Polytetrafluoroethylene phase diagram

Marx and Dole and Miyake have presented descriptive models for the 19° C transition in terms of order-disorder theories. Studies of transitions at high pressure in polytetrafluoroethylene have been reported by Bridgman, Weir (1953), and Beecroft and Swenson. The phase diagram in Fig. 7 shows that in addition to the two crystalline phases which are separated by the 19° transition at atmospheric pressure there is a third modification at high pressures. The triple point has been... 

Fig. 7. Phase diagram for polytetrafluoroethylene. (Low temperature transitions according to Beecroft and Swenson, melting according to McGeer and Duus)...

Fig. 4A Phase diagram of polytetrafluoroethylene. Diagram drawn after data reviewed in Ref. with an update for the pressure dependence of T, as given in Ref. Solid I rejwesents the condis phase...

Phase Diagram of Polytetrafluoroethylene (Function of Pressure and Temperature)... 

---