SIST-TP CEN ISO/TR 11827:2016
(Main)Textiles - Composition testing - Identification of fibres (ISO/TR 11827:2012)
Textiles - Composition testing - Identification of fibres (ISO/TR 11827:2012)
ISO/TR 11827:2012 describes procedures for the identification of natural and man-made fibres, and may be used, when necessary, to coordinate with methods for the quantitative analysis of fibre blends.
Textilien - Prüfung der Zusammensetzung - Identifizierung der Fasern (ISO/TR 11827:2012)
Dieser Technische Bericht beschreibt Verfahren zur Bestimmung von Natur- und Chemiefasern und kann im Bedarfsfall in Abstimmung mit Verfahren zur quantitativen Analyse von Fasermischungen verwendet werden.
Textiles - Essai de composition - Identification des fibres (ISO/TR 11827:2012)
L'ISO/TR 11827 décrit des procédures d'identification de fibres naturelles et de fibres chimiques, et peut être utilisé, si besoin, en coordination avec les méthodes d'analyses quantitatives de mélanges de fibres.
Tekstilije - Preskušanje sestave - Identifikacija vlaken (ISO/TR 11827:2012)
To tehnično poročilo opisuje postopke za prepoznavanje naravnih in kemičnih vlaken ter se lahko uporablja usklajeno z metodami za kvantitativno analizo mešanic vlaken, kadar je to potrebno.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
kSIST-TP FprCEN ISO/TR 11827:2016
01-marec-2016
Tekstilije - Preskušanje sestave - Identifikacija vlaken (ISO/TR 11827:2012)
Textiles - Composition testing - Identification of fibres (ISO/TR 11827:2012)
Textiles - Essai de composition - Identification des fibres (ISO/TR 11827:2012)
Ta slovenski standard je istoveten z: FprCEN ISO/TR 11827
ICS:
59.060.01 Tekstilna vlakna na splošno Textile fibres in general
kSIST-TP FprCEN ISO/TR 11827:2016 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
kSIST-TP FprCEN ISO/TR 11827:2016
kSIST-TP FprCEN ISO/TR 11827:2016
TECHNICAL ISO/TR
REPORT 11827
First edition
2012-06-01
Textiles — Composition testing —
Identification of fibres
Textiles — Essai de composition — Identification des fibres
Reference number
ISO/TR 11827:2012(E)
©
ISO 2012
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ISO/TR 11827:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
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Published in Switzerland
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ISO/TR 11827:2012(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Safety note .1
3 Normative references.2
4 Terms and definitions .2
5 Principle.2
6 Apparatus and preparation of solutions.3
6.1 Apparatus.3
6.2 Preparation of solutions .3
7 Techniques.4
7.1 Microscopy.4
7.2 Flame tests.6
7.3 Staining Tests .7
7.4 Solubility Tests .7
7.5 Infrared Spectroscopy .8
7.6 Thermal Analysis.12
7.7 Density measurement methods .14
7.8 Other Instrumental Methods.14
8 Examples of procedures.15
8.1 Procedure using microscopy, solubility tests and FT-IR tests (examples) .15
8.2 Procedure using solubility tests (examples).17
8.3 Procedure using combustion tests and melting point determination (example) .19
8.4 Procedure using microscopy, FT-IR analysis and thermal analysis, case of bicomponent
fibres (examples) .19
Annex A (informative) Characteristics relative to fibre identification testing .24
Annex B (informative) Photomicrographs of Fibres (Light Microscopy) .29
Annex C (informative) Scanning Electron Micrographs of Fibres .34
Annex D (informative) Solubility of fibres .42
Annex E (informative) Examples of Infrared Spectra .45
Annex F (informative) Thermal transition temperature.50
Annex G (informative) Density.54
Annex H (informative) Alphabetical index of figures .55
Bibliography.58
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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 committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 11827 was prepared by Technical Committee ISO/TC 38, Textiles.
iv © ISO 2012 – All rights reserved
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Introduction
The correct identification of fibres in textiles and the accurate determination of the composition of each fibre
present is a legal requirement in many countries throughout the world for imported textile goods and at the
point of sale to the public. Fibre identification can be carried out by a number of different techniques, e.g.
microscopy, solubility, spectroscopy, melting point, pyrolysis, density, refractive index, etc.
kSIST-TP FprCEN ISO/TR 11827:2016
kSIST-TP FprCEN ISO/TR 11827:2016
TECHNICAL REPORT ISO/TR 11827:2012(E)
Textiles — Composition testing — Identification of fibres
IMPORTANT — The electronic file of this document contains colours which are considered to be
useful for the correct understanding of the document. Users should therefore consider printing this
document using a colour printer.
1 Scope
This Technical Report describes procedures for the identification of natural and man-made fibres, and may be
used, when necessary, to coordinate with methods for the quantitative analysis of fibre blends.
Textile Fibres
Natural fibres Man-made fibres
Animal fibres Mineral fibres
Vegetable fibres
From organic From inorganic
chemistry
chemistry
Animal Hairs Asbestos
From Seed
Glass
Artificial fibres Synthetic fibres
Wool (Sheep)
Cotton
Metallic fibres
Cashmere, Mohair
Kapok
Cer amics
(Goat)
From cellulose
Other fibres
Car bon
Acrylic, Modacrylic
Alpaca, Guanaco,
Other fibres
Vicuna (Llama) Chlorofibre
Viscose, Cupro
From Stem
Angora (Rabbit) Fluorofibre
Modal, Lyocell
Other fibres Polyamide
Acetate, Triacetate
Polyester
Flax
Other fibres
Aramid
Secretion fibres Hemp
Polyimide
Ramie
Polyethylene
Jute
Silk
Polypropylene
Other fibres
Others
Other fibres
Polylactide
Elastane
Elastodiene
From leaf
(from latex)
Elastodiene
Protein fibres
Elastolefin
Sisal
Alginate
Melamine
Alfa
Other fibres
Polycarbamide
Other fibres
Trivinyl
From Fruit Elastomultiester
Polypropylene/
Polyamide-
Coir
bicomponent
Other fibres
Other fibres
Figure 1 — Classification of the textile fibres in relation to their origin
2 Safety note
This Technical Report calls for the use of substances/procedures that may be injurious to the health/
environment if appropriate conditions are not observed. It refers only to technical suitability and does
not absolve the user from legal obligations relating to health and safety/environment at any stage.
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3 Normative references
The following referenced documents are indispensable for the application 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 1833-4, Textiles — Quantitative chemical analysis — Part 4: Mixtures of certain protein and certain other
fibres (method using hypochlorite)
ISO 2076, Textiles — Man-made fibres — Generic names
ISO 6938, Textiles — Natural fibres — Generic names and definitions
4 Terms and definitions
For the purposes of this document, the following terms and definitions given in ISO 2076 and ISO 6938 and
the following apply.
4.1
natural fibre
fibre which occurs in nature: it can be categorized according to its origin into animal, vegetable and mineral
fibre
4.2
man-made fibre
manufactured fibre
fibre obtained by a manufacturing process
4.2.1
artificial fibre
manufactured fibre made by transformation of natural polymers (macromolecular material existing in nature)
4.2.2
synthetic fibre
manufactured fibre made from synthetic polymers (macromolecular material which has been chemically
synthesised)
4.2.3
bicomponent fibre
fibre composed of two fibres forming polymer components, which are chemically or physically different or both
5 Principle
Objective: identify the fibres
Means: based on fibre properties (single or combination)
Properties for example:
• Morphology
• Solubility
• Light absorption or transmission by IR
• Burning behaviour
• Thermal behaviour
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• Colouration
• Optical behaviour
• Elemental composition
6 Apparatus and preparation of solutions
6.1 Apparatus
6.1.1 Light Microscope, using transmitted light
6.1.2 Scanning Electron Microscope
6.1.3 Bunsen Burner or other flame source
6.1.4 Infrared Spectrometer
6.1.4.1 Attenuated Total Reflection (ATR) spectroscopy device
6.1.4.2 Fourier Transform Infrared (FT-IR) spectrometer
6.1.5 Melting Point device (heated block)
6.1.6 Differential Scanning Calorimeter (DSC)
6.1.7 Thermal Gravimetric Analysis (TGA) device (thermobalance)
6.1.8 Gravimetric device (density gradient column)
6.1.9 Energy Dispersive X-ray (EDX) device
6.2 Preparation of solutions
Use only reagents of recognized analytical grade.
6.2.1 Sodium hydroxide and calcium oxide
Prepare a mixture of sodium hydroxide and calcium oxide (mass ratio of 1:1,4)
6.2.2 Iodine/potassium iodine solution
Dissolve 20 g of potassium iodide in 20 ml to 50 ml of distilled water. In this solution dissolve 2,5 g of iodine
and dilute to 100 ml
6.2.3 Zinc chloride/iodine solution
Dissolve 66 g of zinc chloride, anhydrous, and 6 g of potassium iodide in 34 ml of water.
Add a small amount of iodine crystal so that the solution is saturated.
6.2.4 Chlorine bleaching solution
Prepare the solution according to ISO 1833-4.
6.2.5 Zinc chloride/formic acid solution
Dissolve 100 g of zinc chloride, anhydrous in 100 ml of water.
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Set the density of this solution to 1,566 g/ml.
Add 6 ml of concentrated formic acid to 100 ml of this solution.
6.2.6 Sodium carbonate 0,25 % solution
Add 0,25 g of sodium carbonate to 100 ml of distilled water and dissolve.
6.2.7 Sodium hydroxide 5 % solution
Dissolve 5 g of sodium hydroxide in distilled water and dilute to 100 ml.
6.2.8 Sulphuric acid 75 % solution
Add carefully, while cooling, 700 ml of concentrated sulphuric acid (ρ 1,84 g/ml) to 350 ml of distilled water.
After the solution has cooled to room temperature, dilute to 1 l with water.
6.2.9 Chloroform/trichloroacetic acid solution
Dissolve 50 g of trichloroacetic acid in 50 g of chloroform.
6.2.10 Ethanol / potassium hydroxide solution
Dissolve 15 g of potassium hydroxide in 100 ml of ethanol.
7 Techniques
7.1 Microscopy
7.1.1 Light Microscopy
Examine the longitudinal view and/or the cross section of a fibre sample under a light microscope (6.1.1) using
transmitted light and magnification.
Compare with photomicrographs in Annex B.
7.1.2 Scanning Electron Microscopy
Examine the longitudinal view and/or the cross section of the surface of a fibre sample under a scanning
electron microscope (6.1.2) using magnification.
Compare with photomicrographs in Annex C.
7.1.3 Refractive Index
7.1.3.1 General
Refractive index governs the visibility of all colourless and transparent objects.
When a fibre is examined in air (n=1,0), the relatively large difference in refractive index between the fibre and
air causes about 5 % of the incident light to be reflected and the transmitted light to be markedly refracted.
These effects produce heavy shadows that obscure fine details of the fibre structure and can introduce
misleading identification. To reduce the degree of contrast in the shadow regions the fibres are mounted in a
medium of suitable refractive index for microscopic evaluation.
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7.1.3.2 Mounting media
If fibres are mounted in a medium of similar refractive index, surface characteristics are practically invisible but
internal structure and the presence of voids, or inclusions such as pigmentation, are clearly revealed. When it
is desired to examine the surface details of a fibre a mounting medium of significantly different refractive index
should be selected, preferably one with a much higher refractive index than that of the fibre, e.g.
1-bromonapthalene or di-iodo-methane.
Mountants should be relatively stable, and should not be volatile or react with the polymer fibre. The most
commonly used mountant is liquid paraffin which gives an image of satisfactory contrast for all fibres except
for cellulose diacetate and triacetate, for which n-decane is recommended.
It is recommended that all fibres be examined as soon after mounting as possible. Some fibres if left for a
period may be penetrated by the mountant, or they may swell which makes fibre diameter measurements
incorrect, or the mountant may evaporate.
7.1.3.3 Factors governing refractive indices
Factors governing the refractive index of fibres are the chemical nature of the molecules, the physical
arrangement of these molecules, the wavelength of incident light, moisture content, and other substances that
may be present in the fibre. In order to make accurate determinations it is necessary to use plane-polarised
light under conditions of controlled temperature and relative humidity.
Birefringent substances exhibit different indices of refraction for a given wavelength depending on the
direction of light passing through them, as well as upon its direction of transmission. For positive birefringent
fibres the maximum and minimum refractive index corresponds to the long axis of the fibres and at right
angles to the axis respectively. For negative birefringent fibres the reverse occurs.
7.1.3.4 Behaviour under polarised light
Determination of the behaviour under polarised light of a fibre can be carried out by mounting the fibre in a
mountant of known refractive index (Table 2), then viewing under polarised light such that the microscope
provides light polarised in the 6-12 o’clock direction.
Align the fibre in the direction of the light and set the microscope to provide axial illumination. Focussing
carefully on the outlines of the fibre adjust the focus to just above the fibre. For cylindrical fibres, if the
refractive index is higher than that of the mountant the fibre will act like a lens and a bright line of light will
move into the middle of the fibre as the focus is raised. If the refractive index is lower that that of the mountant
the light will flare out as the focus is raised and the middle of the fibre will become darker.
The test works best on round fibres, for flat ribbons it may be easier to see movement of a bright line at the
outlines of the fibre.
Rotating the specimen 45° and setting the microscope to provide cross polars allows birefringence to be seen.
Record if the fibre appears very bright (strong birefringence), dim (weak birefringence), or dark (no
birefringence).
Repeat the test using different mountants (see Table 2). As the refractive index of the liquid approaches that
of the fibre the fibre becomes less distinct until almost invisible. From the table match the liquid to the fibre for
identification. This technique is particularly useful for the identification of polyester.
Compare the observations made with the Table 1 to identify possible fibres.
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Table 1 — Refractive Indices of Fibres (cf. [1])
Refractive Index Birefringence
Fibre
Long n Cross n ∆n
// ┴
Diacetate 1,476 1,473 0,003 Weak
Acetate
Triacetate 1,469 1,469 0 Weak
Acrylic
1,511 1,514 -0,003 Weak, negative
Aramid
(Para-)aramid >2,000 - - -
Chrysotile 1,50 - 1,56 - varies Strong
Asbestos Amosite 1,64 – 1,69 - varies -
Crocidolite 1,68 – 1,71 - varies -
Chlorofibre 1,541 1,536 0,005 Weak
Cupro 1,553 1,519 0,034 Strong
Glass
1,52 – 1,55 - - None
Modacrylic
1,52 – 1,54 1,52 – 1,53 0,002 – 0,004 Weak
Polyamide 11 1,553 1,507 0,046 Strong
Polyamide Polyamide 6 1,575 1,526 0,049 Strong
Polyamide 6.6 1,578 1,522 0,056 Strong
Polyester 1,706 1,546 0,160 Intense
Polypropylene 1,530 1,496 0,034 Strong
Polyolefin
Polyethylene 1,574 1,522 0,052 Strong
Viscose 1,54 – 1,55 1,51 – 1,52 0,02 2– 0,039 Strong
Wool 1,557 1,547 0,010 Weak
Cotton 1,577 1,529 0,048 Strong
Silk Degummed 1,591 1,538 0,053 Strong
Flax 1,58 – 1,60 1,52 – 1,53 0,06 Strong
Table 2 — Refractive Indices of Mountants for Microscopy (cf. [1])
Mountant Refractive Index
Water 1,33
n-Heptane 1,39
Silicone Fluid (200/100,000cs) 1,406
n-Decane 1,41
Butyl stearate 1,445
Liquid Paraffin 1,47
Olive oil 1,48
a
Cedarwood oil 1,513-1,519
Anisole 1,515
Ethyl Salicylate 1,525
Methyl Salicylate 1,537
o-Dichlorobenzene 1,549
Bromobenzene 1,56
1-Bromonaphthalene 1,658
Di-iodo-methane (Methylene iodide) 1,74
a
refractive index of cedarwood oil changes with time
7.2 Flame tests
7.2.1 Burning Test
Burning fibres and assessing the characteristics of the flame and fumes given off is a classical method of
identifying a class of fibre, such as cellulosic, protein, synthetic, etc.
Present the sample, where possible, to the flame of a Bunsen burner (6.1.3) in the same physical state, e.g.
as a twisted thread, to minimise burning differences due to the physical nature of the sample
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Characteristics such as melting or shrinking from the flame should be noted. If the sample burns it should be
removed from the flame to see if it continues to burn. The nature of the residue or the odour should also be
noted.
Care must be taken in interpreting results where a mixture of fibres is present as one fibre type may mask the
presence of another. Also, the presence of finishes or coatings may give misleading results.
Results of the reaction of fibres to flame can be found in Annex A.
7.2.2 Chlorine detection test
Heat a copper wire in a Bunsen burner flame (6.1.3) until any green colouration disappears.
Remove the wire from the flame and touch the fibre with the hot end so that some adheres to it.
Again introduce the wire into the flame. The presence of chlorine in the fibre is indicated by green colour in the
flame.
NOTE 1 Chlorine containing fibres - chlorofibre, polyvinylidene and modacrylic fibres.
NOTE 2 Chlorine detection test is called “Beilstein test”.
7.2.3 Nitrogen detection test
Put a few fibres (approximately 100 mg has been found suitable) into a test tube and cover with soda lime or a
mixture of sodium hydroxide and calcium oxide (6.2.1) and heat the bottom of the test tube.
NOTE 1 A piece of cotton pad can be inserted in the tube in order to avoid any spitting.
When exposed at the opening of the tube, a wet red litmus paper will change to blue if the fibre contains
nitrogen component.
NOTE 2 Nitrogen-containing fibres: silk, wool and animal hairs, polyamide, acrylic, modacrylic, elastane, aramid and
melamine fibres.
7.3 Staining Tests
7.3.1 Colouration test with iodine/ potassium iodide solution
Observe the colouration of a fibre sample after immersion of the sample into iodine/ potassium iodide solution
(6.2.2) for 30 to 60 seconds and then washing it, and compare the observation with that in Annex A.
7.3.2 Xanthoproteic reaction
Detect protein components in a fibre.
Drop nitric acid onto a fibre sample on a slide glass under a microscope and observe the colour of the fibre. In
case yellow colour appears and it changes to orange with neutralization by ammonium, the fibre is composed
of proteins.
NOTE Silk, wool and animal hairs, and protein fibre will come under this category.
7.4 Solubility Tests
7.4.1 Polyester confirmation
In the light microscope preparation add some drops of ethanol / potassium hydroxide solution (6.2.10) to the
fibres (don’t use immersion oil or other fluid). Warm up slightly, observe in light microscope (6.1.1). Polyester
fibres changes morphologically (« hair » grows in the surface of the fibres).
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7.4.2 Cellulose confirmation
Under light microscope (6.1.1), add some drops of copper (II) ethylenediamine reagent to the fibres. Cellulosic
fibres are dissolved by this solution.
Compare with data on fibre solubility in Annex D.
7.5 Infrared Spectroscopy
7.5.1 General
The identification of polymers in general and synthetic fibres in particular can be achieved readily by this
technique, which provides an instrumental alternative to the classical tests: microscopy, solubility, and staining
tests. One great advantage of infrared examination is that the spectrum obtained is determined mainly by the
chemical constitution of the fibre and is, in general, less dependent on physical structure, variations in which
can affect the results obtained from staining, solubility, and other physical tests used for fibre identification.
Where only a few milligrams of sample are available, infrared spectroscopy is probably the most valuable
single test. The method is particularly useful with synthetic fibres such as polyolefin, aramids and acrylic
fibres, especially the latter, where the constitution and proportion of the acrylonitrile comonomer used are
frequently modified.
NOTE However, if two or more synthetic fibres are derived from the same basic monomer, whose properties have
been modified by the addition of the same comonomer in different amounts, and if the percentage difference is small, it
may not be possible to distinguish the fibres by qualitative infrared examination. Where the comonomer is different,
however, then the infrared spectrum obtained will be specific for that particular fibre.
When infrared radiation is passed through a substance, the energies of the IR photons are sufficient to cause
rotations and vibrations of molecules and atomic groups. Certain frequencies are absorbed and others are
transmitted depending on the nature of the chemical groups.
The absorption of the IR radiation by organic components consists in two main types of vibrations:
• Elongation vibrations (stretching)
• Deformation vibrations (bending)
Infrared spectroscopy, therefore, consists of determining the frequencies at which absorption occurs and
preparing a plot of percentage radiation absorbed against frequency. In practice, this is carried out
automatically by the infrared spectrometer (6.1.4).
Infrared absorption spectra are measured either with dispersive double-beam (grating) spectrophotometers or
with Fourier transform spectrometers, which give a digital interferogram that is subsequently transformed by a
computer into the recognizable infrared spectrum.
The majority of commercial spectrophotometers scan the spectrum from 2 to 15 nm, that is to say from 4000
-1 -1
to 670 cm in wavenumber.
cm
Due to the number and complexity of the absorption bands, the infrared spectrum of a given molecule is
characteristic of that compound and may be used for identification. In comparative studies of two substances,
therefore, identical infrared spectra denote identical substances.
7.5.2 Procedure
The spectra of relatively simple organic molecules are usually determined with the compound itself or in a
medium transparent to infrared radiation. Sample preparation of synthetic fibres is more complicated and, of
the several methods available, the final choice will depend on the nature of the fibre, and the individual
operator. The more suitable methods of sample preparation are described in detail.
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7.5.2.1 Pressed-disc Technique
In the pressed-disc technique, one can obtain spectra of relatively large particles that are suitable for
qualitative identification purposes, by choosing as the matrix a halide whose refractive index closely matches
that of the sample. In general, potassium bromide (n =1,56) is suitable.
D
Briefly, the method consists of mixing the finely divided fibre with finely powdered potassium bromide, which is
stored in an oven.
In preparing the disc, a few milligrams of the fibre are cut up finely with scissors. A portion of the finely
chopped or powdered material is uniformly mixed in an agate mortar with 300 mg to 500 mg of finely
powdered potassium bromide and pressed into a small disc about 1 mm thick in a suitable vacuum die under
a pressure of about 500 kPa to 750 kPa. Vacuum alone is applied to the die for 2 minutes, then vacuum and
press load are applied simultaneously for 2 minutes. Clear pellets have only small absorption bands at 2,9 µm
and 6,1 µm owing to moisture.
NOTE It should always be borne in mind that potassium bromide is very hygroscopic and that water-absorption
bands, which may be present in spectra run by this method, can lead to wrong identity. The potassium bromide method
has the important advantage over mulling techniques that extremely small samples may be analysed.
7.5.2.2 Mulling
This type of sample preparation pertains to solids that do not lend themselves to other methods of
preparation. The mulling liquid should be non-volatile and as non-absorbing as possible in the 2 nm to 15 nm
region. Nujol, which is highly purified mineral oil, is the most readily available and generally useful mulling
liquid. Absorption bands, due to the oil, occur at 3,4 nm, 6,9 nm and 7,3 nm. Mulling agents which are free
from absorption in the preceding regions are hexachlorobutadiene and perfluorocarbon oil.
The customary method, whereby the substance is ground to a fine powder from which the mull is prepared, is
satisfactory for well-defined crystalline materials, but less satisfactory for textile fibres and inapplicable to
viscous, plastic, and rubbery substances. The method described below, as well as being applicable to these
relatively intractable substances, is very much faster to operate and the mull is prepared in a single operation.
In this method the material is rubbed between ground-glass plates, thus enabling a more powerful abrasive
action to be obtained.
The grinding plates are prepared from 5 mm glass plate cut to a convenient size. Pairs of these are ground
together with 200-mesh carborundum powder until uniformly rough, then rubbed together using a few drops of
Nujol as lubricant until no further glass powder is produced. Minute flat areas with sharp cutting edges are
formed on the plates.
Textile yarns or fabrics are cut to short lengths, i.e., about 0,5 mm to 2 mm and these are mulled a little at a
time, more yarn and Nujol being added at intervals. Excellent mulls of the toughest fibres can be obtained in a
few minutes. In preparing a mull, the intention is to produce a paste of petroleum jelly-like consistency. The
correct consistency is judged by appearance, by the drag of the grinding plates, and by the disappearance of
such tell-tale signs as rats' tails in the mull that indicate that macroscopic particles are still present. Finally, the
plates are separated and the mull is transferred to rock salt plates for infrared measurement.
7.5.2.3 Solvent-cast Films
In general, a solvent-cast film gives a better spectrum than that obtained by dispersing the same fibre in
potassium bromide or in a mull. The cast-film method is not as generally applicable as the pressed-disc
technique since a suitable solvent must first be selected, and for some fibres there is no such solvent. Further
requirements are that the solvent must not react with the fibre and it must leave no residue on evaporation.
If films are cast from a solvent onto a smooth glass surface, the films obtained may produce an interference
fringe pattern in the spectrum owing to a high degree of parallelism between their front and back surfaces.
The fringes may interfere with the identification of the weaker infrared bands, but the difficulty can be obviated
by the simple expedient of using a roughened glass surface. One surface of the film will then be irregular and
fringes are not produced.
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An approximately 5 % solution is made by dissolving the fibre in the hot solvent. Sufficient solution to cover an
area of about 50 mm x 25 mm is poured on to a level glass plate whose surface has been roughened with
400-500 mesh carborundum. The temperature of the solution should be well below that at which bubbles form,
otherwise holes are left in the film. Most of the solvent is evaporated off at a temperature low enough to avoid
bubble formation and, when the film has solidified, it is heated to a higher temperature, preferably in vacuum,
to remove the remaining solvent.
The film can usually be peeled from the glass plate after lifting an edge with a razor blade; wetting with water
sometimes helps if the film sticks.
Most solvents are completely removed by the heating, but, where any solvent remains, it may be removed by
Soxhlet extraction or refluxing; for example, dimethylformamide (DMF) is tenaciously held by acrylic fibres but
is completely removed by boiling the film for 0,5 h to 1,0 h in water. It is essential with this method of sample
preparation that the solvent be completely removed, otherwise absorption bands (principally at 5,98 µm),
owing to the retention of the DMF, will be present in the spectrum of the fibre.
7.5.2.4 Melt-cast Films
Melt-cast films of thermoplastic fibres can be prepared by pressing fibres between polytetrafluoroethylene
(PTFE) sheets between heated platens in a laboratory hydraulic press. As a general guide the films should be
thin enough to be nearly transparent (5 µm to 35 µm).
7.5.2.5 Attenuated Total Reflection (ATR)
ATR spectroscopy is used for the analyses of the surface of materials by the mean of ATR spectroscopy
device (6.1.4.1). Since it requires no preparation of the sample, it is much quicker than the previous methods.
The infrared radiation is passed through an infrared transmitting crystal with a high refractive index, allowing
the radiation to reflect several times within the ATR element.
The sampling surface is pressed into intimate optical contact with the top surface of the crystal.
The commonest material used for the crystal in ATR attachments is Thallium Bromide-Iodide KRS-5.
Typically, a prism may be 5 cm long x 2 cm wide x 4 mm thick, with side angles of 45°. Light enters from the
angled side of the prism and the radiation is reflected approximately 25 times before emerging from the
crystal.
Fibres and fabrics, which are among the most difficult materials to handle by transmission spectroscopy, have
proved to be quite amenable to study by multiple internal reflection spectroscopy since they require no special
preparation techniques for the purpose. The word 'multiple' should be emphasized since the nature of the fibre
itself results in poor contact and many reflections are needed in order to ensure sufficient absorption. See
Figure 2.
Figure 2 — Multiple internal effect
7.5.2.6 Diffuse Reflectance Spectroscopy
Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) is a newer technique than ATR. Using
DRIFT Spectrometer (6.1.4.2), samples can be analysed either directly or as dispersions in non-absorbing
matrices, e.g. KBr. A comparison of sampling techniques for the characterisation of cotton textiles showed that
the best spectrum was obtained by simply placing a cut circle of fabric in the sample dish.
10 © ISO 2012 – All rights reserved
kSIST-TP FprCEN ISO/TR 11827:2016
ISO/TR 11827:2012(E)
When infrared radiation is directed onto the surface of a solid sample two types of reflected radiation can
occur. One is specular reflection and the other is diffuse reflection. The specular component is the radiation
which reflects directly off the sample surface. Diffuse reflectance is the radiation which penetrates into the
sample and then emerges. A diffuse reflectance accessory is designed so that the diffusely reflected energy is
optimised and the specular component is minimised. The scattered radiation is collected by a spherical mirror
that is focused onto the detector.
7.5.2.7 FT-IR Microscopy
Single fibres can be examined and these are usually flattened with a roller, this being the only destructive part
of the technique. Fibres are flattened before analysis to minimise diffusion of radiation, to produce a more
uniform thickness (thus minimising deviation from Beer’s law and absorption by the fibre) and to increase the
sample surface area, thereby enhancing the signal-to-noise ratio while reducing diffraction effects at fibre
edges. The minimum sample size is generally of the order of (10 x 10) µm².
In the infrared microscope, the sample is mounted on a sample holder (a slide with a 13 mm window or
supporting a 13 mm gold reflecting disc). The sample is then brought into focus on the microscope stage
using either transmitted or reflected visible illumination. The area of interest on the sample is identified and
isolated using adjustable apertures. At this stage, a photograph of the sample may be obtained. An infrared
spectrum of the sample is then recorded by switching from visible to infrared radiation using a series of mirrors
built into the microscope. The infrared beam penetrates or reflects from the sample and the resultant beam is
taken to a highly sensitive detector, which is optimised for the small images generally encountered in FT-IR
microscopy.
7.5.3 Interpretation of Spectra
The infrared method depends primarily upon establishing that the spectrum of the unknown matches exactly
the spectrum of a known substance examined in the same physical form.
In order to do this, it is necessary to be able to name a compound from the absorption bands it displays in the
infrared region.
For example, Table 3 gives several absorption peaks which are characteristic of some main chemical bonds.
Table 3 — Examples of wavenumber of some chemical bonds
-1
Wave number (cm ) Chemical bond Chemical family
Around 3 300 O-H < 3 300 in alcohols
> 3 300 in acids
Around 3 250 N-H Amines, amides
Around 3 000 C-H 2 800 to 3 000 in aliphatic components
> 3 000 in aromatic components
Around 2 200 C≡N Nytril components (Acrylics)
Around 1 700 C=0 Ketones, amides, acids
Around 1 200 C-O-C Ester components
Around 800 C-Cl Chloro components
kSIST-TP FprCEN ISO/TR 11827:2016
ISO/TR 11827:2012(E)
A laboratory carrying out qualitative analyses customarily sets up its own collection of absorption curves of
substances it is likely to encounter. Spectra recorded on the same instrument are to be preferred to literature
spectra, because no allowance need be made for differences of resolving power or wavelength calibration.
When the spectrum cannot be matched in this way, there is still a possibility that a matching spectrum exists
in the literature. A simple method of visual comparison of the unknown spectrum with spectra of known fibres
is used in Annex E.
Computerised spectral libraries now exist and most FT-IR software packages incorporate a search routine
whereby these commercial libraries or user developed libraries can be accessed.
7.6 Thermal Analysis
7.6.1 Melting Point Determination
If the fibre is made from a thermoplastic polymer it will have a melting point. The melting point can be defined
as the temperature (or temperature range) at which crystalline regions melt or the point at which the solid fibre
becomes liquid.
Techniques for measuring melting point are usually based on a heated block (6.1.5) for which the temperature
can be raised at a variable but controlled rate. Fibres can be placed directly in contact with the block or in a
glass capillary tube, the base of which is embedded in a block. If a polarising microscope (or viewer) is used
information on crystalline melting can be obtained. Otherwise the temperature at which liquid forms is
recorded.
Information on melting points can be found in Annex F.
NOTE Other transition temperatures can also be found in annex F related to non-thermoplastic fibres.
More sophisticated techniques exist (Differential Scanning Calorimetry or Thermal Gravimetric Analysis) but
these are usually employed when more detailed information about the fibre is required (see 7.6.2 and 7.6.3).
7.6.2 Differential Scanning Calorimetry (DSC)
7.6.2.1 General
Differential Scanning Calorimetry is an instrumental technique which can be used to study phenomena such
as various phase transitions and chemical reactions involving either the absorption or the evolution of heat
that may occur when a substance is heated. In the case of fibres, these changes may include the second
order or glass transition, desorption of moisture, crystallisation, fusion, chemical reactions and irreversible
decomposition processes. For identification purposes, one of the most interesting characteristic is the melting
point of a fibre, which can help in distinguishing even fibres classified within the same fibre class, e.g. different
types of polyamide (polyamide 6 and polyamide 6.6).
Differential Scanning Calorimetry is a technique in which the difference between the heat flow (power) into a
test specimen and that into a reference specimen is measured as a function of temperature and/or time while
the test and the reference specimens are subjected to a controlled temperature programme. The result is a
curve or thermogram in which temperature or time is plotted on the x-axis and heat flux difference on the y-
axis. Peaks in thermogram represent variations from the thermally steady state and correspond to
transformations that the sample has undergone. The nature of the measurements makes it possible to
distinguish endothermic and exothermic changes; the first ones are usually plotted in downward direction with
exotherms shown as upward deflections.
The instrumentation (6.1.6) used for measurement can have two different designs: power-compensation DSC
and heat-flux DSC. In the first case, the temperature of both test and reference specimens is kept equal and
the difference between the heat flux into the two specimens is measured as a function of temperature or time
while varying the temperature of the specimens in accordance with a controlled programme. In the second
case, the difference in temperature between the test and reference specimen is proportional to the difference
in heat flux which is measured as a function of temperature or time while varying the temperature of the
specimens in accordance with a controlled programme.
12 © ISO 2012 – All rights reserved
kSIST-TP FprCEN ISO/TR 11827:2016
ISO/TR 11827:2012(E)
It has been shown, in some conditions, that for textile materials, as well as for other materials, the
endothermic and exothermic changes observed are both reproducible and uniquely characteristic for a given
material, so that DSC curve constitutes a fingerprint and may be used for identification purposes. For this aim,
DSC can also be used in the case of fibre mixtures, provided that the melting points of the various
constituents the mixture are sufficie
...
SLOVENSKI STANDARD
01-september-2016
Tekstilije - Preskušanje sestave - Identifikacija vlaken (ISO/TR 11827:2012)
Textiles - Composition testing - Identification of fibres (ISO/TR 11827:2012)
Textiles - Essai de composition - Identification des fibres (ISO/TR 11827:2012)
Ta slovenski standard je istoveten z: CEN ISO/TR 11827:2016
ICS:
59.060.01 Tekstilna vlakna na splošno Textile fibres in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN ISO/TR 11827
TECHNICAL REPORT
RAPPORT TECHNIQUE
June 2016
TECHNISCHER BERICHT
ICS 59.060.01
English Version
Textiles - Composition testing - Identification of fibres
(ISO/TR 11827:2012)
Textiles - Essai de composition - Identification des
fibres (ISO/TR 11827:2012)
This Technical Report was approved by CEN on 22 May 2016. It has been drawn up by the Technical Committee CEN/TC 248.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TR 11827:2016 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (CEN ISO/TR 11827:2016) has been prepared by Technical Committee ISO/TC 38
“Textiles” in collaboration with Technical Committee CEN/TC 248 “Textiles and textile products” the
secretariat of which is held by BSI.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
Endorsement notice
The text of ISO/TR 11827:2012 has been approved by CEN as CEN ISO/TR 11827:2016 without any
modification.
TECHNICAL ISO/TR
REPORT 11827
First edition
2012-06-01
Textiles — Composition testing —
Identification of fibres
Textiles — Essai de composition — Identification des fibres
Reference number
ISO/TR 11827:2012(E)
©
ISO 2012
ISO/TR 11827:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Safety note .1
3 Normative references.2
4 Terms and definitions .2
5 Principle.2
6 Apparatus and preparation of solutions.3
6.1 Apparatus.3
6.2 Preparation of solutions .3
7 Techniques.4
7.1 Microscopy.4
7.2 Flame tests.6
7.3 Staining Tests .7
7.4 Solubility Tests .7
7.5 Infrared Spectroscopy .8
7.6 Thermal Analysis.12
7.7 Density measurement methods .14
7.8 Other Instrumental Methods.14
8 Examples of procedures.15
8.1 Procedure using microscopy, solubility tests and FT-IR tests (examples) .15
8.2 Procedure using solubility tests (examples).17
8.3 Procedure using combustion tests and melting point determination (example) .19
8.4 Procedure using microscopy, FT-IR analysis and thermal analysis, case of bicomponent
fibres (examples) .19
Annex A (informative) Characteristics relative to fibre identification testing .24
Annex B (informative) Photomicrographs of Fibres (Light Microscopy) .29
Annex C (informative) Scanning Electron Micrographs of Fibres .34
Annex D (informative) Solubility of fibres .42
Annex E (informative) Examples of Infrared Spectra .45
Annex F (informative) Thermal transition temperature.50
Annex G (informative) Density.54
Annex H (informative) Alphabetical index of figures .55
Bibliography.58
ISO/TR 11827:2012(E)
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 committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 11827 was prepared by Technical Committee ISO/TC 38, Textiles.
iv © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
Introduction
The correct identification of fibres in textiles and the accurate determination of the composition of each fibre
present is a legal requirement in many countries throughout the world for imported textile goods and at the
point of sale to the public. Fibre identification can be carried out by a number of different techniques, e.g.
microscopy, solubility, spectroscopy, melting point, pyrolysis, density, refractive index, etc.
TECHNICAL REPORT ISO/TR 11827:2012(E)
Textiles — Composition testing — Identification of fibres
IMPORTANT — The electronic file of this document contains colours which are considered to be
useful for the correct understanding of the document. Users should therefore consider printing this
document using a colour printer.
1 Scope
This Technical Report describes procedures for the identification of natural and man-made fibres, and may be
used, when necessary, to coordinate with methods for the quantitative analysis of fibre blends.
Textile Fibres
Natural fibres Man-made fibres
Animal fibres Mineral fibres
Vegetable fibres
From organic From inorganic
chemistry
chemistry
Animal Hairs Asbestos
From Seed
Glass
Artificial fibres Synthetic fibres
Wool (Sheep)
Cotton
Metallic fibres
Cashmere, Mohair
Kapok
Cer amics
(Goat)
From cellulose
Other fibres
Car bon
Acrylic, Modacrylic
Alpaca, Guanaco,
Other fibres
Vicuna (Llama) Chlorofibre
Viscose, Cupro
From Stem
Angora (Rabbit) Fluorofibre
Modal, Lyocell
Other fibres Polyamide
Acetate, Triacetate
Polyester
Flax
Other fibres
Aramid
Secretion fibres Hemp
Polyimide
Ramie
Polyethylene
Jute
Silk
Polypropylene
Other fibres
Others
Other fibres
Polylactide
Elastane
Elastodiene
From leaf
(from latex)
Elastodiene
Protein fibres
Elastolefin
Sisal
Alginate
Melamine
Alfa
Other fibres
Polycarbamide
Other fibres
Trivinyl
From Fruit Elastomultiester
Polypropylene/
Polyamide-
Coir
bicomponent
Other fibres
Other fibres
Figure 1 — Classification of the textile fibres in relation to their origin
2 Safety note
This Technical Report calls for the use of substances/procedures that may be injurious to the health/
environment if appropriate conditions are not observed. It refers only to technical suitability and does
not absolve the user from legal obligations relating to health and safety/environment at any stage.
ISO/TR 11827:2012(E)
3 Normative references
The following referenced documents are indispensable for the application 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 1833-4, Textiles — Quantitative chemical analysis — Part 4: Mixtures of certain protein and certain other
fibres (method using hypochlorite)
ISO 2076, Textiles — Man-made fibres — Generic names
ISO 6938, Textiles — Natural fibres — Generic names and definitions
4 Terms and definitions
For the purposes of this document, the following terms and definitions given in ISO 2076 and ISO 6938 and
the following apply.
4.1
natural fibre
fibre which occurs in nature: it can be categorized according to its origin into animal, vegetable and mineral
fibre
4.2
man-made fibre
manufactured fibre
fibre obtained by a manufacturing process
4.2.1
artificial fibre
manufactured fibre made by transformation of natural polymers (macromolecular material existing in nature)
4.2.2
synthetic fibre
manufactured fibre made from synthetic polymers (macromolecular material which has been chemically
synthesised)
4.2.3
bicomponent fibre
fibre composed of two fibres forming polymer components, which are chemically or physically different or both
5 Principle
Objective: identify the fibres
Means: based on fibre properties (single or combination)
Properties for example:
• Morphology
• Solubility
• Light absorption or transmission by IR
• Burning behaviour
• Thermal behaviour
2 © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
• Colouration
• Optical behaviour
• Elemental composition
6 Apparatus and preparation of solutions
6.1 Apparatus
6.1.1 Light Microscope, using transmitted light
6.1.2 Scanning Electron Microscope
6.1.3 Bunsen Burner or other flame source
6.1.4 Infrared Spectrometer
6.1.4.1 Attenuated Total Reflection (ATR) spectroscopy device
6.1.4.2 Fourier Transform Infrared (FT-IR) spectrometer
6.1.5 Melting Point device (heated block)
6.1.6 Differential Scanning Calorimeter (DSC)
6.1.7 Thermal Gravimetric Analysis (TGA) device (thermobalance)
6.1.8 Gravimetric device (density gradient column)
6.1.9 Energy Dispersive X-ray (EDX) device
6.2 Preparation of solutions
Use only reagents of recognized analytical grade.
6.2.1 Sodium hydroxide and calcium oxide
Prepare a mixture of sodium hydroxide and calcium oxide (mass ratio of 1:1,4)
6.2.2 Iodine/potassium iodine solution
Dissolve 20 g of potassium iodide in 20 ml to 50 ml of distilled water. In this solution dissolve 2,5 g of iodine
and dilute to 100 ml
6.2.3 Zinc chloride/iodine solution
Dissolve 66 g of zinc chloride, anhydrous, and 6 g of potassium iodide in 34 ml of water.
Add a small amount of iodine crystal so that the solution is saturated.
6.2.4 Chlorine bleaching solution
Prepare the solution according to ISO 1833-4.
6.2.5 Zinc chloride/formic acid solution
Dissolve 100 g of zinc chloride, anhydrous in 100 ml of water.
ISO/TR 11827:2012(E)
Set the density of this solution to 1,566 g/ml.
Add 6 ml of concentrated formic acid to 100 ml of this solution.
6.2.6 Sodium carbonate 0,25 % solution
Add 0,25 g of sodium carbonate to 100 ml of distilled water and dissolve.
6.2.7 Sodium hydroxide 5 % solution
Dissolve 5 g of sodium hydroxide in distilled water and dilute to 100 ml.
6.2.8 Sulphuric acid 75 % solution
Add carefully, while cooling, 700 ml of concentrated sulphuric acid (ρ 1,84 g/ml) to 350 ml of distilled water.
After the solution has cooled to room temperature, dilute to 1 l with water.
6.2.9 Chloroform/trichloroacetic acid solution
Dissolve 50 g of trichloroacetic acid in 50 g of chloroform.
6.2.10 Ethanol / potassium hydroxide solution
Dissolve 15 g of potassium hydroxide in 100 ml of ethanol.
7 Techniques
7.1 Microscopy
7.1.1 Light Microscopy
Examine the longitudinal view and/or the cross section of a fibre sample under a light microscope (6.1.1) using
transmitted light and magnification.
Compare with photomicrographs in Annex B.
7.1.2 Scanning Electron Microscopy
Examine the longitudinal view and/or the cross section of the surface of a fibre sample under a scanning
electron microscope (6.1.2) using magnification.
Compare with photomicrographs in Annex C.
7.1.3 Refractive Index
7.1.3.1 General
Refractive index governs the visibility of all colourless and transparent objects.
When a fibre is examined in air (n=1,0), the relatively large difference in refractive index between the fibre and
air causes about 5 % of the incident light to be reflected and the transmitted light to be markedly refracted.
These effects produce heavy shadows that obscure fine details of the fibre structure and can introduce
misleading identification. To reduce the degree of contrast in the shadow regions the fibres are mounted in a
medium of suitable refractive index for microscopic evaluation.
4 © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
7.1.3.2 Mounting media
If fibres are mounted in a medium of similar refractive index, surface characteristics are practically invisible but
internal structure and the presence of voids, or inclusions such as pigmentation, are clearly revealed. When it
is desired to examine the surface details of a fibre a mounting medium of significantly different refractive index
should be selected, preferably one with a much higher refractive index than that of the fibre, e.g.
1-bromonapthalene or di-iodo-methane.
Mountants should be relatively stable, and should not be volatile or react with the polymer fibre. The most
commonly used mountant is liquid paraffin which gives an image of satisfactory contrast for all fibres except
for cellulose diacetate and triacetate, for which n-decane is recommended.
It is recommended that all fibres be examined as soon after mounting as possible. Some fibres if left for a
period may be penetrated by the mountant, or they may swell which makes fibre diameter measurements
incorrect, or the mountant may evaporate.
7.1.3.3 Factors governing refractive indices
Factors governing the refractive index of fibres are the chemical nature of the molecules, the physical
arrangement of these molecules, the wavelength of incident light, moisture content, and other substances that
may be present in the fibre. In order to make accurate determinations it is necessary to use plane-polarised
light under conditions of controlled temperature and relative humidity.
Birefringent substances exhibit different indices of refraction for a given wavelength depending on the
direction of light passing through them, as well as upon its direction of transmission. For positive birefringent
fibres the maximum and minimum refractive index corresponds to the long axis of the fibres and at right
angles to the axis respectively. For negative birefringent fibres the reverse occurs.
7.1.3.4 Behaviour under polarised light
Determination of the behaviour under polarised light of a fibre can be carried out by mounting the fibre in a
mountant of known refractive index (Table 2), then viewing under polarised light such that the microscope
provides light polarised in the 6-12 o’clock direction.
Align the fibre in the direction of the light and set the microscope to provide axial illumination. Focussing
carefully on the outlines of the fibre adjust the focus to just above the fibre. For cylindrical fibres, if the
refractive index is higher than that of the mountant the fibre will act like a lens and a bright line of light will
move into the middle of the fibre as the focus is raised. If the refractive index is lower that that of the mountant
the light will flare out as the focus is raised and the middle of the fibre will become darker.
The test works best on round fibres, for flat ribbons it may be easier to see movement of a bright line at the
outlines of the fibre.
Rotating the specimen 45° and setting the microscope to provide cross polars allows birefringence to be seen.
Record if the fibre appears very bright (strong birefringence), dim (weak birefringence), or dark (no
birefringence).
Repeat the test using different mountants (see Table 2). As the refractive index of the liquid approaches that
of the fibre the fibre becomes less distinct until almost invisible. From the table match the liquid to the fibre for
identification. This technique is particularly useful for the identification of polyester.
Compare the observations made with the Table 1 to identify possible fibres.
ISO/TR 11827:2012(E)
Table 1 — Refractive Indices of Fibres (cf. [1])
Refractive Index Birefringence
Fibre
Long n Cross n ∆n
// ┴
Diacetate 1,476 1,473 0,003 Weak
Acetate
Triacetate 1,469 1,469 0 Weak
Acrylic
1,511 1,514 -0,003 Weak, negative
Aramid
(Para-)aramid >2,000 - - -
Chrysotile 1,50 - 1,56 - varies Strong
Asbestos Amosite 1,64 – 1,69 - varies -
Crocidolite 1,68 – 1,71 - varies -
Chlorofibre 1,541 1,536 0,005 Weak
Cupro 1,553 1,519 0,034 Strong
Glass
1,52 – 1,55 - - None
Modacrylic
1,52 – 1,54 1,52 – 1,53 0,002 – 0,004 Weak
Polyamide 11 1,553 1,507 0,046 Strong
Polyamide Polyamide 6 1,575 1,526 0,049 Strong
Polyamide 6.6 1,578 1,522 0,056 Strong
Polyester 1,706 1,546 0,160 Intense
Polypropylene 1,530 1,496 0,034 Strong
Polyolefin
Polyethylene 1,574 1,522 0,052 Strong
Viscose 1,54 – 1,55 1,51 – 1,52 0,02 2– 0,039 Strong
Wool 1,557 1,547 0,010 Weak
Cotton 1,577 1,529 0,048 Strong
Silk Degummed 1,591 1,538 0,053 Strong
Flax 1,58 – 1,60 1,52 – 1,53 0,06 Strong
Table 2 — Refractive Indices of Mountants for Microscopy (cf. [1])
Mountant Refractive Index
Water 1,33
n-Heptane 1,39
Silicone Fluid (200/100,000cs) 1,406
n-Decane 1,41
Butyl stearate 1,445
Liquid Paraffin 1,47
Olive oil 1,48
a
Cedarwood oil 1,513-1,519
Anisole 1,515
Ethyl Salicylate 1,525
Methyl Salicylate 1,537
o-Dichlorobenzene 1,549
Bromobenzene 1,56
1-Bromonaphthalene 1,658
Di-iodo-methane (Methylene iodide) 1,74
a
refractive index of cedarwood oil changes with time
7.2 Flame tests
7.2.1 Burning Test
Burning fibres and assessing the characteristics of the flame and fumes given off is a classical method of
identifying a class of fibre, such as cellulosic, protein, synthetic, etc.
Present the sample, where possible, to the flame of a Bunsen burner (6.1.3) in the same physical state, e.g.
as a twisted thread, to minimise burning differences due to the physical nature of the sample
6 © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
Characteristics such as melting or shrinking from the flame should be noted. If the sample burns it should be
removed from the flame to see if it continues to burn. The nature of the residue or the odour should also be
noted.
Care must be taken in interpreting results where a mixture of fibres is present as one fibre type may mask the
presence of another. Also, the presence of finishes or coatings may give misleading results.
Results of the reaction of fibres to flame can be found in Annex A.
7.2.2 Chlorine detection test
Heat a copper wire in a Bunsen burner flame (6.1.3) until any green colouration disappears.
Remove the wire from the flame and touch the fibre with the hot end so that some adheres to it.
Again introduce the wire into the flame. The presence of chlorine in the fibre is indicated by green colour in the
flame.
NOTE 1 Chlorine containing fibres - chlorofibre, polyvinylidene and modacrylic fibres.
NOTE 2 Chlorine detection test is called “Beilstein test”.
7.2.3 Nitrogen detection test
Put a few fibres (approximately 100 mg has been found suitable) into a test tube and cover with soda lime or a
mixture of sodium hydroxide and calcium oxide (6.2.1) and heat the bottom of the test tube.
NOTE 1 A piece of cotton pad can be inserted in the tube in order to avoid any spitting.
When exposed at the opening of the tube, a wet red litmus paper will change to blue if the fibre contains
nitrogen component.
NOTE 2 Nitrogen-containing fibres: silk, wool and animal hairs, polyamide, acrylic, modacrylic, elastane, aramid and
melamine fibres.
7.3 Staining Tests
7.3.1 Colouration test with iodine/ potassium iodide solution
Observe the colouration of a fibre sample after immersion of the sample into iodine/ potassium iodide solution
(6.2.2) for 30 to 60 seconds and then washing it, and compare the observation with that in Annex A.
7.3.2 Xanthoproteic reaction
Detect protein components in a fibre.
Drop nitric acid onto a fibre sample on a slide glass under a microscope and observe the colour of the fibre. In
case yellow colour appears and it changes to orange with neutralization by ammonium, the fibre is composed
of proteins.
NOTE Silk, wool and animal hairs, and protein fibre will come under this category.
7.4 Solubility Tests
7.4.1 Polyester confirmation
In the light microscope preparation add some drops of ethanol / potassium hydroxide solution (6.2.10) to the
fibres (don’t use immersion oil or other fluid). Warm up slightly, observe in light microscope (6.1.1). Polyester
fibres changes morphologically (« hair » grows in the surface of the fibres).
ISO/TR 11827:2012(E)
7.4.2 Cellulose confirmation
Under light microscope (6.1.1), add some drops of copper (II) ethylenediamine reagent to the fibres. Cellulosic
fibres are dissolved by this solution.
Compare with data on fibre solubility in Annex D.
7.5 Infrared Spectroscopy
7.5.1 General
The identification of polymers in general and synthetic fibres in particular can be achieved readily by this
technique, which provides an instrumental alternative to the classical tests: microscopy, solubility, and staining
tests. One great advantage of infrared examination is that the spectrum obtained is determined mainly by the
chemical constitution of the fibre and is, in general, less dependent on physical structure, variations in which
can affect the results obtained from staining, solubility, and other physical tests used for fibre identification.
Where only a few milligrams of sample are available, infrared spectroscopy is probably the most valuable
single test. The method is particularly useful with synthetic fibres such as polyolefin, aramids and acrylic
fibres, especially the latter, where the constitution and proportion of the acrylonitrile comonomer used are
frequently modified.
NOTE However, if two or more synthetic fibres are derived from the same basic monomer, whose properties have
been modified by the addition of the same comonomer in different amounts, and if the percentage difference is small, it
may not be possible to distinguish the fibres by qualitative infrared examination. Where the comonomer is different,
however, then the infrared spectrum obtained will be specific for that particular fibre.
When infrared radiation is passed through a substance, the energies of the IR photons are sufficient to cause
rotations and vibrations of molecules and atomic groups. Certain frequencies are absorbed and others are
transmitted depending on the nature of the chemical groups.
The absorption of the IR radiation by organic components consists in two main types of vibrations:
• Elongation vibrations (stretching)
• Deformation vibrations (bending)
Infrared spectroscopy, therefore, consists of determining the frequencies at which absorption occurs and
preparing a plot of percentage radiation absorbed against frequency. In practice, this is carried out
automatically by the infrared spectrometer (6.1.4).
Infrared absorption spectra are measured either with dispersive double-beam (grating) spectrophotometers or
with Fourier transform spectrometers, which give a digital interferogram that is subsequently transformed by a
computer into the recognizable infrared spectrum.
The majority of commercial spectrophotometers scan the spectrum from 2 to 15 nm, that is to say from 4000
-1 -1
to 670 cm in wavenumber.
cm
Due to the number and complexity of the absorption bands, the infrared spectrum of a given molecule is
characteristic of that compound and may be used for identification. In comparative studies of two substances,
therefore, identical infrared spectra denote identical substances.
7.5.2 Procedure
The spectra of relatively simple organic molecules are usually determined with the compound itself or in a
medium transparent to infrared radiation. Sample preparation of synthetic fibres is more complicated and, of
the several methods available, the final choice will depend on the nature of the fibre, and the individual
operator. The more suitable methods of sample preparation are described in detail.
8 © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
7.5.2.1 Pressed-disc Technique
In the pressed-disc technique, one can obtain spectra of relatively large particles that are suitable for
qualitative identification purposes, by choosing as the matrix a halide whose refractive index closely matches
that of the sample. In general, potassium bromide (n =1,56) is suitable.
D
Briefly, the method consists of mixing the finely divided fibre with finely powdered potassium bromide, which is
stored in an oven.
In preparing the disc, a few milligrams of the fibre are cut up finely with scissors. A portion of the finely
chopped or powdered material is uniformly mixed in an agate mortar with 300 mg to 500 mg of finely
powdered potassium bromide and pressed into a small disc about 1 mm thick in a suitable vacuum die under
a pressure of about 500 kPa to 750 kPa. Vacuum alone is applied to the die for 2 minutes, then vacuum and
press load are applied simultaneously for 2 minutes. Clear pellets have only small absorption bands at 2,9 µm
and 6,1 µm owing to moisture.
NOTE It should always be borne in mind that potassium bromide is very hygroscopic and that water-absorption
bands, which may be present in spectra run by this method, can lead to wrong identity. The potassium bromide method
has the important advantage over mulling techniques that extremely small samples may be analysed.
7.5.2.2 Mulling
This type of sample preparation pertains to solids that do not lend themselves to other methods of
preparation. The mulling liquid should be non-volatile and as non-absorbing as possible in the 2 nm to 15 nm
region. Nujol, which is highly purified mineral oil, is the most readily available and generally useful mulling
liquid. Absorption bands, due to the oil, occur at 3,4 nm, 6,9 nm and 7,3 nm. Mulling agents which are free
from absorption in the preceding regions are hexachlorobutadiene and perfluorocarbon oil.
The customary method, whereby the substance is ground to a fine powder from which the mull is prepared, is
satisfactory for well-defined crystalline materials, but less satisfactory for textile fibres and inapplicable to
viscous, plastic, and rubbery substances. The method described below, as well as being applicable to these
relatively intractable substances, is very much faster to operate and the mull is prepared in a single operation.
In this method the material is rubbed between ground-glass plates, thus enabling a more powerful abrasive
action to be obtained.
The grinding plates are prepared from 5 mm glass plate cut to a convenient size. Pairs of these are ground
together with 200-mesh carborundum powder until uniformly rough, then rubbed together using a few drops of
Nujol as lubricant until no further glass powder is produced. Minute flat areas with sharp cutting edges are
formed on the plates.
Textile yarns or fabrics are cut to short lengths, i.e., about 0,5 mm to 2 mm and these are mulled a little at a
time, more yarn and Nujol being added at intervals. Excellent mulls of the toughest fibres can be obtained in a
few minutes. In preparing a mull, the intention is to produce a paste of petroleum jelly-like consistency. The
correct consistency is judged by appearance, by the drag of the grinding plates, and by the disappearance of
such tell-tale signs as rats' tails in the mull that indicate that macroscopic particles are still present. Finally, the
plates are separated and the mull is transferred to rock salt plates for infrared measurement.
7.5.2.3 Solvent-cast Films
In general, a solvent-cast film gives a better spectrum than that obtained by dispersing the same fibre in
potassium bromide or in a mull. The cast-film method is not as generally applicable as the pressed-disc
technique since a suitable solvent must first be selected, and for some fibres there is no such solvent. Further
requirements are that the solvent must not react with the fibre and it must leave no residue on evaporation.
If films are cast from a solvent onto a smooth glass surface, the films obtained may produce an interference
fringe pattern in the spectrum owing to a high degree of parallelism between their front and back surfaces.
The fringes may interfere with the identification of the weaker infrared bands, but the difficulty can be obviated
by the simple expedient of using a roughened glass surface. One surface of the film will then be irregular and
fringes are not produced.
ISO/TR 11827:2012(E)
An approximately 5 % solution is made by dissolving the fibre in the hot solvent. Sufficient solution to cover an
area of about 50 mm x 25 mm is poured on to a level glass plate whose surface has been roughened with
400-500 mesh carborundum. The temperature of the solution should be well below that at which bubbles form,
otherwise holes are left in the film. Most of the solvent is evaporated off at a temperature low enough to avoid
bubble formation and, when the film has solidified, it is heated to a higher temperature, preferably in vacuum,
to remove the remaining solvent.
The film can usually be peeled from the glass plate after lifting an edge with a razor blade; wetting with water
sometimes helps if the film sticks.
Most solvents are completely removed by the heating, but, where any solvent remains, it may be removed by
Soxhlet extraction or refluxing; for example, dimethylformamide (DMF) is tenaciously held by acrylic fibres but
is completely removed by boiling the film for 0,5 h to 1,0 h in water. It is essential with this method of sample
preparation that the solvent be completely removed, otherwise absorption bands (principally at 5,98 µm),
owing to the retention of the DMF, will be present in the spectrum of the fibre.
7.5.2.4 Melt-cast Films
Melt-cast films of thermoplastic fibres can be prepared by pressing fibres between polytetrafluoroethylene
(PTFE) sheets between heated platens in a laboratory hydraulic press. As a general guide the films should be
thin enough to be nearly transparent (5 µm to 35 µm).
7.5.2.5 Attenuated Total Reflection (ATR)
ATR spectroscopy is used for the analyses of the surface of materials by the mean of ATR spectroscopy
device (6.1.4.1). Since it requires no preparation of the sample, it is much quicker than the previous methods.
The infrared radiation is passed through an infrared transmitting crystal with a high refractive index, allowing
the radiation to reflect several times within the ATR element.
The sampling surface is pressed into intimate optical contact with the top surface of the crystal.
The commonest material used for the crystal in ATR attachments is Thallium Bromide-Iodide KRS-5.
Typically, a prism may be 5 cm long x 2 cm wide x 4 mm thick, with side angles of 45°. Light enters from the
angled side of the prism and the radiation is reflected approximately 25 times before emerging from the
crystal.
Fibres and fabrics, which are among the most difficult materials to handle by transmission spectroscopy, have
proved to be quite amenable to study by multiple internal reflection spectroscopy since they require no special
preparation techniques for the purpose. The word 'multiple' should be emphasized since the nature of the fibre
itself results in poor contact and many reflections are needed in order to ensure sufficient absorption. See
Figure 2.
Figure 2 — Multiple internal effect
7.5.2.6 Diffuse Reflectance Spectroscopy
Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) is a newer technique than ATR. Using
DRIFT Spectrometer (6.1.4.2), samples can be analysed either directly or as dispersions in non-absorbing
matrices, e.g. KBr. A comparison of sampling techniques for the characterisation of cotton textiles showed that
the best spectrum was obtained by simply placing a cut circle of fabric in the sample dish.
10 © ISO 2012 – All rights reserved
ISO/TR 11827:2012(E)
When infrared radiation is directed onto the surface of a solid sample two types of reflected radiation can
occur. One is specular reflection and the other is diffuse reflection. The specular component is the radiation
which reflects directly off the sample surface. Diffuse reflectance is the radiation which penetrates into the
sample and then emerges. A diffuse reflectance accessory is designed so that the diffusely reflected energy is
optimised and the specular component is minimised. The scattered radiation is collected by a spherical mirror
that is focused onto the detector.
7.5.2.7 FT-IR Microscopy
Single fibres can be examined and these are usually flattened with a roller, this being the only destructive part
of the technique. Fibres are flattened before analysis to minimise diffusion of radiation, to produce a more
uniform thickness (thus minimising deviation from Beer’s law and absorption by the fibre) and to increase the
sample surface area, thereby enhancing the signal-to-noise ratio while reducing diffraction effects at fibre
edges. The minimum sample size is generally of the order of (10 x 10) µm².
In the infrared microscope, the sample is mounted on a sample holder (a slide with a 13 mm window or
supporting a 13 mm gold reflecting disc). The sample is then brought into focus on the microscope stage
using either transmitted or reflected visible illumination. The area of interest on the sample is identified and
isolated using adjustable apertures. At this stage, a photograph of the sample may be obtained. An infrared
spectrum of the sample is then recorded by switching from visible to infrared radiation using a series of mirrors
built into the microscope. The infrared beam penetrates or reflects from the sample and the resultant beam is
taken to a highly sensitive detector, which is optimised for the small images generally encountered in FT-IR
microscopy.
7.5.3 Interpretation of Spectra
The infrared method depends primarily upon establishing that the spectrum of the unknown matches exactly
the spectrum of a known substance examined in the same physical form.
In order to do this, it is necessary to be able to name a compound from the absorption bands it displays in the
infrared region.
For example, Table 3 gives several absorption peaks which are characteristic of some main chemical bonds.
Table 3 — Examples of wavenumber of some chemical bonds
-1
Wave number (cm ) Chemical bond Chemical family
Around 3 300 O-H < 3 300 in alcohols
> 3 300 in acids
Around 3 250 N-H Amines, amides
Around 3 000 C-H 2 800 to 3 000 in aliphatic components
> 3 000 in aromatic components
Around 2 200 C≡N Nytril components (Acrylics)
Around 1 700 C=0 Ketones, amides, acids
Around 1 200 C-O-C Ester components
Around 800 C-Cl Chloro components
ISO/TR 11827:2012(E)
A laboratory carrying out qualitative analyses customarily sets up its own collection of absorption curves of
substances it is likely to encounter. Spectra recorded on the same instrument are to be preferred to literature
spectra, because no allowance need be made for differences of resolving power or wavelength calibration.
When the spectrum cannot be matched in this way, there is still a possibility that a matching spectrum exists
in the literature. A simple method of visual comparison of the unknown spectrum with spectra of known fibres
is used in Annex E.
Computerised spectral libraries now exist and most FT-IR software packages incorporate a search routine
whereby these commercial libraries or user developed libraries can be accessed.
7.6 Thermal Analysis
7.6.1 Melting Point Determination
If the fibre is made from a thermoplastic polymer it will have a melting point. The melting point can be defined
as the temperature (or temperature range) at which crystalline regions melt or the point at which the solid fibre
becomes liquid.
Techniques for measuring melting point are usually based on a heated block (6.1.5) for which the temperature
can be raised at a variable but controlled rate. Fibres can be placed directly in contact with the block or in a
glass capillary tube, the base of which is embedded in a block. If a polarising microscope (or viewer) is used
information on crystalline melting can be obtained. Otherwise the temperature at which liquid forms is
recorded.
Information on melting points can be found in Annex F.
NOTE Other transition temperatures can also be found in annex F related to non-thermoplastic fibres.
More sophisticated techniques exist (Differential Scanning Calorimetry or Thermal Gravimetric Analysis) but
these are usually employed when more detailed information about the fibre is required (see 7.6.2 and 7.6.3).
7.6.2 Differential Scanning Calorimetry (DSC)
7.6.2.1 General
Differential Scanning Calorimetry is an instrumental technique which can be used to study phenomena such
as various phase transitions and chemical reactions involving either the absorption or the evolution of heat
that may occur when a substance is heated. In the case of fibres, these changes may include the second
order or glass transition, desorption of moisture, crystallisation, fusion, chemical reactions and irreversible
decomposition processes. For identification purposes, one of the most interesting characteristic is
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