Phase equilibria of linear polyethylene with supercritical propane

Cloud-point data and solid-supercritical fluid equilibria are reported for two fractions of linear and for unfractionated nearly linear polyethylene with supercritical propane at temperatures from approx 110-130 deg C and to pressures of approx 650 bar. The data cover the temperature range just below and just above that of the second critical end point that lies at the intesection of the solid--liquid--vapor equilibrium lines that originate at the polymer's triple point with the vapor--liquid critical locus. For a fairly high molecular weight fraction (M sub n = 100 500, M sub w = 119 600), that point is estimated to lie at 118 deg C and 640 bar.