om the group consisting of 1 to 2 alkyl radicals of 1-3 carbons each, 1 to 2 alkoxy radicals of 1-2 carbons each, phenoxy and chloro; R is selected from the group consisting of alkyl of 1-5 carbon atoms and aryl; and m is an integer sufficient to provide an inherent viscosity of at least 0.1 as measured at 30 C. as an 0.5% by weight solution in sulfuric acid, to cyclize said polyurea into the corr