IMPACT OF APPROXIMATING THE INITIAL BUBBLE PRESSURE ON CELL NUCLEATION IN POLYMERIC FOAMING PROCESSES

摘要

According to the classical nucleation theory, the free energy barrier for bubble nucleation and thereby the nucleation rate are functions of the bubble pressure, P_(bubble). In computer simulations of polymeric foaming processes, almost all previous research has approximated the value of P_(bubble) by the saturation pressure, P_(sat). In this paper, the thermodynamic equilibrium condition and the Sanchez-Lacombe (SL) equations of state (EOS) are employed to determine the value of P_(bubble). It is shown that the P_(bubble) approximation using P_(sat) will lead to significant overestimations of the nucleation rate and the final cell density.