The thermodynamic numerical model of nitrogen diffusivity in poly (vinyl alcohol)

In this work, we recommended a numerical model in which the diffusivity of nitrogen in poly (vinyl alcohol) (PVA) could be determined from the specific volume of polymer/gas system. In this study, PVA with applicable properties was used as polymer matrix and supercritical nitrogen (N 2 ), was selected as a gas or blowing agent. Firstly, the solubility and diffusivity of nitrogen into PVA were calculated via a magnetic suspension balance (MSB) system. The effects revealed that the thermodynamic parameters like solubility and diffusivity of nitrogen improved with an increase in pressure. Furthermore a diffusion model was proposed, considering the thermodynamic aspects of PVA/N 2 system. It has been proven that there was an appropriate overlapping among the experimental and expected amounts from the model. Also it was shown that the model effectively predict the diffusion coefficient of nitrogen in PVA whenever the chemical potential derivative and the absolute specific free volume of N 2 in PVA were known.