GOALI: Thermodynamics of Fluid-Solid Equilibria in Solutions of Crystallizable Aromatic-Ring Containing Polymers

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ABSTRACTCTS-9908610Maciej RadoszCrystallallizable polymers can precipitate from solution in the form of a structure solid phase by cooling or compression. The overall goal of the proposed research is to understand the solid-phase behavior of crystallizable aromatic-ring containing polymers in compressible-fluid streams, such as near critical- and supercritical-fluid solutions. Such understanding is needed not only to develop new polymeric materials, but also to develop new and improve existing manufacturing processes; to make then less energy intensive and more environmentally acceptable. For example, such understanding is needed to accomplish desirable phase transitions and to avoid undesirable phase transitions that cause fouling phenomena in pipelines, reactors and separators.The proposed approach is to (1) characterize aromatic-containing model polymers, such as poly(ethylene-co-styrene) and poly (1,3-cyclohezadine) derivatives, upon fluid-solid transition in high-pressure experiments, and (2) develop an equation-of-state-based thermodynamic model that can account for and predict the crystallizable solid-phase transitions. The basis for this approach is a series of preliminary but promising experimental results and computational results with recent versions of an equation of state referred to as SAFT (statistical associating fluid theory). SAFT can explicitly account for the effects of microstructure and aromaticity on the thermodynamic properties of polymers and copolymers. This has never been done before and will impact the way we characterize very large, structured molecules.Specifically, the knowledge generated in this project will seed future research on more predictive thermodynamic models and on the other polymer structures, for example, structures with different branch lengths, shapes (e. g. graft polymers and stars), increasing degree of the backbone rigidity (all the way to the liquid-crystalline polymers), and varying degree of inter- and intra-molecular association. This is because the proposed model polymers with aromatic rings in the backbone and side branches can be the basic building block for numerous more complicated macromolecular and supremolecular structures, which will be the target of future research.In addition to seeding future research, this project will have an immediate and long-term impact on the existing and future polymer technologies. For example, the SAFT model will allow for predicting the undesirable phase transition that lead to fouling of real heat-exchanger and reactor systems in real commercial polyolefin processes, such as the existing solution poly(ethylene-co-styrene) process and future polyphenylene processes.