Impact of approximating the initial bubble pressure on cell nucleation in polymeric foaming processes

According to the classical nucleation theory, the free energy barrier for bubble nucleation, and thereby the nucleation rate, are functions of the initial bubble pressure, P bubble, 0 . In almost all of the previous studies that have used computer simulations to investigate polymeric foaming processes, the value of P bubble, 0 has been approximated using the saturation pressure, P sat . This article employs the thermodynamic equilibrium condition and the Sanchez–Lacombe (SL) equation of state (EOS) to determine the value of P bubble, 0 . It is shown that using P sat to approximate P bubble, 0 may lead to significant overestimations of the nucleation rate and the final cell density. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 902–908, 2007