Modeling of pvT behavior of semi-crystalline polymer based on the two-domain Tait equation of state for injection molding

The absence of the influence of cooling rate in the pressure-specific volume-temperature (pvT) models makes them inadequate in the process simulation of injection molding. This work derived new equations of state (EoS) from the traditional two-domain Tait model that describes the pvT behavior of semi-crystalline polymers in both molten and solid state. Especially, the cooling rate was considered. The second aim of this work is to solve the discontinuity problem of the traditional two-domain Tait model. A continuous two-domain Tait EoS was developed. A good agreement between the calculations and experimental results was achieved. The new pvT models were successfully applied in the prediction of specific volume as a function of temperature, pressure and cooling rate during injection molding. A higher value of the specific volume was predicted when the cooling rate was considered. Combining the continuous two-domain Tait EoS, more accurate results can be obtained especially at the transition phase from melt to solid of the semi-crystalline polymer. (C) 2019 The Authors. Published by Elsevier Ltd.