EFFECTS OF FIBER LENGTH AND COARSENESS ON PULP FLOCCULATION

The effects of fiber length and coarseness on pulp flocculation were studied by measuring the mass uniformity of fiber suspensions at rest after turbulence decay. Increasing fiber length led to a decrease in uniformity by increasing the degree of fiber contact (crowding factor) and floc size. Increasing coarseness at the same fiber length and crowding factor further diminished uniformity. Mixtures of long and short fibers of a given length-weighted average length gave the same nonuniformity as individual fractions of the same fiber length. The uniformity obtained at a given fiver length was the same for suspensions containing fibers of equal length or mixtures of long and short fibers of the same length-weighted average length. Both fiber length and coarseness also affected fiber mobility, which reflects floc strength. Mobility was not tested, but it is postulated that, like uniformity, it is a key factor in paper formation on commercial machines.