Model compounds simulating amine–carboxylic acid-based volatile corrosion inhibitors were characterized
by thermogravimetric analysis and Fourier transform infrared spectroscopy. These systems are usually
employed as equimolar mixtures to protect ferrous metals against atmospheric corrosion. The key
finding of this study was that the vapors released by such equimolar mixtures initially contain almost
free amine only. After prolonged vaporization a steady-state azeotrope-like composition is approached.
It contains excess carboxylic acid and features impaired corrosion inhibition efficiency according to the
Skinner test. In part, this behavior can be attributed to the mismatch in the volatilities of the amine
and carboxylic acid constituents.