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Fjellström, Helena
Publications (10 of 16) Show all publications
Logenius, L., Fjellström, H. & Engstrand, P. (2014). A sustainable analysis of sulphonic acid content in CTMP pulps. In: International Mechanical Pulping Conference, IMPC 2014, part of PulPaper 2014 Conference: . Paper presented at International Mechanical Pulping Conference, IMPC 2014; Helsinki; Finland; 2 June 2014 through 5 June 2014; Code 109275. Espoo: Paper Engineers' Association (PI)
Open this publication in new window or tab >>A sustainable analysis of sulphonic acid content in CTMP pulps
2014 (English)In: International Mechanical Pulping Conference, IMPC 2014, part of PulPaper 2014 Conference, Espoo: Paper Engineers' Association (PI) , 2014Conference paper, Published paper (Other academic)
Abstract [en]

Sulphonic acid analyses were performed on wing refiner chemithermomechanical pulps, low sulphite charge pulps, thermomechanical pulps and on wood samples using a new method referred to as the niacin method. This method gives sulphonic acid content comparable to those estimated with the quinoline method or the Schoniger method. The method gives low interference with carboxylic acids and dissolved substances in the pulp if the pH is kept sufficiently low and the pulp is well washed.

Place, publisher, year, edition, pages
Espoo: Paper Engineers' Association (PI), 2014
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-23871 (URN)2-s2.0-84923974401 (Scopus ID)978-000000000-2 (ISBN)
Conference
International Mechanical Pulping Conference, IMPC 2014; Helsinki; Finland; 2 June 2014 through 5 June 2014; Code 109275
Funder
Knowledge Foundation
Available from: 2014-12-17 Created: 2014-12-17 Last updated: 2016-12-30Bibliographically approved
Logenius, L., Engberg, B. A., Fjellström, H. & Engstrand, P. (2013). Mechanical Properties of Sulphonated Spruce Wood. In: : . Paper presented at 8th Fundamental mechanical pulping research seminar. Åre, Sweden
Open this publication in new window or tab >>Mechanical Properties of Sulphonated Spruce Wood
2013 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

The chip-refining stage in the production of high yield pulps as TMP and CTMP determines a large part of the optical and mechanical characteristics of the pulp. Softening of the raw material influences where the fiber walls fracture sites will be located.

In the thermomechanical pulping (TMP) processes, refining is performed at temperatures close to the lignin softening temperature, which normally leads to fractures located in the in the primary wall and outer parts of the secondary wall. When wood material is chemically treated before chip-refining the position of the fracture is altered due to that the softening and swelling properties of the fiber walls are changed. In the chemi-thermomechanical (CTMP) process most of the fractures are, therefore, located in the middle lamella or in the primary wall due to introduction of charged groups in the lignin which facilitates the fiber separation. At alkaline pH phenolic lignin structures are sulphonated, at lower pH non-phenolic structures in the lignin are also sulphonated. In the mechanical pulping processes the wood material is subjected to both low strain rates (e.g. plug screw treatment) and high strain rates (refining). Since wood is a viscoelastic material it behaves differently at different strain rates.

In this study, sulphonation has been carried out using different sulphite concentrations and pH-levels and we have thereby influenced the sulphonation degree as well as where in the lignin the sulphonation takes place.

We used a hydraulic testing machine for low strain-rate testing and a Split-Hopkinson pressure bar device for high strain-rate testing to categorize pretreatments according to their material softening effect and the energy needed for fiber separation. This gives us increased fundamental knowledge of how the mechanical properties of wood are affected by the sulphonation in order to develop new/improved pretreatments.

Place, publisher, year, edition, pages
Åre, Sweden: , 2013
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-20789 (URN)
Conference
8th Fundamental mechanical pulping research seminar
Projects
Pretreatment strategies for high yield pulps
Funder
Knowledge Foundation, 4380632
Available from: 2013-12-18 Created: 2013-12-18 Last updated: 2013-12-19Bibliographically approved
Fjellström, H., Engstrand, P. & Htun, M. (2013). On the relationship between charged groups, chemical environment and delamination during refining.. In: : . Paper presented at 8th International Fundamental Mechanical Pulp Research Seminar (IFMPRS), Åre, Sweden, Jan 29-31, 2013.
Open this publication in new window or tab >>On the relationship between charged groups, chemical environment and delamination during refining.
2013 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Improved understanding regarding how to optimise the degree of swelling in the wood fibre wall may be a way to reduce the energy demand in the refining process. The forces necessary to achieve fibrillation (internal as well as external) are greatly influenced by the swelling properties of the fibre wall. The degree and position of swelling is also the main cause to where in the wood matrix the fibre separation will take place. Refining of wood chips in different state of swelling will result in mechanical pulp fibres with different optical and mechanical properties.

 

The typical parameters that influence the wood fibres’ ability to swell are temperature, pH, ionic form, amount of charged groups and ionic strength. Water retention value is one way to measure the pulp´s capacity to retain water after centrifugation and is strongly correlated to the swelling ability of wood fibres.

 

A blowline-sample of Norway spruce thermomechanical pulp (TMP) taken out directly after the chip-refining step was used as reference material for this study. The sample was treated with sodium sulphite under different conditions to introduce a range of very low to very high degrees of sulphonic acid groups in the cell walls. In a similar way alkaline hydrogen peroxide was used to introduce a range of very low to very high degrees of carboxylic acid groups. Each sample was then ion-exchanged into proton, sodium, calcium and aluminium form.

 

The effect of the amount of sulphonic and carboxylic acid groups in combination with the effect of counter ion, on the swelling capacity of mechanical pulp fibres was investigated. In addition, all samples were measured in a temperature interval between 25°C and 95°C to monitor changes in the softening temperature due to lignin structure modifications.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-20636 (URN)
Conference
8th International Fundamental Mechanical Pulp Research Seminar (IFMPRS), Åre, Sweden, Jan 29-31, 2013
Projects
Maximized Fibre Wall Swelling in TMP & CTMP Refining
Available from: 2013-12-11 Created: 2013-12-11 Last updated: 2013-12-12Bibliographically approved
Fjellström, H., Engstrand, P. & Htun, M. (2013). ON THE RELATIONSHIP BETWEEN WOOD FIBRE WALL SWELLING, CHARGED GROUPS, AND DELAMINATION DURING REFINING. Paper presented at 17th International Symposium on Wood, Fiber and Pulping Chemistry (ISWFPC), Vancouver, Canada, June 12-14 2013. J-FOR-JOURNAL OF SCIENCE & TECHNOLOGY FOR FOREST PRODUCTS AND PROCESSES, 3(4), 30-34
Open this publication in new window or tab >>ON THE RELATIONSHIP BETWEEN WOOD FIBRE WALL SWELLING, CHARGED GROUPS, AND DELAMINATION DURING REFINING
2013 (English)In: J-FOR-JOURNAL OF SCIENCE & TECHNOLOGY FOR FOREST PRODUCTS AND PROCESSES, ISSN 1927-6311, Vol. 3, no 4, p. 30-34Article in journal (Refereed) Published
Abstract [en]

The influence of sulphonic and carboxylic acid groups in combination with the effect of counter ion form, on the swelling capacity of mechanical pulp fibres was studied by means of water retention value (WRV) measured in the temperature range from 25 to 95oC. Mechanical pulp fibres (TMP) were treated with hydrogen peroxide and/or sodium sulphite during conditions resembling those used in chemimechanical and bleaching processes commonly used in the industry. In conventional chemimechanical processes sulphite treatment is used before refining while peroxide treatment can be utilized both before and after refining. In this study we did however also use sulphite after peroxide treatment. When subjecting sodium sulphite treated pulps to a subsequent hydrogen peroxide step, all pulps show a decrease in sulphonic acid groups, which could be owed to dissolution of highly charged lignin. Pulps treated with a high hydrogen peroxide charge (4%), showed a loss in carboxylic acid groups during subsequent treatment with sodium sulphite. This loss is probably due to dissolution of highly charged fibre material such as demethylated pectins. Both increased degree of sulphonation and carboxylation of the lignin reduces the softening temperature by means of reducing the degree of cross-linking in the lignin matrix. This softening probably improves the compressibility of the fibre pads in the sample holders of the WRV centrifuge, which would counteract an otherwise expected increasing WRV-value due to increased swelling potential. This makes it difficult to see clear trends in WRV as a function of increase in degree of sulphonation and carboxylation. When changing counter ion form from proton or calcium form to sodium form there is however always a clear increase in WRV in the range from 20 to 30%.

Keywords
Swelling, Fibre Wall, Water Retention Value, High-Yield Pulp, Ionic Form
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-20634 (URN)000345678900005 ()2-s2.0-84905389461 (Scopus ID)
Conference
17th International Symposium on Wood, Fiber and Pulping Chemistry (ISWFPC), Vancouver, Canada, June 12-14 2013
Projects
Maximized Fibre Wall Swelling in TMP & CTMP Refining
Available from: 2013-12-11 Created: 2013-12-11 Last updated: 2015-01-05Bibliographically approved
Fjellström, H., Engstrand, P. & Htun, M. (2013). On the relationship between wood fibre wall swelling, charged groups, and delamination during refining. Journal of Science & Technology for Forest Products and Processes, 3(4), 30-34
Open this publication in new window or tab >>On the relationship between wood fibre wall swelling, charged groups, and delamination during refining
2013 (English)In: Journal of Science & Technology for Forest Products and Processes, ISSN 1927-6311, E-ISSN 1927-632X, Vol. 3, no 4, p. 30-34Article in journal (Refereed) Published
Abstract [en]

The influence of sulphonic and carboxylic acid groups in combination with the effect of counter-ion form on the swelling capacity of mechanical pulp fibres was studied by means of water retention value (WRV) measured in the temperature range from 25oC to 95oC. Mechanical pulp fibres (TMP) were treated with hydrogen peroxide, sodium sulphite, or both under conditions resembling those used in chemi-thermomechanical and bleaching processes commonly used in the industry. In conventional chemi-thermo-mechanical processes, sulphite treatment is used before refining, whereas peroxide treatment can be used both before and after refining. However, in this study, sulphite was also used after peroxide treatment. When sodium sulphite-treated pulps are subjected to a subsequent hydrogen peroxide step, all pulps show a decrease in sulphonic acid groups, which can be attributed to dissolution of highly charged lignin. Pulps treated with a high hydrogen peroxide charge (4%) show a loss in carboxylic acid groups during subsequent treatment with sodium sulphite. This loss is probably due to dissolution of highly charged fibre material such as demethylated pectins. Both the increased degree of sulphonation and carboxylation of lignin reduce the softening temperature reducing the degree of cross-linking in the lignin matrix. This softening probably improves the compressibility of the fibre pads in the sample holders of the WRV centrifuge, which would counteract the otherwise expected increase in WRV due to increased swelling potential. This phenomenon makes it difficult to see clear trends in WRV as a function of increasing degrees of sulphonation and carboxylation. When changing the counter-ion form from proton or calcium form to sodium form, there is, however, always a clear increase in WRV in the range from 20% to 30%.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-24054 (URN)2-s2.0-84905389461 (Scopus ID)
Note

Export Date: 7 January 2015

Available from: 2015-01-09 Created: 2015-01-07 Last updated: 2017-12-05Bibliographically approved
Fjellström, H., Engstrand, P. & Htun, M. (2012). Aspects of fibre wall swelling in high-yield pulp.. In: PROCEEDING OF THE 4TH INTERNATIONAL CONFERENCE ON PULPING, PAPERMAKING AND BIOTECHNOLOGY (ICPPB '12), VOLS. I AND II: . Paper presented at 4th International Conference on Pulping, Papermaking and Biotechnology (ICCPB’12), Nanjing, China, Nov 7–9 (pp. 1183-1186).
Open this publication in new window or tab >>Aspects of fibre wall swelling in high-yield pulp.
2012 (English)In: PROCEEDING OF THE 4TH INTERNATIONAL CONFERENCE ON PULPING, PAPERMAKING AND BIOTECHNOLOGY (ICPPB '12), VOLS. I AND II, 2012, p. 1183-1186Conference paper, Oral presentation only (Refereed)
Abstract [en]

When producing mechanical pulps the fibre separation will take place in the weakest part of the wood matrix. A prerequisite to swelling in wood and mechanical pulps is that the wood matrix is softened. The position of where the weakest part of the wood matrix is situated can to a large extent be controlled by adjustment of the swelling and softening properties of each of the wood polymers (lignin, hemicelluloses and cellulose). Most probably the efficiency of the external and internal fibrillation of the fibre walls is also influenced by how the swelling and softening properties are controlled. The combination of position of fibre-fibre separation together with the efficiency of the external and internal fibrillation will to a large extent determine the energy demand to produce mechanical pulps. Refining of wood chips with different state of softening and swelling will give rise to fibres with different optical and physical properties. The most important parameters that influence the wood matrix and wood fibres’ ability to swell are temperature, pH, ionic form of and the amount of charged groups in the hemicelluloses and lignin of the cell walls. In order to improve the level of knowledge on how to influence the degree of wood matrix and fibre wall swelling of mechanical pulps we have undertaken to study the swelling properties of wood and fibres produced by means of different mechanical pulping processes.

It was found that pulps not containing sulphonic acid groups need to be heated above the softening temperature of lignin in order to be able to swell to their full capacity. Introduction of sulphonic acid groups also opens up the rigid structure of lignin which lowers the softening temperature and increases the swelling potential even at lower temperatures. The effect of valence of the counter ion was also shown to be more pronounced after adding more carboxylic acid groups to a pulp. Depending on the number and type of anionic acid groups in the fibres, high-yield pulps will have different combinations of properties in different ionic conditions. The preliminary conclusions from this study are that the ability to control swelling properties of mechanical pulps is an important feature to take into account when producing pulp and paper.

Keywords
Swelling; Fibre Wall; Water Retention Value; High-Yield Pulp; Ionic Form.
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-18053 (URN)000323396200237 ()978-7-5019-9043-6 (ISBN)
Conference
4th International Conference on Pulping, Papermaking and Biotechnology (ICCPB’12), Nanjing, China, Nov 7–9
Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2014-08-31Bibliographically approved
Fjellström, H., Engstrand, P., Granfeldt, T. & Logenius, L. (2011). Predicting CTMP bleachability using wood shavings. In: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC: . Paper presented at 16th International Symposium on Wood, Fiber and Pulping Chemistry, ISWFPC;Tianjin;8 June 2011through10 June 2011;Code88003 (pp. 613-616). , 1
Open this publication in new window or tab >>Predicting CTMP bleachability using wood shavings
2011 (English)In: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 2011, Vol. 1, p. 613-616Conference paper, Published paper (Refereed)
Abstract [en]

To predict the brightness reduction in a chemithermomechanical process as well as the bleachability of pulps produced from different species of wood raw materials there are, at present, no shortcuts available. Pulps have to be manufactured in pilot or mill scale and bleached; evaluating and predicting the bleachability has consequently been very resource consuming and thus expensive - until now! Due to this, we have used a laboratory method based on 60 × 60 mm wood shavings making it possible to predict the bleachability of primarily chemithermomechanical pulps but also other mechanical pulps. Our experiments showed that retention time and impregnation temperature appears to have no impact on the final brightness of birch shavings. When being subjected to a simulated chemithermomechanical pulp process, eucalyptus exhibited an increase in chromophore content before the bleaching stage. In addition, eucalyptus suffered from severe alkaline darkening. After the bleaching stage, the alkaline darkening diminished. A higher retention temperature resulted in lower brightness of the eucalyptus shavings compared to when using a lower retention temperature. Birch reached the highest final brightness levels and had a higher overall yield too.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-16752 (URN)2-s2.0-84855713005 (Scopus ID)
Conference
16th International Symposium on Wood, Fiber and Pulping Chemistry, ISWFPC;Tianjin;8 June 2011through10 June 2011;Code88003
Available from: 2012-08-17 Created: 2012-08-17 Last updated: 2013-12-12Bibliographically approved
Fjellström, H., Höglund, H., Paulsson, M. & Forsberg, S. (2009). The UV-screening properties of coating layers: The influence of pigments, binders and additives. Nordic Pulp & Paper Research Journal, 24(2), 206-212
Open this publication in new window or tab >>The UV-screening properties of coating layers: The influence of pigments, binders and additives
2009 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 24, no 2, p. 206-212Article in journal (Refereed) Published
Abstract [en]

The ability of coating colours to obstruct ultraviolet (UV) radiation in the 300-385 nm region was examined with the aim of finding the best photo-stabilising formulation to inhibit discoloration of high-yield pulps. The influence of pigment type, bleaching of the pigments, pigment size, pigment size distribution, type of binder and addition of U-V-absorbing compounds were examined using a newly developed method for studying the reflectance and transmittance properties of thin coating layers.

The pigment type and coat weight was found to be the most important factors for reducing the transmittance of UV-radiation. Kaolin clays were more effective than calcium carbonate pigments and are therefore a better coating pigment for photostability reasons. Bleaching of the pigments, resulted in an overall minor decrease in transmittance for both kaolin and ground calcium carbonate (GCC) pigments, especially at low coat weights. Bleaching of the pigments changed the particle size distribution somewhat, which probably alters the structure in the coating layer. Precipitated calcium carbonate (PCC) pigments have a higher UV-screening potential compared to GCC pigments and should therefore be a better choice among the calcium carbonates. It was further concluded that a narrow pigment size distribution was beneficial for reducing the amount of transmitted UV-radiation that reaches the base paper. Styrene butadiene latex and polyvinylpyrrolidone were better in reducing the transmittance in the UV-region than polyvinyl alcohol.

Adding a fluorescent whitening agent to a coating colour decreased the transmittance in the UV-region when the pigment was of the GCC type, and increased the transmittance when kaolin pigment was used. Addition of titanium dioxide (3 parts) to a coating colour containing kaolin pigment blocked about 90% of the UV-radiation at a coat weight of 10 g/m(2), which is a common coat weight for a single coated paper. Another possibility is to double coat to increase the coat weight, which turns the transmittance factor closed to zero.

Keywords
Coating, Pigments, Kaolin, Calcium carbonate, GCC, PCC, Binders, Additives, FWA, UV, Photo stabilisation
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-993 (URN)10.3183/NPPRJ-2009-24-02-p206-212 (DOI)000268735100012 ()2-s2.0-68049142284 (Scopus ID)5163 (Local ID)5163 (Archive number)5163 (OAI)
Available from: 2008-12-02 Created: 2008-12-02 Last updated: 2017-12-13Bibliographically approved
Fjellström, H., Höglund, H., Paulsson, M. & Rundlöf, M. (2008). Discolouration of mechanical and chemimechanical pulps: influence of wood raw material, process and ageing method. Nordic Pulp & Paper Research Journal, 23(1), 14-18
Open this publication in new window or tab >>Discolouration of mechanical and chemimechanical pulps: influence of wood raw material, process and ageing method
2008 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 1, p. 14-18Article in journal (Refereed) Published
Abstract [en]

The change in colour of a wide range of unbleached and bleached high-yield pulps was assessed using the CIELAB colour system. The influence of ageing method, pulping process and wood raw material is discussed.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-427 (URN)10.3183/NPPRJ-2008-23-01-p014-018 (DOI)000255491400002 ()2-s2.0-50949095750 (Scopus ID)5162 (Local ID)5162 (Archive number)5162 (OAI)
Available from: 2008-11-13 Created: 2008-11-13 Last updated: 2017-12-13Bibliographically approved
Fjellström, H. (2008). Inhibition of light-induced colour reversion of wood-containing papers by means of coating. (Doctoral dissertation). Sundsvall: Mid Sweden University
Open this publication in new window or tab >>Inhibition of light-induced colour reversion of wood-containing papers by means of coating
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The main purpose of this thesis was to find ways to maintain a low level of light‐induceddiscolouration at an increased addition of mechanical and chemimechanical pulps in coated highqualityfine paper and magazine paper grades. Current technology allows the production of highyieldpulps such as thermomechanical and chemimechanical pulps with properties suitable formanufacturing high‐quality paper or paperboard with a low basis weight. Coating of woodcontainingpaper will probably be necessary for photo‐stability reasons if lignin‐containing pulps areto be used as the main fibre furnish in long‐life and high‐value products.In order to find the most suitable pulp for this purpose, light‐induced discolouration of a variety ofpaper samples from unbleached and bleached softwood and hardwood pulps was studied under bothaccelerated and long‐term ambient light‐induced ageing conditions. Hardwood high‐yield pulps,especially aspen pulps, were proven to be more photo‐stable compared to softwood pulps. Hardwoodpulps should therefore be the first choice for applications where a high permanence is desirable.Evaluating ageing characteristics using the CIELAB colour system showed that accelerated ageingconditions tend to mainly increase the b* value and decrease the L* value (i.e. yellow the pulp),whereas long‐term ambient ageing also increases the a* value, which makes the pulp more reddish.A new method for studying the influence of the UV‐screening properties of coating layers on abase paper was developed, and used to investigate the effect of pigment, pigment size distribution,binder and UV‐absorbing additives. The coat weight and pigment type were found to be the mostimportant factors for reducing the transmittance of UV‐radiation. Coating colours containing kaolinpigments had a lower UV‐transmittance than calcium carbonate pigments. Of the calcium carbonates,precipitated calcium carbonates were better than ground calcium carbonates and the difference wasgreater at higher coat weights. The particle size distribution should preferable be narrow. When thebest pigment (bleached kaolin) and the best binder (styrene butadiene latex) were combined withtitanium dioxide, the UV‐transmittance could be reduced by about 90% at a coat weight of ~10 g/m2.At a coat weight close to 20 g/m2, the transmittance was close to zero. This shows that it is possible tomore or less fully protect a double coated base paper from harmful UV‐radiation, when the coatinglayer has an optimum composition for that purpose. A prerequisite to reach so far is that the coatinglayer has an even coat weight.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2008
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 44
Keywords
High-yield pulp, CTMP, birch, light-induced, ageing, photo-stabilising, lignin, coating, pigment, kaolin, calcium carbonate, titanium dioxide, binder, FWA
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-95 (URN)978-91-85317-84-4 (ISBN)
Public defence
2008-01-25, O102, Mittuniversitetet, Sundsvall, 10:00 (English)
Opponent
Supervisors
Available from: 2008-02-14 Created: 2008-02-14 Last updated: 2013-12-18Bibliographically approved
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