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H. Rahman, P. Engstrand, E. Persson, S. An, B. Norlin, F. Zeeshan and T. Granfeldt. Development of improved CTMP with even sulphonate distribution at fibre level using XRF analysis. In Advances in Pulp and Paper Research, Cambridge 2022, Trans. of the XVIIth Fund. Res. Symp. Cambridge, 2022 (D. Coffin and W. Batchelor, eds), pp 3–11. FRC, Manchester, 2022.


Optimizing the fibre property distribution could increase the pulp properties as well as the process efficiency of chemimechanical pulps (CMP/CTMP). This can only be achieved with a better understanding of how evenly distributed sulphonate concentrations are between the individual CTMP fibres. Given that the quality of wood chips varies with the chipping methods used in pulpwood processing and sawmill processing, as well as with the chip screening system, it is a challenge to develop an impregnation process that ensures even distribution of sodium sulphite (Na2SO3) in the liquid used to impregnate the Chemimechanical pulp (CMP/CTMP). Therefore, the distribution of sulphonate groups within wood chips and individual fibres must be measured at the microscale level. On a micro level, the degree of unevenness, i.e., the amount of fibre sulphonation and softening before defibration, cannot be determined due to the use of excessively robust or complex processing methods. By having it, we could better understand how sulphonation occurs before defibration, so we could improve impregnation. Developing a laboratory scale miniaturized energy dispersive X-ray fluorescence (ED-XRF) method that measures sulphur distribution at the fibre level can enable us to study the influence of impregnation improving processes.

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