For example, A may be a dialkyl or dicycloalkyl amine radical having the general formula ##STR13## or a cyclic amine having the general formula ##STR14## In these formulas, R1 is an alkyl, cycloalkyl or aralkyl having from 1 to about 20 carbon atoms, where both R1 groups may be the same or different, and R2 is an alkylene group having from about 6 to about 8 methylene groups.