AN ESR AND TIME-RESOLVED CIDEP STUDY OF THE LIGHT-INDUCED YELLOWING PROCESSES OF TMP PAPER

Integral ESR and time-resolved CIDEP techniques applied to the study o f the light-induced yellowing of bleached and unbleached TMP samples p rovide some further insights into the nature and the mechanisms of the processes. The identity of the phenoxy and ketyl free radical interme diates involved in these processes is established and the primary trip let photochemical mechanisms of their formation are characterized. The radical scavenging mechanisms responsible for the inhibition of light -induced yellowing in the TMP system by ascorbic acid and triphenylmet hyl thiol are formulated.