The relationship between the torsional and flexural rigidity of single fibres, and the flow resistance of pulp suspensions was investigated from the point of the flocculation process.
The torsional and flexural properties of wetted single pulp fibres were measured by the torsional pendulum method and by the bending method respectively, for chemical pulps. A new experimental apparatus to measure the flow resistance of dilute fibre suspensions to rotary motion was developed in our laboratory.
A good correlation between torsional rigidity and the flexural property of single pulp fibres was observed, and the flexibility of fibres was found to increase intensely during the early stages of beating.
It was found that wall-shear stress, motion decay times, and the shapes of the motion decay curves of fibre suspensions depended on the flexural properties of the fibres, their length, and the concentration and temperature of the suspension.