Chemical features of hardwood unbleached kraft pulps and their ECF bleachability
authors Daniel, AID; Evtuguin, DV; Silvestre, AJD; Neto, CP
nationality International
journal JOURNAL OF PULP AND PAPER SCIENCE
author keywords kraft pulps; unbleached pulps; Eucalyptus globulus; bleachability chlorine dioxide bleaching; chemical analysis; lignins
keywords EUCALYPTUS-GLOBULUS LIGNIN; HEXENURONIC ACID; RESIDUAL LIGNIN; CHLORINATED COMPOUNDS; DEGRADATION; CHEMISTRY; BEHAVIOR
abstract Eucalyptus globulus kraft pulps with kappa number 14 (uncorrected for hexenuronic acid (He-A)) were produced with variations in the main pulping parameters and bleached by a conventional DEDED bleaching sequence. Bleachability was affected strongly by the conditions used in pulping. The unbleached pulps were submitted to detailed chemical analysis. The content of residual lignin was shown to be the determining factor in the bleaching response. At constant kappa number, in general, bleachability increased with a decrease in the residual lignin/HexA content ratio in the unbleached pulps. Unsaturated extractives did not play a significant role in the bleaching response of pulp. No clear correlation could be established between bleachability and the content of beta-O-4 structures, phenolic OH groups, the ratio of guaiacyl/syringyl units or the degree of condensation of residual lignins in unbleached pulps. In the series of pulps investigated, the bleaching response was shown to be independent of the brightness of the unbleached pulp.
publisher PULP & PAPER TECHNICAL ASSOCIATION CANADA
issn 0826-6220
year published 2004
volume 30
issue 4
beginning page 94
ending page 98
web of science category Materials Science, Paper & Wood
subject category Materials Science
unique article identifier WOS:000221530800002

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