Determination of the Viscosity in Cadoxen Solvent of Cellulosic Materials Dyed with Reactive Dyes

A modified cadoxen solvent was used to determine the viscosity of reactive‐dyed cellulosic materials. The conditions for completely dissolving cellulosic materials dyed with different types of reactive dyes were standardised. Reactive‐dyed cotton materials showedno anomalous viscosity behaviour in the cadoxen solvent. With viscose rayon samples dyed with bifunctional reactive dyes, higher viscosity values were observed when measurements were carried out immediately after dissolution. However, on storing the solutions for a further 24 h, the viscosity values became independent of the type or the amount of dye andwere identical with those of undyed rayon. Thus, measurements of the viscosity of reactive‐dyed materials can be conveniently carried out in cadoxen solvent.