Fluid phase equilibria in the system polyethylene‐ethylene, II

Experimental data on fluid phase equilibria in the system polyethylene‐supercritical ethylene have been analyzed thermodynamically. The behaviour of the system can be treated as a case of partial miscibility. A quantitative description of this behaviour can be given with the Flory‐Huggins polymer solution theory. A mathematical expression has been derived for the pressure‐temperature projections at constant polymer concentration. Its form resembles a reduced equation of state. An empirical relation was found for the cloud‐point curve, which accounts for its maximum and two inflexions. The expressions obtained permit of extrapolating the experimental data into temperature regions investigated by other authors. The comparison indicates that the different sets of data are consistent.