Journal articles on the topic 'Pulp'
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1
Possot, Odile M., Guillaume Vignon, Natalia Bomchil, Frank Ebel, and Anthony P. Pugsley. "Multiple Interactions between Pullulanase Secreton Components Involved in Stabilization and Cytoplasmic Membrane Association of PulE." Journal of Bacteriology 182, no. 8 (April 15, 2000): 2142–52. http://dx.doi.org/10.1128/jb.182.8.2142-2152.2000.
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ABSTRACT We report attempts to analyze interactions between components of the pullulanase (Pul) secreton (type II secretion machinery) fromKlebsiella oxytoca encoded by a multiple-copy-number plasmid in Escherichia coli. Three of the 15 Pul proteins (B, H, and N) were found to be dispensable for pullulanase secretion. The following evidence leads us to propose that PulE, PulL, and PulM form a subcomplex with which PulC and PulG interact. The integral cytoplasmic membrane protein PulL prevented proteolysis and/or aggregation of PulE and mediated its association with the cytoplasmic membrane. The cytoplasmic, N-terminal domain of PulL interacted directly with PulE, and both PulC and PulM were required to prevent proteolysis of PulL. PulM and PulL could be cross-linked as a heterodimer whose formation in a strain producing the secreton required PulG. However, PulL and PulM produced alone could also be cross-linked in a 52-kDa complex, indicating that the secreton exerts subtle effects on the interaction between PulE and PulL. Antibodies against PulM coimmunoprecipitated PulL, PulC, and PulE from detergent-solubilized cell extracts, confirming the existence of a complex containing these four proteins. Overproduction of PulG, which blocks secretion, drastically reduced the cellular levels of PulC, PulE, PulL, and PulM as well as PulD (secretin), which probably interacts with PulC. The Pul secreton components E, F, G, I, J, K, L, and M could all be replaced by the corresponding components of the Out secretons of Erwinia chrysanthemi and Erwinia carotovora, showing that they do not play a role in secretory protein recognition and secretion specificity.
2
Stankovská, Monika, Mária Fišerová, Juraj Gigac, and Elena Opálená. "EFFECT OF ADDITION OF DEINKED PULP TO BLEACHED KRAFT PULP ON TISSUE PAPER PROPERTIES." WOOD RESEARCH 66(3) 2021 66, no. 3 (July 20, 2021): 505–16. http://dx.doi.org/10.37763/wr.1336-4561/66.3.505516.
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The influence of addition of deinked pulps with low and high brightness to bleached eucalyptus and pine kraft pulps on functional tissue paper properties was studied. Deinked pulps with low and high brightness had some different functional properties. Deinked pulp with high brightness has higher bulk, porosity, water absorption after immersion, initial water absorption, bulk softness as well as brightness. On the contrary, the difference in relative bonded area and porosity e between deinked pulps with low and high brightness was moderate. The mixed pulps laboratory pulp sheets from bleached eucalyptus kraft pulp or bleached pine kraft pulp with addition of 20, 40 and 80% of deinked pulp with low brightness or deinked pulp with high brightness were prepared. The addition of the deinked pulp with high or low brightness to bleached kraft pulp leads to increasing of bulk, bulk softness as well as high water absorption after immersion and initial water absorption. The tensile index rapidly decreased by the addition of deinked pulps with high brightness to bleached eucalyptus and pine kraft pulps. Similarly, the addition of deinked pulp with low brightness to bleached pine kraft pulp led to rapid decreasing of tensile index. On contrary, with the addition of deinked pulp with low brightness to eucalyptus kraft pulp, the decreasing of tensile index was less pronounced. Mixed pulp from bleached eucalyptus kraft pulp with a small content of deinked pulp with low brightness with functional properties suitable for production of tissue papers was found as optimal.
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Koray Gülsoy, Sezgin, and Saffet Uysal. "Effects of Recycled Fiber Fines on Hand Sheet Properties of Different Unbeaten and Beaten Pulps." Drvna industrija 71, no. 4 (September 28, 2020): 327–37. http://dx.doi.org/10.5552/drvind.2020.1904.
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In this study, 5, 10, and 15 % secondary fines of recycled pulp were added to unbeaten and beaten (28 ºSR) samples of recycled pulp, Turkish Calabrian pine (Pinus brutia Ten.) kraft pulp, and European aspen (Populus tremula L.) kraft pulp. The effects of the addition of fiber fines on hand sheets properties were evaluated. The addition of fiber fines to the unbeaten pulps improved the strength properties of hand sheets. The roughness of hand sheets was also decreased with the addition of fines. When fiber fines were added to the beaten pulps, the type of pulp strongly affected the paper strength properties. The strength properties of beaten pulps of Turkish Calabrian pine and European aspen were decreased with the addition of fiber fines, while the strength properties of beaten pulps of recycled pulp were increased. On the other hand, the air permeance of unbeaten and beaten samples was decreased with the addition of fiber fines. Consequently, the addition of fines to unbeaten and beaten pulps had a more pronounced effect on European aspen kraft pulp and recycled pulp than on Turkish Calabrian pine kraft pulp. Also, the strength of paper made of unbeaten recycled pulp with the addition of 15 % fines was higher than that of fines-free beaten recycled pulp.
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Jahan, M. Sarwar, and Sabina Rawshan. "Reinforcing potential of jute pulp with Trema orientalis (nalita) pulp." BioResources 4, no. 3 (May 6, 2009): 921–31. http://dx.doi.org/10.15376/biores.4.3.921-931.
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Two morphologically different pulps, a long-fiber jute pulp from a soda-AQ process and a short-fiber Trema orientalis pulp from a kraft process, were evaluated and compared for their reinforcing potential. T. orientalis pulp needed less beating energy than jute pulp at the same drainage resistance. Addition of jute fiber pulp to the T. orientalis pulp increased tear strength. Sheet density of pulp blends was increased with the increase of beating degree of both pulps and the proportion of T. orientalis pulp. Tensile index and burst index of blended pulp were increased when the beating degree and proportion of T. orientalis pulp increased.
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Korpinen, Risto I., and Pedro E. Fardim. "Reinforcement potential of bleached sawdust kraft pulp in different mechanical pulp furnishes." BioResources 4, no. 4 (October 6, 2009): 1572–85. http://dx.doi.org/10.15376/biores.4.4.1572-1585.
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Bleached unrefined and refined sawdust kraft pulps were added to bleached Norway spruce thermomechanical (TMP) and pressurised groundwood (PWG) pulps in different proportions. Handsheets were prepared and tested for physical properties. In addition, economic calculations were done to estimate the production costs of different bleached pulps in Finland. It was found that the addition of unrefined and refined sawdust kraft pulp improved drainability of the mechanical pulps. Tear strength of PGW furnishes was increased when either unrefined or refined sawdust pulp was added. Tear strength of TMP furnishes was not influenced when different sawdust kraft pulps were added. Up to 30 % of unrefined sawdust kraft pulp could be added and no significant negative effect was observed in TMP and PGW furnishes. On the other hand, when refined sawdust kraft pulp was added into the mechanical pulp furnishes, a clear improvement in the tensile strength was observed. According to the economic calculation the production cost of bleached sawdust kraft pulp is almost as low as the production cost of bleached mechanical pulp. We suggest that economically viable sawdust kraft pulp can be used as a substituent for expensive long fibre reinforcement kraft pulp in the production of mechanical pulp based papers.
6
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.
7
Małachowska, Edyta, Marcin Dubowik, Aneta Lipkiewicz, Kamila Przybysz, and Piotr Przybysz. "Analysis of Cellulose Pulp Characteristics and Processing Parameters for Efficient Paper Production." Sustainability 12, no. 17 (September 3, 2020): 7219. http://dx.doi.org/10.3390/su12177219.
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For economic reasons, increasing the use of various fibrous pulps with high lignin contents—i.e., chemothermomechanical pulp (BCTMP and CTMP), thermomechanical pulp (TMP), and semichemical pulp—is desirable. The relatively good quality and increased efficiency of these pulps make them attractive paper semi-products. In particular, they could alleviate the severe shortage of paper semi-products. Although mechanical pulp and semichemical pulp are achieving increasing quality with substantially increased wood efficiency, their production is often characterised by high consumption of electricity to defibre chips or refine high-lignin-content fibrous pulps. Technological, environmental, and economic evaluations of the manufacture and application of increased efficiency cellulose pulps that take into account potential profits from increased cellulose pulp efficiency and losses due to energy costs and degradation in the properties of the resulting paper are relevant and essential to paper mills. This article reports such an analysis. The authors have analysed the usable properties of ten cellulose pulps with various degrees of digestion and identified the optimum pulp that yields the optimum product properties, considering the yield; pulp refining time, which determines the cost of paper manufacture; and strength properties of the obtained paper.
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XU, ERIC C., and YAJUN ZHOU. "Synergistic effects between chemical mechanical pulps and chemical pulps from hardwoods." November 2007 6, no. 11 (December 1, 2007): 4–9. http://dx.doi.org/10.32964/tj6.11.4.
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Chemical pulps and chemical mechanical pulps from different hardwoods were compared for intrinsic and other pulp properties. Comparisons were made separately and in combination with these two types of pulps. The results showed that hardwood chemical mechanical pulps, such as preconditioned refiner chemical alkaline per-oxide mechanical pulp (P-RC APMP), can be developed to be as strong as chemical pulps, and have higher tensile at the same density, or higher bulk at the same tensile, compared with the chemical pulps. When combining pulps from the two processes, addition of certain percentages of hardwood chemical mechanical pulps to chemical pulp improved pulp intrinsic properties, and the resulting pulp blends had higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. This synergistic effect between the chemical and the chemical mechanical pulps may be used to improve papermaking processes and their paper and paperboard products.
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Gülsoy, Sezgin Koray, Ülkü Burcu Gitti, and Ayhan Gençer. "Comparison of Soda, Kraft, and DES Pulp Properties of European Black Poplar." Drvna industrija 73, no. 2 (May 31, 2022): 215–26. http://dx.doi.org/10.5552/drvind.2022.2112.
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Kraft pulping as the dominant pulping method contributes to several environmental problems. To overcome these problems, environmentally friendly pulping methods have been investigated. In the last years, deep eutectic solvents (DESs) have been identified as up-and-coming reagents in the lignocellulosic material processing and they are characterized as environmentally friendly. This study investigated the use of DES in pulp production from European black poplar chips. The DES mixture was prepared from choline chloride (ChCl) and ethylene glycol (EG). In addition, traditional soda and kraft pulping methods were carried out with poplar chips for comparison with the DES pulps. It was found that pulp production from poplar chips using DES was comparable to the soda and kraft pulps in terms of pulp yield, pulp viscosity, and opacity. The DES pulps easily reached target pulp freeness levels. However, the strength properties and brightness of the DES pulps were lower than those of the soda and kraft pulps. The strength properties of DES pulps can be improved with paper strength enhancers such as starch and micro or nanofibrillated cellulose. Also, the utilization of DES in pulp production may have an important role in cleaner production and it represents a greener alternative to traditional pulp production methods.
10
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.
11
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.
12
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.
13
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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Laine, Christiane, Tarja Tamminen, and Bo Hortling. "Carbohydrate structures in residual lignin-carbohydrate complexes of spruce and pine pulp." Holzforschung 58, no. 6 (October 1, 2004): 611–21. http://dx.doi.org/10.1515/hf.2004.115.
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Abstract Residual lignin carbohydrate complexes (RLCC) were isolated enzymatically from spruce and pine pulp. The RLCCs contained 4.9–9.4% carbohydrates, with an enrichment of galactose and arabinose compared to the original pulp samples. The main carbohydrate units present in all studied RLCCs were 4-substituted xylose, 4-, 3- and 3,6-substituted galactose, 4-substituted glucose and 4 and 4,6-substituted mannose. These units were assigned to carbohydrate residues of xylan, 1,4- and 1,3/6-linked galactan, cellulose and glucomannan. RLCCs of surface material and the inner part of spruce kraft pulp fiber were compared to obtain information on the heterogeneity of layers of the fiber wall. The 1,4-linked galactan was the major galactan in RLCC of fiber surface material of spruce kraft pulp. Towards the inner part of the fiber, the proportion of 1,3/6-linked galactan increased relative to 1,4-linked galactan. This finding is presented for the first time. 1,3/6-Linked galactan structures are suggested to have a role in restricting lignin removal from the secondary fiber wall. RLCCs of three different alkaline pine pulps were studied before and after oxygen delignification to evaluate differences resulting from the cooking method. The pulps were conventional kraft pine pulp (PCK), a polysulfide/anthraquinone pine pulp (PPSAQ) and a soda/anthraquinone pine pulp (PSoAQ); all were cooked to approximately kappa number 30. Small differences were found in the carbohydrate structures of the unbleached pulps. The study indicated that the RLCC of unbleached PSoAQ pulp contained longer oligomeric carbohydrate chains and less branched 1,3/6-linked galactan residues than the RLCCs of unbleached PCK and PPSAQ pulps. The RLCC of the unbleached PSoAQ also contained more 1,4-linked glucose units suggesting a greater number of linkages of lignin to cellulose in the PSoAQ pulp than in the other two pulps. All RLCCs of oxygen-delignified pulps had more non-reducing ends and less 1,3/6-linked galactan than the corresponding RLCCs of the unbleached pulps. The RLCC of the oxygen-delignified PSoAQ pulp had a higher ratio of 1,4-galactan to 1,3/6-linked galactan and shorter xylan residues than the RLCCs of oxygen-delignified PCK and PPSAQ pulps.
15
Al Baik, Seraj, Abbas Al Mkenah, Abdulmomen Khan, Abdullah Alkhalifa, Ahmed Al Makinah, Haitham Alquraini, Ali Al Khars, Alanoud Almakinah, Doaa Almakinah, and Alaa Almalki. "Pulpotomy vs. pulpectomy techniques, indications and complications." International Journal Of Community Medicine And Public Health 5, no. 11 (October 25, 2018): 4975. http://dx.doi.org/10.18203/2394-6040.ijcmph20184261.
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Several pulp therapies were developed to maintain the health and integrity of the teeth pulps because of their necessity for physiological growth of healthy permanent teeth with a long-term preserved function. Pulp therapies aims mainly at protecting the teeth that were affected by caries, infection, or trauma. Pulpotomy and pulpectomy are the most common utilized pulp therapies, and the choice between them depends on several factors, for instance, the vitality of the existing pulp, the portion of the pulp involved (e.g. coronal versus radicular portions), the presence or absence of reversible/irreversible pulpitis, the presence or absence of a necrotic pulp, the state of surrounding bones and soft tissues, and the presence or absence of infection, abscesses, fistulae, or underlying cysts. Basically, pulpotomy is usually therapy of option in patients with vital pulps, whilst pulpectomy is preferred in cases with non-vital teeth pulps. This article will review and summarize the main differences between pulpotomy and pulpectomy particularly regarding their definition, indications, techniques, and complications.
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Kuştaş, Süleyman, and Sezgin Koray Gülsoy. "Boron Compounds-Added Kraft Pulping from Scots Pine." Drvna industrija 74, no. 1 (March 25, 2023): 43–52. http://dx.doi.org/10.5552/drvind.2023.0014.
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In this study, effects of KBH4 (PB), NaBH4 (SB), Etibor-48 (E48), Etidot-67 (E67), and colemanite (Col) on kraft pulp and paper properties of Scots pine (Pinus sylvestris L.) wood were evaluated. The control and boron compound-added kraft pulps were obtained under constant cooking conditions. The boron compounds were used as digester additives in different ratios (2 % and 4 %). The addition of boron compounds to kraft cooking liquor resulted in increases screened and total yield of pulps. The highest screened yield (52.05 %) and total yield (55.09 %) were obtained from PB-4 pulp. The lowest reject ratio (0.61 %) and kappa number (34.60) were determined from PB-2 pulp. Furthermore, the highest tensile properties of handsheets were obtained from E67-4 pulp. Also, E48-4 pulp had the highest burst index and tear index values. E48, E67, and Col are cheaper than PB and SB. From these boron compounds, pulps with relatively low pulp yield but stronger can be obtained.
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Seisto, Anu, and Krisriina Poppius-Levlin. "Fibre characteristics and paper properties of formic acid / peroxyformic acid birch pulps." Nordic Pulp & Paper Research Journal 12, no. 4 (December 1, 1997): 237–43. http://dx.doi.org/10.3183/npprj-1997-12-04-p237-243.
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Abstract The fibre and paper properties of nine unbleached formic acid / peroxyformic acid (MILOX) pulps with kappa number 6-20 were studied and compared with a kraft pulp with kappa number 20. The degree of deformation was greater in the MILOX fibres, affecting the paper properties of the MILOX pulps. The large number of curl and kinks in the MILOX fibres were probably caused mechanically. The MILOX fibres showed greater conformability, resulting in higher paper density. The defects in the MILOX fibres were apparently so severe as to cause fibre breakage during PFI beating of the pulps. As a result of both fibre deformation and breakage, the tensile strengths of the MILOX pulps were lower than that of the reference kraft pulp, and tensile strength development during beating was slower. The tear strength of the best MILOX pulp was lower than that of the kraft pulp when compared at the same tensile index. Fibre deformation in both MILOX and the kraft pulp increased during bleaching. The kinks in the fibres were possibly set into position, giving the bleached MILOX pulps poorer bonding ability and lower paper density. A high degree of fibre defo~mation had the same effect on the tensile strength development of the bleached MILOX pulps as it did in the unbleached state. The light scattering properties of the MlLOX pulps were better than those of the kraft pulp, possibly due to the higher fines content of the MILOX pulps. The results indicate that more attention should be given to mechanical treatments during MILOX pulping in order to bring the strength properties closer to those of kraft pulp.
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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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Pan, X. J., Y. Sano, and T. Ito. "Atmospheric Acetic Acid Pulping of Rice Straw II: Behavior of Ash and Silica in Rice Straw during Atmospheric Acetic Acid Pulping and Bleaching." Holzforschung 53, no. 1 (January 1, 1999): 49–55. http://dx.doi.org/10.1515/hf.1999.009.
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Summary A detailed examination was made of the behavior and distribution of ash and silica during atmospheric acetic acid pulping and subsequent bleaching of rice straw. Ash-rich pulps (in unbleached pulp, about 18%; and in bleached pulp, 16%) with matchable strength properties for conventional alkaline pulps were obtained from rice straw by acetic acid pulping. More than 50% of the ash and about 75% of the silica in rice straw were retained in the pulp after pulping. Because only those acid-soluble mineral components were dissolved during acetic acid pulping, the ash remained in the pulp consisted mainly of silica (92.9% of the ash in unbleached pulp and 97.3% of the ash in bleached pulp). Although part of the ash dissolved during bleaching, the ash content of bleached pulp was still 15.5%, a value much higher than that in other conventional pulps. This type of ash might be good as a filler for paper. Fractionation analysis and the profile and mapping of silica by scanning electron microscope combined with an energy dispersive X-ray analysis (SEM-EDXA) indicated that the silica in the bleached pulp was located mainly in epidermal cells and not in other elements, such as fibers and parenchyma, and that the silica-rich epidermal cells were scattered throughout the pulp as single cells or in bundles.
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Dang, Zheng, Thomas Elder, Jeffery S. Hsieh, and Arthur J. Ragauskas. "Alkaline peroxide treatment of ECF bleached softwood kraft pulps: Part 2. Effect of increased fiber charge on refining, wet-end application, and hornification." Holzforschung 61, no. 4 (June 1, 2007): 451–58. http://dx.doi.org/10.1515/hf.2007.071.
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Abstract The effect of increased fiber charge on refining, cationic starch adsorption, and hornification was examined. Two pulps were investigated: (1) a softwood (SW) kraft pulp (KP) which was bleached elementally chlorine-free (ECF) and served as control; and (2) a control pulp treated with alkaline peroxide, which had a higher fiber charge. It was shown that increased fiber charge can improve the efficiency of the refining treatment, as indicated by differences in tensile index refined from 0 to 1000 revolutions. When the control pulp was refined from 4000 to 8000 revolutions, the tensile index decreased. In contrast, the tensile index of the higher fiber charge pulp (HCP) was higher under the same refining conditions. Upon addition of 2% cationic starch to both pulps, the tensile index of the control pulp increased by 13.7% and that of HCP by 23.7%. Atomic force microscopy did not reveal differences in the surface morphology of the two pulps with and without cationic starch adsorption. Peroxide treatment enhanced the fiber charge of the never-dried pulp. This was beneficial in reducing hornification when pulp was dried at 105°C. However, if the once dried pulp at 105°C was treated with peroxide, this resulted in a drastic decrease in intrinsic viscosity of the pulp and lower tensile and burst indices of the test sheets.
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Das, N., SK Bose, and D. Biswas. "Effect of magnesium-salts on hydrogen peroxide bleaching of non-wood pulps." Bangladesh Journal of Scientific and Industrial Research 51, no. 4 (December 10, 2016): 291–96. http://dx.doi.org/10.3329/bjsir.v51i4.30449.
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Transition metal ions present in pulp, cause wasteful decomposition of hydrogen peroxide, a pulp brightener, and thus significantly affect the delignification selectivity of hydrogen peroxide bleaching. The metal ions also affect the brightness and optical properties of pulp. The free radicals generated during the decomposition degrade carbohydrates resulting in lower viscosity and yield. It is reported in the literature that magnesium sulfate successfully adsorbs transition metal ions and thus decrease their activity. This study dealt with the effect of Mg salts in hydrogen peroxide bleaching of jute caddies pulp. It was observed that prior bleaching treatments like chelation and acid washing of pulp were efficient in removing transition metal ions as indicated by lower consumption of hydrogen peroxide. However EDTA chelation seemed better compared to acid washing. The inclusion of Mg salts improved pulp brightness. The pulp viscosity was the highest with 0.3% Mg addition for both treated kraft and soda-AQ pulps. Considering both pulp viscosity and pulp brightness, it appeared that a 0.3% Mg dose on EDTA chelated pulp, was enough in hydrogen peroxide bleaching of pulps obtained from jute caddies. Bangladesh J. Sci. Ind. Res. 51(4), 291-296, 2016
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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.
Full textAbstract:
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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Liu, Jie, Rongrong Wang, Xinyu Wang, Lvzhu Yang, Yang Shan, Qun Zhang, and Shenghua Ding. "Effects of High-Pressure Homogenization on the Structural, Physical, and Rheological Properties of Lily Pulp." Foods 8, no. 10 (October 10, 2019): 472. http://dx.doi.org/10.3390/foods8100472.
Full textAbstract:
The effects of high-pressure homogenization (HPH) on the structural, physical, and rheological properties of lily pulp (15%, w/w) were investigated. Different pressures ranging from 0 MPa to 100 MPa were used. The focus was on evaluating the changes in the particle size distribution (PSD), structure, pulp sedimentation behavior, serum cloudiness (SC), total soluble solids (TSS), color, and rheological behavior of the pulps. PSD analysis showed that the diameter of suspended lily particles significantly decreased with an increasing homogenization pressure. The suspended particles observed through optical microscopy became small after homogenization, highlighting the effect of HPH on disrupting the suspended particles. Compared with the untreated pulp, the SC and sedimentation velocity of the homogenized pulps decreased due to the disruption of the suspended particles. The effects of HPH on the sedimentation index and SC exhibited an asymptotic behavior similar to that of the changes in the particle size of lily pulp. Moreover, HPH processing reduced the viscosity of lily pulp and increased the TSS and lightness of the homogenized pulps. HPH significantly modified the structural, physical, and rheological properties of lily pulp. The pulp homogenized above 60 MPa had good suspension stability. This finding indicates that HPH technology can be used to improve the stability of lily pulp.
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Chaiarrekij, Somporn, Apiporn Apirakchaiskul, Kuntinee Suvarnakich, and Suda Kiatkamjornwong. "Kapok I: Characteristics of kapok fiber as a potential pulp source for papermaking." BioResources 7, no. 1 (November 27, 2011): 475–88. http://dx.doi.org/10.15376/biores.7.1.475-488.
Full textAbstract:
The potential use of kapok fiber for pulping and papermaking has been investigated. The kapok fibers were cooked using the optimal dosage of sodium hydroxide determined from the experiments. Then, the pulp was refined with two passes using a disc refiner and mixed with commercial hardwood pulp and/or softwood pulp at different blend ratios to make papers. It was found that addition of the kapok pulp to the mixed pulps improved the tensile and burst strengths of the sheets but decreased the tear resistance and elongation. Water repellency of the sheets prepared from the kapok pulp mixed with the commercial pulps was also improved. These results indicate that kapok fiber can be a quality pulp source for papermaking, especially for packaging paper requiring strength and water repellency.
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FERDOUS, TASLIMA, MD IMRAN HOSSAIN, MOUMITA NANJIBA, M. A. QUAIYYUM, and M. SARWAR JAHAN. "CHLORINE DIOXIDE BLEACHING OF PULP FROM CROP RESIDUES: BAGASSE, KASH AND CORN STALKS." Cellulose Chemistry and Technology 55, no. 3-4 (April 20, 2021): 281–87. http://dx.doi.org/10.35812/cellulosechemtechnol.2021.55.28.
Full textAbstract:
"This investigation describes the effect of hot chlorine dioxide delignification (DHT) of bagasse, kash and corn stalk pulps on pulp properties and effluent quality. The pulps were subjected to DHT at 85 °C for 45 min and the results were compared with those of the D0 process carried out at 70 °C for 45 min. The kappa numbers after the alkaline extraction (Ep) stage in DHT bleaching were always lower and brightness was higher, compared to the corresponding parameters in D0 bleaching, without impacting pulp viscosity. The final brightness of the corn stalk pulp was 84.8% at a kappa factor of 0.25 in the D0 process, while in the DHT process, the same type of pulp reached the brightness of 87.2% at a kappa factor of 0.15, saving 40% ClO2 in the first stage. Similarly, kash pulp exhibited 90% brightness at a kappa factor of 0.15, which also saved 40% ClO2, compared to the conventional D0 process. The brightness of bagasse pulp in DHT and D0 processes was almost similar. Oxygen delignified pulp had a lower effluent discharge than unbleached pulps in subsequent ECF bleaching. The COD value in DHT was lower than that in D0."
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Jacobsen, Eirik Ulsaker, Simen Prang Følkner, Jørgen Blindheim, Dag Molteberg, Martin Steinert, and Gary Chinga-Carrasco. "The Effect of Cellulose Nanofibres on Dewatering during Wet-Forming and the Mechanical Properties of Thermoformed Specimens Made of Thermomechanical and Kraft Pulps." Nanomaterials 13, no. 18 (September 7, 2023): 2511. http://dx.doi.org/10.3390/nano13182511.
Full textAbstract:
Due to environmental concerns regarding single-use plastic materials, major efforts are being made to develop new material concepts based on biodegradable and renewable resources, e.g., wood pulp. In this study, we assessed two types of wood pulp fibres, i.e., thermomechanical pulp (TMP) and Kraft pulp fibres, and tested the performance of the fibres in wet-moulding and thermopressing trials. Kraft pulp fibres appeared to retain more water than TMP, increasing the dewatering time during wet-moulding and apparently increasing the compression resistance of the pulp during thermoforming. Additionally, cellulose nanofibres (CNF) were added to the pulps, which improved the mechanical properties of the final thermopressed specimens. However, the addition of CNF to the pulps (from 2 to 6%) had a further decrease in the dewatering efficiency in the wet-moulding process, and this effect was more pronounced in the Kraft pulp specimens. The mechanical performance of the thermoformed specimens was in the same range as the plastic materials that are conventionally used in food packaging, i.e., modulus 0.6–1.2 GPa, strength 49 MPa and elongation 6–9%. Finally, this study demonstrates the potential of wood pulps to form three-dimensional thermoformed products.
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GONG, CHEN, ASIF HASAN, BILJANA M. BUJANOVIC, and THOMAS E. AMIDON. "Novel blend of biorenewable wet-end paper agents." January 2012 11, no. 1 (February 1, 2012): 41–48. http://dx.doi.org/10.32964/tj11.1.41.
Full textAbstract:
Recent studies have shown potential for a designed biorefinery product, polylactic acid (PLA), to increase the strength-to-weight ratio of paper produced from conventional kraft pulp and kraft pulp made from hot-water extracted hardwoods (biorefinery pulp). These results indicated that, after surface-treatment with 2 % PLA (per ovendry [o.d.] fiber basis), paper made from sugar maple biorefinery pulp could be equivalent to or even greater in strength than paper made from sugar maple conventional kraft pulp, while retaining its higher bulk. In the current study, we present the results of reinforcement of the pulps with PLA applied in the wet-end in combination with a known environmentally friendly dry strength agent, cationic starch. The preliminary results obtained with amylopectin-based starch of relatively high nitrogen content (starch B) were encouraging since strength, including wet strength and stretch, of paper reinforced with a blend of 0.5% starch B and 0.5% PLA was higher than strength of paper reinforced with 1% starch B. Moreover, based on the compatible strengths of paper reinforced with 0.6 % PLA-starch B blend (1/5) and of paper reinforced with 1% starch B, we hypothesize that there is a synergistic effect of PLA and starch B on tensile strength of paper. The hypothesis was tested using pulps of different lignin content (Norway spruce thermomechanical pulp [TMP], hardwood unbleached kraft pulp, and softwood bleached kraft pulp). Tensile strength increased for papers made from these pulps. The effect was pronounced in the case of lignin-rich pulps, where tensile strength in the presence of 0.6% PLA-starch blend (1/5) exceeded that in the presence of 1% starch B. This result is in accordance with a higher attraction of lignin-rich fibers to hydrophobic PLA and indicates a promising approach in increasing strength-to-weight ratio of paper made from relatively hydrophobic pulps like TMP or unbleached kraft pulp. Accordingly, paper made from unbleached hardwood kraft pulp with 0.6% PLA-starch B blend (1/5) exhibited an improved resistance to water penetration.
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Kumar, Amit. "Dissolving pulp production: Cellulases and xylanases for the enhancement of cellulose accessibility and reactivity." Physical Sciences Reviews 6, no. 5 (April 30, 2021): 111–29. http://dx.doi.org/10.1515/psr-2019-0047.
Full textAbstract:
Abstract Dissolving pulps are high-grade cellulose pulps that have minimum amount of non-cellulosic impurities. Dissolving pulps are the basic source for the manufacturing of several cellulosic products such as viscose, lyocell, cellulose acetates, cellulose nitrates, carboxymethyl-cellulose, etc. Dissolving pulps are mainly manufactured by pre-hydrolysis kraft and acid sulphite pulping. A high reactivity of dissolving pulps is desirable for its eco-friendly utilization for several purposes. Several approaches including mechanical, chemical, ultrasonic, and enzymatic treatments have been employed for the improvement of pulp reactivity. This review mainly focussed on pulp reactivity improvement through enzymatic approaches. Cellulases and xylanase have been proved effective for the improvement of pulp reactivity of dissolving pulp from different sources. The different combinations of cellulase, xylanase, and mechanical refining have been tested and found more effective rather than the single one.
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Sitholé, Bruce, Salma Shirin, Xiao Zhang, Luc Lapierre, Jorge Pimentel, and Mike Paice. "Deresination options in sulphite pulping." BioResources 5, no. 1 (December 18, 2009): 187–205. http://dx.doi.org/10.15376/biores.5.1.187-205.
Full textAbstract:
Three methods for improved deresination of sulphite pulps were evaluated, namely, alkaline washing, enzyme treatment, and pulp fractionation. Alkaline washing appears to come at a high cost, because caustic is expensive and affects cellulose chain length, as indicated by lower viscosity of the pulps. Thus this is not a viable option for pulps that are sensitive to changes in viscosity. Enzyme treatment did not completely degrade the glycerides under the mill conditions used. Fibre fractionation studies showed that the fines fractions contained 8 to 13 times more residual lipophilic extractives than the whole pulps. Removing this fraction, which represents only a small percentage of the whole pulp, could reduce by about a half the amount of lipophilic extractives in the remaining pulp. Thus pulp fractionation appears to be a viable option to achieve further deresination of sulphite pulps.
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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.
Full textAbstract:
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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Sutradhar, S., M. Sarkar, J. Nayeem, M. Sarwar Jahan, and C. Tian. "Potassium hydroxide pulping of four non-woods." Bangladesh Journal of Scientific and Industrial Research 53, no. 1 (March 11, 2018): 1–6. http://dx.doi.org/10.3329/bjsir.v53i1.35903.
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Four non-woods such as, dhaincha (Sesbania bispinosa), jute stick (Corchorus capsularis), wheat straw (Triticum aestivum) and corn stalks (Zea mays) were cooked by potassium hydroxide (KOH) at the optimum conditions of soda pulping. Dhaincha, wheat straw and corn stalks were delignified to kappa number 19.4, 13.6 and 19, respectively, while jute stick was not delignified sufficiently (kappa number 32.5). All these four raw materials maintained good yield in KOH process. Dhaincha produced the highest pulp yield (50.5%) and wheat straw had the lowest pulp yield (44.7). All pulps were bleached by D0EpD1 bleaching sequences in identical bleaching conditions. Final pulp brightness reached to above 80% ISO except jute stick pulp. Jute stick pulp reached to 74.9% brightness only after the consumption of 30 kg ClO2/ ton of pulp. The overall bleaching yields were 92.6%, 88.4%, 90.1 and 90.8% for dhaincha, jute stick, wheat straw and corn stalks pulps, respectively. The oSR of these four non-wood bleached pulps was above 20, consequently improved papermaking in the unrefined state. Beating rapidly increased papermaking properties, as for example, the tensile index of dhaincha pulps increased from 49 N.m/g in the unrefined pulp to 90 N.m/g in the beaten 50 oSR. It can be seen that KOH is a good substitute to soda process for non-wood.Bangladesh J. Sci. Ind. Res.53(1), 1-6, 2018
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El idrissi, Bouchaib, Éric Loranger, Robert Lanouette, Jean Pierre Bousquet, and Mark Martinez. "Kraft, BCTMP, and TMP dewatering behaviour along the axis of a screw press." BioResources 15, no. 1 (January 7, 2020): 1282–97. http://dx.doi.org/10.15376/biores.15.1.1282-1297.
Full textAbstract:
The drainage- and dewatering-controlling mechanisms in a screw press were detailed in this work. Three pulps (kraft pulp, bleached chemi-thermomechanical pulp, and thermomechanical pulp) were studied to compare a wide range of wood fibre types. The dewatering was controlled by the screw press parameters and the pulps’ properties. Filtration was found to be the controlling mechanism in the first part of the screw press for the three pulps, and it was less important when the fines content was greater. In the compression zone, the degree of compression was affected by the pulp flexibility and the fibres’ tendency to entangle. Filtrate flow rate monitoring along the screw press could be a good indicator of where the transition from filtration to consolidation occurs. The pressure along the screw press did not change much in the filtration zone, and it notably increased near the discharge end. When the drainage was very high, the pulp feed increased, causing the pulp axial velocity in the end part to be greater than the screw’s linear advance.
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Sousa, Cátia T., Dmitry V. Evtuguin, and José L. Amaral. "Hardwood kraft pulp structural features affecting refinability." Holzforschung 71, no. 7-8 (July 26, 2017): 619–24. http://dx.doi.org/10.1515/hf-2016-0205.
Full textAbstract:
Abstract Two industrial bleached Eucalyptus globulus kraft pulps (pulps A and B), cooked from the same wood stock with slightly different alkali charges and temperatures, showed different refinability in the laboratory beating of pulp using a PFI mill. The easy to refine pulp (A) and the difficult to refine pulp (B) did not reveal significant differences in their biometric data and general chemical composition, but pulp A showed ca. 5%–10% higher mechanical strength and twice as high refinability compared to pulp B. These differences were ascribed to slightly higher intrinsic viscosity and higher xylan content of pulp A compared to pulp B (1010 vs. 860 cm3 g−1 and 20.1 vs. 17.8%, respectively). The xylan structure and its location in fiber cells were also different, which affected the pulp’s refinability. The presence of high proportion of xylan in the bulk of fibers, rather than in their outer layers, seems to favor the pulp beating. An interpretation was also proposed, according to which the aggregation of cellulose fibrils during cooking, i.e. a partial coalescence of fibril crystallites, may also have a negative effect on pulp refinability.
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Haque, Moinul, Moumita Nanjiba, M. Sarwar Jahan, M. A. Quaiyyum, M. Zahangir Alam, and Jannatun Nayeem. "Pre-bleaching of kraft acacia pulp." Nordic Pulp & Paper Research Journal 34, no. 2 (May 26, 2019): 165–72. http://dx.doi.org/10.1515/npprj-2018-0082.
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Abstract Kraft pulps from acacia hybrid, Acacia mangium of 8 years old and Acacia auriculiformis of 6, 8 and 10 years old were pre-treated with oxygen, peroxyformic acid and acid treatment prior to bleaching. The kappa number reduction was 52–63 % by oxygen delignification, 31–35 % by peroxyformic acid (PFA) pre-treatment and 11–13 % by acid pre-treatment. Oxygen delignified pulp required less chlorine dioxide charge to reach target brightness. At the consumption of 30 kg ClO2/ton of pulp, the pulp brightness reached to 65–71 % for the untreated pulp, 81–85 % for the oxygen delignified pulp, 81–82 % for the PFA treatment and 79–80 % for acid pre-treated pulp. COD load in bleached effluent was much lower in oxygen delignified pulp. Cold alkali extraction of unbleached and oxygen delignified pulps was also carried out with varying alkali charge to remove hexenuronic acid (HexA) from the pulp. Xylan removal from the pulp was insignificant and resulted in no removal of HexA. Acid pretreatment removed 55.7 % to 17.8 % HexA from acacia hybrid, 57.5 % to 16.3 % from A. auriculiformis of 10 years and 58.6 % to 20.1 % from A. auriculiformis of 6 years old, resulting in improved final pulp brightness.
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Prasertpong, Ruethaichanok, Phattharasaya Rattanawongkun, Nattaya Tawichai, Uraiwan Intatha, and Nattakan Soykeabkaew. "Effect of Valley Beater Refining on Tensile Properties of Molded Pulps from Rice Straws." Key Engineering Materials 889 (June 16, 2021): 73–78. http://dx.doi.org/10.4028/www.scientific.net/kem.889.73.
Full textAbstract:
Rice straw, an abundant agricultural waste, is shown to be a promising resource for pulp and paper packaging manufacturing. In this study, rice straw pulps or cellulose fibers were extracted using a soda-AQ process and then the rice straw pulp slurries were refined by a Valley beater. The effect of refining time (15-60 min) on the pulp fiber characteristics was studied. It was found that both initial fiber length and width were decreased with refining time. The refined fibers became fibrillated, finer, and also more uniform in size confirmed by SEM. The pulp freeness (CSF) was reduced with increasing refining time as expected due to higher water-holding capacity of more fibrillated pulps. Then, the molded sheets were formed from the prepared rice straw pulps and examined. From tensile testing, the results indicated that the tensile properties of the molded sheets from the refined pulps were significantly enhanced (p < 0.05), thanks to an increase in fibrillated fiber surface area and inter-fiber bonding degree. The Valley beater refined rice straw pulp provided the molded sheet with the highest tensile index of 51.96 ± 4.08 Nm/g which are comparable to that of the sheets prepared from PFI mill refining process. The tensile properties of the current refined sheets were also in the acceptable range for typical commercial molded pulp packaging. In addition, the freeness values of the optimal Valley beater refined pulps are relatively high (348-423 ml), implying a benefit in forming process and manufacturing of pulp products.
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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.
Full textAbstract:
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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Lukmandaru, Ganis, Fajar Setiaji, and M. Rena Siagian. "Effects of Mixing Ratio of Heavily Beaten Pinus merkusii Pulp on Physical Properties of Kraft Acacia nilotica Pulp Sheets." Wood Research Journal 10, no. 2 (July 21, 2020): 53–60. http://dx.doi.org/10.51850/wrj.2019.10.2.53-60.
Full textAbstract:
Paper industries commonly produce pulp sourced from a mixture of pulps, rather than from a single pulp, to obtain desired properties. In addition, the beating process is an essential step with respect to physical properties of pulp. Kraft pine (Pinus merkusii/PM) pulps were beaten to different degrees, i.e 200~300 CSF (heavy-beating) and 300~400 CSF (moderatebeating), paper sheets then were formed from each beaten sample. It was found that the strength properties of prepared paper sheets decreased the longer they were beaten, particularly as seen by the tear index and fold number. By microscopic investigation, it was found that cut or shortened fibers occurred very frequently in the pine pulps. Furthermore, the effects of heavily beaten pine pulp additions on handsheet properties of kraft pulps of Acacia nilotica (AN) were investigated. Four different mixing ratios by weight of AN/PM from 100:0, 90:10, 80:20, and 70:30 during beating, as well as four different kappa numbers of AN pulps (32.5, 34.0, 34.2, and 35.9) were applied. In general, the decrease in strength properties (3~25%) that occurred with increasing pine pulp ratio was more evident between pulp without pine and a 30% ratio of pine pulps. Fold number was reduced considerably (2.8~24.7%) by the blend composition but less pronounced in tear index (3.0~8.9%) from the initial values. However, the 10% or 20% ratio of PM pulps could increase opacity, brightness, and strength properties in some cases. No clear trend was found with increasing kappa number.
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Moe, Størker T., and Arthur J. Ragauskas. "Oxygen Delignification of High-Yield Kraft Pulp. Part I: Structural Properties of Residual Lignins." Holzforschung 53, no. 4 (July 1, 1999): 416–22. http://dx.doi.org/10.1515/hf.1999.069.
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Summary The chemistry of oxygen delignification of high-yield kraft pulp was studied by analysis of residual lignin extracted from kraft and kraft-oxygen pulps using the acid hydrolysis/dioxane extraction method. For reference pulps cooked to kappa numbers between 20 and 25, the content of free phenolic groups decreased to about 50% the original value upon oxygen delignification, while the content of carboxylic acid groups increased by 50–100%. For lignins isolated from high-yield kraft pulp and oxygen delignified high-yield kraft pulp, it was shown that high-yield kraft pulping with polysulfide (PS) and anthraquinone (AQ) gives a residual lignin which is chemically different from that of kraft pulps cooked to lower kappa numbers. Lignin extracted from oxygen delignified high-yield PS/AQ kraft pulp was more similar to lignins extracted from kraft pulps cooked to lower kappa numbers.
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Qian, Xueren, Jing Shen, Gang Yu, and Xianhu An. "Influence of pulp fiber substrate on conductivity of polyaniline-coated conductive paper prepared by in-situ polymerization." BioResources 5, no. 2 (March 8, 2010): 899–907. http://dx.doi.org/10.15376/biores.5.2.899-907.
Full textAbstract:
The influences of pulp type, content of acidic groups (i.e., sulfonic and carboxylic groups) in CTMP, kappa number (i.e., residual lignin content) of unbleached kraft pulp, and beating degree of bleached kraft pulp on the conductivity of polyaniline (PAn)-coated conductive paper were investigated. The amounts of PAn coated on chemical pulps were higher than those coated on high yield pulps, and the surface resistivities of conductive papers prepared from chemical pulps were lower than those prepared from high yield pulps. As the substrates for the production of PAn-coated conductive paper, bleached chemical pulps were better than unbleached chemical pulps. The conductivity had a significant positive linear correlation with the amount of PAn coated. The amount of PAn coated increased with increasing content of sulfonic groups in CTMP or decreasing kappa number of unbleached kraft pulp. We hypothesized that this might be associated with the ionizability of acidic groups and the inhibiting effect of lignin on aniline polymerization. The beating degree of pulp seemed to have an insignificant effect on the conductivity of PAn-coated conductive paper. As a whole, the interpretations of the influence of the chemical composition are based on proposed ideas and need to be confirmed by future experimental work.
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Jiang, Zhi-Hua, Jean Bouchard, and Richard Berry. "Evidence for the formation of lignin-hexenuronic acid-xylan complexes during modified kraft pulping processes." Holzforschung 60, no. 2 (March 1, 2006): 137–42. http://dx.doi.org/10.1515/hf.2006.022.
Full textAbstract:
Abstract The finding that hexenuronic acid (HexA) groups can be selectively removed from kraft pulps by acid hydrolysis has provided an opportunity to reduce bleaching chemicals. However, there is evidence that the acid hydrolysis is not uniform. In this report, we evaluate the kinetics of acid hydrolysis of HexA in a xylan sample enriched with HexA, a conventional kraft pulp, and three modified kraft pulps: anthraquinone pulp (Kraft-AQ), polysulfide pulp (PS), and polysulfide-anthraquinone pulp (PS-AQ). We found that HexA present in the xylan and conventional kraft pulp behaved similarly toward the acid hydrolysis throughout. On the other hand, HexA present in the Kraft-AQ, PS-AQ and PS pulps was heterogeneous toward acid hydrolysis and the reaction can be separated into two pseudo-first-order kinetic phases, each of which has a different rate constant. The kinetic data provide evidence for the formation of lignin-HexA-xylan complexes during modified kraft pulping processes.
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Simões, Rogério M. S., Catarina I. A. Ferreira, FIlipa Pires, Margarida Martins, Ana Ramos, António P. M. Sousa, Paula C. R. Pinto, and Ricardo Jorge. "Recycling performance of softwood and hardwood unbleached kraft pulps for packaging papers." February 2023 22, no. 2 (March 1, 2023): 73–86. http://dx.doi.org/10.32964/tj22.2.73.
Full textAbstract:
The scope of this work is to evaluate the recyclability potential of hardwood and softwood unbleached kraft pulps, leading to a sound basis for comparison and even to support a decision about fibers according to the performance achieved. The influence of successive recycling cycles (up to 10 cycles) on the fiber morphology, pulp suspension drainability, water retention capacity, and handsheet mechanical properties were studied for Eucalyptus globulus and Pinus sylvestris unbleached kraft pulps. The performance of these pulps as linerboard and corrugating medium for packaging was also evaluated. The requirements for brown kraftliner and for high performance recycled fluting grades is preserved for E. globulus pulp during all 10 recycling cycles, evidenced by the moderate decrease of burst index and crush resistance index and by the short-span compression index, whereas the P. sylvestris pulp loses this rating after the second cycle. These results strongly support the higher performance of E. globulus pulp for recycling as compared with softwood kraft pulp from the perspective of packaging papers.
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Izzati, Ajrina Faustin, and Fajar Fatriadi. "INDIRECT PULP CAPPING WITH CALCIUM HYDROXIDE IN PERMANENT MOLARS." JURNAL RISET KESEHATAN POLTEKKES DEPKES BANDUNG 15, no. 2 (October 31, 2023): 541–47. http://dx.doi.org/10.34011/juriskesbdg.v15i2.2312.
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Berbagai bahan dan protokol klinis pulp capping telah digunakan selama bertahun-tahun untuk menjaga kesehatan dan vitalitas kompleks pulpa dan menginduksi sel pulpa untuk membentuk jaringan keras (dentin reparatif/tersier). Pulpa dapat diselamatkan dengan perawatan pulp capping. Perawatan ini melibatkan penempatan semacam bahan di atas pulpa untuk melindunginya dan mempertahankan viabilitasnya. Bahan yang paling umum digunakan dalam indirect pulp capping adalah kalsium hidroksida. Laporan kasus ini membahas mengenai perawatan gigi 47 dengan diagnosis pulpitis reversibel dengan menggunakan kalsium hidroksida sebagai bahan indirect pulp capping yang selanjutnya dilakukan perawatan restorasi kelas I komposit. Kalsium hidroksida memiliki beberapa kelemahan, yaitu tingkat kelarutan yang tinggi, kurangnya adhesi dan sifat fisiko-mekanis yang buruk. Tetapi kalsium hidroksida masih menjadi ‘gold standard’. Hal ini karena kemampuannya untuk berdisosiasi menjadi ion kalsium dan hidroksil, memiliki pH tinggi, sifat antibakteri, serta kemampuan untuk merangsang odontoblas dan sel pulpa lainnya untuk membentuk dentin reparatif melalui respon inflamasi. Selain itu, kalsium hidroksida merupakan bahan yang ekonomis dan mudah didapat sehingga menjadi bahan yang paling umum digunakan.
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Andrade, Marcela Freitas, Jorge Luiz Colodette, and Flávia Natalino Oliveira. "Evaluation of bleachability on pine and eucalyptus kraft pulps." CERNE 19, no. 3 (September 2013): 433–39. http://dx.doi.org/10.1590/s0104-77602013000300010.
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In recent decades, the pulp industry has been changing and improving its manufacturing processes in order to enhance production capacity, product quality and environmental performance. The aim of this study was to evaluate the bleachability effect on the efficient washing and alkaline leaching in eucalyptus and pine Kraft pulps using three different bleaching sequences: AD(EP)D, A/D(EP)DP and D HT(EP)DP. This study was carried out in two stages. In the first part, the optimum conditions for pulp bleaching in order to achieve a brightness of 90% ISO were established. The second step was a comparative study between the pulps that received alkaline leaching and efficient washing with reference pulp (without treatment). The brightness, viscosity, kappa number and HexA in pulp were analyzed. The three sequences studied reached the desired brightness, but the sequence AD(EP)D produced a lower reagent consumption for the same brightness. In the three sequences studied, the efficient washing of the pulp after oxygen delignification has contributed significantly to the removal of dissolved organic and inorganic materials in the pulp and the alkaline leaching decreased significantly the pulp kappa number due to a higher pulp delignification and bleachability.
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Jahan, M. Sarwar, Halima Rahman, Purabi Rani Samaddar, and Mostafizur Rahman. "Ethylenediamine in alkaline cooking of jute stick for producing dissolving pulp." Bangladesh Journal of Scientific and Industrial Research 50, no. 1 (June 22, 2015): 7–14. http://dx.doi.org/10.3329/bjsir.v50i1.23804.
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Jute stick is the woody portion of jute plant. It remains as the leftover after extracting the fibre. The ratio of the stick to fibre is about 2.5:1. For producing dissolving pulp, prehydrolysis is carried out prior to pulping to remove hemicelluloses from the lignocelluloses. In this investigation ethylenediamine (EDA) was used with the cooking liquor to remove hemicelluloses from the jute stick. Increasing EDA charge in soda and kraft liquor decreased pentosans content in the pulp. EDA in kraft liquor showed lower kappa number and pentosans content than in the soda-liquor. Prehydrolysis further improved cellulose content and kappa number of jute stick pulp with the sacrifice of pulp yield. The bleachability of soda-EDA pulp was inferoior to the kraft-EDA and prehydrolysed soda-EDA in ECF bleaching sequences. The final brightness of soda-EDA pulp was 85.1% and kraft-EDA pulp 89.7%. Degraded cellulose (R18-R10) in soda-EDA and kraft-EDA pulps was lower than prehydrolysed pulps. Dissolving pulp can be produced to 93% purity without prehydrolysis by reinforcing EDA in kraft liquor.Bangladesh J. Sci. Ind. Res. 50(1), 7-14, 2015
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Andrade, Marcela Freitas, and Jorge Colodette. "PRODUCTION OF PRINTING AND WRITING PAPER GRADE PULP FROM ELEPHANT GRASS." CERNE 22, no. 3 (September 2016): 325–36. http://dx.doi.org/10.1590/01047760201622032186.
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ABSTRACT The main goal of this study was to characterize chemically and morphologically elephant grass (Pennisetum purpureum), and evaluate the potential of its fibers for production of printing and writing paper grade pulp. The elephant grass was chemically and morphologically characterized and cooked by the soda process to two different degrees of delignification (kappa 17.5 and 10.6). The resulting pulps were fully bleached by the O-D*-(EP)-D sequence and characterized for their beatability, drainability and physical-mechanical properties. The lignin content (20.2%) was low, indicating that this grass should be easier to pulp. The morphological analyses of the elephant grass indicated a short fiber material, similar to hardwoods. The soda pulp from elephant grass cooked to kappa number 17.5 presented higher screened yield than 10.6 kappa pulp, with alkali demands of 15.0% and 20.0%, respectively. The total active chlorine required by the 17.5 and 10.6 kappa pulps, were 42.1 and 35.1 kg/odt pulp, respectively, to achieve an ISO brightness of approximately 90.0%. The bleached soda pulps cooked to 17.5 and 10.6 kappa number showed similar refinability and resistance to drainage, but the tensile and burst index were highest for the 17.5 kappa pulp at beating energy consumptions in the range of 0-6 Wh. It was concluded that both 10.6 and 17.5 kappa pulps from elephant grass are suitable for the production of printing and writing paper grade pulps, but the highest kappa 17.5 pulp is more economically attractive given its highest pulping yield, despite the significantly increased of chemical demand for bleaching A produção de papel para impressão e escrita Grau de celulose a partir de capim-elefante.
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Potthast, Antje, Sonja Schiehser, Thomas Rosenau, Herbert Sixta, and Paul Kosma. "Effect of UV radiation on the carbonyl distribution in different pulps." Holzforschung 58, no. 6 (October 1, 2004): 597–602. http://dx.doi.org/10.1515/hf.2004.113.
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Abstract The effect of UV irradiation on unbleached and TCF-bleached dissolving pulp samples of different provenience, a beech sulphite and an eucalyptus prehydrolysis kraft pulp, has been analyzed according to the CCOA method, evaluating the changes in the molecular weight distribution, the total number of carbonyl groups and the carbonyl group profiles of each pulp. In the case of TCF bleached material, slightly more carbonyl groups were introduced into the kraft pulp as compared to the sulfite pulp. Cellulose degradation was relatively low in both pulps. In the case of unbleached sulfite pulps, the residual lignin had only a minor effect on the molecular weight distribution and the oxidation state of the cellulose, whereas for eucalyptus kraft pulp a pronounced introduction of carbonyl groups accompanied by severe degradation of cellulose was observed. The presence of hemicelluloses governed the photochemical behavior and the carbonyl profiles of the low molecular weight region of the cellulose.
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Nocanda, Xolani, Per Tomas Larsson, Andrew Spark, Tamara Bush, Ann Olsson, Mzekelo Madikane, Ajay Bissessur, and Tommy Iversen. "Cross polarisation/magic angle spinning 13C-NMR spectroscopic studies of cellulose structural changes in hardwood dissolving pulp process." Holzforschung 61, no. 6 (November 1, 2007): 675–79. http://dx.doi.org/10.1515/hf.2007.095.
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Abstract Cross polarisation/magic angle spinning 13C NMR spectroscopy has been used to study structural changes in cellulose induced by the dissolving pulp process. The cellulose structure in several dissolving pulps was investigated for commercial and laboratory cooked Eucalyptus 92α and 96α. The average lateral dimension, or average thickness, of the cellulose fibril aggregates is related to the amount of surface area exposed and could be one controlling factor for the chemical reactivity of commercial dissolving pulps during modification reactions. The thickness of the cellulose fibril aggregates governs the amount of surface area present in the fibre wall, and cellulose surface material constitutes the part of the cellulose that is directly accessible to reagents. In all sample series investigated, the raw pulp was found to be less aggregated than the corresponding bleached final pulp. Furthermore, an irreversible increase in fibril aggregate width was observed on free drying for both laboratory cooked and commercial pulps. Upon rewetting with water, the freely dried 96α pulp was found to be more aggregated than the freely dried 92α pulp, although sugar analysis showed very similar carbohydrate compositions. As indicated by the molecular mass distribution, the commercial 92α pulp contained larger amounts of degraded cellulose; this may be a plausible explanation for the different behaviour of the 92α and 96α pulps during free drying.
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Bhatnagar, Anju. "Assessment of Aox Content in Bleaching Effluent of Eucalyptus Tereticornis Kraft Pulps." Current World Environment 17, no. 3 (December 30, 2022): 672–77. http://dx.doi.org/10.12944/cwe.17.3.15.
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The research aim is to reduce the organochlorine content in bleach plant effluents by modifying conventional (CEHH) bleaching sequences. Majority of pulp and paper mills generally adopted CEHH or CEH bleaching sequences, using chlorine or chlorinated compounds to remove the color from pulps. Organochlorine compounds are mainly generated from chlorination and alkali extraction stages. The purpose of the study is to substitute elemental chlorine in bleaching with oxygen, chlorine dioxide, or peroxide. Investigations of AOX content of various traditional and innovative ECF bleaching sequences were conducted. In this study, kraft pulps of Eucalyptus tereticornis with kappa numbers of 44.91 and 26.46 and its oxygen-delignified pulps of kappa numbers 21.32 and 13.03 were used. In terms of AOX, various ECF bleaching sequences were compared to the reference sequence (CEHH). AOX value was 4.45, 3.42, 2.27 kg/tp for the pulp bleached adopting OCEH, ODEH, ODEP bleaching sequence and 9.24 kg/tp for the pulp bleached adopting CEHH bleaching sequence for the pulp corresponding to Kappa number 44.91. Similarly, the AOX value was 2.60 , 1.78 1.24 Kg/tp for the pulps bleached adopting the OCEH, ODEH, ODEP bleaching sequence and 5.56 Kg/tp for the pulp bleached adopting the CEHH sequence for the pulp corresponding kappa number 26.46. Due to partial-delignification of oxygen, AOX production was reduced up to 50%.
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Boschetti, Walter Torezani Neto, Ana Márcia Macedo Ladeira Carvalho, Angélica de Cássia Oliveira Carneiro, Graziela Baptista Vidaurre, Fernando José Borges Gomes, and Déborah Nava Soratto. "Effect of Mechanical Treatment of Eucalyptus Pulp on the Production of Nanocrystalline and Microcrystalline Cellulose." Sustainability 13, no. 11 (May 24, 2021): 5888. http://dx.doi.org/10.3390/su13115888.
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This study aimed to assess the effect of mechanical pretreatment on bleached eucalyptus kraft pulp fibers and investigate the influence of reaction time and temperature on the properties and yield of nanocrystalline cellulose (NCC) and microcrystalline cellulose (MCC). Two types of pulps were hydrolyzed, pulp 1 (control, whole fibers) and pulp 2 (mechanically pretreated, disintegrated fibers). NCC and MCC particles were obtained by sulfuric acid hydrolysis (60% w/w) of eucalyptus pulps under different conditions of time (30–120 min) and temperature (45–55 °C). Physical treatment of kraft pulp facilitated acid hydrolysis, resulting in higher NCC yields compared with no pretreatment. The morphologic properties and crystallinity index (CI) of NCC and MCC were little affected by pulp pretreatment. NCC particles obtained from pulps 1 and 2 were needle-shaped, with mean diameters of 6 and 4 nm, mean lengths of 154 and 130 nm, and CI of 74.6 and 76.8%, respectively. MCC particles obtained from pulps 1 and 2 were rod-shaped, with mean diameters of 2.4 and 1.4 µm, mean lengths of 37 and 22 µm, and CI of 73.1 and 74.5%, respectively. Pulps 1 and 2 and their respective NCC and MCC derivatives had a cellulose I crystalline structure.
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Zhang, Qihua, Shun Kang, Zhiang Xie, Li Cao, Zhaoxu Yan, and Weidong Zhang. "Pulp pumping efficiency II – Designing of a pulp pump." Nordic Pulp & Paper Research Journal 36, no. 2 (March 4, 2021): 265–75. http://dx.doi.org/10.1515/npprj-2021-2008.
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Abstract Based on the loss model of pulp pump set up in the I part of this research, an efficient designing method is proposed by taking account of the influences of head reduction by small blade number, leakage loss via tip clearance, and erosion-corrosion wears in pumps separately. Further, a two-stage optimal designing approach was proposed to tackle the oversized design. The pump designing was performed by coupling with a CFD-based optimization procedure. An efficiency increase of near 10 % was achieved on the pump model validated in laboratory. It was proved that performance could be improved by increasing the impeller blade width and enlarging the impeller blade outlet angle. It was further shown that the erosion-corrosion wear in pulp pump was relatively lighter when compared to particle-impingement wear in slurry and sewage pump. Adoption of composite material showed potential in energy-saving in the pumping system.