Interface modified carbon fiber/polypropylene composite material and preparation method thereof

[0115] Preparation of interface reinforced composites

[0116] The interface-reinforced and modified carbon fiber is prepared by the above method, and then the carbon fiber is fixed on the substrate and molded through a composite material molding process to obtain the composite material.

[0117] The molding process of the interface reinforced composite material of the present invention is not limited, and the available molding processes include (but are not limited to): resin film penetration molding process, autoclave molding process, and compression molding process. Preferably, the molding process of the present invention is a compression molding process.

[0118] In a preferred embodiment of the present invention, the steps of the composite material forming process are as follows:

[0119] A method for preparing a composite material with enhanced interface modification, including:

[0120] Use the method of the present invention to prepare surface-modified carbon fibers, and

[0121] Through a composite material molding process, the carbon fiber is fixed on the substrate and molded to obtain the interface enhanced and modified composite material.

[0122] In another preferred example, the molding process includes: placing 15% maleic anhydride grafted polypropylene film of the same size on the upper and lower layers of the arranged carbon fibers, placing it in a composite press, applying pressure and maintaining 5min to prepare unidirectional carbon fiber polypropylene composite material prepreg sheet; Lay 6-8 pieces of composite material prepreg sheet according to the [0°/90°] direction, and then send it to the composite material press again, apply pressure and hold In 15 minutes, a carbon fiber polypropylene composite board was prepared.

[0123] In another preferred embodiment, the volume content of fibers in the prepared material board is 40-50%.

[0124] In another preferred embodiment, the polypropylene used in the molding process is modified or unmodified polypropylene, preferably a blend containing 5-20% by weight of maleic anhydride grafted polypropylene modified Things.

[0125] In another preferred embodiment, the temperature during the molding process is maintained at 190-230°C.

[0126] In another preferred embodiment, the pressure during the molding process is controlled at 5-20 MPa.

[0127] In another preferred embodiment, the fiber and resin impregnation time in the molding process is 5-30 minutes.

[0128] The composite material prepared by the above-mentioned method can be used to prepare an interface reinforced and modified composite material product.

[0129] Compared with the prior art, the present invention first selects hexachlorocyclotriphosphazene to modify the surface of the carbon fiber, and then uses in-situ graft polymerization to graft a layer of polyphosphazene on the surface of the carbon fiber, by changing the molar ratio of the condensation monomer To control the chemical properties and structure of the carbon fiber surface in a wide range, obtain a series of amino-modified carbon fibers with different numbers and densities on the surface, and then chemically connect the graphene and the aminated carbon fibers. In the grafting reaction, a series of graphenes with different densities are grafted onto the surface of carbon fibers. Therefore, it can effectively increase the surface roughness and specific surface area of ​​the carbon fiber. At the same time, the amino groups on the carbon fiber surface and the carboxyl and amino groups on the graphene surface can form chemical bonds with the maleic anhydride in the polypropylene, which significantly increases the chemical bonding and mechanical engagement of the carbon fiber surface. It can improve the interface bonding strength of carbon fiber resin matrix composites, and finally obtain high-performance carbon fiber resin matrix composites.

[0131] Example 1

[0132] Step (1) Carbon fiber precursor (unsizing) oxidation treatment: Put 10 parts by weight of carbon fiber in 100 parts by weight of 60% nitric acid, and then reflux for 2 hours at a temperature of 60°C, then filter and wash with deionized water to The lotion is neutral and dried at a temperature of 80°C to obtain surface-oxidized carbon fibers;

[0133] Step (2) Prepare carbon fiber with hexachlorocyclotriphosphazene attached on the surface: put the acid binding agent and oxidized carbon fiber in anhydrous tetrahydrofuran according to a weight ratio of 40:100, and then dissolve 15 parts by weight of hexachlorotriphosphazene Slowly add the above reaction solution to the solvent, react at 30°C for 12 hours, take out the carbon fiber and wash it with the solvent several times, and dry it in a vacuum oven at a temperature of 60°C for use.

[0134] Step (3) Grafting polyphosphazene on the surface of carbon fiber: Put 100 parts by weight of the carbon fiber grafted with hexachlorocyclotriphosphazene into anhydrous acetonitrile, and then add 60 parts by weight of 4,4'-diamino Diphenyl ether and hexachlorotriphosphazene are added to the above reaction solution, wherein the molar ratio of 4,4'-diaminodiphenyl ether and hexachlorotriphosphazene is 4.0:1.0, and 120 parts by weight are added after dissolution The acid binding agent is reacted in a water bath ultrasonically for 6 hours, and the carbon fiber is taken out and washed with solvent and water repeatedly ultrasonically for many times, and dried in a vacuum oven at 60°C for use.

[0135] Step (4) Grafting graphene on the surface of carbon fiber: Put 100 parts by weight of the carbon fiber grafted with polyphosphazene on the surface into dry N,N-dimethylformamide (DMF), and add 2 parts by weight of graphene oxide , And add 4 parts by weight of condensing agent HATU, stir and react at 60°C for 12 hours, take out the carbon fiber, wash it repeatedly with solvent and water repeatedly ultrasonically, and dry it at 100°C for use.

[0136] Step (5) Preparation of carbon fiber resin-based composite material: fix the modified carbon fiber bundles in a unidirectional arrangement with a size of 300mm×300mm, and then place the 15% maleic anhydride grafted polypropylene film of the same size in the arrangement The upper and lower layers of carbon fiber are placed in a composite press with a preheating temperature of 200°C, and a pressure of 10MPa is applied for 5 minutes to prepare a unidirectional carbon fiber polypropylene composite prepreg. Finally, 8 composite prepregs are made according to [ It is laid in the direction of 0°/90°], and then sent to a composite material press preheated to 210°C, and a pressure of 15 MPa is applied for 15 minutes to prepare a carbon fiber polypropylene composite material board, in which the volume content of the fiber is 40%.

[0137] The interfacial shear strength (IFSS) of the modified carbon fiber polypropylene composite is 15.6MPa.

[0138] Example 2

[0139] Step (1) Carbon fiber precursor (unsizing) oxidation treatment: Put 10 parts by weight of carbon fiber in 100 parts by weight of 60% nitric acid, and then reflux for 2 hours at a temperature of 60°C, then filter and wash with deionized water to The lotion is neutral and dried at a temperature of 80°C to obtain surface-oxidized carbon fibers;

[0140] Step (2) Prepare carbon fiber with hexachlorocyclotriphosphazene attached on the surface: put the acid binding agent and oxidized carbon fiber in anhydrous tetrahydrofuran according to a weight ratio of 40:100, and then dissolve 15 parts by weight of hexachlorotriphosphazene Slowly add the above reaction solution to the solvent, react at 30°C for 12 hours, take out the carbon fiber and wash it with the solvent several times, and dry it in a vacuum oven at a temperature of 60°C for use.

[0141] Step (3) Grafting polyphosphazene on the surface of carbon fiber: Put 100 parts by weight of the carbon fiber grafted with hexachlorocyclotriphosphazene into anhydrous acetonitrile, and then add 60 parts by weight of 4,4'-diamino Diphenyl ether and hexachlorotriphosphazene are added to the above reaction solution, wherein the molar ratio of 4,4'-diaminodiphenyl ether and hexachlorotriphosphazene is 4.0:1.0, and 120 parts by weight are added after dissolution The acid binding agent is reacted in a water bath ultrasonically for 6 hours, and the carbon fiber is taken out and washed with solvent and water repeatedly ultrasonically for many times, and dried in a vacuum oven at 60°C for use.

[0142] Step (4) Grafting graphene on the surface of carbon fiber: Put 100 parts by weight of the carbon fiber grafted with polyphosphazene on the surface into dry N,N-dimethylformamide (DMF), and add 6 parts by weight of aminated graphite And add 12 parts by weight of condensing agent HATU, react at 60°C under constant temperature stirring or water bath ultrasonic for 24 hours, take out the carbon fiber, wash it repeatedly with solvent and water repeatedly ultrasonically, and dry at 100°C for use.

[0143] Step (5) Preparation of carbon fiber resin-based composite material: fix the modified carbon fiber bundles in a unidirectional arrangement with a size of 300mm×300mm, and then place the 15% maleic anhydride grafted polypropylene film of the same size in the arrangement The upper and lower layers of good carbon fiber are placed in a composite material press with a preheating temperature of 200℃, and a pressure of 10MPa is applied for 5 minutes to prepare a unidirectional carbon fiber polypropylene composite prepreg. Finally, 8 composite prepregs [0°/90°] direction, and then sent to a composite material press preheated at 210 ℃, applying a pressure of 15 MPa to maintain 15 min to prepare a carbon fiber polypropylene composite board, in which the volume content of the fiber is 50%.