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water solubilizing capacity of AOT in the latter solvents is reduced because of more favorable AOT-solvent interactions.In cyclohexane, motional differences in the AOT alkyl chains exist between the inverted micelles and the w/o microemulsions. Frequency-dependent data indicate a complex series of motions in the inverted micelles; motion at each carbon-carbon bond cannot be considered independent of other motional contributions. While NMR offers the promise of a complete description of the motional factors involved, in practice this may be impossible.In all three solvents the relaxation of the carbons nearest the head group is dominated by overall aggregate motion.This correlation holds up to intermediate R values. At higher R, other motions, such as monomer diffusion, are contributing to the relaxation process. This work has further emphasized the distinction between Aerosol OT inverted micelles, and w/o microemulsions.

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An isothermal scanning calorimeter controlled by linear pressure variations is described for the pressure range 0.1–400 MPa at temperatures from 303 to 573 K. The rate of pressure variations can be as low as 0.002 MPa/s over the whole pressure range. The functioning of the instrument was tested by measuring the coefficient of thermal expansivity of liquid n-hexane, with calibration performed with gaseous nitrogen and by measuring the coefficient of thermal expansivity of benzene with calibration performed with liquid n-hexane. The results are compared with literature results obtained by the piezothermal technique and with results obtained in the present instrument by the use of a pressure stepwise scanning mode. An example of an investigation of an isothermal solid-to-liquid transition in benzene is also given.

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