Temperature-pressure equivalence for the component segmental dynamics of a miscible polymer blend

Using broad-band dielectric spectroscopy (10(-2)-10(7) Hz), we have investigated the effect of hydrostatic pressure on the segmental dynamics of the poly(vinyl methyl ether) (PVME) chains in a blend with polystyrene. Our results evidence that, for a given value of the relaxation rate, the relaxation process observed is, within the experimental uncertainties, independent of the particular values of pressure and temperature of the sample. This finding, which also applies for the dynamics of pure PVME, indicates that the effects on the component dynamics of hydrostatic pressure and temperature are equivalent. This result is rationalized on the basis of previous results obtained at atmospheric pressure in the same system. The implications of the present results concerning different proposed models for polymer blend dynamics are also discussed.