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Applications of Piezoelectric Quartz Crystal Microbalances deals with the theory, design, artifacts, and varied applications of the piezoelectric quartz crystal microbalance. Applications of microbalances range from thin film deposition process control to simultaneous measurement of mass and temperature, analytical chemistry, and space system contamination studies. Stress effects in microbalances are also considered. Comprised of 10 chapters, this volume begins with a historical background and overview of applications of piezoelectric quartz crystal microbalances, followed by an analysis of the theory and practice of microbalances. The role of acoustic impedance in a quartz crystal microbalance and design considerations for a microbalance are given emphasis. Subsequent chapters focus on applications of microbalances in thin film deposition process control; simultaneous measurement of mass and temperature; surface science and analytical chemistry; plasma-assisted etching and space system contamination studies; and aerosol mass measurement. This monograph will be of interest to students and practitioners of physics, chemistry, and materials science.
Los Alamos National Laboratory (LANL) has recently procured a quartz crystal microbalance (QCM). Current popular uses are biological sensors, surface chemistry, and vapor detection. LANL has projects related to analyzing curing kinetics, measuring gas sorption on polymers, and analyzing the loss of volatile compounds in polymer materials. The QCM has yet to be employed; however, this review will cover the use of the QCM in these applications and its potential.
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 38 (thesis year 1993) a total of 13,787 thesis titles from 22 Canadian and 164 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 38 reports theses submitted in 1993, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
This thesis demonstrates the use of the quartz crystal microbalance/heat conduction calorimeter (QCM/HCC) in obtaining data that sheds light on the sorption of water into polymer films. Subsequently, it describes the application of this device towards the investigation of the effects of chemical and physical modifications on the sorption properties of polylactide, a biobased polymer. This project is par of an overall research program seeking to improve the moisture barrier properties of polylactide while maintaining its desirable properties of biodegradability and being predominantly derived from renewable feedstocks. The Quartz Crystal Microbalance/Heat Conduction Calorimeter (QCM/HCC) is a new instrument that is capable of concurrently measuring very small changes in mass and releases of heat. Moisture sorption into a material results in changes in its microscopic conformation that can be quantified through the measurement of the heat released or absorbed over the term of the process. The QCM/HCC is capable of obtaining these two measurements and correlating them to external vapor activity in order to produce sorption isotherms and thermodynamic data. There has recently been increased interest in bio-based polymers as a replacement for a portion of the petroleum-based polymers that are commonly used in present-day society. The utility of such polymers has been hindered by their tendency to take up water, which precludes their extended use. It is desirable to develop polymers produced primarily from biological feedstocks that retain their biodegradability while exhibiting improved moisture barer properties. This thesis presents an experimental set-up centered around the QCM/HCC that demonstrates the effectiveness of the device in efficiently obtaining mass uptake and heat evolution data that quantify the effects of water sorption on a polymer film. It then provides data on the effects of the addition of hydrophobic additives to polylactide through both copolymerization and physical blending. Sorption data on PLA films demonstrate an increasing enthalpy of sorption that gradually approaches the value of the enthalpy of vaporization of water, indicating the clustering of water molecules within this polymer, in contrast to similar data on films of the more hydrophilic PHEMA, where the enthalpy of sorption is significantly lower. Although blending polylactide with poly(dihexadecylglycolide) results in a decreased solubility, the amount of the more hydrophobic component that must be added to produce a significant change is prohibitive. Copolymerization with poly(dihexadecylglycolide) appears to be a more promising technique for changing the moisture barer properties of polylactide.
Cited in Sheehy, Chen, and Hurt . Volume 38 (thesis year 1993) reports a total of 13,787 thesis titles from 22 Canadian and 164 US universities. As in previous volumes, thesis titles are arranged by discipline and by university within each discipline. Any accredited university or college with a grad
Quartz crystal microbalances (QCMs) are piezoelectric thickness-shear-mode resonators where the resonant frequency has long been known to vary linearly with the mass of rigid layers on the surface when the device is in contact with air. This reports summarizes the results from a Laboratory Directed Research and Development effort to use an array of QCMs to measure and identify volatile organic compounds (VOCs) in water solutions. A total of nine polymer-coated QCMs were tested with varying concentrations of twelve VOCs while frequency and damping voltage were measured. Results from these experiments were analyzed using a Sandia-developed pattern recognition technique called visually empirical region of influence (VERI) developed at Sandia. The VERI analyses of data with up to 16% and 50% sensitivity drifts were carried out on an array with six signals obtained from five sensors. The results indicate that better than 98% and 88% correct chemical recognition is maintained for the 16% and 50% drifts, respectively. These results indicate a good degree of robustness for these sensor films.
Developing methods to detect, adsorb, and decompose chemical warfare agents (CWAs) is of critical importance to protecting military and civilian populations alike. The sorption of dimethyl methylphosphonate (DMMP), a CWA simulant, into trisilanolphenyl-POSS (TPP) films has previously been characterized with reflection absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and uptake coefficient determinations [1]. In our study, the quartz crystal microbalance (QCM) is used to study the sorption phenomena of DMMP into highly ordered Langmuir-Blodgett (LB) films of TPP. In a saturated environment, DMMP sorbs into the TPP films, binding to TPP in a 1:1 molar ratio. Although previous work indicated these DMMP-saturated films were stable for several weeks, DMMP is found to slowly desorb from the TPP films at room temperature and pressure. Upon application of vacuum to the DMMP-saturated films, DMMP follows first-order desorption kinetics and readily desorbs from the film, returning the TPP film to its original state.