  Polytetrafluoroethylene can be considered as a model for calorimetric studies
of complex systems with thermodynamics transitions at ambient temperature. This
polymer exhibits two phase transitions of different nature at 292 K and 303 K.
We show that sensitive ac-calorimetry measurements allow us to study the
thermodynamic behaviour of polytetrafluoroethylene when it is brought out of
thermodynamic equilibrium. Thanks to the thermal modelisation of our
calorimetric device, the frequency dependent complex heat capacity of this
polymer is extracted. The temperature and frequency variations of the real and
imaginary parts of the complex heat capacity are obtained when
polytetrafluoroethylene undergoes its first-order structural phase transition
at 292 K.
