ON THE INTERACTION OF WOOD AND MECHANICAL PULPING EQUIPMENT .2. PULP QUALITY

In Part I, the development of pulp fibres and the generation of fines by grinding and refining were shown to be significantly different. The consequences of these differences on the pulp properties are discusse d here. There is no single correlation between the fines content of me chanical pulps and their freeness. For an equal amount of fines, the f reeness of groundwood is considerably higher than that of refiner pulp . The apparent sheet density of groundwood is higher compared to refin er pulp because groundwood contains fewer and coarser fibres. The quan tity and the coarseness of long fibres influence the tear strength. Ma ximum tear index values of groundwood and refiner pulp and linearly re lated to the long fibre fraction. The correlation is improved when fib re coarseness also is taken into account. The scattering coefficient o f all mechanical pulps, irrespective of pulping method, is uniquely re lated to the amount of fines in pulp.