prov:value
| - It has been discovered that hindered piperazinone stabilizers, containing one or more functional groups of the formula of Structure I: ##STR1## where R1, R2, R3, and R4 may be the same or different lower alkyl group, for example lower alkyl of from 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tertiary-butyl, n-amyl, iso-amyl, hexyl and its isomers, and the
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