European hardwoods versus Eucalyptus globulus as a raw material for pulping |
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Authors: | R Patt O Kordsachia J Fehr |
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Institution: | (1) Chemical Technology of Wood, Leuschnerstr. 91, 21031 Hamburg, Germany |
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Abstract: | The importance of eucalypt as a raw material for pulping is steadily growing. Eucalyptus globulus was compared with European hardwood species using two alkaline pulping processes, kraft and alkaline sulfite, anthraquinone
pulping (ASA), which is a recently developed modified alkaline sulfite process. All cooks were performed to similar kappa
numbers. Poplar cooks resulted in the highest yields followed by eucalypt and birch which were on the same level. Yield of
beech pulps was definitely lower. ASA pulps show a moderate higher yield due to the less alkaline pH-profile of the cooking
liquor. This yield advantage was maintained and even enhanced after TCF-bleaching. The bleaching response of all pulps was
excellent. The birch pulps had the highest tensile strength followed by the poplar and beech pulps. Surprisingly eucalypt
pulps had the lowest tensile strength. But this was compensated by the very good tear index of eucalypt pulps. The runnability
factor, as an index for the overall strength potential, was on the same level for all pulps. Due to the higher hemicellulose
content of the ASA pulps their tensile strengths were higher, but tear strengths lower compared to the kraft pulps. The different
morphology of the hardwoods investigated resulted in different volumes and light scattering coefficients of the corresponding
pulps.
Dedicated to Prof. Dr. Dr. h. c. mult.Walter Liese on the occasion of his 80th birthday. |
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