ISO/TS 10818:2023

Nanotechnologies - Textiles containing nanomaterials and nanostructures - Superhydrophobic characteristics and durability assessment

This document specifies the characteristics and performance(s) of the superhydrophobic textiles containing nanomaterials and nanostructures (TCNNs) based on contact angle measurement before and after being subjected to washing/drying (laundry), ironing processes, light sources and abrasion, that are to be determined by agreement between customer and supplier. This document solely covers woven and nonwoven fabrics. This document does not address safety and health related issues.

Nanotechnologies — Textiles contenant des nanomatériaux et des nanostructures — Caractéristiques superhydrophobiques et évaluation de la durabilité

General Information

• Status: Published
• Publication Date: 03-Aug-2023
• ICS: 07.120 - Nanotechnologies
• ICS: 59.080.01 - Textiles in general
• Technical Committee: ISO/TC 229 - Nanotechnologies
• Drafting Committee: ISO/TC 229 - Nanotechnologies
• Current Stage: 6060 - International Standard published
• Start Date: 04-Aug-2023
• Due Date: 29-Apr-2025
• Completion Date: 04-Aug-2023

Overview

ISO/TS 10818:2023 - "Nanotechnologies - Textiles containing nanomaterials and nanostructures - Superhydrophobic characteristics and durability assessment" defines how to characterize and report the superhydrophobic performance and durability of textiles that incorporate nanomaterials or nanostructures (TCNNs). This technical specification applies to woven and nonwoven fabrics and details mandatory and recommended measurements based on contact angle and contact angle hysteresis taken before and after ageing (laundry, ironing, abrasion, light exposure). The standard does not address safety or health issues.

Key topics and requirements

• Definition of superhydrophobicity: water contact angle > 150° and contact angle hysteresis < 10°.
• Durability (ageing) conditions to be assessed by agreement between customer and supplier:
  • Washing/drying (laundry) and dry cleaning
  • Ironing
  • Mechanical abrasion (rubbing)
  • Light exposure
• Mandatory measurement characteristics:
  • Contact angle and contact angle hysteresis (before and after ageing)
  • Nanomaterial size and size distribution
  • Nanomaterial/nanostructure morphology
  • Chemical composition
• Recommended measurements (application-dependent):
  • Nano-roughness
  • Phase analysis
• Reporting: standardized reporting formats, grading procedures and a durability performance index are defined to communicate results between suppliers and buyers.
• Emphasis on: measurement repeatability, sampling guidance (ISO 2859-1 or mutually agreed methods) and clear documentation of test conditions.

Practical applications

• Quality control and product specification for superhydrophobic textiles used in:
  • Outdoor apparel and sportswear
  • Protective clothing and workwear
  • Self-cleaning textile surfaces (furniture, filtration materials)
• Product development and R&D for formulators and textile finishers using nanocoatings, nanofibres or surface nano-roughening techniques (e.g., silica, TiO2, CNTs, ZnO).
• Supplier–buyer contracts where measurable durability grades and performance indices are required.
• Test and certification laboratories implementing standardized contact angle and durability testing for TCNNs.

Who should use this standard

• Textile manufacturers and finishers working with nanomaterials and superhydrophobic treatments
• Independent testing laboratories and quality managers
• Product designers, procurement teams and standards bodies seeking objective durability metrics
• Small and medium enterprises (SMEs) aiming to demonstrate sustainable performance (reduced water use, longer-lasting finishes)

Related standards

• Cited or relevant documents include ISO 19403 (contact angle / wettability standards) and ISO 2859‑1 (sampling procedures). ISO/TS 10818:2023 was prepared by ISO/TC 229 (Nanotechnologies).

Keywords: ISO/TS 10818:2023, superhydrophobic textiles, TCNNs, contact angle, contact angle hysteresis, durability assessment, nano-roughness, washing, ironing, abrasion, light exposure.

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 10818
First edition
2023-08
Nanotechnologies — Textiles
containing nanomaterials and
nanostructures — Superhydrophobic
characteristics and durability
assessment
Nanotechnologies — Textiles contenant des nanomatériaux et
des nanostructures — Caractéristiques superhydrophobiques et
évaluation de la durabilité
Reference number
© ISO 2023
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 3
4 Mandatory and recommended measurement characteristics and their
measurement methods . 3
4.1 General . 3
4.2 Ageing for superhydrophobic durability assessment . 4
4.2.1 General . 4
4.2.2 Washing and dry cleaning . 4
4.2.3 Ironing . 4
4.2.4 Mechanical abrasion . 4
4.2.5 Light exposure . 5
4.3 Nanomaterial and nanostructure evaluation . 5
4.3.1 General . 5
4.3.2 Size and size distribution . 5
4.3.3 Nano-roughness (recommended characteristics) . 6
4.3.4 Morphology . 6
4.3.5 Chemical composition . . 7
4.4 Superhydrophobicity . 8
4.4.1 General . 8
4.4.2 Contact angle . 9
4.4.3 Dynamic contact angle . 9
4.5 Superhydrophobic durability assessment . 9
4.5.1 General . 9
4.5.2 Grade of superhydrophobic durability . 9
4.5.3 Index of durability performance . 11
5 Reporting .12
5.1 General .12
5.1.1 Introduction . 12
5.1.2 General information .12
5.1.3 Measurement results .12
5.2 Table format example for reporting . 13
Annex A (informative) Safety, health and environmental issues .14
Annex B (informative) Superhydrophobicity .16
Bibliography .17
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 229, Nanotechnologies.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Recently superhydrophobic textiles (woven and nonwoven) have gained significant scientific
and industrial interest for its potential applications in outdoor wear and protective clothing. The
superhydrophobic textile surfaces refer to superior water repellency with a water contact angle
exceeding 150° and low contact angle hysteresis of less than 10° (see Annex A). For this superhydrophobic
textile, dirt and soils are loosely attached, and a rolling water drop can easily attach and remove them
from the surface, giving self-cleaning properties. According to Young’s, Wenzel and Cassie-Baxter
Models superhydrophobicity of textile surface can be made by both the surface treatment with very
low surface free energy materials and making nano-roughness (see Annex B).
Nanotechnology is employed to artificially change the surface free energy and/or cause nano- roughness
on the surface. The following methods are normally utilized in this respect:
— using nano-objects such as silica, TiO , CNT, ZnO, etc., in various ways;
— surface etching, i.e. nano roughening (UV-laser or plasma), followed by grafting or physically/
chemically attaching compounds with low surface energy;
— using nanofibres.
The establishment of superhydrophobic relies on
a) superhydrophobic (non-polar) surface chemistry, and
b) nanostructured surface texture (nano-roughness).
One of the most important obstacles affecting the market growth of textiles containing nanomaterials
and nanostructures (TCNNs) showing superhydrophobic response is their relevant durability under
different utilization and working conditions. This includes, laundering (washing), ironing, mechanical
abrasion (rubbing) and light radiation exposure. If superhydrophobic properties are not durable, the
TCNNs are useless in long term applications. Therefore, durability of superhydrophobic TCNNs over
repeated use and wash are necessary.
In this regard, the durability and persistence of superhydrophobic behaviour of TCNNs needs to be
assessed under above mentioned condition based on standard methods. Generally, from the consumer’s
perspective, the superhydrophobic durability of TCNNs is very important. However, there is no specific
measurement method to evaluate the superhydrophobic durability. In fact, there is a lack of grading
procedure for this characteristic.
This document both specifies the characteristics, performance and durability of the TCNNs subjected to
laundry (washing), ironing, mechanical abrasion (rubbing) and light exposure. The superhydrophobic
durability of such textiles are assessed and reported based on contact angle and hysteresis measurement
of the samples before and after subjected to mentioned conditions. In fact, a specific grading method is
established in this document. Further, this document also recommends relevant measurement methods
to promote communication and mutual understanding of TCNNs for superhydrophobic application
between buyers and sellers.
This document supports less water consumption and less waste water production. In addition,
this document supports responsible production in terms of superhydrophobic durability of textile.
Furthermore, this document can provide a potential for the economic growth for small and medium
size enterprises. These items conform with several Sustainability Development Goals (SDGs) defined by
United Nations.
v
TECHNICAL SPECIFICATION ISO/TS 10818:2023(E)
Nanotechnologies — Textiles containing nanomaterials
and nanostructures — Superhydrophobic characteristics
and durability assessment
1 Scope
This document specifies the characteristics and performance(s) of the superhydrophobic textiles
containing nanomaterials and nanostructures (TCNNs) based on contact angle measurement before
and after being subjected to washing/drying (laundry), ironing processes, light sources and abrasion,
that are to be determined by agreement between customer and supplier. This document solely covers
woven and nonwoven fabrics.
This document does not address safety and health related issues.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
contact angle
θ
angle to the base line within the drop, formed by means of a tangent on the drop counter through one of
the three-phase points
Note 1 to entry: See Figure 1.
Note 2 to entry: The contact angle is preferably indicated in degrees (°). 1° = (π/180) rad. If the system is in
thermodynamic equilibrium, this contact angle is also referred to as thermodynamic equilibrium contact angle.
Key
1 three-phase point
2 liquid phase
3 solid phase
4 gas phase
5 base line
σ surface tension of the liquid surface
l
σ surface free energy of the solid surface
s
σ interfacial energy between solid surface and liquid surface
s,l
θ contact angle
Figure 1 — Illustration of a contact angle in a wetting equilibrium
[SOURCE: ISO 19403-1:2022, 3.1.9, modified — "Illustration of a contact angle in a" has been added to
the title of Figure 1.]
3.1.2
contact angle hysteresis
θ
ar
difference between the advancing angle and the receding angle
[SOURCE: ISO 19403-6:2017, 3.4]
3.1.3
nano-roughness
surface texture in the nanoscale
3.1.4
textile containing nanomaterials and nanostructures
TCNNs
textile products incorporated by nanotechnologies in the form of coatings, treatments, fibre material
composites and nanoscale fibres
[1]
Note 1 to entry: TCNNs have been subdivided into three major types :
— nanofinished textiles;
— nanocomposite textiles;
— nanofibrous textiles.
3.1.5
superhydrophobic surface
surface made from hydrophobic material for which the contact angle (3.1.1) with a water droplet
exceeds 150° and contact angle hysteresis (3.1.2) is less than 10°
3.1.6
superhydrophobic durability
ability of superhydrophobic properties to withstand washing, ironing, abrasion and light exposure
Note 1 to entry: Durability means “ability to exist for a long time without significant deterioration in quality or
value”.
3.1.7
wettability
degree of wetting
Note 1 to entry: Contact angle (3.1.1) θ = 0° indicates a fully wetted surface and θ = 180° indicates a not wetted
surface.
[SOURCE: ISO 19403-1:2022, 3.3.2]
3.2 Abbreviated terms
AFM Atomic force microscopy
EDX Energy dispersive X-ray analysis
ICP/AES Inductively coupled plasma atomic emission spectroscopy
ICP/MS Inductively coupled plasma mass spectrometry
ICP/OES Inductively coupled plasma optical emission spectroscopy
SAXS Small angle X-ray spectroscopy
SEM Scanning electron microscopy
SPM Scanning probe microscopy
TEM Transition electron microscopy
XRD X-ray diffraction
XRF X-ray fluorescence
4 Mandatory and recommended measurement characteristics and their
measurement methods
4.1 General
The characteristics to be measured of TCNNs are classified into two groups; mandatory characteristics
and recommended ones. The mandatory characteristics listed in Table 1 shall be measured, and the
recommended characteristics listed in Table 2 are provided for information. The recommended
characteristics of TCNNs listed in Table 2 can be useful to measure depending on the application.
All measurements shall be carried out before and after ageing for durability assessment.
NOTE 1 The ageing for durability assessment has been explained in 4.2.
NOTE 2 Sampling method can be determined according to ISO 2859-1 or a procedure determined between the
user and the manufacturer.
Table 1 — Mandatory measurement characteristics and their measurement methods for
superhydrophobic durability
Item Characteristics Measurement method
Size and size distribution See 4.3
Nanomaterials/nanostructure Morphology See 4.3
Chemical composition See 4.4
Contact angle See 4.5
Superhydrophobicity
Contact angle hysteresis See 4.5
Table 2 — Recommended measurement characteristics of TCNNs and their measurement
methods
Item Characteristics Measurement method
Nanomaterials/nanostructures Phase analysis See 4.4
Superhydrophobicity Nano-roughness See 4.3
4.2 Ageing for superhydrophobic durability assessment
4.2.1 General
The durability of superhydrophobicity of TCNNs can be changed by ageing process. The ageing includes
heat, abrasion, laundering and light exposure. In fact, the superhydrophobicity of the TCNNs depends on
existence and quality of the nano-roughness on the fibres’ surfaces. The ageing process may change or
destroy the surface nano-roughness. Therefore, contact angle and contact hysteresis shall be measured
before and after ageing process to evaluate the durability of superhydrophobicity of the TCNNs. The
ageing process may be due to the processes listed in 4.2.2 to 4.2.5.
4.2.2 Washing and dry cleaning
As most textile fabrics undergo repeated laundering and dry cleaning during their lifetime, the washing
and dry cleaning durability of such highly hydrophobic fabric is of significant importance. Domestic
washing and dry cleaning shall be carried out in accordance with manufacturer instructions.
NOTE If the manufacturer does not give instruction, guidance can be taken from ISO 6330.
Different washing machine type, detergent type and type of drier can affect the test results. Therefore,
the parties should agree on above mentioned parameters.
4.2.3 Ironing
Ironing can affect the superhydrophobic durability and performance of TCNNs for superhydrophobicity.
Ironing/steam ironing procedure shall be performed under the conditions agreed between the user
and the buyer.
4.2.4 Mechanical abrasion
Mechanical abrasion (rubbing) is one of the processes that can affect the superhydrophobic durability
of TCNNs. In this respect, mechanical abrasion effect shall be applied in accordance with ISO 105-
X12 followed by assessment of superhydrophobic durability before and after being subjected due the
abrasion process.
The rubbing finger shall exert a downward force of 9 N ± 0,2 N, moving to and fro in a straight line along
a 104 mm ± 3 mm track.
4.2.5 Light exposure
Light exposure is one of the processes that can affect the hydrophobic durability of TCNNs. Light
exposure is performed according to ISO 105-B01. The exposure device shall provide for placement of
specimens and any designated sensing devices in positions that allow uniform irradiance from the light
source. The relative spectral irradiance produced by the device should be a very close match to that
of solar radiation, especially in the short wavelength UV region. Exposure devices shall be designed
such that the variation in irradiance at any location in the area used for specimen exposure shall not
exceed ±10 % of the mean. The configuration of the lamp with respect to the specimens on exposure,
including the differences in distance between the lamp(s) and the samples can affect uniformity of
exposure.
To simulate different environments, testing can be carried out under different conditions. The type of
conditions should be agreed between parties. The chosen conditions shall be reported (exposure cycle
A1, A2, A3 and B).
4.3 Nanomaterial and nanostructure evaluation
4.3.1 General
Size and size distribution, nano-roughness, morphology and chemical composition of nanomaterials
and nanostructure in TCNNs can be evaluated.
4.3.2 Size and size distribution
4.3.2.1 General
The superhydrophobic properties and superhydrophobic durability of TCNNs are sensitive to the size
and size distribution of nano-objects incorporated into or coated on the fibres as well as nanostructure
(nano-roughness).
Nano-objects are three-dimensional objects with different shapes. It is impossible to represent the size
of nano-object using a single number. Consequently, in most techniques it is assumed that the shape is
spherical because a sphere is the shape that can be represented by a single number, its diameter (see
ISO 19430).
Nanostructured materials have internal or surface structure in the nanoscale.
A test specimen for measurements of size and size distribution is taken from the TCNNs sample. The
average size of a nano-object shall be measured using an appropriate measurement method. The
measurement results shall be expressed in the unit of nanometres.
An appropriate measurement method from among SAXS, electron microscopy (TEM and SEM) and AFM
is recommended to be taken for measuring the average diameter of nano-objects.
4.3.2.2 Small angle X-ray spectroscopy
The size of nano-objects in solid medium can be measured via SAXS. The SAXS technique is used to
measure the primary and secondary nano-object size distribution, and primary and secondary nano-
object average size.
NOTE ISO 17867 specifies a method for the application of SAXS to the estimation of average nano-objects
sizes distributed in solid phase where the interaction between the nano-object is negligible. Both number- and
volume-based size distributions is measured via the SAXS method.
4.3.2.3 Electron microscopy
The size of nano-objects can also be measured by electron microscopy. TEM and SEM are used for size
measurement of nano-objects (see ISO 21363 and ISO 19749, respectively). TEM and SEM methods
provide two-dimensional images of the nano-object, which are number-based size distribution.
NOTE 1 For the case of nano-object incorporated in a fibre matrix of TCNNs, (cryo) ultramicrotomy can be
utilized to prepare samples for TEM.
NOTE 2 SEM and AFM can be utilized for size measurement of nano-object coated on the fibres in TCNNs.
4.3.2.4 Atomic force microscopy
The size of nano-objects in dry form on a flat substrate can also be measured by AFM using height
measurement (z-displacement). AFM provides a three-dimensional surface profile. While the lateral
dimensions are influenced by the shape of the probe, displacement measurements can provide the
height of nanoparticles with a high degree of accuracy and precision (see ASTM E2859-11).
4.3.3 Nano-roughness (recommended characteristics)
4.3.3.1 General
The superhydrophobic properties of TCNNs are sensitive to nano-roughness/nano-texture on fabric
fibres. In order to observe the nano-roughness, scanning probe microscopy (SPM) methods should be
utilized to evaluate nano-roughness of the superhydrophobic textiles. Surface microscopy should be
employed to image test surfaces and fabric samples before and after ageing process/es. Both AFM and
STM are appropriate for surface topography, however, the size of nanomaterials with 3D morphology
are difficult to determine. It is impossible to represent the size of nanomaterials using a single number.
The measurement results shall be expressed in the form of graphical representation or surface
porfilometry in nanometres (depth and width).
NOTE It can be assumed that the nano-roughness shape is cylindrical because a cylinder is the shape that
can be represented by two numbers: its diameter (width) and its height (depth).
A test specimen for measurements of depth and width and morphology is taken from the TCNNs sample.
4.3.3.2 SPM
An appropriate method for graphical measurement
...