Process for preparing dopes from which shaped articles of oxadiazole/N-alkylhydrazide copolymers are obtained

A process for preparing a dope comprising an acid and a copolymer consisting essentially of recurring units (I) of the formula ##STR7## and recurring units (II) of the formula ##STR8## wherein the mole ratio of units I to II is between 20:80 and 95:5, consisting of

• a. combining and mixing (i) a slurry of monomers consisting essentially of one or more dihydrazides in particulate form of the formula ##STR9## in one or more diesters in the liquid state of the formula ##STR10## wherein the mole ratio of dihydrazide to diester is between about 1:1 and about 2:1, and (ii) an acid selected from the group consisting of oleum, chlorosulfonic acid, polyphosphoric acid, and mixtures thereof, whereby a monomer solution is formed, and then
• b. maintaining said monomer solution for a period of time at a temperature sufficient to polymerize said monomers, thereby obtaining a dope comprising said fiber-forming copolymer in said acid,
• wherein Ar represents a divalent aromatic radical, R represents a C.sub.1 to C.sub.4 alkyl, and -X represents an anion present in said acid.