Journal articles: 'Softwood pulp'

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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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10

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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11

J. OGLESBY, ROBERT, HUMPHREY J. MOYNIHAN, RICARDO B. SANTOS, ASHOK GHOSH, and PETER W. HART. "Does kraft hardwood and softwood pulp viscosity correlate to paper properties?" October 2016 15, no. 10 (November 1, 2016): 643–51. http://dx.doi.org/10.32964/tj15.10.643.

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The impact of commercially prepared, fully bleached pulp viscosity variation on handsheet physical properties was evaluated at different levels of pulp refining. Hardwood pulps from the same brownstock species mix, cooking parameters, and kappa numbers were processed through two different commercial bleach plants: one with a D0(EP)D1D2 sequence and the second with an OD0(EOP)D1 sequence. Additionally, a commercial softwood (predominately Scotts pine) brownstock pulp bleached by an OD0(EP)D1D2 sequence was employed in this study. Pulps with viscosities ranging from 14 to 21 mPa∙s were refined in a Valley beater to two freeness levels, and the associated handsheet physical properties were measured in this study. Over the pulp viscosity range of 14 to 21 mPa∙s, no clear correlation was found to exist between pulp viscosity and related paper physical properties. Finally, a series of laboratory prepared bleached pulps were purposely prepared under non-ideal conditions to reduce their final viscosities to lower values. Handsheets made from these pulps were tested in their unbeaten condition for physical strength properties. Significant and rapid strength loss occurred when the measured pulp viscosity dropped below 12 mPa∙s; overall strength properties showed no correlation to viscosity above the critical 12 mPa∙s value.

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12

Du, Min, Xin Ping Li, and Meng Luo. "Influence of Cellulase to Filtration and Fiber Morphology of Bleached Softwood Pulp." Advanced Materials Research 550-553 (July 2012): 1182–85. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1182.

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Cellulase named as Celluclast 1.5L was used to deal with bleached softwood pulp. By analyzing the changes of fiber polymerization, fiber length and pulp freeness before and after enzymatic treatment, studied the influence of cellulase to filtration and fiber morphology of bleached softwood pulp, and discussed the mode of action of cellulase to bleached softwood pulp. The results show that while the enzyme dosage increasing, the degree of cellulose hydrolysis increases; the pulp polymerization degree decreases; fiber length decreases and the content of fines increase. Pulp filtration first increases and then decreases, but fiber surface does not appear the phenomenon of fibrillating. It indicates that the action of cellulase to fiber is from the inside to outside.

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13

Fernandez, Francisco J., D. Mark Martinez, and James A. Olson. "Investigation of low consistency reject refining of mechanical pulp for energy savings." Nordic Pulp & Paper Research Journal 33, no. 1 (May 23, 2018): 21–27. http://dx.doi.org/10.1515/npprj-2018-3006.

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AbstractIn this study, the effects of low consistency refining (LCR) energy and intensity on mechanical pulp properties have been studied for three different types of reject pulps (softwood TMP, softwood CTMP and hardwood CTMP), which were refined at varying intensity. Resulting pulp properties have been compared with high consistency refining (HCR) of the same reject pulps. For all furnish types, it was shown that LCR can develop pulp properties matching those developed through HCR with significantly less energy. The resulting pulp properties were found to be affected not only by refining intensity and energy, but also by initial fibre morphology. Pilot LCR trials demonstrated that high freeness reject pulp is initially insensitive to refining intensity as specific energy is applied. This enables the first stage of LCR to be carried out at a higher specific energy and intensity, which can reduce the number of stages of LCR required to reach a target quality. This work shows that low intensity LCR is capable of achieving the same tensile index as HCR pulp at a target freeness of 200 ml CSF.

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Aksenov, Andrey S., Irina V. Tyshkunova, Daria N. Poshina, Anastasia A. Guryanova, Dmitry G. Chukhchin, Igor G. Sinelnikov, Konstantin Y. Terentyev, Yury A. Skorik, Evgeniy V. Novozhilov, and Arkady P. Synitsyn. "Biocatalysis of Industrial Kraft Pulps: Similarities and Differences between Hardwood and Softwood Pulps in Hydrolysis by Enzyme Complex of Penicillium verruculosum." Catalysts 10, no. 5 (May 13, 2020): 536. http://dx.doi.org/10.3390/catal10050536.

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Kraft pulp enzymatic hydrolysis is a promising method of woody biomass bioconversion. The influence of composition and structure of kraft fibers on their hydrolysis efficiency was evaluated while using four substrates, unbleached hardwood pulp (UHP), unbleached softwood pulp (USP), bleached hardwood pulp (BHP), and bleached softwood pulp (BSP). Hydrolysis was carried out with Penicillium verruculosum enzyme complex at a dosage of 10 filter paper units (FPU)/g pulp. The changes in fiber morphology and structure were visualized while using optical and electron microscopy. Fiber cutting and swelling and quick xylan destruction were the main processes at the beginning of hydrolysis. The negative effect of lignin content was more pronounced for USP. Drying decreased the sugar yield of dissolved hydrolysis products for all kraft pulps. Fiber morphology, different xylan and mannan content, and hemicelluloses localization in kraft fibers deeply affected the hydrolyzability of bleached pulps. The introduction of additional xylobiase, mannanase, and cellobiohydrolase activities to enzyme mixture will further improve the hydrolysis of bleached pulps. A high efficiency of never-dried bleached pulp bioconversion was shown. At 10% substrate concentration, hydrolysates with more than 50 g/L sugar concentration were obtained. The bioconversion of never-dried BHP and BSP could be integrated into working kraft pulp mills.

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Lund, M., M. Eriksson, and C. Felby. "Reactivity of a Fungal Laccase Towards Lignin in Softwood Kraft Pulp." Holzforschung 57, no. 1 (January 8, 2003): 21–26. http://dx.doi.org/10.1515/hf.2003.004.

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SummaryThe reactivity of a fungal laccase to lignin of six different spruce kraft pulps with kappa numbers ranging from 15 to 110 was studied. Enzymatic oxidation of lignin was investigated by monitoring the oxygen consumption in a suspension of the pulp and the number of radicals generated in the pulp, as measured by electron paramagnetic resonance spectroscopy. The laccase catalyzed oxidation of lignin in kraft pulp followed a double exponential function. This indicates the presence of two types of substrates oxidized by the enzyme at different rates. The two substrates were interpreted as lignin located on the surface of the pulp fibers and as lignin in the cell wall. A linear relationship was found between the kappa number of the pulps and the observed first-order rate constant for oxidation of substrate in the cell wall. Quantification of free radicals in the pulp showed a linear dependence on the lignin content and the number of free radicals generated upon oxidation with laccase.

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Li, Dongfang, Olena Sevastyanova, and Monica Ek. "Pretreatment of softwood dissolving pulp with ionic liquids." Holzforschung 66, no. 8 (December 1, 2012): 935–43. http://dx.doi.org/10.1515/hf-2011-0180.

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Abstract Few Scandinavian pulp mills produce dissolving pulps; however, the demand on textile fibers is increasing. This study investigates the chemical interaction of dissolving pulp with ionic liquids (ILs), where softwood and hardwood industrial dissolving pulps were pretreated with ILs 1-butyl-3-methy-limidazolium acetate ([C4mim+]CH3COO-) and 1-butyl-3-methyl-imdazolium chloride ([C4mim+]Cl-). Time and temperature dependence of the dissolution process as well as the impact of the pretreatment on the molecular weight properties, thermal stability, morphology, and crystallinity of the cellulose were evaluated by means of size exclusion chromatography (SEC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and solid state nuclear magnetic resonance (NMR). It was shown that the dissolution of cellulosic material in ILs is a temperature-dependent process; however, the viscosity of ILs affected the efficiency of dissolution at a given temperature. Molecular weight properties were affected negatively by increased dissolution temperature, while the type of antisolvent for the regeneration had no major impact on the degree of polymerization of cellulose. Water was more efficient than ethanol for the regeneration of cellulose when performed at an elevated temperature. The pretreatment decreased the crystallinity of cellulosic material. This might lead to the increased accessibility and reactivity of cellulose.

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Kimura, Minoru, Kiyotaka Ninomiya, and Takashi Kadoya. "Press-drying of softwood bleached pulp." JAPAN TAPPI JOURNAL 39, no. 4 (1985): 399–406. http://dx.doi.org/10.2524/jtappij.39.399.

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18

Brelid, Harald, Tornrny Friberg, and Rune Sirnonson. "TCF bleaching of softwood kraft pulp." Nordic Pulp & Paper Research Journal 10, no. 4 (December 1, 1995): 222–26. http://dx.doi.org/10.3183/npprj-1995-10-04-p222-226.

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Brelid, Harald, Tommy Friberg, and Rune Simonson. "TCF bleaching of softwood kraft pulp." Nordic Pulp & Paper Research Journal 11, no. 2 (May 1, 1996): 105–8. http://dx.doi.org/10.3183/npprj-1996-11-02-p105-108.

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Brelid, Harald, Tommy Friberg, and Rune Simonson. "TCF bleaching of softwood kraft pulp." Nordic Pulp & Paper Research Journal 12, no. 2 (May 1, 1997): 80–85. http://dx.doi.org/10.3183/npprj-1997-12-02-p080-085.

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Brelid, Harald, Tommy Friberg, and Rune Sirnonson. "TCF bleaching of softwood kraft pulp." Nordic Pulp & Paper Research Journal 13, no. 1 (January 1, 1998): 50–56. http://dx.doi.org/10.3183/npprj-1998-13-01-p050-056.

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Brelid, Harald, and Tommy Friberg. "TCF bleaching of softwood kraft pulp." Nordic Pulp & Paper Research Journal 13, no. 2 (May 1, 1998): 112–18. http://dx.doi.org/10.3183/npprj-1998-13-02-p112-118.

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HOSTACHY, JEAN-CHRISTOPHE. "Ozone-enhanced bleaching of softwood kraft pulp." August 2010 9, no. 8 (September 1, 2010): 16–23. http://dx.doi.org/10.32964/tj9.8.16.

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By using ozone in their bleaching processes, many hardwood pulp mills in various parts of the world have improved product quality and their environmental and process performance, and reduced operating costs to increase competitiveness. The challenge for softwood pulp is to rethink the use of ozone according to their specific requirements. This paper summarizes results obtained using ozone bleaching on softwood (Pinus radiata) kraft pulp, for which the brightening ability of limited ozone dosages can enhance the economic benefits without impairing pulp quality. This work evaluated the chemical justification to use ozone at the end of the bleaching sequence and the effect on pulp quality, and considered the practical consequences of this new option. Special attention was given to the economic and technical aspects, including investment cost, variable cost, and process implementation. Ozone was shown to be the ideal complement of chlorine dioxide for final pulp bleaching. Both chemicals can easily be combined at the end of the bleaching sequence. Taking into account pulp mill capacity, capital investment, and total operating cost, the financial savings were calculated to be in the range of EUR 5 million (USD 6 million) per year, with a payback period of about 1.5 years.

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Liu, Yan Xue, Yu Xin Liu, Bing Sun, Bin Shen, and Dong Fang Zhang. "Study on the Strength Properties of Superior Shoes Board and Furnish." Advanced Materials Research 887-888 (February 2014): 861–64. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.861.

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The shoe board emphasizes the strength and the bear to fold especially, so it chooses the long fiber raw material. The experiment confirms optimal beating condition and formula through the analysis of beating of the jute pulp and the softwood (Larch) pulp and a series of condition experiment. The board raw material category is: jute: softwood = 7:3; Jute: 40 oSR, softwood: 30 oSR. The properties of original board are: breaking length: 6115 meters, index: 15.79mN·m2/g, fold endurance: 2125 times.

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Ruffin, Brigitte, Stéphane Grelier, Aziz Nourmamode, and Alain Castellan. "Attempt to approach the role of phenolic phenylpropenol structures in the photoyellowing of softwood mechanical pulps." Canadian Journal of Chemistry 80, no. 9 (September 1, 2002): 1223–31. http://dx.doi.org/10.1139/v02-123.

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Three biphenyl (I, II, III) compounds and a benzylarylether (IV) compound were synthesized to detect and quantify the presence of phenolic phenylpropenols in unbleached, peroxide-bleached, or sodium borohydride-reduced mechanical softwood pulps. The methodology used is based on a gas chromatography mass spectrometry search of the prepared compounds in the residue obtained after ethylation, thioacidolysis, and desulfurization of the pulps. Detection of biphenyl I ([Formula: see text]4 × 106 mol g1) in unbleached and NaBH4-reduced pulps is indicative of the presence of phenolic coniferaldehyde units in these pulps. Traces of biphenyl II, found in the peroxide-bleached pulp, probably came from ferulic acid units formed by oxidation of coniferaldehyde by H2O2. No biphenyl ether III or benzylaryl ether IV were detected in the three pulps. This result indicates that phenolic phenylpropenol units are not present in softwood mechanical pulps and do not contribute to the fast part of their photoyellowing.Key words: mechanical pulp, photoyellowing, phenol, coniferyl alcohol, biphenyl.

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Lawoko, M., G. Henriksson, and G. Gellerstedt. "New Method for Quantitative Preparation of Lignin- Carbohydrate Complex from Unbleached Softwood Kraft Pulp: Lignin-Polysaccharide Networks I." Holzforschung 57, no. 1 (January 8, 2003): 69–74. http://dx.doi.org/10.1515/hf.2003.011.

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Summary A new method for the quantitative preparation of pulp representative lignin-carbohydrate complexes (LCC) has been developed, in which LCC has been systematically prepared at quantitative yield, fractionated and qualitatively determined. At least 90% of residual lignin in softwood kraft pulp is proposed to be chemically bonded to carbohydrates. A major part of LCC (92%) in softwood kraft pulp was observed between lignin, xylan and glucomannan, whereas a minor part (8%) was linked to cellulose. Half of the hemicelullosic LCC is a lignin-glucomannan complex. The other half is lignin-xylan complex and xylan-lignin-glucomannan complex. Thus, part of the residual lignin in softwood kraft pulp crosslinks xylan and glucomannan. The proposed linkages are of covalent type. At most 10% of the residual lignin is not bonded covalently to carbohydrates.

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Chen, Zhiwen, Thomas Q. Hu, Ho Fan Jang, and Edward Grant. "Multivariate Analysis of Hemicelluloses in Bleached Kraft Pulp Using Infrared Spectroscopy." Applied Spectroscopy 70, no. 12 (October 28, 2016): 1981–93. http://dx.doi.org/10.1177/0003702816675363.

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The hemicellulose composition of a pulp significantly affects its chemical and physical properties and thus represents an important process control variable. However, complicated steps of sample preparation make standard methods for the carbohydrate analysis of pulp samples, such as high performance liquid chromatography (HPLC), expensive and time-consuming. In contrast, pulp analysis by attenuated total internal reflection Fourier transform infrared spectroscopy (ATR FT-IR) requires little sample preparation. Here we show that ATR FT-IR with discrete wavelet transform (DWT) and standard normal variate (SNV) spectral preprocessing offers a convenient means for the qualitative and quantitative analysis of hemicelluloses in bleached kraft pulp and alkaline treated kraft pulp. The pulp samples investigated include bleached softwood kraft pulps, bleached hardwood kraft pulps, and their mixtures, as obtained from Canadian industry mills or blended in a lab, and bleached kraft pulp samples treated with 0–6% NaOH solutions. In the principal component analysis (PCA) of these spectra, we find the potential both to differentiate all pulps on the basis of hemicellulose compositions and to distinguish bleached hardwood pulps by species. Partial least squares (PLS) multivariate analysis gives a 0.442 wt% root mean square errors of prediction (RMSEP) for the prediction of xylan content and 0.233 wt% RMSEP for the prediction of mannan content. These data all support the idea that ATR FT-IR has a great potential to rapidly and accurately predict the content of xylan and mannan for bleached kraft pulps (softwood, hardwood, and their mixtures) in industry. However, the prediction of xylan and mannan concentrations presented a difficulty for pulp samples with modified cellulose crystalline structure.

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Brogdon, Brian. "Revised steady-state model for chlorine dioxide brightening that considers extraction washer carryover effects." March 2016 15, no. 3 (April 1, 2016): 178–85. http://dx.doi.org/10.32964/tj15.3.178.

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In an earlier investigation, a generalized model was developed to simulate the first chlorine dioxide (ClO2) brightening stage (D1). That stoichiometric model accurately predicts pulp brightness values for given bleach charges and vice versa for laboratory softwood pulps. The equation parameters are dependent on the kappa number and brightness of the extracted pulp. In this study, the earlier model was refined to include the negative effects of extraction carryover to simulate more realistically a mill’s D1 stage. Extracted pulps that contain washer carryover were found to brighten as if the pulp had a kappa number equal to the sum of the extracted kappa and the kappa value of extraction dissolved solids. If this higher kappa (i.e., apparent or wet kappa) is used in place of the extracted kappa with the D1 model, the equations suitably predicted the bleached brightness for a given bleach charge. The modified expressions were used to quantify the amount of carryover and to calculate carryover bleach consumption for a softwood D0(EOP)D1 fiber line. The mill’s washed pulps were found to have carryover levels of 1.4 kappa units, which was consuming 48% of the total D1 bleach charge. Additional analyses revealed that extraction carryover consumes 2.5-4.6 kg ClO2/ton pulp per kappa unit of carryover when bleaching a pulp to 78% to 84% ISO.

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Salmén, Lennart, and Joanna Hornatowska. "A comparison of fibre deformations from mill like and laboratory kraft cooking of softwood." Nordic Pulp & Paper Research Journal 29, no. 2 (May 1, 2014): 211–17. http://dx.doi.org/10.3183/npprj-2014-29-02-p211-217.

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Abstract The fact that industrial pulps have a lower strength than their corresponding laboratory pulps is an unsolved problem affecting in various ways the potential fibre utilisation in different mills. The loss of pulp strength has to a great extent been attributed to changes at the fibre level. In order to clarify in what way changes in fibre properties contribute to the strength losses, cooking experiments were conducted using a laboratory batch digester in which mechanical forces may be introduced. Fibre properties, i.e. fibre structure and fibre strength, of laboratory-made pulps were compared with those of an industrial pulp. It was concluded that two essentially different mechanisms may be identified; one related to the transverse fibre shape, the other to fibre damage. The latter is manifested as lower rewetted zero-span strength which reduces tear resistance and tensile strength of the pulp. The former is a collapse of the fibre, reducing the lumen area and resulting in a pulp with lower water-retaining capacity, given sheets of lower density and a pulp that has to be beaten to a higher degree to reach the desired bonding and the desired tensile strength.

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ANTONSSON, STEFAN, and ANDERS HJORT. "Comparison of cooking technologies for production of softwood kraftliner pulp." March 2014 13, no. 3 (April 1, 2014): 9–15. http://dx.doi.org/10.32964/tj13.3.9.

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Kraftliner, used as the top and bottom layers in corrugated board, is one of the major paper products in the United States and worldwide and is a long-term growth business area for the pulp and paper industry. However, for many years pulping development for kraftliner has been limited. The lack of development may be because corrugated board standards in many countries have specified basis weight and not strength demands on the corrugated board. With the modifications of Item 222/Rule 41, the situation in the United States has changed. Recently, a new cooking technology has been developed enabling defibration of softwood pulps at considerably higher kappa number with low reject content. Pulp quality as a function of kappa number has been evaluated for this new cooking technology compared to pulp produced using a conventional kraftliner cooking technology. Lower H-factor demands and increased strength, measured as tensile energy absorption, were the most important differences found between the two cooking systems in this study.

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31

Harirforoush, R., J. Olson, and P. Wild. "Indications of the onset of fiber cutting in low consistency refining using a refiner force sensor: The effect of pulp furnish." Nordic Pulp & Paper Research Journal 33, no. 1 (May 23, 2018): 58–68. http://dx.doi.org/10.1515/npprj-2018-3013.

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Abstract Detection of the onset of fiber cutting is beneficial in low consistency refining as it may prevent reduction of average fiber length, optimize fiber quality improvements by operating at gaps just wider than the critical gap, avoid decreasing the strength properties of paper, and increase energy efficiency. The objective of this study is to understand the effect of pulp furnish on measured bar forces and, more specifically, on the detection of fiber cutting. Bar forces, i. e. forces applied to pulp fibers by the refiner bars, are measured with a custom-designed piezoelectric force sensor. Trials were conducted with an AIKAWA 16-in. single-disc refiner using hemlock/balsam softwood thermomechanical pulp, SPF softwood thermomechanical pulp, northern bleached softwood kraft pulp, and aspen hardwood thermomechanical pulp at 3.0 to 3.5 % consistency at rotational speeds of 1200 and 1400 rpm. The power of the time domain signal of the measured forces is introduced as an indicator of the onset of fiber cutting. Our results show that this new fiber cutting metric is a sensitive and reliable metric for determination of fibre cutting for a range of pulp furnishes. The study suggests that the refiner force sensor has potential to be exploited for in-process detection of fiber cutting.

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32

Arnoul-Jarriault, Benoît, Raphaël Passas, Dominique Lachenal, and Christine Chirat. "Characterization of dissolving pulp by fibre swelling in dilute cupriethylenediamine (CUEN) solution in a MorFi analyser." Holzforschung 70, no. 7 (July 1, 2016): 611–17. http://dx.doi.org/10.1515/hf-2015-0167.

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Abstract The swelling of dissolving pulps has been investigated by a new method based on the MorfiR analyser, which is measuring the width variation of thousands of fibres in a cupriethylenediamine (CUEN) solution in a few minutes. Pulps from various origins were analysed coming from softwood, birch wood, eucalyptus wood, kraft pulps, sulphite pulps and ECF and TCF bleached pulps, which were modified by several treatments including chemical (cold caustic extraction, hypochlorite) or enzymatic (cellulase) methods. The swelling was much affected by the crystalline form of cellulose and the hemicellulose content but did not depend neither on the cellulose DP nor on the fibre structure (hardwood vs. softwood). The dissolving pulp reactivity in the viscose process was also assessed by swelling in dilute solutions of cupriethylenediamine (CUEN) instead of the Fock’s method.

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33

Du, Min, Xin Ping Li, and Wu Guang Li. "Modification of Bleached Softwood Pulp with Xylanase." Advanced Materials Research 393-395 (November 2011): 855–58. http://dx.doi.org/10.4028/www.scientific.net/amr.393-395.855.

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Xylanse named as Pulpzyme HC was used to modify bleached softwood pulp before refining. The efficiency of modification by different enzyme dosage was invested in this paper. The result showed that enzymatic treatment decreased the dissolved charge and absolute Zeta potential of the slurry and increased the fiber surface wettability. Appropriate Pulpzyme HC (0.4u/g) could improve the refining efficiency by 9.5°SR. The brightness and bulk of hand sheets increased with the increasing of the enzyme. Tensile index and tear index of hand sheets reached the maximum at the enzyme dosage of 0.2u/g. In this dosage, fiber length, knot index and curl index of fiber increased. But excessive enzyme decreased the tear index and had no effect on the tensile index.

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34

Zhang, Dongcheng, Yunqiao Pu, Xing-Sheng Chai, Ved Naithani, Hasan Jameel, and Arthur J. Ragauskas. "Elucidating carboxylic acid profiles for extended oxygen delignification of high-kappa softwood kraft pulps." Holzforschung 60, no. 2 (March 1, 2006): 123–29. http://dx.doi.org/10.1515/hf.2006.020.

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Abstract Two laboratory high-lignin-content softwood (SW) kraft pulps with kappa values of 48.0 and 49.5, prepared by cooking at high and low active alkali (AA), were used for the study of fiber charge development during two-stage oxygen delignification with inter-stage washing (OwO). It was established that the first oxygen delignification (O) stage increased total fiber charge by 2–4%, and further O-delignification via a second O-stage led to a 3–18% decrease in total fiber charge. Carboxylic acid content in pulp holocelluloses decreased by 12–26% with respect to a 35–70% kappa number reduction due to an O and OwO stage of delignification for high and low AA cooked SW kraft pulps. After an OwO-stage delignification, the residual lignin was found to exhibit a 50–100% increase in carboxylic acid content. 13C NMR spectral data for the residual lignin samples indicated that the unconjugated/conjugated acid ratio was approximately (3–4):1. Generally, the carboxylic acid content in low AA cooked softwood kraft pulp and the corresponding oxygen-delignified pulps was systematically higher (13–23%) than that in high AA cooked SW kraft pulp and the corresponding oxygen-delignified pulps. The experimental results also demonstrated that maximum acid-group content in total fiber occurred after 45–50% oxygen delignification of the SW kraft pulps studied.

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35

SUN, CHENGGUI, RICHARD CHANDRA, and YAMAN BOLUK. "From biorefineries to bioproducts: conversion of pretreated pulp from biorefining streams to lignocellulose nanofibers." TAPPI Journal 18, no. 4 (May 1, 2019): 233–41. http://dx.doi.org/10.32964/tj18.4.233.

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This study investigates the use of pretreatment and enzymatic hydrolysis side streams and conversion to lignocellulose nanofibers. We used a steam-exploded and partial enzymatic hydrolyzed hardwood pulp and an organosolv pretreated softwood pulp to prepare lignocellulose nanofibers (LCNF) via microfluidization. The energies applied on fibrillation were estimated to examine the energy consumption levels of LCNF production. The energy consumptions of the fibrillation processes of the hardwood LCNF production and the softwood LCNF production were about 7040-14080 kWh/ton and 4640 kWh/ton on a dry material basis, respectively. The morphology and dimension of developed hardwood and softwood LCNFs and the stability and rheological behavior of their suspensions were investigated and are discussed.

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36

DAS, N., S. K. BOSE, and R. C. FRANCIS. "Kraft pulp bleaching with a P-stage catalyzed by both bicarbonate and TAED." July 2019 18, no. 7 (August 1, 2019): 409–14. http://dx.doi.org/10.32964/tj18.7.409.

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Peroxide bleaching of softwood and hardwood (eucalypt) kraft pulps was performed in solutions of sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3), and sodium hydroxide (NaOH). The conventional P stage (hydrogen peroxide + sodium hydroxide; H2O2 + NaOH) was the most effective brightening system without an additional activator. However, peroxide activation by bicarbonate anion (HCO3–) was obvious in all cases where NaHCO3 or Na2CO3 was used. When N,N,N’,N’-tetraacetylethylenediamine (TAED) was added to the bleaching system, Na2CO3 as the alkali source afforded equal or slightly higher bleached brightness compared to NaOH usage for both the softwood and hardwood pulps. This outcome is attributed to simultaneous peroxide activation by HCO3 and TAED. When applied to the eucalypt pulp, the H2O2/Na2CO3/TAED bleaching system also decreased the brightness loss due to thermal reversion.

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37

Bourbonnais, Robert, Loredana Valeanu, and Michael G. Paice. "Voltammetric analysis of the bleachability of softwood kraft pulps." Holzforschung 58, no. 6 (October 1, 2004): 581–87. http://dx.doi.org/10.1515/hf.2004.111.

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Abstract Kraft and oxygen delignified pulps with various kappa numbers were prepared from black spruce and western hemlock chips. The bleachability (ratio of kappa number decrease to chlorine dioxide applied) of the different pulps at the same kappa number varied with both wood furnish and delignification process. Thus, unbleached kappa number alone is not a reliable indicator of bleachability for these pulps. This may be due in part to the variable hexenuronic acid content of the pulps; those with higher ratio of hexenuronic acid content to kappa number (HexA/kappa) are harder to bleach. Voltammetric analysis of the same kraft pulps in the presence of redox mediators was found to measure both the content and reactivity of residual lignin. Peak current ratios of redox mediators correlated with pulp bleachability for all pulps. These ratios may therefore provide a more accurate prediction of bleachability than unbleached kappa number.

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38

Sarıkaya, Engin, and Hakan Demirel. "Development of cellulose-based toys with moulded fibre production method." BioResources 15, no. 3 (July 21, 2020): 6902–11. http://dx.doi.org/10.15376/biores.15.3.6902-6911.

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In this work, a toy was developed from bleached sulphate pulp via a moulded fibre production technique. Moulded fibre products are generally used to preserve main products from damage during transportation and stow them in a particular order. This work investigated the use of moulded fibre products in daily life as final products. Bleached softwood sulphate pulp was used for the experiments to avoid the potential hygiene problems of using recycled paper for toy production. The physical properties of different degrees of refined sulphate pulp were evaluated during toy sample production. The results indicated that toys produced with bleached softwood sulphate pulp had optimum compression strength (22 kpgf) at the 35 SR° freeness level. Produced prototypes satisfied EN 71-3:2013+A1(2014) in terms of migration element limits.

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39

Du, Min, Xin Ping Li, and Zhi Min Yao. "Influence of Cellulase to Aggregation Structure of Bleached Softwood Pulp." Advanced Materials Research 549 (July 2012): 255–59. http://dx.doi.org/10.4028/www.scientific.net/amr.549.255.

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Cellulase named as Celluclast 1.5L was used to deal with bleached softwood pulp. By analyzing the changes of water retention value and crystallinity of fiber after enzymatic treatment, studied the influence of cellulase to aggregation structure of bleached softwood pulp. The results show that with the increasing of the enzyme dosage, the proportion of long-fiber decreases and the content of fines increases. Water retention value of pulp first decreases and then increases. The fiber crystal does not change with the enzymatic treatment, but with the increasing of the enzyme dosage, the crystallinity of fiber first increases and then decreases. It indicates that the cellulase would act on the crystalline region of fiber in the higher enzyme dosage.

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40

FISKARI, JUHA, OLGA DERKACHEVA, and TUOMAS KULOMAA. "QUICK NON-DESTRUCTIVE ANALYSIS OF CONDENSED LIGNIN BY FTIR. PART 2. PULP SAMPLES FROM ACID SULFITE COOKING." Cellulose Chemistry and Technology 55, no. 3-4 (April 20, 2021): 263–70. http://dx.doi.org/10.35812/cellulosechemtechnol.2021.55.26.

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"In our previous work, we demonstrated how lignin condensation and precipitation taking place in kraft pulping can be detected and even quantified by Fourier Transform Infrared (FTIR) spectroscopy. Because lignin reactions in acid sulfite pulping are very different from those occurring during kraft cooking, a new analysis method is proposed to rapidly analyze the condensed lignin in acid sulfite pulp. This kind of analysis is useful for sulfite pulp mills to detect the elevated risk of black cook. This paper presents and discusses the novel method using FTIR spectroscopy to rapidly analyze lignin condensation in softwood pulp samples from acid sulfite processes. Several softwood pulp samples from acid sulfite pulping at varying levels of condensation were included in this research. According to the results, FTIR spectroscopy allows indirect quantification of lignin condensation in a difficult matrix of wood constituents, such as in incompletely delignified acid sulfite pulp."

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41

Mandlez, Daniel, Lukas Zangl-Jagiello, Rene Eckhart, and Wolfgang Bauer. "Softwood kraft pulp fines: application and impact on specific refining energy and strength properties." Cellulose 27, no. 17 (October 9, 2020): 10359–67. http://dx.doi.org/10.1007/s10570-020-03467-1.

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AbstractAlong with the emergence of micro and nanofibrillated celluloses and their application in papermaking, the influence of the so called fines fraction of pulps on both process and product properties has received increasing research interest in recent years. Several researchers have experimented with primary and/or secondary pulp fines to assess their effects on paper properties with not always consistent results. Our work focuses on the targeted application of the primary fines fraction of an unbleached softwood kraft pulp. The primary fines are separated from the pulp to be subsequently added to achieve blends of $$5\%, 9\%$$ 5 % , 9 % and $$12\%$$ 12 % primary fines content. These blends were then refined in a PFI mill to evaluate the effect of the primary fines on refining as well as on paper properties of hand sheets prepared from these pulps. It is shown that the addition of primary fines enhances tensile strength in the unrefined and slightly refined state, while the maximum tensile strength of the highly refined reference pulp is not increased. A slightly increased dewatering resistance (Schopper Riegler) at comparable air permeability (Gurley) for a given tensile strength was also observed. The linear relationship between tensile index and apparent sheet density seems to be affected in the unrefined and slightly refined state where the breaking length of the fines enriched samples is higher for a given apparent density.

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42

Lucia, Lucian A., and Rachel S. Smereck. "Effect of lignin content and magnesium-to-manganese ratio on the selectivity of oxygen delignification in softwood kraft pulp." Pure and Applied Chemistry 73, no. 12 (January 1, 2001): 2059–65. http://dx.doi.org/10.1351/pac200173122059.

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A series of oxygen delignification experiments were performed on two softwood kraft pulps that had differing starting lignin contents. One had an initial kappa of 40 and the other 25, corresponding to lignin contents of 6% and 3.75% by dry mass, respectively. Several chemical process modifications were examined to determine their influence over the delignification selectivity and final pulp viscosity. A 2k factorial format was used to assess the significance of varying the temperature, time, and Mg/Mn ratio during the oxygen delignification of the pulps. It was found that the lower lignin content pulp displayed greater delignification selectivity than the higher lignin content pulp. Kappa numbers, viscosity values, and ICP metals contents were determined and are the basis of discussion for the results obtained.

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43

NAITHANI, VED, LUCIAN LUCIA, HASAN JAMEEL, and PETER W. HART. "Soybean peroxidase treatment of ultra-high kappa softwood pulp to enhance yield and physical properties." September 2020 19, no. 9 (October 1, 2020): 437–43. http://dx.doi.org/10.32964/tj19.9.437.

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The working hypothesis serving as basis for this study is that pulping to a higher kappa number will produce a higher yield pulp, and then treating that pulp with a surface reactive lignin peroxidase to ablate surface lignin will increase specific bonding area. In the present case, the working hypothesis was modified so that soybean peroxidase (SBP) works like lignin peroxidase to modify surface lignin on high-kappa, high-yield softwood pulps to facilitate enhanced fiber-to-fiber bonding such that the resulting paper strength is similar to the lower kappa soft-wood pulp generally used to make linerboard. Soybean peroxidase is actually a plant peroxidase that exhibits lignin peroxidase-like activity. It is not a lignin peroxidase derived from white rot fungus. The current work did show a significant improvement in pulp yield (62.2% vs. 55.2% yield for a 103-kappa control linerboard grade sheet), while treatment with SBP showed that tensile, burst, and STFI properties of the pulp were improved, although more convincing data needs to be obtained.

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44

Liukko, Sirje, Ville Tasapuro, and Tiina Liitiä. "Fluorescence spectroscopy for chromophore studies on bleached kraft pulps." Holzforschung 61, no. 5 (August 1, 2007): 509–15. http://dx.doi.org/10.1515/hf.2007.107.

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Abstract Fluorescence techniques are highly sensitive and, since aromatic lignin is the most likely source of natural pulp fluorescence, they are suitable for detailed investigation of residual lignin in bleached pulps. Such investigations are important to our understanding of the bleachability and brightness reversion of pulps. In this study, the effect of bleaching on pulps was evaluated using fluorescence spectra of two softwood kraft pulps bleached in six elemental chlorine-free and totally chlorine-free sequences. Fluorescence spectra were recorded in each bleaching stage using four different instrument settings. In general, pulp fluorescence at excitation wavelengths of 270 and 350 nm increased as bleaching proceeded. Below a certain lignin content, however, pulp fluorescence measured at an excitation wavelength of 430 nm decreased with the residual lignin content. Carbonyl groups have a quenching effect on fluorescence, and the formation of carbonyl groups after oxygen and ozone delignification induced a decrease in pulp fluorescence. The increase in pulp fluorescence after peroxide bleaching stages was due to the removal of carbonyl groups. Reactions of chromophores during brightness reversion also had an effect on pulp fluorescence. These findings demonstrate that fluorescence spectroscopy provides an interesting tool for pulp bleaching studies.

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45

Harirforoush, R., J. Olson, and P. Wild. "Bar force measurement in low consistency refining: the effect of plate pattern." Nordic Pulp & Paper Research Journal 33, no. 2 (July 26, 2018): 210–19. http://dx.doi.org/10.1515/npprj-2018-3036.

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Abstract The effect of plate pattern on forces applied to pulp fibers by refiner bars in low consistency refining is investigated in an AIKAWA 16-inch single-disc refiner. These forces are measured using a custom-built piezoelectric sensor. Trials are conducted using SPF softwood thermomechanical pulp, northern bleached softwood kraft pulp, and aspen hardwood thermomechanical pulp at 3.3 to 3.6 % consistency at rotational speeds of 1200 and 1400 rpm. The pulp is sampled at regular intervals, and the length-weighted fiber length, freeness, tear index, and tensile index are measured for each sample. The results show that the plate with higher bar edge length results in lower mean peak normal and shear forces. The mean peak normal and shear forces at the onset of fiber cutting depend on rotational speed, pulp furnish and plate pattern, and these parameters are lower for a plate pattern with higher bar edge length. In addition, the mean coefficient of friction is a function of plate gap, pulp furnish, and plate pattern. The plate having higher bar edge length results in higher mean coefficient of friction.

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46

Li, Jianguo, Hongjie Zhang, Chao Duan, Yishan Liu, and Yonghao Ni. "Enhancing hemicelluloses removal from a softwood sulfite pulp." Bioresource Technology 192 (September 2015): 11–16. http://dx.doi.org/10.1016/j.biortech.2015.04.107.

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47

Zhao, Hong, Lin Qi, Fei Du, and Chang Jiang Yu. "The Effect of Fiber Constitution and Beating Process on Surface Strength of Packing Paper." Advanced Materials Research 199-200 (February 2011): 1785–88. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.1785.

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This article studied on these factors which influences the surface strength of packing paper. Through a series of tests, a model has been found. This model could guide the adjustment about fiber composition and beating process. And then a pilot scale test about this model has been carried out in Henan. The conclusion indicated that surface strength, printability and other strength indexes have been improved by adjustment of fiber composition and beating process scientifically. The ratio of softwood pulp has been reduced from 28% to 23%~25%. And the surface strength has been increased from 0.8~1.2m/s to 1.5~1.8m/s. Furthermore, when the ratio of softwood pulp is 23% and chemical-mechancial pulp is 7%, the packing paper still has a good printability.

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48

Lapierre, Luc, Jean Bouchard, and Richard Berry. "On the relationship between fibre length, cellulose chain length and pulp viscosity of a softwood sulfite pulp." Holzforschung 60, no. 4 (July 1, 2006): 372–77. http://dx.doi.org/10.1515/hf.2006.058.

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Abstract Many chemical pulp mills use pulp viscosity as an indicator of pulp strength, and some mill customers stipulate a particular viscosity threshold for the delivered product. Nevertheless, the value of the viscosity-strength relationship is often questioned, particularly as it varies with the wood species and the pulping process. To provide some insight, the viscosity, degree of polymerisation and fibre length were measured for a bleached softwood sulfite pulp segregated into different fractions with respect to fibre length using a Bauer-McNett fractionator. It was demonstrated that fractions with a longer average fibre length also had a higher degree of polymerisation and higher viscosity. The cellulose chain length in chemical pulps is approximately three orders of magnitude shorter than the fibre length, and thus a relationship between these two properties should not be expected. The possible causes of the correlation between fibre length and viscosity are discussed. In this work, viscosity appears to be an indirect measurement of the average fibre length of a pulp, which would be the direct contributor to the strength of that pulp.

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Vander Wielen, Lorraine C., Derek H. Page, and Arthur J. Ragauskas. "Enhanced wet tensile paper properties via dielectric-barrier discharge." Holzforschung 59, no. 1 (January 1, 2005): 65–71. http://dx.doi.org/10.1515/hf.2005.011.

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Abstract Dielectric-barrier discharge treatment was used to modify fully bleached softwood kraft and unbleached softwood thermomechanical pulp handsheets. The effect of dielectric-barrier discharge treatment on the physical strength properties and dimensional stability of handsheets were analyzed. Increased dielectric-barrier discharge treatment power resulted in significant increases in the wet tensile index of handsheets. Increases in the surface acid content of pulp fibers do not appear to contribute to changes in paper properties, nor do changes to relative bonded area within handsheets. Enhanced wet strength via dielectric-barrier discharge treatment corresponds to increased dimensional stability. This appears to be due to fiber cross-linking in the case of bleached kraft pulp, since the wet-strain decreases as wet tensile and wet Young's modulus increase. In the case of unbleached thermomechanical pulp, the wet-strain shows no decrease, yet the wet Young's modulus increases as the wet tensile index increases.

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50

Bujanovic, Biljana, Sally A. Ralph, Richard S. Reiner, and Rajai H. Atalla. "Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)." Holzforschung 61, no. 5 (August 1, 2007): 492–98. http://dx.doi.org/10.1515/hf.2007.102.

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Abstract Commercial softwood kraft pulp with kappa number 30.5 (KP30.5) was delignified with polyoxometalates (POM, Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40]), and POM-treated kraft pulp of kappa number 23.6 was obtained (KPPOM,23.6). Residual lignin from pulps was isolated by mild acid hydrolysis and characterized by analytical and spectral methods to gain insight into lignin reactions taking place during the initial delignification phase. Lignin from POM-delignified pulp was isolated in lower yield. Comparative analysis of residual lignins (RL-KP30.5, RL-KPPOM,23.6) showed that POM leads to products enriched in carbonyl/carboxyl groups and carbohydrates. POM lignins have a lower molecular mass and a lower content of phenolic hydroxyl and methoxyl groups. Based on these results and FTIR spectra, we suggest that aromatic ring cleavage and quinone formation occur during POM delignification. The degree of lignin-cellulose association increases after POM delignification. Lignin-cellulose association was found to be partially unstable under mild alkaline conditions, as residual lignin isolated after alkaline extraction of KPPOM,23.6 pulp (RL-KPPOM/NaOH) exhibited lower glucose content, higher Klason lignin content, and less extraneous material.

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Journal articles on the topic 'Softwood pulp'

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