Papers by Göran Gellerstedt
Acta Chemica Scandinavica, 1975
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… -International Journal of the …, 1984
... 151 Holzforschung 38(1984)151-158 Structural Changes in Lignin During Kraft Pulping1 By Göran... more ... 151 Holzforschung 38(1984)151-158 Structural Changes in Lignin During Kraft Pulping1 By Göran Gellerstedt and Eva-Lisa Lindfors Swedish Forest Products Research Laboratory, Box 5604, S-114 86 Stockholm, Sweden ... PURIFIED KRAFT PULP ball milling BLACK LIQUOR ...
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ACS Symposium Series, 1993
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Acta Chemica Scandinavica, 1977
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Acta Chemica Scandinavica
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The present document relates to a thermally reactive thermoplastic intermediate product. More par... more The present document relates to a thermally reactive thermoplastic intermediate product. More particularly, the present disclosure relates to an intermediate product made from a composition containing a purified or optionally unpurified softwood lignin and at least a first additive. The present document further relates to a method for providing the intermediate and uses of the intermediate.
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Residual lignins have been isolated by acid hydrolysis from untreated, oxygen delignified, chlori... more Residual lignins have been isolated by acid hydrolysis from untreated, oxygen delignified, chlorine dioxide prebleached and ozone prebleached softwood kraft pulps and from a softwood magnesium bisulphite pulp (Picea abies and Pinus sylvestris). The residual lignins have been analysed for free phenolic hydroxyl groups, carboxylic/sulphonic acid groups, ß-aryl ether content, methoxyl groups and elemental composition. Results are discussed in comparison with data from the literature. INTRODUCTION Since lignin cannot be analysed in situ, it must be isolated from the wood/pulp. Either, lignin can be iso-lated by dissolution or destruction of carbohydrates leaving a lignin residue, or the lignin can be dissoluted in a more or less unchanged form or as a derivate. Björkman [1] developed a widely used separation method based on extraction of lignin from milled wood with a neutral solvent, a dioxane/water mixture. The isolated lignin is referred to as milled wood lignin (MWL) or Björkman lig...
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Acta Chemica Scandinavica, 1994
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Acta Chemica Scandinavica, 1980
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ACS Symposium Series, 2001
ABSTRACT A variety of analytical methods, applied on pulp and isolated lignin samples, has been u... more ABSTRACT A variety of analytical methods, applied on pulp and isolated lignin samples, has been used to obtain information about the chemical changes that take place in an oxygen and a hydrogen peroxide stage respectively. Modern 2-D NMR techniques, in particular, have proven to be of particular importance. The major portion of an oxygen delignification stage is a reinforced extraction of a lignin which resembles structurally the lignin being dissolved in the last part of the cook. In hydrogen peroxide bleaching, a limited oxidation of chromophoric structures is accompanied by a delignification reaction starting from intact phenolic phenylpropane units of the benzyl alcohol type. The degree of delignification and bleaching in a P-stage seems to be dependant on the amount of remaining β-O-4 structures in lignin after the cook.
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Acta Chemica Scandinavica, 1972
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Acta Chemica Scandinavica, 1968
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Acta Chemica Scandinavica, 1968
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Journal of Pulp and Paper Science
Kappa number is now practically applied to determine lignin content not only in pulping but also ... more Kappa number is now practically applied to determine lignin content not only in pulping but also in oxygen delignification and other bleaching stages, although it has been known that kappa number may not reflect the "true" lignin content in the cases where the history of the pulp includes an oxidative treatment. This paper examines the relationship between kappa number and oxidizable structures in various kinds of bleached spruce kraft pulps, including residual lignin, hexenuronic acid and other non-lignin structures. By performing modified (Ox-Dem) kappa number and oxidation equivalent determinations, it was found that the relationship between lignin content and kappa number from lignin is different from the case of unbleached pulp. Tiffs is attributed to the oxidative fragmentation of aromatic rings and formation of carboxyl and non-aromatic unsaturated structures in the lignin structure without obvious depolymerisation. Contribution from non-lignin oxidizable groups oth...
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Nordic Pulp and Paper Research Journal
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Tappi Journal
ABSTRACT: The time-dependent behavior of material that affects the kappa number of birch kraft pu... more ABSTRACT: The time-dependent behavior of material that affects the kappa number of birch kraft pulp was experimentally tested in an industrial, two-stage, oxygen–alkali delignification process. The pulps were leached, and the leached material was divided into four different fractions: the wash loss fraction and the easily leachable, slowly leachable, and stagnant fractions. These fractions were further characterized according to their chemical natures, representing residual lignin, extractives, hexenuronic acids, and other chemical structures contributing to the kappa number of the pulps. The apparent and actual delignification responses in the two reactors and the effects of the leaching operation were thoroughly evaluated based on the behaviors of these different pulp components. Application: Improved procedures for measuring and reporting the results of delignification could lead to better evaluation and control of a modern oxygen delignification process. ------------------------...
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Papers by Göran Gellerstedt