Mass Diffusion Coefficients of Cellulose Acetate Butyrate in Methyl Ethyl Ketone Solutions at Temperatures between (293 and 323) K and Mass Fractions from 0.05 to 0.60 Using the Soret Forced Rayleigh Scattering Method

The binary mass diffusion coefficients of cellulose acetate butyrate in methyl ethyl ketone solutions (CAB + MEK) have been measured under atmospheric pressure at temperatures from (293 to 323) K and mass fractions from 0.05 to 0.6. The present experimental apparatus is based oil the Soret forced Rayleigh scattering method (S-FRSM), which utilizes the Soret effect to create periodic spatial concentration modulation of micrometer-order fringe spacing in a sample binary liquid mixture due to the absorption of an optical interference grating generated by two intersecting heating laser beams. The decay of the concentration modulation by the mass diffusion process is monitored by the diffraction of a probing laser beam. This method provides several advantages in comparison with conventional techniques such as Taylor dispersion or diaphragm cells; namely, a single measurement can be performed within a short time [(10(-3) to 10(-2)) s], with small temperature and concentration changes (Delta T < 10(-2) K and Delta(c) < 10(-5)) using a microliter-order sample volume. To check the reliability of S-FRSM to measure mass diffusion coefficients, the mass diffusion coefficients of toluene + n-hexane, ethanol + benzene, and acetone + carbon tetrachloride were also measured. The expanded (k = 2) uncertainty in mass diffusion coefficients for CAB + MEK solutions is estimated to be within +/- 3.6%.