DIFFERENTIAL THERMAL-ANALYSIS AND PVT MEASUREMENTS ON 2,2,2-TRICHLORO-ETHANOL UNDER HIGH-PRESSURE

The phase behaviour, the calorimetric and volumetric properties of 2,2 ,2-trichloro-ethanol (TCE) have been studied with differential thermal analysis (DTA) and pVT measurements in the pressure range 1 atm to 30 0 MPa and temperatures between 250 K to 355 K. TCE displays a metastab le plastic phase (solid I') and a non-plastic solid phase II at atmosp heric pressure. At least two pressure-induced solid phases have been d etected: a stable plastic phase (solid I) and a non-plastic phase (sol id III). There are two sets of triple points: a) 123 MPa and 308 K wit h the phases solid I, solid II and the liquid, b) 243 MPa and 316 K fo r solid I, II, III. Furthermore a metastable low-temperature brittle f orm (solid II') has been found, which transforms to solid I at a consi derably lower temperature than solid II. The melting curve of solid I' can be pursued to higher pressures up to 260 MPa. On the other hand, the melting curve of the stable plastic phase solid I can be extrapola ted beyond the triple point to pressures below 123 MPa. Volume and ent halpy changes are reported for all phase transitions.