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Title
Influence of alkaline and alkaline/oxidation pretreatments of hornbeam wood on the properties of kraft pulp
Authors
Rastislav Solar Jarmila Geffertova Miroslav Mamon Anton Geffert and Bozena Kosikova
Received
December 10, 2008
Published
Volume 43 Issue 4-6 April-June
Keywords
hornbeam wood, pretreatment, kraft pulp, kappa, interactions, fibre distribution, mechanical strength, optical
Abstract
A series of comparable specimens of hornbeam wood were pretreated with diluted sodium hydroxide, sodium hydroxide and hydrogen peroxide, or peracetic acid sequences. Under identical conditions of kraft cooking, all pretreatments improved the digestibility of hornbeam wood. Pulps from pretreated wood differed much from that obtained from untreated wood. Pretreatments reduced the yield of the pulps, diminished their Kappa number noticeably, reduced the degree of polymerisation and increased extremely their brightness. One-step peroxide bleaching of pulps from pretreated wood gave a much higher brightness, compared to that of bleached pulp from sound wood. Bleached, unrefined pulps from sound and pretreated wood evidenced different fibre dimensions, as well as a different distribution according to length and width. Unexpected, however, was the higher consumption of energy for refining bleached pulps from pretreated wood. Pretreatments increased the rate of pulp interactions with water in the initial phase of wetting, but markedly reduced the final value of their swelling. Pretreatments also improved the breaking length and tear index of the sheets from bleached, refined pulps. From the viewpoint of improved pulp properties, the most efficient pretreatments were the sodium hydroxide/peracetic acid and sodium hydroxide/activated H O sequences. 2 2
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