Modelling the solubility of CO2 in rubbery and glassy amorphous PS and PMMA with the SAFT-γ Mie group-contribution EoS and the NET-GP approach
File(s)
Published version
Author(s)
Nguyen, Louis
Valsecchi, Michele
Jackson, George
Galindo, Amparo
Tighe, Christopher J
Type
Journal Article
Abstract
The sorption of fluids in polymers is important for their industrial application in e.g. separation
membranes, corrosion protection liners and permeation barriers. The solubility of CO2 in
polymers is of interest for its transport and storage. In this work, CO2 solubility in polystyrene
(PS) and polymethyl methacrylate (PMMA), above and below the glass transition temperature
of the pure polymers (both ~105 ºC), is modelled by combining the SAFT-γ Mie group-contribution equation of state (EoS), together with the framework of nonequilibrium
thermodynamics for glassy polymers (NET-GP). Selected parameters of the EoS are optimised to
fit pure polymer density and CO2 solubility measurements from the literature at pressures up to
20 MPa, and temperatures from 150 – 200 °C (although in fact, the default parameters already
give good agreement for CO2 solubility in PS). A good agreement with solubility measurements
at lower temperatures, though still above Tg, is obtained at up to 40 MPa. Below the of the
pure polymers, between 35 °C and 81 °C, application of NET-GP results in only a small increase
in the predicted CO2 solubility at < 2 - 3 MPa, when the amount of sorbed CO2 is small, over that
determined from the EoS alone. Thus CO2 appears to readily plasticise both polymers, inducing
an equilibrium rubbery state. The methodology presented is a computationally efficient tool for
the investigation of fluid sorption in amorphous polymers, which can be readily extended to
other fluid+polymer pairs, including ones with novel chemistries.
membranes, corrosion protection liners and permeation barriers. The solubility of CO2 in
polymers is of interest for its transport and storage. In this work, CO2 solubility in polystyrene
(PS) and polymethyl methacrylate (PMMA), above and below the glass transition temperature
of the pure polymers (both ~105 ºC), is modelled by combining the SAFT-γ Mie group-contribution equation of state (EoS), together with the framework of nonequilibrium
thermodynamics for glassy polymers (NET-GP). Selected parameters of the EoS are optimised to
fit pure polymer density and CO2 solubility measurements from the literature at pressures up to
20 MPa, and temperatures from 150 – 200 °C (although in fact, the default parameters already
give good agreement for CO2 solubility in PS). A good agreement with solubility measurements
at lower temperatures, though still above Tg, is obtained at up to 40 MPa. Below the of the
pure polymers, between 35 °C and 81 °C, application of NET-GP results in only a small increase
in the predicted CO2 solubility at < 2 - 3 MPa, when the amount of sorbed CO2 is small, over that
determined from the EoS alone. Thus CO2 appears to readily plasticise both polymers, inducing
an equilibrium rubbery state. The methodology presented is a computationally efficient tool for
the investigation of fluid sorption in amorphous polymers, which can be readily extended to
other fluid+polymer pairs, including ones with novel chemistries.
Date Issued
2025-10-01
Date Acceptance
2025-04-13
Citation
Fluid Phase Equilibria, 2025, 597
ISSN
0378-3812
Publisher
Elsevier BV
Journal / Book Title
Fluid Phase Equilibria
Volume
597
Copyright Statement
© 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
License URL
Identifier
10.1016/j.fluid.2025.114445
Subjects
Fluid Phase Equilibria solubility
EoS
polymer
rubbery
glassy
equilibrium
nonequilibrium
Publication Status
Published
Article Number
114445
Date Publish Online
2025-04-14