Illustrative diamines are trimethylenediamine, tetramethylenediamine, pentamethylenediamine, octamethylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, m-phenylenediamine and m-xylylenediamine. [0052] The dicarboxylic acids may be represented by the formula HOOC???B???COOH [0053] wherein [0054] B is a divalent aliphatic or aromatic group containing at least 2 carbon atoms.