Determination of the frequency-dependent bulk modulus of glycerol using a piezoelectric spherical shell

Through the coupling between the electrical capacitance of a spherical piezoceramic shell and the mechanical stiffness of a liquid contained therein, the frequency-dependent adiabatic bulk modulus Kₛ({ω}) of the liquid can be derived. Using this method, Kₛ({ω}) of glycerol in the range 15 Hz--15 kHz has been measured at the glass transition. The loss peak frequencies of the compressibility κₛ({ω})=Kₛ^-1({ω}) and the specific heat cₚ({ω}) have the same temperature dependence, but the frequency dependences are different.