Overview
EN ISO 21627-2:2009 - Plastics - Epoxy resins - Determination of chlorine content - Part 2: Easily saponifiable chlorine is a CEN-adopted ISO method for quantifying the easily saponifiable chlorine fraction in epoxy resins. The measured value indicates the concentration of chlorine present mainly as chlorohydrin (1,2-chlorohydrin) impurities formed during epoxy resin manufacture from epichlorohydrin. Results support quality control and compliance testing for resin producers, test laboratories and downstream formulators.
Key topics and technical requirements
- Scope and purpose: Specifies a chemical method to determine easily saponifiable chlorine in epoxy resins; values are indicative of chlorohydrin content.
- Principle: Saponification of organic chlorides with NaOH in an appropriate solvent, followed by acidification and potentiometric titration of liberated chloride ions with standardized silver nitrate (0.01 mol/L). A correction for inorganic (ionic) chlorine is made using ISO 21627-1.
- Reagents and solvents: Includes 2‑butoxyethanol, methanol (for glycidyl esters), glacial acetic acid, 2‑butanone, acetone, and a 120 g/L NaOH solution (prepared in 2‑butoxyethanol or methanol depending on sample type).
- Apparatus: Standard lab glassware plus potentiometric titration equipment with a silver/silver‑chloride electrode, analytical balance (0.1 mg), water bath (50 °C for glycidyl esters), reflux condenser and magnetic stirrer.
- Procedure highlights:
- Dissolve an accurately weighed test portion.
- React with NaOH at room temperature (2 h) in 2‑butoxyethanol (or at 50 °C in methanol for glycidyl esters).
- Acidify, extract/dilute, then titrate potentiometrically with AgNO3.
- Run blank and correct for inorganic chlorine per ISO 21627-1.
- For QC, a validated shorter saponification time (30 min) may be used and must be reported.
- Analytical quality: Standardization of silver nitrate, blank tests, and storage/handling precautions for light‑sensitive reagents are specified. Safety and laboratory practice warnings are included.
Applications - who uses it
- Epoxy resin manufacturers for process control and impurity monitoring.
- Independent testing laboratories performing compositional analysis and certification.
- Formulators and composite manufacturers verifying resin quality for electrical, adhesive, coating or structural applications where chlorohydrin impurities affect performance.
- Regulatory and procurement teams requiring documented analytical methods for specifications and acceptance testing.
Related standards
- ISO 21627-1 - Determination of inorganic chlorine (ionic chlorine)
- ISO 21627-3 - Determination of total chlorine
- ISO 3696 - Water for analytical laboratory use
- ISO 4615 - Methods for other epoxy resin impurities
Keywords: EN ISO 21627-2:2009, epoxy resins, easily saponifiable chlorine, chlorohydrin, potentiometric titration, silver nitrate, resin quality control.