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Mechanical Properties of Sulphonated Spruce Wood
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. (High yield pulping technology)
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. (High yield pulping technology)ORCID iD: 0000-0003-3381-5516
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. (High yield pulping technology)
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. (High yield pulping technology)
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: urn:nbn:se:miun:diva-20789OAI: oai:DiVA.org:miun-20789DiVA, id: diva2:680828
Conference
8th Fundamental mechanical pulping research seminar
Projects
Pretreatment strategies for high yield pulps
Funder
Knowledge Foundation, 4380632Available from: 2013-12-18 Created: 2013-12-18 Last updated: 2013-12-19Bibliographically approved

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Logenius, LouiseEngberg, Birgitta A.Fjellström, HelenaEngstrand, Per

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