The influence of some fibre and solution properties on pulp fibre friction

A novel method, presented in an earlier paper, was used to measure the inte rfibre fiction of single kraft pulp fibres under dry and wet conditions. Th e coefficient of friction of dry fibres was around 0.6 and was not affected by the kappa number. On wet fibres it ranged from 0.6 to 0.8 and decreased with decreasing kappa number and with the addition of NaCl (1 mol/L), HCl (pH 3) or NaOH (pH 10). Extrapolation of the frictional force to zero norma l force yielded values around 0.01 mN for dry fibres. Under wet conditions, the extrapolated values ranged from 0.02 to 0.06 mN and correlated with th e yield stress of the fibre suspensions.