THERMODYNAMIC MODEL FOR ASSOCIATING POLYMER SOLUTIONS A Dissertation Presented to The Academic Faculty By Ibrahim Ali Ozkan In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy in Chemical and Biomolecular Engineering Georgia Institute of Technology July 2004 THERMODYNAMIC MODEL FOR ASSOCIATING POLYMER SOLUTIONS Approved by: Dr. Amyn S.Teja, Advisor Dr. William J. Koros Dr. Peter J. Ludovice Dr. J. Carson Meredith Dr. Thomas H. Sanders Date Approved: 05 / 03 / 2004 ACKNOWLEDGEMENTS I would like to express my deepest appreciation to my thesis advisor, Dr. Amyn S. Teja, for his wise guidance and advice throughout my years of graduate research. He is the most influential person behind my work, and I really appreciate him a lot for his assistance. I would like to thank my parents, Vahdet and Fusun Ozkan, for their support and for being so patient and caring. I would like to thank the members of my thesis committee for their input to my research: Dr. P.J. Ludovice, Dr. J.C. Meredith, Dr. W.J. Koros, and Dr. T. H. Sanders. Other research scientists to whom I am grateful are Dr. S. Michielsen, and Dr. J. Jones. I am especially thankful to Dr. Sun for the time and advice he has given me when I needed them. I would like to express my gratitude to current and past graduate students, Dr. Linda Cote, Dr. Kim Abbett, Yalin Hao, Drs. Izumi and Shutaro Kurosawa, Chunbao Xu, Michael Beck, Kanrakot Thamanavat for the exchange of ideas and making it pleasurable to come to Bunger-Henry and ES&T. I would also like to thank several friends too numerous to name here who have made a social life and pleasurable. Finally, I would like to express my deepest gratitude to my wife and best friend, Kerry Bullock-Ozkan, for sharing and enriching my life experiences for the past 3 years, and for her love, affection and support. Support for this work is provided by School of Chemical and Biological Engineering at Georgia Institute of Technology and the Fluid Properties Research Institute. iii TABLE OF CONTENTS Acknowledgements ..........................................................................................................iii List of Figures.................................................................................................................viii List of Tables ..................................................................................................................xiv List of Symbols ................................................................................................................ xv Summary.......................................................................................................................xviii Chapter 1 Introduction..................................................................................................... 1 Chapter 2 Phase Diagrams of Binary Mixtures of Small and Large Molecules ........ 6 Phase Behavior of Binary Mixtures............................................................................................................6 Type –I...................................................................................................................................................7 Type-II...................................................................................................................................................9 Type-III..................................................................................................................................................9 Type-IV ...............................................................................................................................................11 Type-V.................................................................................................................................................12 Type-VI ...............................................................................................................................................12 Type-VII and Type-VIII ......................................................................................................................13 Phase Behavior of Polymer Solutions in Supercritical CO2.....................................................................19 Chapter 3 Modeling The Phase Behavior of Polymer Solutions ................................ 25 Equation of State (EOS) models for polymer solutions ............................................................................25 Sanchez-Lacombe (SL) equation of state ............................................................................................26 Perturbed Hard-Chain Theory (PHCT)................................................................................................31 Statistical Associated Fluid Theory (SAFT)........................................................................................37 Activity Coefficient models .......................................................................................................................43 Flory- Huggins Theory ........................................................................................................................44 iv UNIFAC-FV........................................................................................................................................48 The generalized associative reformulation of thermodynamics (gART-L) model.....................................49 Entropy of Mixing ...............................................................................................................................51 Enthalpy of mixing ..............................................................................................................................55 Gibbs Energy of mixing.......................................................................................................................56 Model parameters.....................................................................................................................................57 Equilibrium Constant K and Specific Interaction parameter χa ...........................................................57 Dispersion Interaction Parameterχu: ....................................................................................................60 Chapter 4 Lattice-Based Extended Liquid Activity Coefficient (LELAC) Model .. 66 A modified gART-L model ........................................................................................................................66 Calculation of cloud point curves.............................................................................................................73 Cloud point calculations using LELAC model .........................................................................................78 Calculation of solubility of CO2 in polymer .............................................................................................79 Chapter 5 In Situ FT-IR Spectroscopy of Polymer- Supercritical CO2 systems...... 82 Experimental.............................................................................................................................................83 Materials ..............................................................................................................................................83 Preparation of Films.............................................................................................................................84 Transmission Spectra...........................................................................................................................85 Results ......................................................................................................................................................87 PMMA-CO2 .........................................................................................................................................87 Poly (ethylmethacrylate)(PEMA)-CO2 and Poly(butylmethacrylate)(PBMA)-CO2............................94 Poly(vinylmethylketone)(PVMK)-CO2 ...............................................................................................94 Poly(vinylchloride)(PVC)-CO2............................................................................................................94 Poly(vinylacetate)(PVAc)-CO2............................................................................................................98 Poly(vinylflouride)(PVF)-CO2 ............................................................................................................98 Poly(ethylene terephthalate) (PET ) - CO2 ..........................................................................................99 v Polyethylene (PE )- CO2 and Polystyrene (PS) – CO2.........................................................................99 Discussion ..............................................................................................................................................100 Chapter 6 Estimation of Polymer- Supercritical CO2 phase behavior using A Lattice-based Extended Liquid Activity Coefficient (LELAC) Model .................... 102 Correlation of cloud point behavior of polymer-CO2 mixtures ..............................................................102 Extrapolation and prediction of cloud point curves using LELAC model ..............................................121 Prediction of sorption behavior using LELAC model.............................................................................131 Prediction of cloud point curves using parameters