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Pressure‐volume‐temperature measurements on polymers and polymer mixtures
Author(s) -
Walsh David J.,
Dee Gregory T.,
Ougizawa Toshiaki
Publication year - 1990
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19900380121
Subject(s) - thermodynamics , polymer , equation of state , phase diagram , materials science , core (optical fiber) , hard core , enthalpy , flory–huggins solution theory , phase (matter) , physics , statistical physics , quantum mechanics , composite material
We have measured the PVT properties (density as a function of pressure and temperature) for polymers and polymer mixtures and analyzed these in terms of equations‐of‐state. The Cell Model equation (CM) gives a better description of the PVT properties of the pure polymers than the equation of Flory, Orwoll and Vrij (FOV). For the pure polymers we obtain the hard core pressure and hard core temperature. The hard core pressure depends on the cohesive energy, whereas the hard core temperature depends on the energy divided by the entropy. When we use the pure component parameters to describe mixture phase diagrams the CM equation is more consistent with experimental data. For the mixtures the energy depends on those of the pure components modified by an interaction parameter. The interaction parameter can thus be determined from the hard core pressures and temperatures. For high polymer mixtures the resulting parameter determined from the hard core pressure is unphysically large and negative whereas that from the hard core temperature is unphysically large and positive. Neither value coincides with those required to explain the phase diagrams or those obtained from methods such as heats of mixing of oligomers. We suggest possible reasons for this discrepancy.