Fibre development during mechanical pulp refining

The development of fibre bonding ability during refining is discussed from the point of earlier published work and some new results from pulps sampled in commercial refiners. Special attention is given to summerwood fibres. Fibre bonding ability, an important property for printing papers of good runnability and printability is influenced by many factors. Cross-sectional dimensions of the fibre and fibre wall stiffness determine its ability to collapse. Chemical and structural differences of the fibre surface are also important. The development of fibre properties also indirectly influences the properties of the other fractions, as the finer fractions are composed of material removed from the fibres by the mechanical treatment In the experimental work described in this paper the change in fibre properties did not occur uniformly for all fibres. Fibre shortening happened primarily for thin-walled springwood fibres, and unravelling of the S-2 layer was more marked for thick-walled summerwood fibres.