Preparation of microwave-assisted polymer-grafted softwood kraft pulp fibers. Enhanced water absorbency

Cross-linked fluff pulp fibers for use in, for example, acquisition layers in absorption products can be found in the patent literature. Cross-linking improves properties such as the wet resilience of fluff pulp fiber networks. Among the more commonly seen cross-linkers are polycarboxylic acids, such as 1,2,3,4-butanetetracarboxylic acid (BTCA). These acids form ester bonds with the hydroxyl groups in the fiber wall. In this study, softwood kraft pulp fibers were cross-linked with BTCA. The swelling behavior of the fibers and properties related to acquisition in absorption products were studied. It was found that the water retention value (WRV) decreased as a consequence of the introduced cross-linker. After deprotonization of a large part of the introduced carboxylic acids, the WRV increased, but the cross-linker was still able to limit significant swelling of the fiber wall. The wet bulk under load of fiber networks, composed of cross-linked fibers, generally increased with a decrease in WRV. Furthermore, it was found that the property development obtained after a cross-linking reaction with BTCA may be predicted by introducing a relative reaction intensity, RIrel, that takes into account both time and temperature in the curing step. This shows that the time and temperature in the curing step are interchangeable.

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Alkali Extraction of Kraft Pulp Fibers: Influence on Fiber and Fluff Pulp Properties

Journal of Engineered Fibers and Fabrics ◽

10.1177/155892501200700206 ◽

2012 ◽

Vol 7 (2) ◽

pp. 155892501200700 ◽

Cited By ~ 3

Author(s):

Kristoffer Lund ◽

Karin Sjöström ◽

Harald Brelid

Keyword(s):

Kraft Pulp ◽

Pulp Fibers ◽

Fiber Network ◽

Alkali Extraction ◽

Flexible Fiber ◽

Softwood Pulp ◽

Softwood Kraft Pulp ◽

Patent Literature ◽

Network Strength ◽

Birch Kraft Pulp

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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Effect of Fiber Wall Pore Structure on Pulp Sheet Density of Softwood Kraft Pulp Fibers

BioResources ◽

10.15376/biores.8.2.2719-2737 ◽

2013 ◽

Vol 8 (2) ◽

Cited By ~ 4

Author(s):

Olli P. Joutsimo ◽

Sari Asikainen

Keyword(s):

Pore Structure ◽

Kraft Pulp ◽

Pulp Fibers ◽

Fiber Wall ◽

Softwood Kraft Pulp ◽

Sheet Density

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The relationship between shrinkage and elongation of bleached softwood kraft pulp sheets

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2018-3057 ◽

2018 ◽

Vol 33 (3) ◽

pp. 522-533 ◽

Cited By ~ 2

Author(s):

Jarmo Kouko ◽

Elias Retulainen

Keyword(s):

Kraft Pulp ◽

Drying Shrinkage ◽

Total Elongation ◽

Reference Points ◽

Pulp Fibers ◽

Fiber Network ◽

Softwood Kraft Pulp ◽

The Difference ◽

Novel Concept ◽

The Relationship

AbstractThe relationship between shrinkage and elongation of hand sheets was examined. The results show that the same dimensional contraction brought about by shrinkage can be strained out in tensile testing. However, percentage-wise the elongation is greater than the shrinkage due to different reference points, and the difference increases strongly at higher shrinkage levels. Elongation of paper can be explained mainly by two factors: the shrinkage and the net elongation of paper. Here shrinkage refers to all kinds of in-plane contraction of the fiber network (drying shrinkage, in-plane-compaction and creping). The novel concept ‘net elongation’ was proposed in order to separate the effect of shrinkage from the total elongation of paper. Net elongation is the elongation of corresponding unshrunken paper dried under restraint. Sheets with high elongation were prepared from bleached softwood kraft pulp and the effects of shrinkage on elongation, strength and stiffness of the paper were investigated. Mechanical treatment methods of pulp fibers and chemical strength additives were applied in order to maximize the strength and elongation. In-plane compaction and creping were used to further boost shrinkage of the high basis weight (100 g/m2) sheets up to 160 percent. Experimental elongation data confirmed the proposed theoretical relationships.

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Optimization of elemental chlorine-free bleaching for a softwood kraft pulp • part 2: economic analysis of chemical and steam consumption

TAPPI Journal ◽

10.32964/tj9.9.47 ◽

2010 ◽

Vol 9 (9) ◽

pp. 47-53 ◽

Cited By ~ 2

Author(s):

BRIAN N. BROGDON

Keyword(s):

Chlorine Dioxide ◽

Previous Investigation ◽

Kraft Pulp ◽

Energy Costs ◽

Alkaline Extraction ◽

Stage Versus ◽

Kraft Pulps ◽

Steam Consumption ◽

Elemental Chlorine ◽

Softwood Kraft Pulp

Our previous investigation [1] re-analyzed the data from Basta and co-workers (1992 TAPPI Pulping Conference) to demonstrate how oxidative alkaline extraction can be augmented and how these changes affect chlorine dioxide consumption with elemental chlorine-free (ECF) sequences. The current study manipulates extraction delignification variables to curtail bleaching costs with a conventional U.S. Southern softwood kraft pulp. The economic advantages of ~0.35% to 0.65% H2O2 peroxide reinforcement in a 70°C (EOP)-stage versus 90°C (EO)-stage are predisposed to the brightness targets, to short or long bleach sequences, and to mill energy costs. Minimized bleaching costs are generally realized when a 90°C (EO) is employed in D0(EO)D1 bleaching, whereas a 70°C (EOP) is economically advantageous for D0(EOP)D1E2D2 bleaching. The findings we disclose here help to clarify previous ECF optimization studies of conventional softwood kraft pulps.

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An effective method for determining the retention and distribution of cellulose nanofibrils in paper handsheets by dye labeling

TAPPI Journal ◽

10.32964/tj17.03.157 ◽

2018 ◽

Vol 17 (03) ◽

pp. 157-164 ◽

Cited By ~ 3

Author(s):

Shengdan Wang ◽

Wenhua Gao ◽

Kefu Chen ◽

Jinsong Zeng ◽

Jun Xu ◽

...

Keyword(s):

Correlation Coefficient ◽

Congo Red ◽

Kraft Pulp ◽

Cellulose Nanofibrils ◽

Standard Curve ◽

Congo Red Dye ◽

Mechanical Disintegration ◽

Softwood Kraft Pulp ◽

White Water ◽

Red Dye

Cellulose nanofibrils (CNF) were prepared by cellulase in conjunction with mechanical disintegration from the bleached softwood kraft pulp and labelled by Congo red dye. The labelled CNF were used to investigate the retention and distribution of CNF in paper handsheets. The retention of the labelled CNF was obtained by measuring the absorbance of white water using an ultraviolet-visible spectrophotometer. The results showed that this method for measuring the retention was rapid, feasible, and sensitive, owing to the high correlation coefficient R2 (0.9993) of the standard curve. The labelled CNF showed even distribution in paper handsheets. The colorimetric values of paper handsheets were explored with a residual ink analyzer.

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