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Study of Paper Dry Strength Additives on Cellulose Fibres
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Paper packaging is commonly found in the form of paper and cardboard boxes, but recently paper packing is being used in food packaging, trays, beverage packaging and even paper straws, among others. Paper strength additives have been developed to increase the efficiency of the joint strength and the joint areas and potentially maintain bulk in paper products. In this thesis, a fundamental study of paper dry strength additives was performed involving kraft birch fibres and model cellulose materials to explore the interaction between strength additives and cellulose fibres. The same techniques used in paper strength additives were extended to the adsorption of fire-retardant polymers on fibres. 

Adsorption behaviours of cationic starch (CS) and anionic polyacrylamide (APAM) or anionic polyelectrolyte complexes (PECs) were studied on kraft birch fibres with different surface charges. It was found that the saturation adsorption of CS on birch fibres in 0.01 M NaCl showed a linear relationship with the surface charge of fibre, while the adsorption of APAM and PECs was independent of the surface charge of fibres. Higher surface charge of fibres expands the saturation adsorption capacity of strength additives, consequently, improves the tensile strength properties of handsheets made of kraft birch fibres with CS/APAM or CS/PECs. Bending stiffness of handsheets was improved by CS and boosted by PECs or APAM. In addition, sheet density was not significantly compromised by adding strength additives. Cationic strength additives were investigated on model cellulose surfaces, model cellulose nanofibrils filaments, and model cellulose beads. CSs produced an increase in the mass of the cellulose surface, while cationic PAMs led to a decrease in the total mass of cellulose surface determined by Quartz Crystal Microbalance with Dissipation monitoring. All types of strength additives affected the filament joints but in different ways, while most of them made filaments form intermixed interphases in the joints. The adsorption of chitosan and sodium hexamethaphosphate increased steadily and formed three bilayers on cellulose fibres. These materials formed stable lightweight materials after freeze-drying suspensions of the coated fibers containing them and show good fire retardant properties.

The fundamental study of paper dry strength additives and other polymers on the cellulose fibres can facilitate the development of new polymers for wood fibre-based materials. 

Abstract [sv]

Cellulosafiberbaserade förpackningar, så som förpackningar av kartong, används flitigt för till exempel livsmedels- och dryckesförpackningar och snabbmatsförpackningar. På senare tid har även fiberbaserade material börjat an vändas för att göra sugrör. Tillsatsämnen, så som styrkeökande kemikalier, används vid tillverkning av papper och kartong för att förbättra produktens egenskaper. De styrkeökande kemikalierna är ofta utvecklade för att öka fogstyrkan och den totala fogarean, det vill säga den totala kontaktytan mellan överlappande fibrer. Detta bör helst uppnås i kombination med en hög bulk (låg densitet). Denna avhandling studerar på grundläggande nivå interaktionen mellan modellsystem av cellulosa samt cellulosafiber (sulfatfibrer från björk) och hur denna interaktion påverkas vid tillsats av en rad styrkekemikalier.

 

Fibrer med olika initial ytladdning studerades med avseende på adsorption av katjonstärkelse, följt av efterföljande adsorption av anjonisk polyakrylamid eller anjoniska polyelektrolytkomplex. Resultaten visar att mättnadsadsorptionen av katjonstärkelse vid en jonstyrka motsvarande 0,01 M NaCl har linjärt proportionell mot fiberns ytladdning, medan den efterföljande adsorptionen av anjonisk polyakrylamid eller anjonisk polyakrylamid var oberoende av fibrernas initiala ytladdning. Högre fiberytladdning ökade mättnadsadsorptionen av styrkekemikalierna, vilket också förbättrade de mekaniska egenskaperna hos ark tillverkade efter adsorption av dessa kemikalier. Böjstyvheten hos arken förbättrades av tillsats av katjonstärkelse och ökade ytterligare vid ytterligare tillsats av både anjoniska polyelektrolytkomplex och anjonisk polyakrylamid. Arkens densitet förändrades inte nämnvärt till följd av styrkekemikalierna. 

 

Katjoniska styrkekemikalier undersöktes också på tre olika modellmaterial: filmer och kulor av regenererade cellulosa samt filament tillverkade av. På cellulosafilmerna studerades i detalj adsorptionen av styrkekemikalierna (katjonstäkelse av potatis och majs, glyoxalerad polyakrylamid samt blandning av katjonisk polyakrylamid / polyDADMAC) med en kvartskristallmikrovåg. Vid adsorption av katjonstärkelse ökade total massan, medan katjonisk polyakrylamid (CPAM) indikerade mätningarna en minskad total massa, vilket härleds vara en följd av en inducerad avsvällning av cellulosafilmen i samband med adsorptionen. Modell filament och kullor används för att bilda fogar i form av fiberkors eller sammanfogade kulor vid torkning. Modifiering av filament och kulor med styrkekemikalier påverkade de formade fogarna på olika sätt, de flesta styrkekemikalierna fick filamenten att bilda en mixad materialfas i den torkade fogen. 

 

Vid frystorkning av cellulosafibrer kan skumliknande material bildas om tillräckligt starka fogar mellan fibrerna kan bildas. Med hjälp av fibermodifiering med kitosan och natriumhexametafosfat via lager-på-lager-teknik kan lättviksskum bildas som visar sig ha brandhämmande egenskaper. 

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2022. , p. 67
Series
TRITA-CBH-FOU ; 2023:1
Keywords [en]
Paper dry strength additives, adsorption of polymer, polyelectrolyte, birch fibres, model cellulose surface, cellulose beads, filaments, light-weight paper board, polyacrylamide, cationic starch
Keywords [sv]
Torrstyrkekemikalier, polymeradsorption, polyelektrolyter, cellulosafibrer, modellcellulosaytor, cellulosakulor, lättviktsliner, polyakrylamid, katjonstärkelse
National Category
Paper, Pulp and Fiber Technology Composite Science and Engineering
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-322556ISBN: 978-91-8040-452-5 (print)OAI: oai:DiVA.org:kth-322556DiVA, id: diva2:1720600
Public defence
2023-01-27, F3, Lindstedtsvägen 26, Stockholm, Stockholm, 09:00 (English)
Opponent
Supervisors
Note

QC 2022-12-20

Embargo godkänt Mikael Lindström, skolchef CBH, via e-post 2022-12-20

Available from: 2022-12-20 Created: 2022-12-19 Last updated: 2024-01-26Bibliographically approved
List of papers
1. Effect of saturation adsorption of paper strength additives on the performance of paper
Open this publication in new window or tab >>Effect of saturation adsorption of paper strength additives on the performance of paper
2022 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 37, no 4, p. 624-635Article in journal (Refereed) Published
Abstract [en]

The use of paper dry strength additives is oneof the methods for producing packaging boards with alower grammage while maintaining mechanical properties.In the present work, papers were formed using dissolvinggrade kraft fibres, kraft fibres and carboxymethylatedcellulose (CMC) modified kraft fibres (C-kraft fibres),with either cationic starch (CS), anionic polyacrylamide(APAM) or anionic polyelectrolyte complexes (PECs). Fibresand sheets were characterized to evaluate how the saturationadsorption of the different strength additives influencesthe properties of the treated fibres and the finalhandsheets. The tensile index of papers made from C-kraftfibres was the highest due to the highest adsorption capacityof strength additives. Moreover, the strength additivesincreased the tensile index by 33–84 %, while z-directional tensile strength was increased dramatically by 46–139 %.Bending stiffness was improved by 2.6–25 %, and the combination of CS and APAM or PECs resulted in a significantimprovement in bending stiffness compared to the addition of CS alone. Importantly, the strength improvement did not sacrifice the density significantly. In summary, theknowledge gained from the current study expands the understanding of strength additives and their relationship with fibres of different surface charge and the overall paper properties.

Place, publisher, year, edition, pages
Walter de Gruyter GmbH, 2022
Keywords
bending stiffness; birch fibres; dry strength additives; dry strength of paper; surface charge.
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-322552 (URN)10.1515/npprj-2022-0080 (DOI)000879890700001 ()2-s2.0-85142334676 (Scopus ID)
Note

QC 20221227

Available from: 2022-12-19 Created: 2022-12-19 Last updated: 2024-03-15Bibliographically approved
2. Adsorption of paper strength additives to hardwood fibres with different surface charges and their effect on paper strength
Open this publication in new window or tab >>Adsorption of paper strength additives to hardwood fibres with different surface charges and their effect on paper strength
2022 (English)In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 29, no 4, p. 2617-2632Article in journal (Refereed) Published
Abstract [en]

Light-weight paper products that contain less fibres, but with a maintained bulk and improved strength properties, are highly desirable due to the low cost of raw materials and improved logistics of packaged goods. In this respect, the adsorption capacity of dry strength additives onto fibres, which is affected by the surface charge of said fibres, is very important for the development of these mechanically robust paper products. The influence of the surface charge on the adsorption of strength additives was investigated for, dissolving grade fibres, kraft fibres and kraft fibres modified with carboxymethyl cellulose (CMC) with different surface charge densities, but the same fibre dimensions. The strength additives investigated were cationic starch (CS), anionic polyacrylamide (APAM) and polyelectrolyte complexes (PECs), containing CS and APAM. A linear relationship was found between the surface charge of the fibres and the saturated adsorbed amount of CS. However, when either APAM or PECs adsorbed as secondary layers onto the CS, no correlation between cellulose charge and the saturation adsorption could be observed. The adsorption of APAM was dramatically affected by the pre-adsorbed amount of CS, whereas PECs were less influenced. Moreover, the additives improved the tensile strength (60%) and strain at break (> 100%) of handsheets formed with the kraft fibres and adsorbed APAM. It was also found that CS/APAM increased the sheet density while CS/PECs lowered it. In conclusion, the gained fundamental understanding of these adsorption of additives is of significant importance to facilitate the industrial development of sustainable low-cost high-end packaging products. Graphical abstract: [Figure not available: see fulltext.]

Place, publisher, year, edition, pages
Springer Nature, 2022
Keywords
Anionic polyacrylamide, Birch fibres, Cationic starch, Paper dry strength, Polyelectrolytes complexes, Surface charge, Additives, Cellulose, Costs, Fibers, Paper, Polyelectrolytes, Starch, Tensile strength, Birch fiber, Cationic starches, Dry strengths, Kraft fibers, Low-costs, Paper strengths, Polyelectrolyte complexes, Strength additives, Adsorption
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-320552 (URN)10.1007/s10570-022-04447-3 (DOI)000752239900001 ()2-s2.0-85124309994 (Scopus ID)
Note

QC 20221027

Available from: 2022-10-27 Created: 2022-10-27 Last updated: 2022-12-20Bibliographically approved
3. Exploration of the molecular mechanisms behind paper strength additives using model cellulose surfaces, filaments and beads
Open this publication in new window or tab >>Exploration of the molecular mechanisms behind paper strength additives using model cellulose surfaces, filaments and beads
Show others...
(English)Manuscript (preprint) (Other academic)
Keywords
Cationic strength additives; Model cellulose surface; QCM-D; Model cellulose beads; Cellulose filament joints; Strength properties
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-322553 (URN)
Note

QC 20230214

Available from: 2022-12-19 Created: 2022-12-19 Last updated: 2023-02-14Bibliographically approved
4. Flame-retardant Lightweight materials from layer-by-layer coated cellulose fibers
Open this publication in new window or tab >>Flame-retardant Lightweight materials from layer-by-layer coated cellulose fibers
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Cellulose fibers were functionalized using the layer-by-layer approach, which allows for the formation of a coating by positively and negatively charged layers of polyelectrolytes on the fiber surface, consisting of sodium hexametaphosphate and chitosan. By using this coating approach, it was possible to obtain a bio-based, homogeneous and flame-retardant coating. Self-extinguishing properties was achieved at 1 bi-layer (BL) as visible in a horizontal flame test, while non-ignitability was obtained after 3BL coating. The coated cellulose fibers were used to produce foams, a self-standing lightweight 3D structure, by freeze-drying. Even though made by mainly cellulose, these foams gave self-extinguishing results when prepared by 1BL coated fibers and non-ignitability when prepared with 3BL coated fibers. Cone calorimetry showed a decrease in heat release rate and total heat release of 56% and 68% respectively for the foam containing 3BL coated fibers.

National Category
Composite Science and Engineering Textile, Rubber and Polymeric Materials Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-322555 (URN)
Note

QC 20221221

Available from: 2022-12-19 Created: 2022-12-19 Last updated: 2022-12-21Bibliographically approved

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Zhao, Mengxiao

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