Modelling and investigation of the influence of operating conditions on the expansion process of extruded polystyrene foam

This study explores a modified bubble number density model developed to examine the growth process and bubble nucleation in extruded polystyrene foam under isothermal condition and finite pressure release. The model considers bubble nucleation through gas supersaturation following a finite pressure release and describes the bubble growth via mass transfer of the supersaturated gas in the bulk mixture to the created nucleons within the polymer. The set of ordinary differential equations describing the temporal foam growth model are solved numerically. The impact of pressure drop rate on bubble number density, bubble size and foam density was investigated. It was observed that higher pressure release results in smaller bubble size and an increased bubble number density while an upsurge in the gas concentration raises the bubble number density and the bubbles are with smaller diameter. Validation of the model and numerics was checked with standard models published in the Literature.