Studies in isothermal heat conduction calorimetry: I. The 2-drop calorimeter and educational applications. II. The quartz crystal microbalance/heat conduction calorimeter (QCM/HCC) and applications in studying the thermodynamic and rheological properties of polymer and protein thin films at a solid-gas interface.

摘要

Heat conduction calorimetry is a well-developed technology that can be used on a variety of levels ranging from high school and undergraduate laboratories to diverse applications in industry and research. Both the educational and research aspects of heat conduction calorimetry are explored in this study.; The 2-Drop Calorimeter was designed as an educational project in collaboration with researchers at Dow Chemical, Midland, MI and Lund University, Lund, Sweden. Calorimetry Sciences Corporation has since marketed a commercial model. Several educational applications have been explored spanning the physical, biological and chemical sciences. The calorimeter design is described along with the calibration procedure. Six different experiments are discussed which provide experience in measuring heats from a variety of reactions and processes including acid-base titrations, vaporization and insect metabolism.; The Quartz Crystal Microbalance/Heat Conduction Calorimeter (QCM/HCC) is a new instrument coupling quartz crystal mass detecting capabilities with heat conduction calorimetry. Both thermodynamic and rheological properties of thin films are studied as a function of vapor activity. The instrument is capable of simultaneously measuring mass (±10ng), thermal (±50nW), and motional resistance (±0.5Ω) changes in a thin film (0.5–9 μm) upon interaction with a solvent vapor. The results of the sorption experiments allow for the determination of sorption enthalpies, sorption isotherms, partition coefficients, and diffusion coefficients.; Studies have been conducted on the cycloaliphatic poly (ether urethane) polymer, Tecoflex. Several films (0.75–8.5 μm) were exposed to water and ethanol vapor. The sorption/desorption properties were evaluated for their thermodynamic and rheological properties. Comparisons are given for thin versus thick films and for water sorption versus ethanol sorption.; Protein hydration/dehydration studies of lysozyme and myoglobin have been accomplished using the QCM/HCC. Comparisons have been made between sorption enthalpies, isotherms and diffusion coefficients. The protein films were very sensitive to the direction of hydration with results differing when the protein was hydrated from higher vapor activities versus the lower vapor activities. The presence of sodium phosphate buffer in the myoglobin film influenced the hydration results. Separate hydration studies were conducted on a sodium phosphate buffer film with results suggesting the formation of hydrates in the phosphate buffer film.