Transitiometry Examples of applications

Fig. 1. Isochoric investigation of a supercritical system: {0.21 caffeine + 0.79 CO2}: MH - % of the digitally controlled heating power in the calorimetric block; T/K - temperature rise at a rate of 2.5 mK/s; V/cc - volume variations (no variations in this case - isochoric run); p1/MPa - pressure variations; p2/MPa - the second pressure detector is not connected to the pressure line; Calo - calorimetric signal exhibiting three phase transitions.

     Fig. 2. Isothermal investigation of the three phase line in the system {tetracosane-methane}: a pressure increase causes first normal exothermic compression effect, then endothermic dissolution starts; next, a pressure decrease causes first an endothermic effect typical for decompression, then an exothermic crystallisation is observed. Such inverse phenomena are typical for asymmetric systems exhibiting a temperature minimum on the three phase line. Isothermal pressure inducing is extremely useful in detailed investigation of such systems.

Fig. 3. Isobaric in situ investigation of phase transformation in a 50 % water suspension of wheat starch at 90 MPa.