Development of an instrument to determine the effect of cyclic transverse compression on wood-pulp fibres

Mechanical refining processes for producing wood-pulp for paper consume large amounts of energy. With increasing awareness during the last decade of the limitations in our energy producing resources, it has become necessary to reduce the energy consumption in such processes.; In the refining processes it is generally considered that only a small portion of the energy put into the system is actually used in the separation of fibres. In addition, if the fibres produced are to be suitable for papermaking, a certain amount of mechanical flexing of the fibres, creating collapsed, flexible and well fibrillated fibres, is needed. This is accomplished by the cyclic deformations to which the chips and fibres are subjected to during refining. It is essential to gain more knowledge about how energy input is used if any substantial saving in energy consumption is to be possible.; An instrument has been developed to expose an individual fibre to cyclic transverse compression while monitoring its response. The instrument has the capability of measuring sub-micron fibre displacement and can resolve milli-Newton forces.; Experiments were carried out on one population of fibres, which had been exposed to low energy refining and low sulphonation treatment. Results were expressed in terms of apparent modulus and mechanical loss coefficient. In all experiments it was found that apparent modulus increased with the number of cycles, while mechanical loss coefficient decreased with cycle number.