Shear viscosity measurements in the binary mixture butyl cellosolve-water near its upper and lower critical consolute points

To further probe the hypothesis of universality of critical phenomena, the shear viscosity has been measured for a two-component critical liquid system, butyl cellosolve-water, in the region of both the entropy-driven lower (LCST) and the enthalpy-driven upper (UCST) critical solution temperature. The values of the critical exponents ϕn for the shear viscosity were obtained by analysing the results from the viewpoint of multiplicative renormalization of transport coefficients. We have obtained ϕn = 0.038 ± 0.001 (30.14 wt. %) and 0.036 ± 0.007 (24.78 wt. %) for the UCST mixture, and ϕ n, = 0.038 ± 0.001 (30.14 wt. %) and 0.037 ± 0.003 (24.78 wt. %) for the LCST mixture. These exponent values agree well with mode-mode coupling and renormalization-group predictions and satisfy the universality hypothesis.