An equation to calculate the actual methylene middle parameter as a function of temperature

作者：Mohammad Mohammad Amin^*

来源：Journal of Chromatography A, 2015, 1408: 267-271.

DOI：10.1016/j.chroma.2015.07.003

• Adhesion retention factor
• Chromatographic adhesion law
• Inverse gas chromatography
• Methylene middle parameter
• Surface energy
• Surface parameters of methylene

Methylene middle parameter [alpha(CH2)(gamma(CH2))(0.5)], the product of the methylene group's cross-sectional area (alpha(CH2)) and the root square of its dispersive free energy (gamma(CH2)), is the key parameter to calculate the dispersive surface components of solids (gamma(d)(s)) using inverse gas chromatography (IGC) at different temperatures. The only method reported to calculate alpha(CH2)(gamma(CH2))(0.5) as a function of temperature is the Dorris-Gray method. However, the conventional values of alpha(CH2)(gamma(CH2))(0.5) calculated by the Dorris-Gray method depend heavily on theoretical aspects. This paper establishes a novel equation calculating the actual alpha(CH2)(gamma(CH2))(0.5) as a function of temperature using the latest and most accurate surface parameters of seven successive n-alkanes. The obtained actual alpha(CH2)(gamma(CH2))(0.5) values are slightly higher those of the conventional alpha(CH2)(gamma(CH2))(0.5). At 20 degrees C, the actual alpha(CH2)(gamma(CH2))(0.5) generates gamma(d)(s) values less than those generated using the conventional alpha(CH2) (gamma(CH2))(0.5) by similar to 3%, and this reduction in calculated gamma(d)(s) values increases linearly to become similar to 5% at 100 degrees C. Therefore, using the new actual alpha(CH2)(gamma(CH2))(0.5) seems to mitigate the discrepancy between the gamma(d)(s) values measured by IGC and those measured by the contact angle method.

• 出版日期2015-8-21