A Note on the Permeability Method for Determining Surface Development and Swelling During Beating and Refining

Abstract

The permeability method for the determination of specific surfaces (Carman⁽¹⁾) of particles forming an unconsolidated homogeneous bed have been applied by Robertson and Mason⁽⁶⁾ to swollen pulp fibres. The permeability of the bed is measured at several bed concentrations and the data may be used to calculate not only a specific surface, but also a specific volume by suitable application of the Kozeny-Carman equation. The method has since been used by Corte,⁽³⁾ Emerton,⁽⁴⁾ Ingmanson,⁽⁵⁾ Carroll and Mason⁽²⁾ and others.

It has previously been reported⁽⁶⁾ that the development of specific volume during beating as measured by this method ran parallel to the strength development as measured by breaking length or burst. On the basis of rather limited data, the suggestion was made that the two phenomena swelling and strength development might be closely related for a given pulp. At the same time, it was noted that a relationship appeared to exist between the specific surface and the drainage properties as measured by a freeness test. The same observations were subsequently confirmed by Corte⁽³⁾ and in part by Carroll and Mason.⁽²⁾

The present note reports some subsequent work carried out at Svenska Träforskningsinstitutet, which generally confirms the previous picture, but suggests that the relationships are modified by the method of treatment.