A comparative method for developing vapor pressure curves based on evaporation data obtained from a simultaneous TG–DTA unit

Excessively High Vapor Pressure of Al-based Amorphous Alloys

“…The vapor pressure of the amorphous alloys was calculated using the weight loss rate measured by TGA. Conventional TGA equipment was previously used to estimate the vapor pressure of materials at atmospheric pressure [24,25]. According to previous reports, Equation (1) was proposed to estimate the vapor pressure from the evaporation rate, adapting the Knudsen-Langmuir equation that describes free evaporation in a vacuum, as follows:…”

Characterization of tars from Estonian Kukersite oil shale based on their volatility

“…4 compares the experimentally obtained vaporization mass loss curve of the tar with the constructed evaporative mass loss curves of hypothetical tar compounds with molecular weights of 150, 250, 450, 650 and 750 g/mol. During the last decade, several papers have been published describing application of standard thermogravimetric techniques for vapor pressure measurement [8,9]. This application utilizes the Langmuir equation for evaporation and states that the vapor pressure is proportional to the thermogravimetric mass loss rate.…”

A fit of the vapours

“…Phang et al proposed a comparative method whereby a material of known, but similar structure and volatility, was run against the target compound so that a variable calibration "constant" could be employed [42]. Surov reported that the evaporation coefficient depended slightly on the compound being measured [55], although the data presented here in Table 1 does not cover a sufficient variety of compounds to support or refute this observation.…”

“…The approach described above was adopted by Dollimore et al resulting in a series of publications on the technique by re-defining or modifying the calibration protocol [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47]. However, our original intent was not to measure vapour pressures but to determine the enthalpy of vaporisation (DH vap ) of dyes and UV absorbers in order to screen them for a solid-state dye diffusion process [2,48] since the solubilities in target substrates are governed by the cohesive energy density (d) [49]:…”

“…Meanwhile, there were growing concerns that the simple calibration method required to extract vapour pressure data was in some way flawed as the evaporation coefficient (a) appeared to be alarmingly small (of the order of 10 À4 À 10 À5 ) [35,42]. Phang et al proposed a comparative method whereby a material of known, but similar structure and volatility, was run against the target compound so that a variable calibration "constant" could be employed [42].…”