Relationship between dissolution of fiber materials and development of pulp strength in alkaline peroxide bleaching of mechanical pulp

Holzforschung ◽  
2004 ◽  
Vol 58 (4) ◽  
pp. 369-375 ◽  
Author(s):  
G.X. Pan
Keyword(s):  
Carboxylic Acid ◽  
Acid Group ◽  
Strength Properties ◽  
Strength Development ◽  
Mechanical Pulp ◽  
Peroxide Bleaching ◽  
Alkaline Peroxide ◽  
Bonding Properties ◽  
Pulp Strength ◽  
Fiber Materials

Abstract This study elucidates the relationship between the dissolution of pulp components and the development of fiber bonding properties in alkaline peroxide bleaching of aspen mechanical pulp. In general, bleaching reactions cause the removal of pulp substances from the fibers, which in turn improves pulp strength properties. Nonetheless, alkaline hydrolysis is particularly important to the development of strength because this reaction mechanism plays a key role in imparting additional carboxylic acid groups onto the fibers. The strong correlation between fiber carboxylic acid group concentration and the amount of anionic dissolved substances makes it possible for us to predict the strength properties of bleached pulps by estimating the anionicity of bleaching filtrates using analytical methods such as cationic demand. The paper also provides insights into the importance of the alkalinity in peroxide bleaching to the dissolution of pulp materials and the strength development.

Recombinant manganese peroxidase (rMnP) from Pichia pastoris. Part 2: Application in TCF and ECF bleaching

Holzforschung ◽  
2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Haowen Xu ◽  
Gary M. Scott ◽  
Fei Jiang ◽  
Christine Kelly
Keyword(s):  
Pichia Pastoris ◽  
Manganese Peroxidase ◽  
Kraft Pulp ◽  
Energy Savings ◽  
Strength Properties ◽  
Enzymatic Treatment ◽  
Peroxide Bleaching ◽  
Alkaline Peroxide ◽  
Elemental Chlorine ◽  
Ecf Bleaching

AbstractThe recombinant manganese peroxidase (rMnP) produced from the yeastPichia pastorishas been investigated in totally chlorine free (TCF) and elemental chlorine free (ECF) bleaching sequences for improving the bleachability of kraft pulps. In TCF bleaching, oxygen delignified hardwood kraft pulp was treated with rMnP, followed by a sequence combining a chelating and alkaline peroxide bleaching stage. The inclusion of the enzymatic treatment significantly improved the pulp brightness to a level that is difficult to obtain by chemical bleaching alone. Furthermore, the treatment with rMnP resulted in energy savings during pulp refining with PFI mill with a slight improvement in pulp strength properties such as tensile index and burst index. In ECF bleaching, a significant reduction in chlorine dioxide consumption was obtained. A three-stage rMnP treatment combined with alkaline extraction, followed by DED bleaching sequence for hardwood kraft pulp (HWKP) or DEDED bleaching sequence for softwood kraft pulp (SWKP), reduced the total effective chlorine by 41% and 32% for HWKP and SWKP, respectively, compared with the conventional bleaching sequences without enzymatic treatment. The strength properties of the enzyme-treated pulp were also slightly better than that of the control pulp. Further reductions in the consumption of total effective chlorine were obtained when a xylanase pretreatment was incorporated into the bleaching sequence before the repeated rMnP treatment.

Improving Hydrogen Peroxide Bleaching of PRC-APMP by Using Urea

2013 ◽  
Vol 295-298 ◽  
pp. 335-338
Author(s):  
Zong Quan Li ◽  
Hong Yan Dou ◽  
Xiao Qian Chen ◽  
Chao Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Fiber Length ◽  
High Yield ◽  
Mechanical Pulp ◽  
Peroxide Bleaching ◽  
Bleached Pulp ◽  
Alkaline Peroxide ◽  
Tear Index ◽  
Breaking Length ◽  
Urea Addition

Preconditioning Refiner Chemic Alkaline Peroxide Mechanical Pulp (PRC-APMP) is one of the most currently used high yield pulps in China. During the bleaching of PRC-APMP, hydrogen peroxide is a commonly used bleaching agent. In order to improve the bleaching efficiency of PRC-APMP, urea was used as an activator in peroxide bleaching of aspen PRC-APMP. The results showed that the brightness of the urea-based bleached pulp higher than that without urea addition at the same hydrogen peroxide dosage. The physical properties such as the breaking length, tear index and fiber length of the bleached pulp were comparable to those without urea addition in peroxide bleaching.

Enhancement of Pulp Strength by Forming Polyelectrolyte Multilayers on APMP Fibers

2014 ◽  
Vol 496-500 ◽  
pp. 171-174
Author(s):  
Ge Tian ◽  
Yun Yun Sun ◽  
Fan Gong Kong ◽  
Shou Juan Wang ◽  
Jia Chuan Chen
Keyword(s):  
Treatment Time ◽  
Fiber Surface ◽  
Strength Properties ◽  
Polyelectrolyte Multilayers ◽  
Layer By Layer ◽  
Physical Strength ◽  
Alkaline Peroxide ◽  
Treatment Conditions ◽  
Layer Deposition ◽  
Pulp Strength

The layer-by-layer deposition technique was adopted in this paper to improve the physical strength properties of alkaline peroxide mechanical pulp (APMP). The cationic starch (CS), anionic polyacryamide (APAM) and cationic polyacryamide (CPAM) were chosen and used to build-up polyelectrolyte multilayers on surface of APMP fibers. The improvements of physical strength of pulp through adsorption of different polyelectrolyte onto fibers were discussed and compared. The results showed that when the APMP fibers were treated with CPAM, the breaking length and burst index were 53% and 83% respectively, higher than that of untreated pulp. The optimal treatment conditions are 60 mgCPAM/g pulp, 1.5% pulp concentration and 9min treatment time. The pulp deposited by CPAM-APAM polyelectrolyte multilayer gave a highest physical strength compared with pulp with other multilayer deposition such as CS-APAM. At the whole beating degree range investigated in this paper, the CPAM-APAM deposition on fiber surface can improve the physical strength properties significantly, especially when the beating degree is at 40oSR. In addition, the improvement of physical strength can be remained even after pulp refining.

Crystal structure of tofacitinib dihydrogen citrate (Xeljanz®), (C16H21N6O)(H2C6H5O7)

2021 ◽  
pp. 1-8
Author(s):  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Density Functional ◽  
Acid Group ◽  
Dimensional Network ◽  
Van Der Waals Contacts ◽  
Citrate Anion

The crystal structure of tofacitinib dihydrogen citrate (tofacitinib citrate) has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Tofacitinib dihydrogen citrate crystallizes in space group P212121 (#19) with a = 5.91113(1), b = 12.93131(3), c = 30.43499(7) Å, V = 2326.411(6) Å3, and Z = 4. The crystal structure consists of corrugated layers perpendicular to the c-axis. Within the layers, cation⋯anion and anion⋯anion hydrogen bonds link the fragments into a two-dimensional network parallel to the ab-plane. Between the layers, there are only van der Waals contacts. A terminal carboxylic acid group in the citrate anion forms a strong charge-assisted hydrogen bond to the ionized central carboxylate group. The other carboxylic acid acts as a donor to the carbonyl group of the cation. The citrate hydroxy group forms an intramolecular charge-assisted hydrogen bond to the ionized central carboxylate. Two protonated nitrogen atoms in the cation act as donors to the ionized central carboxylate of the anion. These hydrogen bonds form a ring with the graph set symbol R2,2(8). The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).

New Research on the Use of Hardening Plastics for Aircraft Construction

1940 ◽  
Vol 44 (349) ◽  
pp. 44-73
Author(s):  
Wilhelm Kuech
Keyword(s):  
Strength Properties ◽  
Dynamic Loads ◽  
Absorbed Energy ◽  
Good Strength ◽  
Different Temperatures ◽  
Bonding Properties ◽  
Static And Dynamic Loads ◽  
Impact Bending ◽  
New Research ◽  
Laminated Materials

Laminated materials incorporating plastics seem to be especially well suited lor highly stressed aircraft components, by reason of their good strength properties. Paper, fabric and wood veneers treated with plastics on a phenolic basis were tested with regard to their strength, especially in bending, shear, absorbed energy in impact bending, notching strength and in their resistance against moisture. Further, the behaviour of compressed plastics was studied at different temperatures under static and dynamic loads. A part of the research was extended to pure phenol resin and to thermoplastics based on methacrylate and polyvinylchloride. The bonding properties of laminated compressed plastics were established. Concluding, some experiments relating to the practical manufacture of aeroplane components are communicated.

The inner salt 4-carboxy-2-(pyridinium-4-yl)-1H-imidazole-5-carboxylate monohydrate

2006 ◽  
Vol 62 (7) ◽  
pp. o2751-o2752 ◽  
Author(s):  
Ting Sun ◽  
Jian-Ping Ma ◽  
Ru-Qi Huang ◽  
Yu-Bin Dong
Keyword(s):  
Carboxylic Acid ◽  
Dihedral Angle ◽  
Title Compound ◽  
Acid Group ◽  
Planar Structure ◽  
Carboxyl Group ◽  
Carboxylic Acid Group ◽  
Pyridyl Group ◽  
Compound C

In the title compound, C10H7N3O4·H2O, one carboxyl group is deprotonated and the pyridyl group is protonated. The inner salt molecule has a planar structure, apart from the carboxylic acid group, which is tilted from the imidazole plane by a small dihedral angle of 7.3 (3)°.

scholarly journals Crystal structure of betulinic acid methanol monosolvate

2014 ◽  
Vol 70 (12) ◽  
pp. o1242-o1243 ◽  
Author(s):  
Wei Tang ◽  
Neng-Hua Chen ◽  
Guo-Qiang Li ◽  
Guo-Cai Wang ◽  
Yao-Lan Li
Keyword(s):  
Carboxylic Acid ◽  
Solvent Molecule ◽  
Acid Group ◽  
Carboxylic Acid Group ◽  
Syzygium Jambos ◽  
Carboxylic Acid Groups ◽  
Pentacyclic Triterpenoid ◽  
Naturally Occurring ◽  
Dimensional Network ◽  
Chinese Medicinal Plant

The title compound [systematic name: 3β-hydroxylup-20(29)-en-28-oic acid methanol monosolvate], C30H48O3·CH3OH, is a solvent pseudopolymorph of a naturally occurring plant-derived lupane-type pentacyclic triterpenoid, which was isolated from the traditional Chinese medicinal plantSyzygium jambos(L.) Alston. The dihedral angle between the planes of the carboxylic acid group and the olefinic group is 12.17 (18)°. TheA/B,B/C,C/DandD/Ering junctions are alltrans-fused. In the crystal, O—H...O hydrogen bonds involving the hydroxy and carboxylic acid groups and the methanol solvent molecule give rise to a two-dimensional network structure lying parallel to (001).

scholarly journals Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill

2012 ◽  
Vol 36 (6) ◽  
pp. 1163-1172 ◽  
Author(s):  
María Graciela Aguayo ◽  
Regis Teixeira Mendonça ◽  
Paulina Martínez ◽  
Jaime Rodríguez ◽  
Miguel Pereira
Keyword(s):  
Eucalyptus Globulus ◽  
Lignin Content ◽  
Strength Properties ◽  
Kraft Pulping ◽  
Pulp Yield ◽  
Chemical Characteristics ◽  
Kraft Pulps ◽  
Opposite Wood ◽  
Alkali Consumption ◽  
Pulp Strength

Tension (TW) and opposite wood (OW) of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively). The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes) were slightly higher or similar in tension as compared with opposite wood pulps. After an OD0(EO)D1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.

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