Effect of cooking and bleaching conditions on the properties of eucalyptus kraft fluff pulps

authors	Rebola, SM; Azevedo, CA; Evtuguin, DV
nationality	International
journal	CELLULOSE
author keywords	Bleaching; Eucalyptus globulus; Fluff pulp; Kraft pulping; Absorption capacity; Hornification; Network strength; Dry defibration
abstract	A series of Eucalyptus globulus kraft pulps was cooked under the same conditions (160 degrees C, 2 h) using different active alkali (AA) charges of 13%, 15%, 17% and 18%. All pulps were further oxygen delignified (100 degrees C, 1 h) and bleached using the elemental chlorine free (ECF) and the totally chlorine free (TCF) sequences. The obtained bleached pulps were dry-defibrated on a pilot scale hammermill at different intensities (rpm) and analysed for knot content, absorption capacity and air-laid fibre network strength. These fluff pulp parameters were related to the chemical composition of pulps, fibre morphology and the physical structure of the cellulose assessed by solid-state C-13 nuclear magnetic resonance spectroscopy (C-13 NMR). Being dry-defibrated, pulps cooked at an increased AA revealed a reduction of the knots and the ECF pulps showed better defibration ability than TCF pulps. It was concluded that absorption capacity of the fluff pulps is the result of multiple occurring factors, such as the knot content, fibre ' s hydrophilicity and morphology and the water retention capacity of the fibre web, whose contributions are not always unambiguous. This explains the non-evident dependence of the absorption capacity of fluff pulps on cooking and bleaching conditions. At the same time, the fibre network strength was sensitive to the conditions of pulping and bleaching and always increased with the increase in cooking AA. The network strength of TCF fluff pulps was 20-70% greater than that of ECF fluff pulps.
publisher	SPRINGER
issn	0969-0239
isbn	1572-882X
year published	2021
volume	28
issue	7
beginning page	4411
ending page	4426
digital object identifier (doi)	10.1007/s10570-021-03789-8
web of science category	16
subject category	Materials Science, Paper & Wood; Materials Science, Textiles; Polymer Science
unique article identifier	WOS:000626407400001