Morphological changes in never-dried kraft fibers under mechanical shearing
Abstract
The modification of bleached never-dried cellulose fibers was studied under controlled compression and shearing conditions. Fibers were further treated in a high-intensity mixing device in low-consistency to determine if the fiber structure was weakened in the in-pad attrition. The difference between the development of the softwood and hardwood fibers was examined. The fiber properties were analyzed using a fiber morphology analyzer, fractional fiber analysis and an electron microscope. The results indicate that the shearing under the controlled compression at high consistency modified the softwood and hardwood fibers already at low-energy consumptions. The fiber length and width decreased, and the formation of curls and kinks was pronounced. However, the intensive mixing after in-pad attrition revealed that the fiber structure was not weakened under compression and shear forces; conversely, the fiber cell wall was more resistant for the intensive mixing. When comparing the results for hardwood and softwood fibers, the softwood fibers were more modified during in-pad attrition, whereas the fiber wall strengthening was more significant in the hardwood fibers.
Keywords
Cellulose structure Fiber morphology Bleached kraft pulp Compressibility Internal friction In-pad attritionNotes
Acknowledgments
The authors thank Mr. Jani Österlund for his help during the practical work and the Graduate School in Chemical Engineering (GSCE) for the financial support.
References
- Alén R (2000) Structure and chemical composition of wood. In: Stenius P (ed) Papermaking science and technology book 3: papermaking part 1, forest products chemistry, 1st edn. Fapet Oy, Helsinki, Finland, pp 11–57Google Scholar
- Bäckström M, Kolar MC, Htun M (2008) Characterisation of fines from unbleached kraft pulps and their impact on sheet properties. Holzforschung 62:546–552CrossRefGoogle Scholar
- Bergander A, Salmén L (2002) Cell wall properties and their effects on the mechanical properties of fibers. J Mater Sci 37:151–156CrossRefGoogle Scholar
- Chakraborty A, Sain M, Kortschot M (2005) Cellulose microfibrils: a novel method of preparation using high shear refining and cryocryshing. Holzforschung 59:102–107CrossRefGoogle Scholar
- Donaldson L (2008) Microfibril angle: measurement, variation and relationships—a review. IAWA J 29(4):345–386Google Scholar
- Fardim P, Durán N (2003) Modification of fibre surfaces during pulping and refining as analysed by SEM, XPS and ToF-SIMS. Colloids Surf A Physicochem Eng Aspects 223:263–2276CrossRefGoogle Scholar
- Fernando D, Daniel G (2004) Micro-morphological observations on spruce TMP fibre fractions with emphasis on fibre cell wall fibrillation and splitting. Nordic Pulp Paper Res J 19(3):278–285CrossRefGoogle Scholar
- Hamad WY (1998) On the mechanism of cumulative damage and fracture in native cellulose fibres. J Mater Sci 17:433–436Google Scholar
- Hamad WY, Provan JW (1995) Microstructural cumulative material degradation and fatigue-failure micromechanisms in wood-pulp fibres. Cellulose 2:159–177CrossRefGoogle Scholar
- Hartler N (1995) Aspects on curled and microcompressed fibers. Nordic Pulp Paper Res J 1:4–7CrossRefGoogle Scholar
- Hartman RR (1984) Mechanical treatment of pulp fibers for property development, dissertation. The institute of Paper Science and Technology, Atlanta, GeorgiaGoogle Scholar
- Illikainen M, Niinimäki J (2007) Energy dissipation in a TMP refiner disc gap. In: Proceedings of the 6th Biennal Johan Gullichsen Colloquium, Espoo, Finland, pp 49–57Google Scholar
- Illikainen M, Härkönen E, Ullmar M, Niinimäki J (2008) Disruptive shear stress in spruce and pine TMP pulps. Paperi Ja Puu Paper Timber 90(1):47–52Google Scholar
- Karnis A (1989) High-consistency refining of bleached sulfate pulps. Tappi J 72(6):96–102Google Scholar
- Karnis A (1994) The mechanism of fibre development in mechanical pulping. J Pulp Paper Sci 20(10):J280–J288Google Scholar
- Koskenhely K (2008) Refining of chemical pulp fibres. In: Paulapuro H (ed) Papermaking science and technology book 8: papermaking part 1, stock preparation and wet end, 2nd edn. Finnish Paper Engineers’ Association/Paperi ja Puu Oy, Helsinki, Finland, pp 94–139Google Scholar
- Laine C, Wang X, Tenkanen M, Varhimo A (2004) Changes in the fiber wall during refining of bleached pine kraft pulp. Holzforschung 58:233–240CrossRefGoogle Scholar
- Laitinen O (2011) Utilisation of tube flow fractionation in fibre and particle analysis, dissertation. Department of process and environmental engineering, University of Oulu, FinlandGoogle Scholar
- Lowe RM, Page DH, Waterhouse JF, Hsieh J, Cheluka N, Ragauskas AJ (2007) Deformation behavior of wet lignocellulosic fibers. Holzforschung 61:261–266CrossRefGoogle Scholar
- Lumiainen J (2000) Refining of chemical pulp. In: Paulapuro H (ed) Papermaking science and technology book 8: papermaking part 1, stock preparation and wet end, 1st edn. Fapet Oy, Helsinki, Finland, pp 87–122Google Scholar
- Lundin T, Batchelor W, Fardim P (2008) Fiber trapping in low-consistency refining: new parameter to describe the refining process. Tappi J 7(7):15–21Google Scholar
- Luo XL, Zhu JY, Gleisner R, Zhan HY (2011) Effects of wet-pressing-induced fiber hornification on enzymatic saccharification of lignocelluloses. Cellulose 18:1055–1062CrossRefGoogle Scholar
- Mahoney TC, Paulapuro H (1999) The formation of pores in the cell wall. J Pulp Paper Sci 25(12):430–436Google Scholar
- Marton R, Agarwal AK (1965) Papermaking properties of hardwood vessel elements. Tappi J 48(5):264–269Google Scholar
- Miles KB, Karnis A (1991) The response of mechanical and chemical pulps to refining. Tappi J 74(1):157–164Google Scholar
- Page DH (1989) The beating of chemical pulps—the action and effect. 9th Fundamental Research Symposium Notes, UK, Cambridge, p 1Google Scholar
- Salmén L, Burgert I (2009) Cell wall features with regard to mechanical performance. A review. Holzforschung 63(2):121–129CrossRefGoogle Scholar
- Sjöberg JC, Höglund H (2007) High consistency refining of kraft pulp for reinforcing paper based on TMP furnishes. International Mechanical Pulping Conference, Minneapolis, Minnesota, USAGoogle Scholar
- Stone JE, Scallan AM, Abrahamson B (1968) Influence of beating on cell wall swelling and internal fibrillation. Svensk Papperstidning 19:687–694Google Scholar
- Wang X, Maloney TC, Paulapuro H (2007) Fibre fibrillation and its impact on sheet properties. Paperi Ja Puu Paper Timber 89(3):148–151Google Scholar
- Xu EC, Koefler H, Antensteiner P (2003) Some latest developments in alkali peroxide mechanical pulping, part 2: low consistency secondary refining. Pulp Paper Canada 104(10):T256–T260Google Scholar