. . . "A suitable stabilizer includes (1) an amino acid selected from (a) a monoamino carboxylic acid of the formula, H2N???R???COOH (I), (b) a monoamino dicarboxylic acid of the formula, H2N???R(COOH)2 (II) and (c) a diamino monocarboxylic acid of the formula (H2N)2???R COOH (III), where R is a straight or branched alkyl radical of from 1 to 22 carbon atoms, which can be mono or poly-substituted with mo" .