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Academic literature on the topic 'Softwood pulp'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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Journal articles on the topic "Softwood pulp"

GUSTAFSON, RICHARD, GAURAV RAYAL, MING QIAO, and JINGLIANG MAO. "The Nature of Single Fiber Kappa Distributions." March 2009 8, no. 3 (April 1, 2009): 26–31. http://dx.doi.org/10.32964/tj8.3.26.

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We examined the uniformity of a variety of kraft pulps with the University of Washington’s single fiber kappa analyzer (FKA). Some consistent patterns and trends with regard to pulp uniformity have emerged. This paper provides a synthesis of the significant observations we made in examining the kappa uniformity of kraft pulps. Hardwood pulps are generally more uniform than pulps from softwoods, but all the single fiber kappa distributions are broad. Virtually all softwood pulps have high kappa tails, whereas hardwood pulps have a high kappa tail only if the pulping is extremely non-uniform. Hardwood pulp kappa distributions appear to be Gaussian. Softwood pulps from commercial digesters are generally much less uniform than those made in the laboratory. The differences in uniformity in hardwood pulps from laboratory and commercial digesters are less dramatic than for softwood pulps. Hardwoods that we have examined appear to be much easier to pulp with uniformity than softwoods.

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Kühne, L., J. Odermatt, and T. Wachter. "Application of a Catalyst in Peroxide Bleaching of Eucalyptus Kraft Pulp." Holzforschung 54, no. 4 (July 4, 2000): 407–12. http://dx.doi.org/10.1515/hf.2000.068.

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Summary A binuclear [Mn(III)Mn(IV)(μ-O)2(μ-CH3COO)L](ClO4−)2 complex with L = 1,2 Bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane, described as a selective catalyst in hydrogen peroxide bleaching of softwood pulps, was tested in hardwood kraft pulp bleaching. The catalyst application gave rise to a higher consumption of peroxide which resulted in higher pulp brightness. The delignification improvement caused by the catalyst was shown to be much lower compared to catalysed peroxide bleaching of softwood kraft pulp. In contrast to the results of softwood pulp bleaching no selectivity improvements could be found when using the catalyst in bleaching of eucalyptus kraft pulp.

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POTUCEK, FRANTIŠEK, MOSTAFIZUR RAHMAN, and JOZEF MIKLÍK. "DISPLACEMENT WASHING OF KRAFT PULP WITH VARIOUS CONSISTENCY." Cellulose Chemistry and Technology 54, no. 9-10 (November 11, 2020): 943–52. http://dx.doi.org/10.35812/cellulosechemtechnol.2020.54.91.

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The paper deals with the displacement washing of kraft softwood and hardwood pulps with various consistency of the pulp fibre bed. The results obtained revealed differences between the two types of kraft pulp with various morphological properties of fibres. The washing efficiency decreased with decreasing Péclet number for both kraft pulps, but, due to lower longitudinal dispersion of the wash liquid, greater washing efficiency was achieved for the short-fibred hardwood pulp. On the other hand, the long-fibred softwood pulp exhibited lower hydraulic resistance of the pulp fibre bed. The change in pulp consistency and, similarly, the volumetric mass transfer coefficient, characterising the rate of leaching of alkali lignin from pulp fibres, did not have a significant effect on the washing efficiency. However, the mass transfer coefficient decreased with increasing specific resistance of the pulp bed. With increasing bed consistency of both softwood and hardwood pulps, as the amount of black liquor in the inter-fibre pores decreased, the difference between the space time, characterising the holding time of wash liquid, and the mean residence time of alkali lignin increased.

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Lund, Kristoffer, Karin Sjöström, and Harald Brelid. "Alkali Extraction of Kraft Pulp Fibers: Influence on Fiber and Fluff Pulp Properties." Journal of Engineered Fibers and Fabrics 7, no. 2 (June 2012): 155892501200700. http://dx.doi.org/10.1177/155892501200700206.

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The importance of hemicelluloses for the papermaking properties of pulp fibers is well documented. In the patent literature, it can be seen that there is also an interest in this type of modification of pulp fibers for use in absorption products. In this study, a Scandinavian softwood kraft pulp and a birch kraft pulp were alkali extracted at 3 different concentrations of NaOH (2%, 4% and 8% NaOH in the suspension). The alkali extraction removed a large part of the hemicelluloses from the pulp fibers and decreased the content of the charged groups. After extraction, the pulps were dried in the form of sheets (approx. 600 g/m2). The alkali extracted pulp fibers exhibited a greater decrease in swelling when re-wetted than untreated pulp. A significant increase in the curl index after extraction with 4% and 8% NaOH was also noted. The tensile strength index of the formed sheets increased at the lowest concentration of NaOH and, at the higher concentrations, a decrease was observed. The pulp sheets were dry defibrated at different defibration intensities and the performance of the resulting pulps in fluff pulp applications was studied. The air-laid fiber networks of softwood pulp fibers showed higher network strength than the networks of birch pulps. The birch pulp extracted at the highest alkali level tended to give the highest network strength. The results from the network strength tests also indicated that the increased curl of the fibers from the softwood pulp extracted at the highest alkali level rendered a more flexible fiber network. In water absorption tests, the alkali treated softwood fibers tended to give networks with a somewhat enhanced water holding capacity under pressure.

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Janzon, Ron, Jürgen Puls, and Bodo Saake. "Upgrading of paper-grade pulps to dissolving pulps by nitren extraction: Optimisation of extraction parameters and application to different pulps." Holzforschung 60, no. 4 (July 1, 2006): 347–54. http://dx.doi.org/10.1515/hf.2006.055.

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Abstract Xylans were selectively removed from paper-grade pulps by nitren extraction to produce dissolving pulps. Extraction parameters were optimised for a birch kraft pulp regarding time, temperature, liquor/pulp ratio, and total nitren charge. Furthermore, the applicability of the method was investigated for two other kraft pulps obtained from eucalyptus and mixed softwood, and for one beech sulfite pulp. Extracted pulps were characterised regarding their carbohydrate content and Cuen viscosity. The nitren charge was a decisive factor for xylan removal and pulp purity. The combination of a high nitren concentration and low liquor/pulp ratio was most effective for xylan removal. However, a high liquor/pulp ratio with a lower nitren concentration proved to be more selective and minimised cellulose degradation as well. Glucomannans were almost insoluble under the extraction conditions investigated. Therefore, softwood pulps were not suitable for the upgrading of chemical pulps to dissolving pulps by nitren extraction. On the other hand, hardwood pulps obtained by kraft and sulfite processes contained 96–97% cellulose after nitren extraction.

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SUNDBERG, ANNA, LARI VÄHÄSALO, and BJARNE HOLMBOM. "Acid methanolysis: An analytical tool for estimating the proportions of different pulp types in deinked pulp or recovered paper." August 2013 12, no. 8 (September 1, 2013): 45–51. http://dx.doi.org/10.32964/tj12.8.45.

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A method was developed to estimate the composition of deinked pulp or recovered paper in termsof hardwood kraft pulp, softwood kraft pulp, and mechanical pulp through analysis of the sugar units in hemicellulosesand pectins. Different pulps (i.e., bleached chemical pulp from hardwoods and softwoods and mechanical pulp) were obtainednfrom different mills. The pulps were mixed in different proportions and dried. The content of arabinose, xylose, mannose, galactose, rhamnose, galacturonic acid, and 4-O-methyl-glucuronic acid, sugar units in hemicelluloses and pectins in the different pulps and in the mixtures were determined by acid methanolysis and gas chromatography. The contents of the sugar units were significantly different in the three pulp types but quite similar in the same pulp type, irrespectively of bleaching sequence. The modeling was performed using standard partial least squares regression (PLSR) and cross-validation using venetian blinds subsets. The data were autoscaled before regressions. The best model had two latent variables. The cumulative variation of X captured by the model was 0.988 (R2X), the cumulative variation of Y captured by the model was also 0.988 (R2Y), and the cumulative cross-validated variation of Y captured by the model was 0.974 (Q2). Accordingly, the PLS model is more than capable of predicting the validation set. It was concluded that the proportion of chemical pulp from hardwoods, chemical pulp from softwoods, and mechanical pulp can be estimated in recovered paper or deinked pulp using a mathematical model based on the content of selected sugar units in hemicelluloses and pectins.

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Watson, Paul, and Michael Bradley. "Canadian pulp fibre morphology: Superiority and considerations for end use potential." Forestry Chronicle 85, no. 3 (June 1, 2009): 401–8. http://dx.doi.org/10.5558/tfc85401-3.

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Four physical attributes of fibres confer the end use potential of a pulp, namely fibre length, fibre coarseness, fibre strength and uniformity. Long, slender, fine fibred pulps, which are low in thick-walled summerwood content, provide superior reinforcement strength. The natural species endowment that Canada enjoys can, when accompanied by superior operational performance and technical vision, result in significant advantages for strategically focused companies and their customers. Factor and multivariate analysis of more than 60 industrial pulp samples confirm that on the basis of fundamental morphological differences, Canadian pulps exhibit clear superiority. Canadian northern bleached softwood kraft pulp is the undoubted industry leader, yet unrealized potential still exists, and additional research effort is required, to maintain this market position. Key words: kraft pulp, softwood, fibre morphology, intrinsic properties, length, coarseness, fibre strength, tensile strength, biogeoclimatic zone, factor analysis, reinforcement, premium reinforcement pulp, PRP, refining

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Du, Min, Xin Ping Li, Jin Wang, and Peng Zhou Wang. "Modification of Cellulase to Different Bleached Softwood Pulp." Advanced Materials Research 550-553 (July 2012): 1186–89. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1186.

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Cellulase named as Novozym 476 was used to modify three kinds of bleached softwood pulps respectively. By analyzing the changes of refining degree, water retention value, specific surface area, wetting properties of fiber before and after enzymatic treatment, studied the influence of characteristics of raw material to the effect of enzymatic modification. The results indicate that in the same conditions, the refining property, water retention value, specific surface area and wetting property of the three pulps all increase. Among these three pulps, the pulp of Kamloops Kraft has the best modification effect. Refining degree of Kamloops Kraft pulp increases 36.0 °SR when refining for 10,000 PFI revolutions, and the water retention value increases by 68.0%, the dye loading increases with 0.1 mg/g, the contact angle decreases by 4.5%. It illustrates that the fiber raw material with a thin cell wall would have a better effect of enzymatic modification and the wrapping way of microfibers would influence the effect of enzymatic modification.

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de Assis, Tiago, Joel Pawlak, Lokendra Pal, Hasan Jameel, Richard Venditti, Lee W. Reisinger, Dale Kavalew, and Ronalds W. Gonzalez. "Comparison of wood and non-wood market pulps for tissue paper application." BioResources 14, no. 3 (July 8, 2019): 6781–810. http://dx.doi.org/10.15376/biores.14.3.6781-6810.

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A comparison among ten market pulps at a laboratory scale using uncreped tissue handsheets was performed to study the performance of wood and non-wood pulps for tissue manufacturing, evaluate what fiber features are desired for a specific tissue property, and determine how non-wood pulps can be used to replace or complement wood pulps in tissue products. A characterization of the fiber morphology and handsheet properties (softness, water absorbency, and strength) was performed at different mechanical refining levels. The results showed that the fiber morphology had a major impact on tissue properties. Market pulps with a combination of long fibers, high coarseness, and low fines content can provide superior bulk and water absorbency. Short fibers with thin cell walls and low fines content can impart superior softness. Bleached bamboo soda pulp can replace hardwood and softwood pulps to provide an excellent combination of water absorbency and strength. Bleached bamboo soda pulp can also replace Northern bleached softwood kraft (NBSK) pulp to impart strength without sacrificing softness. Bleached and semi-bleached wheat straw soda pulps presented a similar combination of softness and strength as Southern bleached hardwood kraft (SBHK) pulp. The wheat straw pulps can be used to replace deinked pulp (DIP) pulp to impart intermediate levels of water absorbency and strength.

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Yanagisawa, Masahiro, and Akira Isogai. "Size exclusion chromatographic and UV-VIS absorption analyses of unbleached and bleached softwood kraft pulps using LiCl/1,3-dimethyl-2-imidazolidinone as a solvent." Holzforschung 61, no. 3 (May 1, 2007): 236–41. http://dx.doi.org/10.1515/hf.2007.046.

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Abstract Unbleached and bleached kraft pulps and holocellulose prepared from softwood were totally soluble in 8% LiCl/1,3-dimethyl-2-imidazolidinone (LiCl/DMI). The solutions were analyzed by size exclusion chromatography with photodiode array and multi-angle laser light scattering detection (SEC-PDA-MALLS). The mobile phase consisted of 1% LiCl/DMI. The degree of polymerization (DP) and DP distribution of the softwood kraft pulps were determined, as well as the DP distribution of residual lignins based on their UV-VIS absorption patterns. Changes in DP for kraft pulps after a conventional bleaching sequence were evaluated, and the residual lignins were analyzed in the same way. Approximately half of the residual lignin in unbleached and bleached kraft pulps was present in polysaccharide fractions with high DP, which represented approximately 90% of the total yield. Some characteristic differences in the UV-VIS absorption pattern were observed between kraft pulps bleached with oxygen and chlorine. DP, DP distribution of polysaccharides, and distribution of residual lignin were clearly different for unbleached kraft pulp, unbleached sulfite pulp, and holocellulose. An unbleached kraft pulp prepared from hardwood showed different properties to the corresponding softwood preparation. The UV-VIS absorption patterns due to residual lignins were also very characteristic for the various pulps and holocellulose.

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Dissertations / Theses on the topic "Softwood pulp"

Yuan, Zhirun. "Peracetic acid brightening of softwood kraft pulp." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ29474.pdf.

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Toven, Kai. "Ozone based ECF bleaching of softwood kraft pulp." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2000. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-457.

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The objective of this work was to explore fundamental aspects of utilizing (DZ) and (ZD) bleaching stages in the prebleaching of oxygen delignified Scandinavian softwood kraft pulp, and compare paper properties of fully bleached pulps with a DEoD₁ED₂ bleached EDF reference pulp. According to the literature, the use of chlorine dioxide and ozone in combination in (DZ) and (ZD) bleaching stages seems advantageous from both environmental and economical points of view. A significant reduction in the formation of chloro-organic compounds and efficient delignification relative to chemical consumption is obtained.

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Karlsson, Hanna. "Strength Properties of Paper produced from Softwood Kraft Pulp : Pulp Mixture, Reinforcement and Sheet Stratification." Doctoral thesis, Karlstads universitet, Avdelningen för kemiteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-5612.

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For paper producers, an understanding of the development of strength properties in the paper is of uttermost importance. Strong papers are important operators both in the traditional paper industry as well as in new fields of application, such as fibre-based packaging, furniture and light-weight building material. In the work reported in this thesis, three approaches to increasing paper strength were addressed: mixing different pulps, multilayering and reinforcement with man-made fibres. In specific: The effects of mixing Swedish softwood kraft pulp with southern pine or with abaca (Musa Textilis) were investigated. Handsheets of a softwood kraft pulp with the addition of abaca fibres were made in a conventional sheet former. It was seen that the addition of abaca fibres increased the tearing resistance, fracture toughness, folding endurance and air permeance. Tensile strength, tensile stiffness and tensile energy absorption, however, decreased somewhat. Still it was possible to add up to about 60% abaca without any great loss in tensile strength. As an example, with the addition of 30% abaca, the tear index was increased by 36%, while the tensile index was decreased by 8%. To study the effect of stratification, a handsheet former for the production of stratified sheets, the LB Multilayer Handsheet Former was evaluated. The advantage of this sheet former is that it forms a stratified sheet at low consistency giving a good ply bond. It was shown to produce sheets with good formation and the uniformity, evaluated as the variation of paper properties, is retained at a fairly constant level when the number of layers in the stratified sheets is increased. The uniformity of the sheets produced in the LB Multilayer Handsheet Former is generally at the same level as of those produced in conventional sheet formers. The effects of placing southern pine and abaca in separate layers, rather than mixing them homogeneously with softwood pulp were studied. Homogeneous and stratified sheets composed of softwood and southern pine or softwood and abaca were produced in the LB Multilayer Handsheet Former. It was found that by stratifying a sheet, so that a pulp with a high tear index and a pulp with a high tensile index are placed in separate layers, it was possible to increase the tear index by approximately 25%, while the tensile index was decreased by 10-20%. Further, by mixing a pulp with less conformable fibres and no fines with a pulp with more flexible fibres and fines, a synergy in tensile strength (greater strength than that predicted by linear mass fraction additivity) was obtained. The effects of stratifying sheets composed of softwood and abaca were compared to the effects of refining the softwood pulp. Homogeneous and stratified sheets composed of softwood with three different dewatering resistances and abaca were also produced in the LB Multilayer Handsheet Former. It was found that by stratifying the sheets the tear index was retained while the tensile index was increased by the refining. The effects of reinforcing softwood pulp of different dewatering resistances with man-made fibres with low bonding ability were also investigated. Man-made fibres (i.e. regenerated cellulose, polyester and glass fibres) were added in the amounts 1, 3, or 5 wt% to softwood pulp of three different dewatering resistances. It was found that with refining of a softwood pulp and subsequent addition of long fibres with low bonding ability the tensile-tear relationship can be shifted towards higher strength values. The bonding ability of the man-made fibres was evaluated by pull-out tests and the results indicated that, in relation to the fibre strength, regenerated cellulose (lyocell) was most firmly attached to the softwood network while the glass fibres were most loosely attached.

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Sillanpää, M. (Mervi). "Studies on washing in kraft pulp bleaching." Doctoral thesis, Oulun yliopisto, 2005. http://urn.fi/urn:isbn:9514278771.

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Abstract Washing during kraft pulping can be divided into two separate areas each with its own distinct features: namely brownstock washing and washing in bleaching. Research interest has so far concentrated mostly on investigating brownstock washing and factors affecting its efficiency. Pulp washing in bleaching, however, has been practically neglected. The basic phenomena are the same as in brownstock washing, but there are differences which have not been taken into consideration to a sufficient extent. This less explored area is the focus of this research. In this thesis, it is shown that brownstock washing and pulp washing between bleaching stages are distinct areas with their own specific features. They differ for example in terms of the composition and molecular size of the impurities in the pulp suspension. Various process conditions, pH, temperature and so on cause further differences between washing in bleaching and brownstock washing. The removal of specific compounds can be clearly affected by the appropriate selection of wash liquor. It is shown that the dynamic behaviour during washing is different for different compounds and depends on the properties of the wash water. The key element is to find the most harmful compounds in specific positions in bleaching and on the basis of that finding, to determine the most suitable wash liquor system. Chemical oxygen demand (COD) is a widely used method for evaluating the washing result, but as a collective measurement variable it does not describe the actual compounds that cause the "loss" of bleaching chemicals. Studies have shown that many compounds contribute to COD load but ultimately most of them have no real effect on the bleaching result. A suggestion for more precise definition of wash loss is offered than COD.

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Deshpande, Raghu. "The initial phase of the sodium bisulfite pulping of softwood dissolving pulp." Licentiate thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-36494.

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The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of single stage sodium bisulfite cooking of either 100 % spruce or 100 % pine wood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate and sulfate.
Single stage sodium bisulfite cooking was carried out on either spruce or pine wood chips to investigate the influence of several process parameters in the initial phase of such a cook i.e. between 100 % and 60 % pulp yield. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and time in the initial stage were varied. The influence of dissolved organics and inorganics components in the cooking liquor on the final pulp properties and side reactions were investigated. The impact of temperature and time on the pulp components were analyzed with respect to carbohydrates, lignin, extractives and thiosulfate. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. It was found that if using a mill prepared cooking acid, this had a beneficial effect with respect to side reactions, better extractives removal and higher pH stability during the cook, compared to a corresponding cook with a lab prepared cooking acid. Cooking with mill prepared and lab prepared cooking acids showed the same behaviour with respect to delignification and carbohydrate degradation, but the lab acid experiments resulted in a higher thiosulfate formation during the cook. The cellulose yield was not affected at all during the initial phase of the sulfite cook verifying earlier results by other researchers. The temperature had an influence on both the delignification rate and the rate of hemicelluloses removal. The corresponding activation energies were found to increase in the following order; cellulose, xylan, glucomannan and lignin.

Artikel 1: "The Initial Phase of Sodium Bisulfite Pulping of Spruce: Part 1" ingick i avhandlingen som manuskript. Nu publicerad.

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Severtson, Steven J. "Sorption of 2,4-dichlorophenol and 2,4,5-trichlorophenol by softwood fibers." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/5798.

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Sugiharto, Andoyo. "The effect of chemical and xylanese pretreatment on the quality of softwood kraft pulp bleached with CED sequence." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/25316.

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Svedinger, Andersson Maria. "The Effect of Different Xylan Contents on the Strength Properties of Softwood Kraft pulp." Thesis, Karlstads universitet, Fakulteten för teknik- och naturvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-28850.

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The aim of this Master thesis was to investigate if the xylan content had any influence on the physical properties of softwood kraft pulps. To achieve pulps with different xylan content different kraft cooking conditions were used; two different temperatures and two different effective alkali levels. The cooking conditions used were 160°C with 30% effective alkali (EA) referred to as reference cook and 145°C with 17% effective alkali (EA) referred to as the mild cook. The first step in this study was to determine the cooking time needed for reaching a certain kappa number, i.e.30. It was also determined whether the difference in xylan content between the pulp samples was sufficient when these cooking conditions were used. When the correct cooking time and cooking conditions had been found new cooks were made using these conditions. All cooks were made at a liqour to wood ratio of 4:1. The difference in xylan content between the corresponding pulp samples was found to be 3%. The physical testing showed no significant difference in the tensile strength between the two pulps after beating. There was a difference in tear index however and the pulp with the highest content of xylan had the lowest tear index. Zero-span index was the same for the two pulps when unbeaten. After beating the zero-span index decreased for the pulp with highest xylan content but stayed unchanged for the pulp with the lower amount of xylan. These results can be explained by the results from the fibre analysis which showed that the fibres with high xylan content were longer, thicker and had a higher coarseness. Thicker fibres are probably stiffer than thinner fibres which gives the paper fewer bonding points and a lower strength. The result from the zero-span test indicated that the fibres with higher xylan content are affected more by beating than fibres with the lower xylan content.
Målet med examensarbetet var att undersöka om och hur mycket xylaneti pappersmassan påverkar fiberns och därmed papperets fysikaliska egenskaper. Egenskaperna som undersöktes var drag- och rivstyrka samt zero-spanstyrka. Xylaninnehållet skulle varieras genom att kokförhållandena förändrades dels genom olika koktemperaturer dels olika satsningar av effektivt alkali vid given sulfiditet. Dessa var 160ºC med 30% effektivt alkali(EA) hädanefter benämnd referenskoket och 145ºC med 17% effektivt alkali(EA) som benämns det milda koket i fortsättningen.En bestämning av koktiden gjordes för att nå 30 i kappatal och två provkok, ett vid varje temperatur behövde göras.Skillnaden i xylanhalt mellan de slutliga massaproverna låg på c:a 3% enheter. Styrkeproverna gav inga entydiga svar på om skillnaden i xylanhalt gav någon effekt på massastyrkan. Dragproverna visade att för omald massa var massan från referenskoket starkast men att massan från det mildare koket reagerade kraftigare på malningen. Redan vid 1000 varv hade den i princip samma dragindex som referensmassan vid samma malgrad. Zero-span mätningarna visade att fibrerna hade samma styrka när de var omalda. Resultaten från fiberanalysenverifierade resultaten från styrketesterna eftersom en tjockare fiber bör ge en styvare fiber och därmed erhålls färre bindningspunkter. Färre bindningspunkter ger en lägre dragstyrka och det krävs mindre energi för att bryta bindningarna. Efter malningen kan man se att zero-span styrkan har minskat betydligt för massan med högre xylanhalt medan referensmassan behöll styrkan. Dessutom har dragstyrkan ökat för båda massorna men mest för massan med högre xylanhalt. Det kan förklaras med att malningen ger små fibriller på ytan av fibern och en mjukare och böjligare fiber. Därmed ökar bindningsstyrkan då bindningsarean ökar och fibern blir mjukare och böjligare. Den ökade bindningsgraden samt den minskade fiberstyrkan kan förklara varför rivindex fortfarande var lägre för massan med högre xylanhalt trots att dragindex ökade med ökad malning.En annan förklaring kan vara att vid ett långt kok med låg temperatur är det troligt att lignin adsorberas på fibrerna.Ligninet på ytan ger en sämre bindningsförmåga vilket leder till att de är lättare att dra ur nätverket med lägre energiåtgång som följd.

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Mackinnon, John 1963. "Dynamic simulation of the first two stages of a kraft softwood bleach process." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66188.

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Rahman, Hafizur. "Modifying kraft pulping to produce a softwood pulp requiring less energy in tissue paper production." Licentiate thesis, Mittuniversitetet, Avdelningen för kemiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-32833.

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Modification of softwood kraft pulp by the addition of either polysulfide (PS) or sodium borohydride (NaBH4) has been shown to increase the pulp yield due to a higher retention of glucomannan. The pulps with higher yield gave a paper with higher tensile index than reference pulp, especially at lower degrees of refining. The higher yield pulps also showed a greater porosity of the fibre wall, indicating an increase in the swelling potential of the fibres. This can lead to increased fibre flexibility and increased joint strength between the fibres and to the higher handsheet tensile index. However, the swelling increase associated with the higher hemicellulose content could also make dewatering more challenging because of the higher water retention of the pulp. The results of this study show however that the positive influence of the increase in yield (fewer fibres and a more open sheet structure) dominates over the negative influence of the higher hemicellulose content on the dewatering properties, especially at lower refining energy levels. Studies simulating full-scale tissue machine dewatering conditions showed that pulps with a higher yield and a higher hemicellulose content had a higher tensile index at the same dryness. Moreover, the same dryness level was achieved in a shorter dwell-time. A given tensile index was also achieved with less refining energy. Increasing the yield and hemicellulose content by the addition of either an oxidizing or a reducing agent in the softwood kraft pulping process thus has a potential for giving high quality fibres for tissue paper production with less refining energy and lower drying energy costs.

Vid tidpunkten för framläggningen av avhandlingen var följande delarbeten opublicerade: delarbete 2 inskickat.

At the time of the defence the following papers were unpublished: paper 2 submitted.

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Books on the topic "Softwood pulp"

Myers, Gary C. Small-diameter trees used for chemithermomechanical pulps. Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003.

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Myers, Gary C. Small-diameter trees used for chemithermomechanical pulps. Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003.

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Myers, Gary C. Small-diameter trees used for chemithermomechanical pulps. Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003.

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Myers, Gary C. Small-diameter trees used for chemithermomechanical pulps. [Madison, WI]: United States Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003.

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Myers, Gary C. Small-diameter trees used for chemithermomechanical pulps. Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003.

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Myers, Gary C. Small-diameter trees used for chemithermomechanical pulps. Madison, WI: U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, 2003.

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Marcoccia, Bruno Sisto. Photo-enhanced oxygen delignification of softwood kraft pulp. 1992.

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Earl, Paul Francis. The chlorination of softwood kraft pulp in a high-intensity laboratory mixer. 1990.

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Book chapters on the topic "Softwood pulp"

Fanta, George F., Robert C. Burr, and William M. Doane. "Oil Absorbency of Graft Copolymers from Softwood Pulp." In Renewable-Resource Materials, 107–14. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4613-2205-4_9.

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van Heiningen, Adriaan R. P., Yun Ji, and Vahid Jafari. "Recent Progress on Oxygen Delignification of Softwood Kraft Pulp." In Cellulose Science and Technology, 67–97. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2018. http://dx.doi.org/10.1002/9781119217619.ch4.

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Robert, Sylvain, Claude Daneault, François Lepine, Christian Viel, and Dany Rousseau. "Gamma-Ray Induced Chromophore Modification of Softwood Thermomechanical Pulp." In ACS Symposium Series, 167–76. Washington, DC: American Chemical Society, 1993. http://dx.doi.org/10.1021/bk-1992-0531.ch013.

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Wong, Ken K. Y., Patricia Clarke, and Sandra L. Nelson. "Possible Roles of Xylan-Derived Chromophores in Xylanase Prebleaching of Softwood Kraft Pulp." In ACS Symposium Series, 352–62. Washington, DC: American Chemical Society, 1996. http://dx.doi.org/10.1021/bk-1995-0618.ch023.

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Bajpai, Pratima. "Softwood Anatomy." In Biermann's Handbook of Pulp and Paper, 105–52. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-814240-0.00004-5.

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Yin, C. F., T. W. Joyce, and H.-M. Chang. "DECHLORINATION OF CONVENTIONAL SOFTWOOD BLEACHING EFFLUENT BY SEQUENTIAL BIOLOGICAL TREATMENT." In Biotechnology in Pulp and Paper Manufacture, 231–44. Elsevier, 1990. http://dx.doi.org/10.1016/b978-0-409-90192-4.50025-x.

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Clark, T. A., A. G. McDonald, D. J. Senior, and P. R. Mayers. "MANNANASE AND XYLANASE TREATMENT OF SOFTWOOD CHEMICAL PULPS: EFFECTS ON PULP PROPERTIES AND BLEACHABILITY." In Biotechnology in Pulp and Paper Manufacture, 153–67. Elsevier, 1990. http://dx.doi.org/10.1016/b978-0-409-90192-4.50018-2.

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Mansfield, Shawn D., Neil R. Gilkes, R. Antony J. Warren, and Douglas G. Kilburn. "The Effects of Recombinant Cellulomonas fimi β-1,4-glycanases on Softwood Kraft Pulp Fibre and Paper Properties." In Progress in Biotechnology, 301–10. Elsevier, 2002. http://dx.doi.org/10.1016/s0921-0423(02)80033-8.

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Ebeling, Kari. "ROLE OF SOFTWOOD FIBRE FORM AND CONDITION ON ITS REINFORCEMENT CAPABILITY." In Cellulosic Pulps, Fibres and Materials, 209–25. Elsevier, 2000. http://dx.doi.org/10.1533/9781845698546.209.

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Conference papers on the topic "Softwood pulp"

Heck, G. F. "Demonstration of very high temperature kiln for drying softwood lumber." In 2010 56th IEEE Pulp and Paper Industry Conference - PPIC. IEEE, 2010. http://dx.doi.org/10.1109/papcon.2010.5556517.

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Talcott, Sarah M., and Theodore J. Heindel. "Gas Holdup in Opaque Cellulose Fiber Slurries." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77043.

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Three different cellulose fiber types are used to study their effect on gas holdup and flow regime transition in a 10.2 cm semi-batch bubble column. The three natural fiber types include bleached softwood chemical pulp (softwood), bleached hardwood chemical pulp (hardwood), and bleached softwood chemithermomechanical pulp (BCTMP). Gas holdup is recorded over a range of fiber mass fractions (0 ≤ C ≤ 1.6%) and superficial gas velocities (Ug ≤ 23 cm/s). Experimental results show that gas holdup decreases with increasing fiber mass fraction. Homogeneous, transitional, and heterogeneous flow is observed for all three fiber types at low fiber mass fractions. All three fiber types produce similar results in the homogeneous flow regime while significant differences are recorded in the heterogeneous flow regime; those being low mass fraction hardwood (softwood) fiber slurries produce the highest (lowest) gas holdup. At higher fiber mass fractions, only pure heterogeneous flow is observed and softwood fiber slurries still produce the lowest gas holdup, although the differences in gas holdup between fiber types are small. The Zuber-Findlay drift flux model is used to describe the gas holdup results in cellulose fiber slurries when the flow conditions are heterogeneous. The Zuber-Findlay drift flux model is also used to identify the superficial gas velocity at which homogeneous flow is no longer observed with some success. Generally, the superficial gas velocity at which the flow deviates from homogeneous flow decreases with increasing fiber mass fraction.

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Leshchinskaya, Alexandra. "A. Leshchinskaya. MICROWAVE WOOD CHIP TREATMENT USE IN CHEMICAL PULP MANUFACTURING (TECHNICAL-ECONOMIC ASSESMENT)." In Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9706.

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MICROWAVE WOOD CHIP TREATMENT USE IN CHEMICAL PULP MANUFACTURING (TECHNICAL-ECONOMIC ASSESMENT) A. Leshchinskaya Plekhanov Russian University of Economics. 36 Stremyannyy Pereulok, 115093 Moscow, Russia, e-mail: alixfl@mail.ru] Keywords: chemical pulping, microwave wood modification, pulp, softwood, wood chips. Large volumes of cellulose are produced from wood chips by chemical methods. Low permeability of many wood species causes problems in the chemical pulp industry. These include: very long cooking times, high chemical consumption, large material losses, high energy consumption, and environmental pollution. New microwave (MW) wood modification technology can provide an increase in wood permeability for liquids and gases, which solves many of these problems. The technology works by applying intensive MW power to green wood, which generates steam pressure within wood cells. High internal pressure destroys weak elements of wood structure, opens pores and forms micro and macro cracks. A several thousand-fold increase in wood permeability can be achieved in species previously found to be impermeable to liquids and gases. It allows a significant increase in the speed of pulp cooking and improves a production processes. The study of the technology showed radical potential improvements in the pulp industry through: increase in mill throughput significant reduction of chemical consumptionreduction of energy consumption • increase in pulp quality and yield improvement of environmental performance. Pulp manufacturing process includs timber chipping, microwave chip treatment, steaming, cooking, washing, and pulp making. The use of MW wood chip treatment in pulp mills with outputs of 50,000 to 500,000 air dry tons (ADT) per year requires MW equipment with power from 1000 to 10,000 kW. Economic modelling of this technology used in different pulp mill conditions allowed assessment of the effect of capital costs, electricity costs, labour costs and other cost components to specific total costs of MW chip processing. Economic assessment of MW technology application showed that specific costs of softwood chip processing at electricity costs of 0.08 - 0.12 US$/kWh are 25.4 -33.7 US$/ADT of pulp. Electricity costs form the most significant part of the total specific costs of MW processing and form 51-69% shear in the total specific costs. Under the same conditions capital costs form 15-20% shear, and labour costs form 5-18% shear of the total specific costs. The electricity cost increase from $0.04 to $0.24/kWh provides specific MW processing cost rise by 2.7 to 3.1 times at pulp mill output range 50,000 to 500,000 ADT/year. New technology use allows benefits up to 7 – 22 Mil US$ per year for pulp mills with output of more than 200,000 ADT/year. The technology can be used by pulp mills with batch and continuous digesting and is not limited by mill throughput. Ecological impacts and high economic advantages of this MW technology application in pulp and paper industry provide good opportunity for commercialisation.

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Bamberger, Judith Ann. "Using Ultrasound to Characterize Pulp Slurries With Entrained Air." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98325.

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The development of fast and practical methods for inspecting fiber suspensions is of great interest in the paper making industry. For process control and paper quality prediction, several elements of the refining process during paper making must be accurately monitored, including specific fiber properties, weight percent fiber (composition), degree of refining, amount of solids, and entrained air content. The results of previous ultrasonic studies applied to wood pulp provide guidance that ultrasound attenuation is information rich, and it does potentially provide a tool for consistency measurement. Ultrasound has the ability to penetrate dense suspensions such as wood pulp slurries. It is has been shown, in some studies, that ultrasound is sensitive to degree of refining. The effects of entrained air, additives, the origin and treatment of the fibers do however all influence the measured data. A series of measurements were made with hardwood and softwood slurries to evaluate the ability of measuring pulp consistency, solids, and entrained air. The attenuation through the slurry was measured as the ultrasound travels from one transducer through the slurry to the other. The measurements identified the presence of entrained air in the pulp samples. To better understand the effects of air, measurements were made at increasing pressures to show how increased pressure reduced the amount of air observed in the spectrum.

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Reports on the topic "Softwood pulp"

Simo Sarkanen. Producing a True Lignin Depolymerase for Biobleaching Softwood Kraft Pulp. Office of Scientific and Technical Information (OSTI), February 2002. http://dx.doi.org/10.2172/792705.

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