Temperature-frequency equivalence of the viscoelastic properties of anhydrous lanolin USP.

Methods of data analysis novel to pharmaceutical semisolids have been applied to the dynamic mechanical data obtained for anhydrous lanolin USP. It was found that the viscoelastic parameters determined over a wide range of temperatures and shear frequencies could be superposed. Elastic moduli (G') and viscous moduli (G") obtained at low temperatures (T) and frequencies (nu), were equivalent to moduli obtained at high T and nu. Empirical shifts of modulus versus shear frequency data obtained at different temperatures were used to produce G' and G" versus nu master curves (complete log modulus versus log frequency behavior at a constant temperature). A method of reduced variables, in conjunction with an Arrhenius-type relation, proved useful in calculating the energy of activation for the structural processes involved in a major mechanical transition.