ISO 10548:2002

Overview

ISO 10548:2002 defines standardized test methods for determining the size content of carbon fibre yarn. Applicable to both continuous‑filament yarns and staple‑fibre yarns, the standard specifies specimen handling, conditioning, test procedures and result expression so that manufacturers, test laboratories and buyers can obtain comparable and reproducible measurements of the mass percentage of sizing on carbon fibre yarn.

Key topics and technical requirements

• Scope and definitions: Defines “size” (material applied to fibres to facilitate handling/use) and “size content” (mass of size as a percentage of the sized yarn).
• Sampling and specimens: At least two test specimens per lot; lot sampling may follow ISO 1886.
• Conditioning: Samples must reach laboratory temperature and be dried where required before weighing.
• Three validated removal methods:
  • Method A - Solvent extraction (Soxhlet): Examples of solvents include methyl ethyl ketone, tetrahydrofuran, dichloromethane, acetone. Typical extraction is 2 h with at least four reflux cycles, followed by drying (e.g., 110 °C ±5 °C) to constant mass.
  • Method B - Chemical digestion: Oxidation with concentrated sulfuric acid (≥96 %) and hydrogen peroxide (≈30 %) in a controlled digestion block (example temperature 260 °C ±5 °C for specified time). Requires fume hood, PPE, filtration on sintered‑glass filters and drying to constant mass. A blank test on unsized fibre is used to correct for any fibre mass loss.
  • Method C - Pyrolysis: High‑temperature decomposition in a nitrogen stream (N2 purity >99.996 %) using an electric furnace. Manufacturer‑specified decomposition temperature/time and controlled cooling under nitrogen are required.
• Result expression: Size content reported as mass percentage (difference between initial and final mass divided by initial mass), averaged over determinations.
• Precision, reporting and safety: Recommends repeating drying/weighing until mass change < ±0.2 mg and details test report contents. Methods include safety controls (fume cupboard, gloves, face shield) where hazardous reagents are used.

Applications and users

• Quality control in carbon fibre production to verify sizing levels for handling, sizing transfer and composite processing.
• Incoming inspection by composite manufacturers and textile converters to confirm supplier claims.
• R&D and troubleshooting where sizing formulation or bake‑out/pyrolysis processes are evaluated.
• Third‑party testing laboratories providing certification data for materials used in aerospace, automotive and sporting goods composites.

Related standards

• ISO 1886:1990 (sampling plans for received batches) is normative for lot sampling referenced by ISO 10548.

Keywords: ISO 10548:2002, carbon fibre size content, size determination, Soxhlet extraction, chemical digestion, pyrolysis, carbon fibre yarn testing, sizing analysis.