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Processing
^ Catalytic Oxidation of Odorous Molecules
R. Masel,* N. Ali, J. Ackerman, C. Lu
Illinois Council on Food and Agricultural Research

Production of odorous molecules from livestock production facilities is a current national problem. Researchers are exploring catalytic combustion as a cost effective way of destroying the odorous molecules. So far the team has measured the kinetics of acetic, n-butyric, i-butyric, n-valeric, and i-valeric acids on Cu/Al2O3. Researchers find that these molecules strongly adsorb onto the catalysts. TPD indicates that the molecules form a carboxylate upon adsorption, and the carboxylate is easily oxidized in the presence of excess oxygen.

^ Engineering Approximations for Parameter Estimation in Chemical Kinetics
R. Masel,* P. Blowers, L. Ford
National Science Foundation, CTS 96-10115

In industry, correlations are often used to estimate rate constants, but the accuracy of the correlations is low. Researchers have been doing high-level ab initio calculations of transition state properties to learn about the key forces that cause reactions to be activated. The team then uses the results of the ab initio calculations to derive better models of transition state properties with adjustable parameters that can be fit to data. The result has been better than an order of magnitude improvement in the accuracy of approximate rate constants.

^ Fuel Cells
R. Masel,* N. Chen, I. Lee
U.S. Department of Energy, DEFG-02-99ER14993; Defense Advanced Research Projects Office, F33615-01-C-2172

The objective of this project is to examine production of ions and facilitation of carbon monoxide shuttling in fuel cells. Researchers have developed a novel UV/HREELS technique that can look directly at the changes in the electronic structure of adsorbed molecules as the surface composition is changed. The team is using the instrument to measure the metal surface electronegativity. They have also built novel fuel cells and are testing their performance.

^ Microchemical Systems
R. Masel,* F. Thomas, C. Jensen
Army Research of the DAA019-01-11-0582

Micromechanical systems have been proposed as small-scale power sources and as bioterrorism protection devices, but so far flames have gone out when the flames are confined in a small space. Researchers have been doing studies to see if the combination of hot walls and special coatings could be used to produce microburners. So far the research team has demonstrated that they can get flames to burn in 100-micron spaces by choosing a wall coating according to an equation that they derived previously. Work in progress examines the fundamentals of wall quenching to try to understand how to best balance thermal quenching and chemical quenching in a practical device.

^ Continuum Modeling of Flow-induced Crystallization
A. J. McHugh,* A. Doufas
National Science Foundation; SBC Clemson; DuPont

Models of flow-induced crystallization are developed based on theories of nucleation-controlled and strain-induced crystallization, coupled with the irreversible thermodynamic formalism of the continuum Hamiltonian brackets. Model analyses include the effects of relaxation and orientation processes as well as simultaneous deformation histories on the crystallization kinetics in terms of molecular relaxation times, a crystallization parameter, and the melt molecular weight. Calculations of the crystallization rate, chain elongation, stress, and birefringence are done for a variety of flow kinematic histories, including transient flow. Results are compared to experimentally observed trends reported in the literature.

^ Dynamics of Phase Inversion
A. J. McHugh,* Z. Gou
National Science Foundation, CTS 97-31509

Researchers are developing quantitative models to describe the mechanisms involved in membrane structure formation by phase inversion of polymer solutions. Experiment and theory are being pursued for both the nonsolvent and thermal quench processes. The former involves optical techniques the research team developed for the measurement of mass transfer and gelation rates and comparison to models based on ternary diffusion formalisms. The latter involves measurements of small-angle scattering behavior in thermally quenched films and comparison to models for phase transformation by spinodal decomposition and nucleation and growth. Both experiments also involve analyses of film morphologies by scanning electron microscopy.

^ Rheooptics of Helical, Dendrimeric, and Hyperbranched Polymers
A. J. McHugh,* A. L. Lee
American Chemical Society, Petroleum Research Fund; Department of the Army, DAAG97-1-0126

The effects of shear flow, temperature, and solvent on conformational states and phase stability of macromolecules are being investigated using rheooptics. Birefringence shows the helix-to-coil transition in poly-l-lysine (PLL) in methanol solutions can be dramatically affected by shear. Researchers are also investigating the role of chain architecture and branching on the rheooptics of dendrimeric and hyperbranched polymer solutions. Studies are on a polyether-imide-based system and various linear hybrids. Transient and steady birefringence, combined with a model based on a discrete version of the semiflexible, wormlike chain, are used to evaluate the effects of chain architecture on molecular flexibility and dynamics.

^ Structure Formation and Processing of Highly Filled Organo-Ceramic Composites
A. J. McHugh,* J. A. Walberer
National Science Foundation, Center for Advanced Cement-Based Composites

Reactive organo-ceramic composites are high-strength materials formed from extrudable pastes created by high shear mixing. Torque rheometry allows monitoring the evolution of the mixing mechano-chemistry. The kinetics of structure formation are measured in four model systems that stiffen by polymerization of the organic phase, crosslinking of the organic phase, flocculation of the ceramic phase, and chemical or physical linking of the ceramic particles to the organic phase. Rheological analyses based on viscoelastic models for highly filled systems allow analysis of the time/stress history of structuring in terms of a time-dependent modulus that follows a kinetic equation.

^ The Rheology of Dendritic Macromolecules
A. J. McHugh,* I. Sendijarevic
Department of the Army, DAAG97-1-0126

The solution and melt rheology of dendritic molecules, including dendrimers, hyperbranched polymers, and linear hybrids are being studied. Molecules examined are available in a wide range of molecular weights with different end-groups and core functionality. Analyses of the shear stress-shear rate behavior under steady and oscillatory flows at different temperatures, solvent conditions, and concentrations are being pursued. Step shear strain experiments are employed to obtain relaxation responses. Dendrimer molecules exhibit a Newtonian behavior, while polyether amide-based HBPs exhibit shear thinning behavior. However, in comparison to linear molecules, the viscosity of dendrimers and HBPs is significantly lower.

^ Formation of Hemispherical Grained Silicon for DRAMs
E. G. Seebauer,* D. Llera-Rodriguez
National Science Foundation, CTS 98-06329

Hemispherical grained silicon (HSG) is a material that is being ramped into production to improve device capacitance in dynamic random access memories. The material forms by slowly heating amorphous silicon so that surface diffusion permits the surface to roughen on a nanometer length scale. Researchers are developing quantitative models for this process and coupling them to experimental measurements in which they try to modify surface diffusion through adsorption and photon illumination.

^ Simulation of Transient-enhanced Diffusion
E. G. Seebauer,* R. D. Braatz,* M. Y. L. Jung, R. Gunawan
Sematech

Transient-enhanced diffusion (TED) during annealing after ion implantation limits how the shallow junctions can be made in next-generation transistors. Models for TED in current commercial process simulation software does not incorporate surface effects such as band bending. The simulators also do not account for photon-induced effects that can occur during rapid thermal processing. Researchers are incorporating these new aspects of physics to make such software more realistic.


Summary of Engineering Research