ISO 1628-1:2021 pdf download – Plastics — Determination of the viscosity of polymers in dilute solution using capillary viscometers — Part 1: General principles. 6.2 Concentration Where no standard exists, careful consideration shall be given to the choice of solvent and the solution concentration. The solution concentration shall be chosen so that the ratio of the efflux time of the solution to the efflux time of the solvent is at least 1,2 and less than 2,0. NOTE A lower limit of 1,2 ensures sufficient precision of the measured difference in efflux times. The upper limit of 2,0 prevents shear effects...