Overview
ISO 11566:1996 specifies a standardized test method for determining the tensile properties of single carbon‑fibre filaments. The procedure is applicable to filaments extracted from multifilament yarns, woven fabrics, braids and related products. The standard defines specimen preparation, required apparatus, cross‑sectional area determination, system compliance correction and reporting requirements for consistent tensile testing results.
Key Topics
- Scope: Test method for single‑filament tensile strength and elastic modulus applicable to carbon fibres from various product forms.
- Specimen count: Prepare at least 20 specimens per unit to permit 20 determinations for each reported result.
- Apparatus:
- Tensile testing machine with constant traverse speed and force and elongation recorders (force indicator accuracy better than 1%).
- Mounting plate (recommended light length 25 mm ± 0.5 mm; sheet thickness ~0.1 mm) to reduce misalignment.
- Adhesive: epoxy resin, colophony or sealing wax to bond the filament to the plate.
- Tape for temporary placement.
- Specimen preparation: Removal of sizing (if present) by solvent extraction, chemical digestion or pyrolysis following ISO 10548 methods.
- Cross‑sectional area: Determine independently by one of the methods in ISO 11567 - optical microscopy of a polished transverse section, calculation from linear mass and density, or laser diffraction diameter measurement. If area is determined from optical or laser diameter, use the same specimens for tensile testing.
- Test conditions: Perform tests in one of the standard atmospheres defined by ISO 291. Traverse speeds are set between 1 mm/min and 5 mm/min.
- System compliance (K): Correct measured elongation for machine and mounting compliance. Annex A describes determining K experimentally using multiple gauge lengths (example lengths: 5, 10, 20, 30, 40 mm).
- Elastic modulus: Calculated as a secant modulus by Method A (force/strain limits) or Method B (alternate strain limits); force ranges reference limits of 400 mN/tex and 800 mN/tex where applicable.
- Fidelity: Interlaboratory precision is not provided in ISO 11566:1996; a fidelity statement will be added when data become available.
Applications
- Quality control of carbon fibres in composites manufacturing, textile reinforcement and research & development.
- Comparative evaluation of filament tensile strength and modulus for material selection.
- Verification of supplier claims for single‑filament properties used in composite design and textile engineering.
Related Standards
- ISO 11567 - Methods to determine filament diameter and cross‑sectional area (referenced for area measurement).
- ISO 10548 - Procedures for removal of sizing (solvent, chemical, pyrolysis) prior to testing.
- ISO 291 - Standard conditioning atmospheres for testing.
Use ISO 11566:1996 to ensure reproducible single‑filament tensile data by following its specimen, mounting, area‑measurement and compliance‑correction requirements. Proper adherence improves comparability of tensile strength and modulus results across laboratories and product evaluations.