Rapid Estimation of Thermodynamic Parameters and Vapor Pressures of Volatile Materials at Nanoscale

Hikal, Walid M.; Paden, Jeffrey T.; Weeks, Brandon L.

doi:10.1002/cphc.201200355

Cited by 9 publications

(1 citation statement)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this article we illustrate the successful use of UV-Vis absorbance spectroscopy in non-isothermal measurement of TNT sublimation kinetics, using different heating rates and three different famous calculation techniques. TNT sublimation kinetics were only determined non-isothermally once before using UV-Vis spectroscopy with a crude temperature integral approximation in the kinetics equation used [11]. No other techniques have been reported to measure the sublimation kinetics of secondary explosives non-isothermally due their low melting point (80 °C for TNT).…”

Section: Introductionmentioning

confidence: 99%

Non-Isothermal Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Nanofilms

Hikal

Weeks

2019

Molecules

View full text Add to dashboard Cite

Non-isothermal sublimation kinetics of low-volatile materials is more favorable over isothermal data when time is a crucial factor to be considered, especially in the subject of detecting explosives. In this article, we report on the in-situ measurements of the sublimation activation energy for 2,4,6-trinitrotoluene (TNT) continuous nanofilms in air using rising-temperature UV-Vis absorbance spectroscopy at different heating rates. The TNT films were prepared by the spin coating deposition technique. For the first time, the most widely used procedure to determine sublimation rates using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) was followed in this work using UV-Vis absorbance spectroscopy. The sublimation kinetics were analyzed using three well-established calculating techniques. The non-isothermal based activation energy values using the Ozawa, Flynn–Wall, and Kissinger models were 105.9 ± 1.4 kJ mol−1, 102.1 ± 2.7 kJ mol−1, and 105.8 ± 1.6 kJ mol−1, respectively. The calculated activation energy agreed well with our previously reported isothermally-measured value for TNT nanofilms using UV-Vis absorbance spectroscopy. The results show that the well-established non-isothermal analytical techniques can be successfully applied at a nanoscale to determine sublimation kinetics using absorbance spectroscopy.

show abstract

Section: Introductionmentioning

confidence: 99%

Non-Isothermal Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Nanofilms

Hikal

Weeks

2019

Molecules

View full text Add to dashboard Cite

show abstract

In Situ Direct Measurement of Vapor Pressures and Thermodynamic Parameters of Volatile Organic Materials in the Vapor Phase: Benzoic Acid, Ferrocene, and Naphthalene

Hikal

Weeks

2013

ChemPhysChem

View full text Add to dashboard Cite

We report the direct determination of vapor pressures and optical and thermodynamic parameters of powders of low-volatile materials in their vapor phase using a commercial UV/Vis spectrometer. This methodology is based on the linear proportionality between the density of the saturated gas of the material and the absorbance of the gas at different temperatures. The vapor pressure values determined for benzoic acid and ferrocene are in good agreement with those reported in the literature with ∼2-7 % uncertainty. Thermodynamic parameters of benzoic acid, ferrocene, and naphthalene are determined in situ at temperatures below their melting points. The sublimation enthalpies of the investigated organic molecules are in excellent agreement with the ICTAC recommended values (less than 1 % difference). This method has been used to measure vapor pressures and thermodynamic parameters of organic volatile materials with vapor pressures of ∼0.5-355 Pa in the 50-100 °C temperature range.

show abstract

Estimations of Vapor Pressures by Thermogravimetric Analysis of the Insensitive Munitions IMX‐101, IMX‐104, and Individual Components

Poda

Chappell

2013

Propellants Explo Pyrotec

View full text Add to dashboard Cite

We have calculated the vapor pressures of the new explosives ordnances IMX‐101 and IMX‐104 and their respective components, 2,4‐dinitroanisole (DNAN), nitroguanidine (NQ), nitrotriazolone (NTO), and hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) by the method of rising temperature thermogravimetric analysis. Clausius‐Clapeyron relationships were assumed for each case and the vapor pressures were estimated from the Langmuir equation over an appropriate temperature range just below substance melting/decomposition points. For vapor pressures extrapolated to room temperature, the rank with respect to decreasing volatility was found to be: DNAN>IMX‐104>IMX‐101>NQ>RDX>NTO. Interestingly, vapor pressure depression is observed in IMX formulations, where the formulation has a lower vapor pressure than its most volatile component, DNAN. The enthalpy of sublimation was determined for each substance and formulation from Clausius‐Clapeyron equations generated by analysis of the thermogravimetric data. The general trends in vapor pressures and sublimation enthalpies associated with the component materials were in good agreement with previous experimental and computational results. The results obtained by this study have importance for future investigations of IMX, specifically for chemical detection and assessment of environmental fate.

show abstract

Rapid Estimation of Thermodynamic Parameters and Vapor Pressures of Volatile Materials at Nanoscale

Cited by 9 publications

References 26 publications

Non-Isothermal Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Nanofilms

Non-Isothermal Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Nanofilms

In Situ Direct Measurement of Vapor Pressures and Thermodynamic Parameters of Volatile Organic Materials in the Vapor Phase: Benzoic Acid, Ferrocene, and Naphthalene

Estimations of Vapor Pressures by Thermogravimetric Analysis of the Insensitive Munitions IMX‐101, IMX‐104, and Individual Components

Contact Info

Product

Resources

About