NC State
O. Joutsimo, R. Wathén and L. Robertsén. Role of fiber deformations and damage from fiber strength to end user. In Advances in Paper Science and Technology, Trans. of the XIIIth Fund. Res. Symp. Cambridge, 2005, (S.J. I’Anson, ed.), pp 591–611, FRC, Manchester, 2018.


Fiber deformations and damage have a considerable influence on both fiber strength and network properties. Through their influence on the fiber network, they can also affect the way paper behaves during converting. Another aspect is their influence on end-use properties, again via their effect on the fiber network.

Separating the effects of fiber deformations and damage is often difficult. We prepared pulps in the laboratory and subjected them to different treatments that change the two relatively
independently in a controlled manner. We found that wet/dry zero-span fiber strength is not dependent on the deformation method or on the extent of the deformations. Neither pulp sheet
density nor Scott bond bonding was greatly affected by the type or method of deformation. In the case of deformed pulps, the pulp sheet tensile properties were dependent on the extent of fiber deformation via fiber segment activation. The pulp that was damaged instead of deformed had fiber deformations to about the same extent as the deformed pulp but lower single fiber strength measured with wet/dry zero-span. It also had lower bonding ability and sheet density. The tear index for the unbleached damaged pulp was 20–25% higher than that of the reference pulps. Fiber deformations (curl and kinks) affect fiber network properties via the lack of fiber segment activation. However, they do not significantly influence fiber shrinkage potential (WRV) or fiber strength.

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