less than 35 u00b0 c with or without the use of a condensation catalyst such as triethyl amine and under anhydrous isothermal polymerization conditions this process tends to give rise to polymers having a higher molecular weight the intermediate polyamic acid reaction product may then be imidized by chemical or heat treatment as set forth above suitable solvents for use in the process include organic solvents whose functional groups do not react with the reactants to any appreciable extent in addition to being inert to the system and preferably being a solvent for the polyamide imide the organic solvent must be a solvent for at least one of the reactants preferably for all of the reactants the normally liquid organic solvents of the n n dialkylcarboxylamide class are useful as solvents in the process the preferred solvents are the lower molecular weight members of this class particularly n n dimethylformamide and n n dimethylacetamide other useful solvents are n n diethylformamide n n diethylacetamide n n dimethylmethoxyacetamide n methyl caprolactam and the like other solvents which ay be used include dimethylsulfoxide n methyl 2 pyrrolidone tetramethyl urea pyridine dimethylsulfone hexamethylphosphoramide tetramethylene sulfone formamide n methylformamide butyrolactone and phenols such as m cresol the solvents can be used alone or in combinations the polymers may be recovered from solution by precipitation in water or in an alcohol such as methanol and washed the degree of polymerization of the polyamide imides is subject to deliberate control the use of equimolar amounts of all reactants under the prescribed conditions provides polyamide imides or reasonably high molecular weight the use of the acid or amino reactants in large excess limits the extent of polymerization in addition to using an excess.