The glass transition of amorphous polymers: About a continuous equation of state and its derivatives

Describing the pressure-volume-temperature (PVT) behavior of polymers is often hindered due to limitations models and theories. In this work, we propose logistic function derive a phenomenological equation state (EOS) that overcomes these limitations. Without dividing temperature domain into several intervals, continuous EOS describes PVT amorphous in equilibrium state, vitreous at glass transition. Discontinuities transition are inherently eliminated. The continuously differentiable with respect pressure. thermal expansion coefficient compression modulus thus can be determined any valid reference state. linearly depends on both Furthermore, parameter interpreted as pressure-dependent temperature. Using data polyethersulfone (PES), measured range 20 − 360 °C pressure 10 200 MPa isobaric standard isothermal mode, validity discussed. Polymer processing simulation solid mechanics benefit from its derivatives, respectively. addition, used determine data.