The Boeing Company

Jay O Rakel

Stephen Christensen

Donald J Ayers

A method is disclosed for forming poly(amide-imide) prepregs that permits forming void-free composites having residual solvent contents of less than 0.2% by weight. Such composite have improved glass transition temperatures near those of the pure polymer. In a preferred method, a poly(amide-imide) prepreg containing a residual N-methyl-2-pyrrolidone solvent is rapidly heated to about 650.degree. F. to evaporate residual solvent to less than 1.0% by weight. The prepreg is rapidly cooled before the thermoplastic poly(amide-imide) polymer begins to significantly advance in molecular weight. The prepreg may then be layed up to form composite articles that are consolidatable by application of further heat and pressure.

Poly(amide-imide) prepreg and composite processing

A method of consolidating fiber reinforced thermoplastic poly(amide-imide) components is disclosed that is suitable for use in fabricating large parts such as aircraft wing skins and the like. The method includes enclosing the part in a vacuum bag and placing the part in the bag in an autoclave. The method includes elevating the temperatures of the part to that where volatile solvent is substantially evaporated. Temperature of the part is then further increased until resin viscosity is reduced to a minimum. A pressure differential on the order of at least 150 psig is then applied at a high rate acting upon the article, causing the resin to flow to consolidate the part, resulting in a void-free composite.

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Warrenville, IL, United States of America

Jay O Rakel