Mathematical Modeling of Thickness Dependent Physical Aging in Polymeric Membranes

Article Preview

Abstract:

The drawback of membrane process that reduces its competitive edge with the conventional separation technologies is ascribed to its decline separative performance over time due to the aging nature of polymeric material. The most widely accepted mechanism that has been thought of governing the volume relaxation process over the course of aging is the dual mode mechanism, whereby it is comprised of two components. The first is the “Lattice contraction” mechanism that describes the uniform collapse of free volume throughout the unrelaxed polymer matrix. The second is the “Diffusion of free volume” mechanism from the interior to the surface of the glassy polymer. Albeit acknowledgement of the dual mode mechanism as the contributing factor, previous aging model renders high implementation challenges to characterize the complicated nature of aging evolution, which requires adaptation of high end computational tools to solve the relatively complex differential equations. In this work, the dual mode mechanism governing the physical aging process has been modelled employing a simple one dimensional finite element numerical solution whereby the film has been divided into many finite slices with equal thickness along the depth of the membrane. The applicability of the mathematical model has been validated with experimental aging data, whereby a small deviation is observed between the two over a wide range of film thicknesses and reasonable intuitive explanation pertaining to the parameters is obtained.

You might also be interested in these eBooks

Info:

Periodical:

Pages:

275-280

Citation:

Online since:

July 2016

Export:

Price:

Permissions CCC:

Permissions PLS:

Сopyright:

© 2016 Trans Tech Publications Ltd. All Rights Reserved

Share:

Citation:

* - Corresponding Author

[1] B.W. Rowe, B.D. Freeman, D.R. Paul, Physical Aging of Membranes for Gas Separations, in: Membrane Engineering for the Treatment of Gases : Volume 1: Gas-separation Problems with Membranes. Royal Society of Chemistry, Cambridge, 2011, pp.58-83.

DOI: 10.1039/9781849733472-00058

Google Scholar

[2] T. Alfrey, G. Goldfinger, H. Mark, The Apparent Second-Order Transition Point of Polystyrene, J. Appl. Phys., 14 (1943), 700-705.

DOI: 10.1063/1.1714949

Google Scholar

[3] J. G. Curro, R. R. Lagasse, R. Simha, Diffusion model for volume recovery in glasses, Macromol., 15 (1982), 1621-1626.

DOI: 10.1021/ma00234a032

Google Scholar

[4] M. S. McCaig, D. R. Paul, J. W. Barlow, Effect of film thickness on the changes in gas permeability of a glassy polyarylate due to physical aging Part II. Mathematical model, Polym., 41 (2000), 639-648.

DOI: 10.1016/s0032-3861(99)00173-1

Google Scholar

[5] S. S. M. Lock, K. K. Lau, F. Ahmad, A. M. Shariff, Modeling, simulation and economic analysis of CO2 capture from natural gas using cocurrent, countercurrent and radial crossflow hollow fiber membrane, Int. J. Greenhouse Gas Control, 36 (2015).

DOI: 10.1016/j.ijggc.2015.02.014

Google Scholar

[6] J. Y. Park, D. R. Paul, Correlation and prediction of gas permeability in glassy polymer membrane materials via modified free volume based group contribution method, J. Membr. Sci., 125 (1997), 23-29.

DOI: 10.1016/s0376-7388(96)00061-0

Google Scholar

[7] N. Hirai, H. Eyring, Bulk viscosity of liquids, J. Appl. Phys., 29 (1958), 810.

Google Scholar

[8] M. Safari, A. Ghanizadeh, M. M. Montazer-Rahmati, Optimization of membrane-based CO2-removal from natural gas using simple models considering both pressure and temperature effects, Int. J. Greenhouse Gas Control, 3 (2009), 3–10.

DOI: 10.1016/j.ijggc.2008.05.001

Google Scholar

[9] M. S. McCaig, D. R. Paul, J. W. Barlow, Effect of film thickness on the changes in gas permeability of a glassy polyarylate due to physical aging Part I. Experimental observations, Polym., 41 (2000) 629-637.

DOI: 10.1016/s0032-3861(99)00172-x

Google Scholar

[10] T. Sandreczki, X. Hong, Y. Jean, Sub-glass transition temperature annealing of polycarbonate studied by positron annihilation spectroscopy, Macromol., 29 (1995), 4015-4018.

DOI: 10.1021/ma951505q

Google Scholar