Faculty

Professor Ronald Danner | Research

The Center for the Study of Polymeric Systems was established as a response to needs expressed by industry. Associate Professor Coray Colina of the Department of Material Sciences and Engineering and I serve as co-directors of the center. The experimental and theoretical results of the center's activities are of interest to scientists and engineers involved with the design, control, and operation of numerous polymer processes including polymerization reactors, polymer devolatilization, and the production of films, coatings, paints, membranes, and foams.

Chromatographic techniques are being extensively used to examine both the solubility and the diffusivity of solvents in polymers. In the case of vapor-liquid studies, inverse gas chromatography is used to determine both the partitioning of the solvent between the two phases and the diffusivity of the solvent into the polymer. In this method, the polymer (the liquid phase) is coated on the inner walls of a capillary chromatographic column and pulses of solvent (the vapor phase) are injected into the column. By carefully modeling the response of the column, the thermodynamic and mass transfer parameters can be obtained. For liquid-liquid system size exclusion chromatography is used to determine the composition of equilibrated liquid phases made up of several polymers and/or solvents.

Thermodynamic studies

Phase equilibria are being measured as described above, frequently in response to specific problems cited by our industrial sponsors. These data, together with data collected from the literature, are being used to develop models to correlate and ultimately predict phase behavior. Equations of state are the primary tool used in these efforts. We have developed equations that require only the specification of the chemical makeup of the molecules-group-contribution methods.

Diffusion studies

We also obtain diffusivity data from the inverse gas chromatography method. In the past this method has been primarily used to measure systems with only an infinitely small amount of a single solvent. We are extending the method to higher concentrations of solvent and to multicomponent cases. Currently there are virtually no multicomponent data available in the literature. Additional data are also being obtained from the absorption uptake method, a time-proven technique. These data are used to develop and improve models for the correlation and prediction of diffusion coefficients. The dominant method in this area has been the free-volume theory as developed by J. L. Duda and J. S. Vrentas. We are striving to develop a completely predictive approach based on the free-volume model.

Industrial orientation

In our research program we have always tried to put a strong emphasis on application. In addition to the typical research journal publications, a lot of our work appears in handbooks and computer software packages used by practicing engineers. In these efforts we have always maintained a close association with industrial research and design groups. This industrial involvement has continually provided motivation and reinforcement for our research programs. We study and learn a lot about molecular theory and statistical mechanics, and we strive to use the insights obtained therefrom to develop methods that will solve real-world problems.

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