The hydrolyzable chloride content of epoxy resins is a vital characteristic in deciding their reactivity and the expected properties of coatings made using such resins.
The OMNIS system is used with the dAg ring electrode to perform a potentiometric titration which yields a rapid and precise determination using silver nitrate as titrant.
Liquid epoxy resin
No sample preparation is required.
The blank is determined the same way as the sample.
Initially, 2 – 3 g sample is pipetted into an Erlenmeyer flask to which 50 mL c(KOH) = 0.1 mol/L in methanol, 20 mL toluene and 20 mL acetone are then added. Following this, the flask is connected to a reflux condenser for refluxing at 120 °C, for 15 ± 1 minute.
In the next step, the Erlenmeyer flask and condenser are taken off the heating plate so that the solution can cool down to ambient temperature. The condenser is rinsed with 20 mL acetone before removing the flask.
The solution is then diluted with acetone to about 125 mL and stirred. During this step of stirring, 50 mL glacial acetic acid is added. The stirred solution is now titrated with c(AgNO3) = 0.0025 mol/L using the dAg ring electrode until the equivalence point is passed.
This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.
For more information on this source, please visit Metrohm AG.