The process of anionic surfactant sodium oleate micelles transforming from sphere or rod to wormlike in solution was investigated by rheological methods under the condition of increased sodium carbonate concentration. The relationship between the shear viscosity and shear rate was firstly measured so as to obtain zero shear viscosities (η₀). The complex viscosities (|η^*|), dynamic modulus (storage modulus G', loss modulus G") and relaxation time τ_s were then defined by dynamic oscillatory experiment. Finally, Cox-Merz rule and Cole-Cole plot were employed to prove that the system of NaOA (0.040～0.080 mol/L)/Na₂CO₃ (0.25～0.50 mol/L) have transformed into wormlike micelles whose dynamic viscoelasticity in the range of NaOA (0.050～0.080 mol/L)/Na₂CO₃ (0.35～0.45 mol/L), complies with Maxwell model, therefore are supposed to be called linear viscoelastic fluid.

Key words: wormlike micelle, rheology, sodium oleate