Determination of the critical anomaly in the viscosity for the dimethyl carbonate + (undecane or dodecane) systems

The viscosity critical behaviour for the binary systems dimethyl carbonate + undecane and dimethyl carbonate + dodecane is investigated. To this end, measurements of viscosity at critical composition for both systems were performed as a function of temperature. Data at non-critical composition were also obtained, since to describe this critical anomaly it is necessary to determine the regular part. As the viscosity measurements are distorted by the non-zero shear conditions in which the data were obtained, corrections to obtain the viscosity at zero shear are needed. They involve the knowledge of the correlation length near the critical point. In order to obtain it, measurements of the heat capacity near the critical point were performed for both systems. From these data and from the universality of the two-scale factor, correlation length is obtained. The critical exponent and the critical amplitude of the viscosity thus obtained are coherent with previous results.