ISO 22836:2020

Overview

ISO 22836:2020 specifies a laboratory method for accelerated moisture absorption and supersaturated conditioning of fibre‑reinforced composites using a sealed pressure vessel (autoclave/sterilizer) at temperatures above 100 °C with saturated water vapour. The procedure is designed to produce practical, near‑saturated moisture states at room temperature much faster than conventional humidity ageing, enabling effective screening of mechanical and thermal property changes in materials such as CFRP (carbon‑fibre reinforced plastics) and CFRTP (carbon‑fibre reinforced thermoplastics) with a glass transition temperature (Tg) greater than 150 °C. The method can also apply to other fibre systems (for example, glass‑fibre) meeting the Tg requirement.

Key topics and requirements

• Scope and purpose: Accelerated moisture conditioning for screening specimens by mechanical or thermal properties; intended to shorten R&D time compared with long term humidity exposure.
• Applicable materials: Carbon‑fibre composites and other fibre‑reinforced materials with Tg > 150 °C (thermoset and thermoplastic matrices).
• Principle: Heat specimens in a sealed vessel with saturated water vapour (examples: 120 °C, ~0.2 MPa) to increase diffusion rates, then cool to room temperature to attain a supersaturated moisture state.
• Apparatus: oven or sealed pressure vessel/autoclave, pressure gauge, relief valve, vacuum oven, balance (0.1 mg resolution), specimen support to avoid contact, deionized water.
• Procedure highlights:
  • Pre‑condition and weigh specimens (typically 23 °C, 50 % RH).
  • Place specimens immersed in water inside the sealed vessel; purge air at ~100 °C, then continue heating (examples: 72 h at 120 °C).
  • Cool to room temperature, reweigh, and repeat conditioning until additional moisture content stabilizes (change < 0.05 %).
  • Determine saturated moisture content by drying (e.g., 100 °C under reduced pressure) and calculating mass changes.
  • Measure mechanical/thermal properties before and after conditioning to confirm no degradation or unintended curing/crystallization.
• Reporting: Include test reference, specimen ID, conditioning parameters (temperature, pressure, time), drying conditions, masses and calculated moisture contents.
• Precision: Interlaboratory precision not established at time of publication.

Applications

• Rapid screening of composite formulations for moisture sensitivity.
• Accelerated environmental conditioning for R&D, material selection, and pre‑qualification tests.
• Comparative assessment of mechanical or thermal property changes (strength, stiffness, Tg) after moisture uptake.
• Useful in aerospace, automotive, marine, sporting goods, and industrial composites development where carbon‑fibre materials are used.

Who uses this standard

• Composite materials R&D teams and test laboratories
• OEMs and suppliers in aerospace, automotive, marine, defense
• Quality and durability engineers validating moisture effects on CFRP/CFRTP

Related standards

• ASTM D5229/D5229M (accelerated moisture absorption by 70 °C, 75 % RH) - referenced in the ISO introduction as a longer‑duration alternative for saturation studies.

Keywords: ISO 22836:2020, fibre‑reinforced composites, accelerated moisture absorption, supersaturated conditioning, sealed pressure vessel, CFRP, CFRTP, moisture conditioning, autoclave.