THE CONSEQUENCES OF APPROXIMATING THE CLASSICAL NUCLEATION THEORY IN SIMULATION OF POLYMER FOAMING PROCESS

摘要

According to the homogeneous classical nucleation theory, the nucleation free energy barrier in the foaming process can be calculated by W = 16πγ~3/3(P_(bubble) - P_(melt))~2. Currently, almost all the simulation results simply substitute the bubble pressure, P_(bubble), with the saturation pressure, P_(sat), and the curvature-dependent surface tension, γ, with the experimentally measurable surface tension, 胈∞. This paper engages a brief discussion of the above two approximations. The consequence of substituting P_(bubble) with P_(sat) on the free energy barrier will be considered with respect to equations of state. The effect of the curvature dependence of surface tension on the prediction of free energy barrier for bubble nucleation, and thereby on the calculation of nucleation rate is explored using the recently proposed scaling function approach.