ISO 24048:2022

Overview

ISO 24048:2022 specifies a laboratory method for determining the bound acrylonitrile content in the continuous phase of acrylonitrile‑butadiene‑styrene (ABS) copolymer using the Dumas combustion method. Applicable to ABS resins with a continuous‑phase acrylonitrile mass fraction between 5 % and 50 %, the standard defines sample preparation, instrumental calibration, measurement and calculation steps for reliable acrylonitrile quantification.

Key topics and technical requirements

• Principle: Dissolve/disperse ABS in acetone, separate continuous phase by high‑speed centrifugation, precipitate the continuous phase with cold methanol, wash with n‑hexane, dry and determine nitrogen via Dumas combustion; convert nitrogen to acrylonitrile content.
• Sample preparation: Reflux dispersion in acetone, centrifuge at ≥ 18 000 r/min (keep centrifuge at 4 °C ± 0.1 °C), precipitate in methanol cooled to −10 °C, final specimen mass typically 50–100 mg (multiple precipitations can be combined).
• Reagents: High‑purity solvents (acetone, methanol, n‑hexane) and reference combustible materials (e.g., acetanilide) for calibration.
• Apparatus: Automatic Dumas analyser (combustion unit, oxygen feeder, reduction unit, absorber/separator, thermal conductivity detector), tin boats, centrifuge, vacuum oven (60 °C ± 1 °C, 1 kPa ± 0.5 kPa).
• Calibration and quality control: At least 5 calibration points, linear regression with correlation coefficient ≥ 0.995, and a calibration factor maintained within 0.98 to 1.02; routine calibration before each batch.
• Measurement parameters (recommended): combustion 900–1 050 °C, reduction 550–700 °C, oxygen and carrier gas pressures per instrument guidelines.
• Precision and reporting: The standard includes sections on repeatability (r) and reproducibility (R) and an informative Annex A summarizing precision data. Test report contents are specified.

Practical applications

• Quality control and verification of ABS resin formulation and batch consistency.
• Routine laboratory testing in plastics manufacturing and inbound material inspection.
• Research and development for polymer formulation and material characterization.
• Regulatory or compliance testing where accurate acrylonitrile content in ABS continuous phase is required.
• Failure analysis and supplier qualification.

Who should use this standard

• Polymer testing laboratories and contract test houses
• ABS resin manufacturers and compounders
• OEMs and product manufacturers using ABS (automotive, consumer electronics, appliances)
• R&D teams and material scientists focused on thermoplastic properties

Related standards

• ISO 472 (Plastics - Vocabulary) is referenced for terms and definitions. For full procedural details, calibration tolerances and precision data consult the complete ISO 24048:2022 document from ISO.