PROCEDURE FOR DETERMINING THE DIFFUSION COEFFICIENT PREVAILING IN THE FIBRE WALL IN A SUSPENSION CONTAINING PRIMARY AND SECONDARY FIBRE AND FOR DETERMINING THE PROPORTION AND PAPERMAKING PROPERTIES OF SECONDARY FIBRE

摘要

The invention relates to a procedure fordetermining a quantity dependent on the rate ofdiffusion in the fibre wall for diffusion occurring throughit, in which procedure a diffusible tracer isintroduced into the fibres under measurement, the fibresare suspended in an aqueous phase and the tracerconcentration is determined after a certain time haselapsed since the time of suspension of the fibres,and the quantity dependent on the rate of diffusion iscalculated on the basis of the concentration and time.In addition, the invention relates to aprocedure for determining the proportion of secondaryfibre in a fibre suspension containing primary fibre andsecondary fibre, in which procedure virtual diffusioncoefficients are determined in the fibre wall fordiffusion taking place through it in at least two fibresuspensions for which the proportions of primary andsecondary fibre are known and in a fibre suspensionunder measurement, and that the proportion ofsecondary fibre in the suspension under measurement isestimated by assuming that the diffusion coefficientdepends mainly linearly on the proportion of primary andsecondary fibre in the fibre suspension.