Abstract: A process for preparing a polyarylene sulfide which comprises reacting an alkali metal sulfide compound and a polyhalo-substituted aromatic compound in an organic polar solvent in the presence of(A) an alkali metal salt of a phenolic aromatic carboxylic acid of the formula:(HO).sub.m --Ar--(COOM).sub.nwherein Ar is a di- to tetravalent aromatic group having 6 to 24 carbon atoms; M is an alkali metal; and m and n are each 1 or 2,(B) an alkali metal hydroxide and/or an alkali metal alcoholate, and optionally,(C) an alkali metal salt of an inorganic acid.

Abstract: A polyamide acid composition for preparing a polyimide which is improved in the stability in a form of solution and can extend the pot life of the composition comprising a solution of a polyamide acid in an organic solvent, the polyamide acid being a precursor of the polyimide, and an N-substituted heterocyclic compound as a chemical treating agent which can lower a rate of conversion of the polyamide acid to the polyimide. The pot life can be extremely extended to give the composition an enough flowability for a long time without reducing the excellent properties such as a heat resistance of the obtained polyimide.

Abstract: A polyamide acid composition for preparing a polyimide which can extend the pot life of the composition comprising a solution of a polyamide acid in an organic solvent, the polyamide acid being a precursor of the polyimide, a dehydrating agent, a catalyst and a pot life extending agent which can lower a rate of conversion of the polyamide acid to the polyimide, and the process for preparing the polyimide from said polyamide acid composition. According to the present invention the pot life can be extremely extended to give the composition an enough flowability for a long time without reducing the excellent properties such as a heat resistance and an electric insulation of the obtained polyimide.