Shear viscosity studies above and below the critical consolute point in a nitrobenzene-decane mixture

The sheer viscosity has been studied in a nitrobenzene-decane critical mixture above the critical consolute temperature T-c, in the homogeneous phase, and below T-c, in coexisting phases. The form of background viscosity for coexisting phases has been postulated. The same value of the critical exponent phi has been obtained in the lower (L), upper (U), and homogeneous (H) phases. The pretransitional amplitudes (A(L,U)) in coexisting phases are approximately the same, whereas A(L,U) /A(H) approximate to 0.965. In the homogeneous phase the possibility of the appearance of the quasinematic, field-induced structure of critical fluctuations has been discussed.