E. Kiran et al., EFFECT OF POLYDISPERSITY ON THE DEMIXING PRESSURES OF POLYETHYLENE INNEAR-CRITICAL OR SUPERCRITICAL ALKANES, The Journal of supercritical fluids, 7(4), 1994, pp. 283-287
Demixing pressures of a polyethylene sample of broad molecular-weight
distribution ((M) over bar(w) = 121,000, (M) over bar(w)/(M) over bar(
n) = 4.43) in n-butane and n-pentane are reported. The results are com
pared with the demixing pressures of polyethylene standards with narro
wer molecular-weight distributions. For these systems at the concentra
tions investigated, the observed demixing pressures (cloud points) are
greatly influenced by the high molecular-weight fractions of the poly
mer. The observations are further substantiated by measurements of the
demixing pressures of synthetic blends (i.e., mixtures in different p
roportions) of polymer standards with narrow molecular-weight distribu
tions.