QCM Thermo-Gravimetric Analysis (QTGA) Comparisons

The ASTM E-1559 apparatus has been used for years at NASA/Goddard Space Flight Center (GSFC) to determine in situ outgassing rate information, as well as pertinent in situ TML and multiple VCM values. The apparatus also affords the opportunity to experimentally compute the evaporation rates of molecular species that are reemitted as the Quartz Crystal Microbalances (QCMs) are gradually warmed up at some controlled temperature. Typically the molecular mass that accumulates onto the test QCMs are a compilation of species that are outgassing from the sample due to their respective activation energies and the desorption processes that the sample undergoes at various tested temperatures. It has been speculated that if there is too much molecular buildup of condensed water vapor (ice) onto the QCM crystal that a significantly higher temperature would be needed to break these "ice" bonds. ASTM E-1559 data plots will be used to demonstrate the thermogravimetric effects of water and other miscible molecular species with various water/ice thicknesses and at different evaporation rates.