On the mobility of flowing papermaking suspensions and its relationship to formation

The mobility of flowing papermaking fibre suspensions has been characterized by measuring the changes in paper properties formed in a novel laboratory device. For the conditions tested, properties such as formation and fibre orientation were observed to change significantly when. the ratio of the yield stress τ0 of the suspension to the energy dissipated by the fluid, defined as ε in this work, exceed ε ∼ 10-2, i.e ε=τ0/ρU2>10-2 (1) where p is the density of the suspension and U is a characteristic velocity. In subsequent work, changes information were measured as a function of ε on both an experimental pilot paper machine and on 18 different industrial machines. Formation was found to diminish at approximately the same level of ε. this implies that paper machine operations may be optimized to a degree hitherto not done.