Method of splicing reinforcement fiber
AssigneeHitco
InventorSidney W. Street
Life of this patent
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Abstract
Reinforcement fiber for fiber-reinforced resin composites such as graphite tows are spliced by applying a solution of a linear, soluble, high glass transition temperature polyimide having good thermal-oxidative stability to the broken ends of a fiber, placing the ends in contact and removing solvent. The preferred polyimide is an aromatic-cycloaliphatic diamine such as 5,(6)-amino-1-(4' amino phenyl)-1,3-trimethylindane (DAPI) imidized with a dianhydride such as PMDA or BTDA. The soluble polyimide can be preapplied to the fiber as a sizing. The splices are not apparent by visual inspection nor by instrumental scanning of cured composites indicating there is no blistering nor loss of strength.
Claims23
A method of splicing a reinforcement fiber for reinforcing a composite with a matrix resin comprising the steps of
- applying to the ends of two of said fibers a solution of linear polyimide having a glass transition temperature of at least 200.degree. C. dissolved in a fast evaporating solvent having a boiling point below 150.degree. F.;
- said polyimide being insoluble in the solvent utilized to dissolve said matrix resin, having high heat resistance and being compatible with said matrix resin;
- placing the coated ends in contact;
- drying the solution to remove said fast evaporating solvent in less than one minute to form a continuous splice of said polyimide joining said ends.
A fiber-reinforced resin matrix article comprising filamentary reinforcement fiber containing a splice formed by coating overlapped ends of the fiber with a linear, aromatic polyimide having a glass transition temperature of at least 200.degree. C., said polyimide being dried from solution in a fast evaporating solvent having a boiling point less than 100.degree. F., being insoluble in solvents for the matrix resin, having a high heat resistance and being compatible with said matrix resin.
Dependencies are inferred from the claim text.