Overview
ISO/TS 21236-2:2021 - Nanotechnologies - Clay nanomaterials - Part 2 specifies the characteristics and measurement methods for clay nanoplates (powder and suspension forms) intended for gas‑barrier film applications. The technical specification defines which properties to measure, the applicable analytical techniques, and measurement protocols. It supports consistent reporting for research, development and commercialization of clay‑based polymer nanocomposites designed to improve gas and water‑vapour barrier performance. Note: the document does not cover post‑manufacturing modification characteristics or health and safety considerations.
Key topics and technical requirements
The standard identifies required and recommended characteristics and links them to standardized measurement methods:
- Required characteristics
- Mineral composition - XRD, polarization microscopy (powder)
- Chemical composition - ICP, AAS, XRF, SEM‑EDX, EPMA (powder)
- Cation exchange capacity (CEC) - Schollenberger method (powder)
- Particle size - DLS or laser diffraction (suspension)
- Loss on ignition - weight measurement or TGA (powder)
- Recommended characteristics
- Methylene blue adsorption capacity - filter paper method or UV‑Vis (powder)
- Aspect ratio - AFM, TEM or SEM (powder)
- Film formability - suspension casting (powder → suspension)
- Viscosity - viscometry (suspension)
Additional practical materials in the specification:
- Annex A: Measurement protocols for individual characteristics
- Annex B: Principles of gas barrier action using clay nanoplates (e.g., tortuosity effects)
- Annex C: Value chains for clay nanoplate materials
- Annex D: Example reporting sheet and recommended reporting formats
Applications and who should use this standard
ISO/TS 21236-2:2021 is intended for organizations involved in:
- R&D and formulation of polymer clay nanocomposites for high‑performance gas‑barrier films
- Manufacturers and suppliers of clay nanomaterials (smectite, kaolinite, mica, talc) in powder or suspension form
- Quality control and analytical laboratories performing XRD, ICP, DLS, AFM/TEM/SEM, TGA, UV‑Vis measurements
- Packaging, electronics (OLED displays), pharmaceutical and hydrogen‑storage industries seeking reproducible barrier performance data
Using this standard helps ensure consistent characterization of critical parameters-particle size, aspect ratio, mineral/chemical composition, CEC, film formability and viscosity-that determine barrier effectiveness in polymer matrices.
Related standards and references
Keywords: ISO/TS 21236-2:2021, clay nanomaterials, clay nanoplates, gas‑barrier films, measurement methods, particle size, XRD, DLS, AFM, TEM, cation exchange capacity.