Inhibition of Light-induced Yellowing of Bleached Mechanical Pulp with Extracts from Casuarinas Barks

摘要

Scavenging activities of the extracts from four kinds of Casuarinas barks to hydroxyl radicals were compared. The extracts from C. junghuhniana bark with the largest activity was used to inhibite light-induced yellowing of the bleached mechanical pulp. ISO brigthness of the sheet coated with the extract was reduced by 8.6%, compared to 19.2% of the blank sheet after light irratiation for 4 h. But the brightness of the sheets coated with and without the extract was almost the same after light irratiation for 24 h. The coating with CaCO3 and the ACH extract showed excellent inhibiting effects on the light-induced yellowing. The larger the scavenging activity of the extracts to hydroxyl radicals was, the better the inhibiting performance of the coating to the light-induced yellowing was.