METHOD FOR INCREASING TENSILE STRENGTH OF FIBER COMPOSITS BY MEANS OF PRELIMINARY MODIFICATION OF CARBON FIBERS WITH CARBON NANOTUBES AND MOLECULES CONTAINING AMINO GROUPS Russian patent published in 2021 - IPC C09D201/00 B82B1/00 C01B32/174 D01F9/12 D01F11/10 B82Y30/00 B05D5/10 

FIELD: industrial chemistry.

SUBSTANCE: invention can be used in the manufacture of composite materials for aircraft parts. A dispersion of carbon nanotubes (CNTs) in n-methylpyrrolidone with a concentration of 20 to 250 μg / ml is applied by aerosol spraying in the form of individual microdrops forming a discontinuous uniform layer of CNT particles on the carbon fiber surface with simultaneous heating of its surface to 65-120 °C. Dispersion flow rate is not more than 0.05 ml / cm² per minute with aerosol spraying in a gas flow that is not less than 3 orders of magnitude greater than the liquid flow rate. For impregnation of carbon fibers, a solution of a hardener containing amino groups is prepared in benzyl alcohol with a hardener concentration of 60-800 μg / ml. The curing agent is selected from polyethylene polyamine, triethylenetetramine, diethylene triamine, tetraethylene pentamine, m-xylylenediamine, m-phenylenediamine, or a mixture thereof. To benzyl alcohol can be added a solvent selected from 2-propanol, ethanol or butanol or a mixture thereof, in a volume ratio to benzyl alcohol from 1:20 to 2: 3; or a solvent selected from ketones containing R1, R2, C1-C4 alkyl group as side groups, or mixtures thereof; or a solvent selected from acetates containing as a side group R3, C1-C4 alkyl group, ethylene glycol monoethyl acetate ether, ethylene glycol monomethyl acetate ether, in a volume ratio to benzyl alcohol from not less than 1:10 to 1: 2. Impregnation of carbon fiber with a hardener is carried out by dipping. Then, the surface of carbon fiber modified with CNTs and curing agent molecules is heat treated by heating to 45-85 °С, followed by washing the carbon fibers in a solvent selected from acetates or ketones, which helps to remove excess curing agent not associated with CNTs.

EFFECT: tensile strength of fibrous composites is increased due to the formation of a network associated with the carbon fiber surface, consisting of CNTs surrounded by molecules of a hardener that chemically interacts with binder molecules.

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