Abstract: Process for the purification of organic polyanhydrides to substantially-completely remove trace metals, such as for the production of metal-free electronic grade polymers. The process comprises decyclizing in an aqueous vehicle to form the polyacid, treating with an adsorption agent, crystallizing the polyacid, filtering and reconverting to the polyanhydride which is substantially free of trace metals. The purified polyanhydride can be reacted with other metal-free monomers to form metal-free polymers having excellent insulating properties for use in electrical components.

Abstract: A method of insolubilizing solvent soluble polyimides comprising the imidized condensation products of an aromatic dianhydride and a primary aromatic diamine wherein at least one of said dianhydride or diamine is selected from the group consisting of 2,2-hexafluoro-bis(3,4-dicarboxyphenyl)propane dianhydride; 2,2-hexafluoro-bis(3-aminophenyl) propane; 2,2-hexafluoro-bis(4-aminophenyl)propane; 2,2-hexafluoro-bis-[4-(3-aminophenoxy)phenyl]propane; 2,2-hexafluoro-bis[4-(4-aminophenoxy)phenyl]propane; 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane; 1,1-bis-[4-(1,2-dicarboxyphenyl)]-1-phenyl-2,2,2-trifluoroethane dianhydride and mixtures thereof.The method comprises forming a shaped article or film comprising the polyimides and subjecting same to a heat annealing process at a temperature of at least 325.degree. C. and for a period of time sufficient to insolubilize the polyimide. Preferred temperatures range from 350.degree. C. to 400.degree. C. for a period of time of at least 45 minutes to about 2 hours.