ISO/TS 21346:2021

TECHNICAL ISO/TS
SPECIFICATION 21346
First edition
2021-03
Nanotechnologies —
Characterization of individualized
cellulose nanofibril samples
Nanotechnologies — Caractérisation d'échantillons de nanofibrilles
individualisées de cellulose
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Characteristics to be measured of iCNF samples and their measurement methods .2
5.1 General . 2
5.2 Characteristics required to be measured or identified . 3
5.2.1 Morphology and size . 3
5.2.2 Total dry matter content . 4
5.2.3 Crystal structure . 4
5.2.4 Optical transmittance . 4
5.2.5 Surface functional groups: Types . 4
5.2.6 Surface functional groups: Content . 5
5.2.7 Viscosity . 5
5.3 Characteristics recommended to be measured or identified. 5
5.3.1 Width and height . 5
5.3.2 Length. 6
5.3.3 Molecular weight distribution . 6
5.3.4 Supernatant dry matter ratio . 6
5.3.5 Crystallinity . 7
5.3.6 Thermal stability. 7
5.3.7 Ash content . 7
5.3.8 Acid-soluble metal content . 8
5.3.9 Organic contaminant content . 8
5.3.10 Acetone-soluble matter content . 8
5.3.11 Constituent sugar content . 8
6 Reporting . 9
Annex A (informative) Protocols for sample preparation, measurement and data analysis .10
Annex B (informative) Description of individualized cellulose nanofibril (iCNF) .27
Bibliography .36
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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This document was prepared by Technical Committee ISO/TC 229, Nanotechnologies.
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iv © ISO 2021 – All rights reserved

Introduction
Cellulose nanomaterials derived from naturally occurring cellulosic fibres are renewable advanced
materials with unprecedented properties. They are of wide variety in morphology, e.g. different shapes,
branching and networking. Basic research related to cellulosic nanomaterials has been increasingly
conducted worldwide. At the same time, manufacturing industries have already started to deliver
cellulose nanomaterials to the market. Application industries are also becoming more and more
interested in these new materials.
All native cellulosic fibres are composed of bundles in which the smallest fibril unit is an elementary
fibril originating from a cellulose terminal enzyme complex. An elementary fibril is made of a
certain number of cellulose molecules and contains crystalline regions predominantly. The size of an
elementary fibril is specific to the native cellulose source. In wood pulp, the cross-sectional dimension
of an elementary fibril is about 3 nm and its aspect ratio can reach more than 200. In native cellulose
fibres, elementary fibrils do not exist as single fibrils but adhere to each other through hydrogen
bonding and are densely packed to form a bundle of fibrils. Very recently, however, some novel methods
to extract and separate these elementary fibrils, through chemical modification of the outer surface
of the fibrils followed by mechanical treatment, were developed. The chemical modification methods
include TEMPO-mediated oxidation and phosphorylation. Using the above treatments, each native
elementary fibril can be converted to an individualized cellulose nanofibril (iCNF) with charges at its
surface. An iCNF has the functional groups on the outer surface of the fibril, and iCNFs can be separated
from each other, one by one, by the static repulsion due to the electrostatic charge of newly introduced
functional groups. Refer to Annex B for more explanations on iCNFs.
Several manufacturing companies have already begun producing iCNFs. iCNFs are now delivered
increasingly to the worldwide market for applications in the industrial fields of polymer composites,
adhesives, additives, gels, etc. Some examples of iCNF-containing commercial products are diapers with
deodorant performance and gel ink for ballpoint pens. In all applications, appropriate characterization
of the iCNF samples is necessary so that desired products can be manufactured.
This document provides a sound basis for the commercialization as well as the research and
development of iCNF materials.
TECHNICAL SPECIFICATION ISO/TS 21346:2021(E)
Nanotechnologies — Characterization of individualized
cellulose nanofibril samples
1 Scope
This document specifies characteristics to be measured of individualized cellulose nanofibril (iCNF)
samples in suspension and powder forms and their measurement methods. In addition, it provides
sample preparation, measurement and data analysis procedures.
This document does not apply to the characterization of iCNFs that have been modified after they are
manufactured.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 80004-2, Nanotechnologies — Vocabulary — Part 2: Nano-objects
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TS 80004-2 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
elementary fibril
structure, originating from a single terminal enzyme complex, having a configuration of cellulose
chains specific to each cellulose-producing plant, animal, algal and bacteria species
[SOURCE: ISO/TS 20477:2017, 3.2.5]
3.2
cellulose nanofibril
CNF
cellulose nanofibre composed of at least one elementary  fibril (3.1), containing crystalline,
paracrystalline and amorphous regions, with aspect ratio usually greater than 10, which may contain
longitudinal splits, entanglement between particles, or network-like structures
[SOURCE: ISO/TS 20477:2017, 3.3.6, modified — The notes to entry have been deleted.]
3.3
individualized cellulose nanofibril
iCNF
discrete cellulose nanofibril (3.2) composed of one elementary fibril (3.1) with ionic functional groups on
its surface
4 Abbreviated terms
AFM atomic force microscopy
CNC cellulose nanocrystal
FT-IR Fourier transform infrared spectrometry
HPLC high performance liquid chromatography
IC ion chromatography
ICP-AES inductively coupled plasma - atomic emission spectrometry
ICP-MS inductively coupled plasma - mass spectrometry
ICP-OES inductively coupled plasma - optical emission spectrometry
NMR nuclear magnetic resonance
SEC-MALS size-exclusion chromatography - multi-angle laser light scattering
TEM transmission electron microscopy
TEMPO 2,2,6,6-tetramethylpiperidine-1-oxyl
TGA thermogravimetric analysis
UV-Vis ultraviolet-visible
XRD X-ray diffraction
5 Characteristics to be measured of iCNF samples and their measurement
methods
5.1 General
The characteristics of iCNF samples listed in Table 1
...