Overview
ISO 21023:2025 - Textiles - Determination of surface chemical properties of carbon fibres using X-ray photoelectron spectroscopy (XPS) - specifies a standardized method to measure the oxygen-to-carbon (O/C) ratio on carbon fibre surfaces. The method is applicable to all types and forms of carbon fibres and defines specimen preparation, XPS measurement conditions, data analysis and reporting requirements for reliable surface chemical characterization.
Key topics and technical requirements
- Measurement technique: X-ray photoelectron spectroscopy (XPS) using an Al Kα source from a micro-focused monochromator and a hemispherical electron energy analyser (typical FWHM ≤ 0.5 eV for Ag 3d).
- Vacuum and instrumentation: Ultra-high vacuum chamber (vacuum better than ~5×10⁻⁹ torr recommended) and charge-neutralization methods as required for insulating samples.
- Specimen preparation: Detailed procedures for desizing (thermal treatment up to 700 °C with nitrogen flow), acidification (nitric acid treatment at ~110 °C), washing to neutral pH and vacuum drying (e.g., 80 °C for several hours).
- Measurement protocol: Wide scan (0–1 000 eV) followed by high-resolution scans of C 1s, O 1s, N 1s, Cl 2p and S 2p; recommended scanning steps and acquisition conditions; dense packing of fibres on sample mount to avoid substrate signal; replicate measurements (three specimens).
- Data analysis: Background subtraction and peak fitting per ISO 10810; use of relative sensitivity factors (ISO 18118) and calibration procedures (ISO 15472) to calculate atomic fractions and the O/C ratio.
- Reporting: Required elements include standard reference, sample description, preparation and measurement conditions, calculated O/C ratio, analytical uncertainty, and deviations from the method.
Practical applications and users
ISO 21023:2025 supports:
- Quality control in carbon-fibre production and finishing - monitoring surface chemistry that affects wettability and adhesion.
- Composite manufacturing - assessing fibre surface treatments to optimize matrix adhesion and mechanical performance.
- Materials research and development - comparing surface modification methods, coatings and functionalization.
- Analytical laboratories and certification bodies that perform XPS surface analysis for textile and composite industries.
Typical users: materials scientists, surface chemists, composite engineers, textile technologists, quality assurance labs and XPS service providers.
Related standards
- ISO 10810 (XPS analysis guidelines)
- ISO 15472 (XPS energy calibration)
- ISO 18115-1 (surface analysis vocabulary)
- ISO 18118 (use of sensitivity factors)
- IEC TS 62607-6-21 (C/O ratio by XPS for graphene-based materials)
ISO 21023:2025 provides a harmonized XPS protocol for consistent, reproducible assessment of carbon fibre surface chemistry - essential for product performance, regulatory compliance and comparative research.