Price, Duncan M.; Vapor Pressure Determination by Thermogravimetry. Proc. 27th North American Thermal Analysis Society Conference, September 20-22 (1999) Savannah, Georgia, USA, pp. 524-529
A method for measuring the vapor pressures of a wide range of materials using a conventional thermobalance and standard sample holders is described. The equipment is calibrated using pure reference materials of known vapor pressure and exploiting the relationship between volatilization rate and vapor pressure based on the Langmuir equation for free evaporation. Accurate enthalpies of vaporization and sublimation can be determined, thus allowing the melting temperature and enthalpy of fusion to be obtained directly from thermogravimetry. Applications to the study of flame retardants and UV absorbers are described. Poor correlation of experimental results with predicted values obtained by molecular modeling is found. The application of Modulated-Temperature Thermogravimetry for the determination of enthalpies of sublimation and vaporization is also explored.
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