.5 and dissolved with 2.5g of catechin, stirred for 12 hours at normal temperature, and repeatedly washed for 2 minutes by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of trimethylolpropane water solution with pH of 8.5 and dissolved with 2.5g of catechin, stirring at normal temperature for 12 hours, and taking supernatant to obtain solution 2;
and immersing the product 1 in 500ml of nickel ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.
Example 6:
0.625g of small tow polyacrylonitrile-based carbon fiber is immersed in 500ml of trihydroxymethyl aminomethane buffer aqueous solution with pH of 8.5 and dissolved with 2.5g of gallic acid, stirred for 12h at normal temperature, and repeatedly washed for 2min by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of trimethylolpropane aminomethane aqueous solution with pH of 8.5 and dissolved with 2.5g of gallic acid, stirring at normal temperature for 12h, and taking supernatant to obtain solution 2;
and immersing the product 1 in 500ml of nickel ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.
Example 7:
0.625g of macrotow polyacrylonitrile-based carbon fiber is immersed in 500ml of trihydroxymethyl aminomethane buffer aqueous solution with pH of 8.5 and dissolved with 2.5g of tannic acid, stirred for 12h at normal temperature, and repeatedly washed for 2min by deionized water to obtain a product 1;
adding 0.625g of graphene oxide into 500ml of a trihydroxymethyl aminomethane aqueous solution with pH of 8.5 and 2.5g of tannic acid dissolved in the aqueous solution, stirring the mixture at normal temperature for 12 hours, and taking supernatant to obtain a solution 2;
and immersing the product 1 in 500ml of nickel ion solution for 40min, immersing in the solution 2 for 45min, washing to be neutral by deionized water, and then drying in vacuum at 50 ℃ for 24h to obtain the modified carbon fiber.