Melting and freezing behavior of polyethylene oxide

Abstract

A compressibility pressure‐temperature cycle has been developed for polyethylene oxide (PEO) by which both the melting and freezing points of this polymer are easily determined. It was found that PEO supercools about 10°C and that the pressure dependencies of the melting and freezing points are approximately the same. Using the pressure dependence of the bulk modulus for PEO the Gruneisen constant, γ, was calculated to be about 5 and was found to have an anomalous temperature dependence. It is shown that the Gruneisen constant and the Rao constant are approximately equal and that Wada's rule holds for transitions in which the volume does not change.