Overview
ISO 21627-3:2009 specifies a standardized analytical method for the determination of total chlorine in epoxy resins. Total chlorine, as defined by the standard, includes both saponifiable organic chlorine (e.g., chlorohydrins and chlorinated glycidyl derivatives) and inorganic chloride present as impurities. The method supports quality control, formulation assessment and regulatory compliance for epoxy products produced from epichlorohydrin-based processes.
Key Topics
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Principle: Dissolve the resin sample in a suitable ether solvent and saponify with an alcoholic potassium hydroxide solution (in propanediol-1,2) under reflux. After work-up, determine chlorine by potentiometric titration with a standardized silver nitrate solution (AgNO3).
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Reagents (selected):
- ether monobutyl diethylene glycol
- potassium hydroxide solution (1 mol/l in propanediol-1,2)
- glacial acetic acid and acetone
- silver nitrate standard solutions (0.1 mol/l and 0.01 mol/l)
- laboratory-quality water (ISO 3696)
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Apparatus (selected):
- potentiometric titration system with silver and reference electrodes
- analytical balance (0.1 mg resolution)
- reflux apparatus, conical flasks, magnetic stirrer, hot plate/bath
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Procedure highlights:
- Weigh a sample mass calculated to provide an expected chlorine amount in the target titration range.
- Dissolve in ether solvent and add KOH solution; heat to reflux with stirring for 10 minutes.
- Cool, add acetone, transfer and rinse with glacial acetic acid.
- Titrate potentiometrically with AgNO3; select concentration of AgNO3 (0.01 or 0.1 mol/l) according to expected chlorine level.
- Run and subtract a blank determination for accurate results.
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Results: The chlorine content is reported as mg/kg (ppm) of total chlorine and rounded to three significant figures. The standard provides the calculation method and instructs inclusion of calibration and blank data.
Applications
- Quality control of epoxy resin production to detect chlorinated impurities that can affect cured properties
- Supplier and incoming material verification
- Process optimization to minimize residual chlorinated species from epichlorohydrin routes
- Supporting compliance documentation for product specifications and regulatory review
Related Standards
- ISO 21627-1 - Chloride (inorganic) determination in epoxy resins
- ISO 21627-2 - Easily saponifiable chlorine in epoxy resins
- ISO 4615 - Chlorine determinations in other resin types
- ISO 5725-2 - Accuracy (repeatability and reproducibility) of measurement methods
- ISO 3696 - Laboratory water quality
Practical value: Using ISO 21627-3:2009 ensures reproducible, comparable measurements of total chlorine across laboratories, enabling robust QC, supplier communication and process control for epoxy resin manufacturers and users.
Open preview (PDF)Plastics — Epoxy resins — Determination of chlorine content — Part 3: Total chlorine