ISO/TS 21346:2021

Overview

ISO/TS 21346:2021 - Nanotechnologies: Characterization of individualized cellulose nanofibril (iCNF) samples specifies which characteristics of iCNF materials should be measured and how to measure them. It covers iCNF samples in both suspension and powder forms, provides sample preparation, measurement and data analysis procedures (see Annex A), and describes iCNFs (see Annex B). The technical specification excludes iCNFs that have been chemically or physically modified after manufacture.

Keywords: ISO/TS 21346:2021, cellulose nanofibril, iCNF, nanotechnologies, characterization, measurement methods.

Key topics and technical requirements

The document defines required and recommended characteristics and associated measurement methods:

Required characteristics (examples)

• Morphology and size - TEM or AFM; qualitative images (≥10) with scale bars to show presence of iCNFs and other solids.
• Total dry matter content - oven drying to constant mass at 105 °C ± 2 °C, expressed in kg/kg.
• Crystal structure - X-ray diffractometry (XRD).
• Optical transmittance - UV‑Vis spectrophotometry.
• Surface functional groups (types) - FT‑IR spectroscopy.
• Surface functional groups (content) - conductometric titration.
• Viscosity - viscometry.

Recommended characteristics (examples)

• Width/height, length - TEM/AFM (width/height) and TEM (length).
• Molecular weight distribution - SEC‑MALS.
• Crystallinity - solid‑state NMR.
• Thermal stability - TGA.
• Ash and impurity analyses - combustion, ICP‑AES/OES or ICP‑MS after appropriate preparation.
• Contaminants, extractables and sugars - HPLC/IC, Soxhlet extraction, solid‑state NMR.

Other important requirements:

• Report the test specimen state (aqueous suspension, freeze/oven‑dried powder).
• When dispersibility affects results (e.g., microscopy), report dispersing methods such as sonication, homogenization or use of surfactants.
• Annex A contains detailed protocols for sample preparation, measurement and data analysis.

Applications and practical value

ISO/TS 21346:2021 supports:

• Quality control and batch release testing for iCNF manufacturers.
• R&D and comparative studies in academia and industry for cellulose nanomaterials.
• Supplier–buyer specifications and technical data sheets to ensure interoperable material data.
• Product development in polymer composites, adhesives, gels, additives, hygiene products (e.g., diapers) and specialty inks where iCNF performance depends on well‑characterized properties.

Who should use this standard

• iCNF manufacturers and formulators
• Quality assurance and metrology labs
• Materials scientists and process engineers
• Procurement/specification teams and regulatory bodies assessing nanomaterials

Related standards

• ISO/TS 80004‑2 (Nanotechnologies - Vocabulary - Part 2: Nano‑objects) is referenced for terminology.
• Prepared by ISO/TC 229 (Nanotechnologies); consult national bodies for implementation and related ISO nanotechnology standards.