Abstract: Novel copolyamides having the recurring unit ##STR1## are disclosed wherein x, in 50 percent to 85 percent of the recurring units, is an integer from 6 to 10 inclusive, and, in 15 percent to 50 percent of the recurring units is 4, and Ar is an arylene radical. The copolyamides are characterized by ease of melt processing such as in molding, extruding, and injection molding, while at the same time possessing good physical properties, and being further characterized by their ease of conversion from the amorphous to the crystalline state which, in turn, gives rise to a high degree of versatility in their fabrication.

Abstract: Novel oligomeric poly N-carboxylic anhydrides having the following structure are disclosed. ##STR1## The unit Ar represents arylene and x represents an integer from 1 to 10 and y represents a number having an average value from 0 to 4. The polyanhydrides serve as useful storage stable intermediates for the production of polyamides to which they are easily converted by the elimination of carbon dioxide. A process for the preparation of the polyanhydrides from arylene diisocyanates and .alpha.,.omega.-alkylene dicarboxylic acids is disclosed. Processes for the conversion of the polyanhydrides to the corresponding polyamides are also disclosed.