ISO 9924-2:2000
(Main)Rubber and rubber products — Determination of the composition of vulcanizates and uncured compounds by thermogravimetry — Part 2: Acrylonitrile-butadiene and halobutyl rubbers
Rubber and rubber products — Determination of the composition of vulcanizates and uncured compounds by thermogravimetry — Part 2: Acrylonitrile-butadiene and halobutyl rubbers
Caoutchouc et produits à base de caoutchouc — Détermination de la composition des vulcanisats et mélanges non vulcanisés par thermogravimétrie — Partie 2: Caoutchoucs acrylonitrile-butadiène et butyl halogéné
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INTERNATIONAL ISO
STANDARD 9924-2
First edition
2000-09-01
Rubber and rubber products —
Determination of the composition of
vulcanizates and uncured compounds by
thermogravimetry —
Part 2:
Acrylonitrile-butadiene and halobutyl
rubbers
Caoutchouc et produits à base de caoutchouc — Détermination de la
composition des vulcanisats et mélanges non vulcanisés par
thermogravimétrie —
Partie 2: Caoutchoucs acrylonitrile-butadiène et butyl halogéné
Reference number
ISO 9924-2:2000(E)
©
ISO 2000
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ISO 9924-2:2000(E)
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ISO 9924-2:2000(E)
Contents Page
Foreword.iv
1 Scope .1
2 Normative reference .1
3 Principle.2
4 Reagents.2
5 Apparatus .2
6 Thermogravimetric analyser checks .3
7 Procedure .4
8 Expression of results .5
9 Precision.8
10 Test report .9
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ISO 9924-2:2000(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 3.
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.
Attention is drawn to the possibility that some of the elements of this part of ISO 9924 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 9924-2 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analyses.
ISO 9924 consists of the following parts, under the general title Rubber and rubber products — Determination of
the composition of vulcanizates and uncured compounds by thermogravimetry:
� Part 1: Butadiene, ethylene-propylene copolymer and terpolymer, isobutene-isoprene, isoprene and styrene-
butadiene rubbers
� Part 2: Acrylonitrile-butadiene and halobutyl rubbers
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INTERNATIONAL STANDARD ISO 9924-2:2000(E)
Rubber and rubber products — Determination of the composition
of vulcanizates and uncured compounds by thermogravimetry
Part 2:
Acrylonitrile-butadiene and halobutyl rubbers
WARNING — Persons using this part of ISO 9924 should be familiar with normal laboratory practice. This
part of ISO 9924 does not purport to address all of the safety problems, if any, associated with its use. It is
the responsibility of the user to establish appropriate safety and health practices and to ensure compliance
with any national regulatory conditions.
1 Scope
1.1 This part of ISO 9924 specifies a thermogravimetric method for determining the total organic content, carbon
black content, carbonaceous residue and ash in vulcanizates and uncured compounds containing polymers which
form a carbonaceous residue on pyrolysis (see 1.2). The loss in mass at around 300 °Cisanapproximate guideto
the volatile-matter content of the compound.
1.2 The method is suitable for the analysis of rubber compounds and vulcanizates containing the hydrocarbon
polymers covered by part 1 of this International Standard plus the following copolymers with polar groups which
form a carbonaceous residue on pyrolysis:
a) acrylonitrile-butadiene copolymers (NBRs);
b) carboxylated acrylonitrile-butadiene copolymers (XNBRs);
c) hydrogenated acrylonitrile-butadiene copolymers (HNBRs);
d) chlorinated isobutylene-isoprene copolymers (CIIRs);
e) brominated isobutylene-isoprene copolymers (BIIRs).
NOTE 1 The field of application of the method may be extended to include the analysis of compounds containing rubbers
different from those given in this clause provided that the applicability of the method is tested beforehand using known
compounds or vulcanizates having similar composition.
NOTE 2 The method is not suitable for compounds containing mineral fillers, such as carbonates or hydrated aluminium
oxides, which decompose in the temperature range from 25 °C to 800 °C, unless suitable corrections based on prior knowledge
of filler behaviour can be made.
NOTE 3 The method is not suitable for the determination of the total polymer content of compounds containing non-rubber
organic ingredients that cannot be completely removed by solvent extraction carried out in accordance with ISO 1407.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this part of ISO 9924. For dated references, subsequent amendments to, or revisions of, this publication do not
apply. However, parties to agreements based on this part of ISO 9924 are encouraged to investigate the possibility
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ISO 9924-2:2000(E)
of applying the most recent edition of the normative document indicated below. For undated references, the latest
edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid
International Standards.
ISO 1407:1992, Rubber — Determination of solvent extract.
3Principle
3.1 A weighed test portion is heated, following a pre-set programme, from 40 °Cto600 °C in a stream of
nitrogen until all the organic material is pyrolysed. If nitrile-butadiene copolymers are present, a small amount of the
polymer will be pyrolysed to form a carbonaceous residue that has to be determined in order to obtain the correct
total organic content.
3.2 For this purpose, the oven temperature is decreased to 400 °C in a stream of nitrogen and maintained at
400 °C for 5 min. The gas stream is then changed from nitrogen to air or oxygen and the oven temperature raised
slowly to 800 °C. During this heating in an oxidizing atmosphere, two distinct losses in mass occur due to
combustion. The first is due to the combustion of the carbonaceous residue, and the amount is determined and
added to the previously determined loss in nitrogen at 600 °C to obtain the correct value of the total organic
content. The second is due to the normal combustion of the carbon black.
NOTE The total rubber content is calculated by subtracting the value of the solvent extract, determined in accordance with
ISO 1407, from the total organic content, provided that all non-rubber ingredients can be extracted.
3.3 The mass of the residue at 800 °C represents the ash.
4 Reagents
4.1 Dry nitrogen, with an oxygen content of less than 10 mg/kg (ppm).
4.2 Dry air or oxygen.
5 Apparatus
5.1 Thermogravimetric analyser
There are many types of analyser commercially available. All should be suitable for use with this part of ISO 9924,
but their suitability should be checked using the procedure in clause 6. Calibrate and operate the thermogravimetric
analyser in accordance with the manufacturer’s instructions.
The basic components of an analyser are as follows:
5.1.1 Thermogravimetric balance.
5.1.2 Electrically heated, thermo-regulated oven.
5.1.3 Temperature programmer, for the oven.
5.1.4 Switching device, allowing either a stream of nitrogen or, alternatively, a stream of air or oxygen to flow
through the oven at a predetermined and constant flow rate.
5.1.5 X/Y recorder, for recording the temperature/mass plot. Alternatively, temperature/time and mass/time plots
may be recorded simultaneously using a two-pen Y/T recorder. Digital data acquisition stations with related
software for drawing the temperature/mass and/or time/mass curves are also suitable: in this case better accuracy
in the calculation of the mass losses can be achieved.
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ISO 9924-2:2000(E)
5.1.6 Auxiliary equipment for producing differential curves (mandatory for this part of ISO 9924).
5.1.7 Analytical balance, capable of weighing to 0,1 mg.
6 Thermogravimetric analyser checks
6.1 Measurement of purge time t
p
6.1.1 Place a test portion of carbon black or black-filled rubber, as specified in the manufacturer’s instructions, in
the thermobalance sample pan and heat to 650 °C in a stream of nitrogen, at the maximum rate allowed by the
temperature programmer.
6.1.2 Maintaining the temperature at 650 °C, introduce air or oxygen and allow the test portion to combust fully.
6.1.3 When there is no further mass change, switch off the oven heater and allow the oven to cool to room
temperature, maintaining the air or oxygen flow. At this point, the oven will have been thoroughly purged with air or
oxygen. The following operations are designed to determine the time t required to completely restore the inert
p
atmosphere of nitrogen.
6.1.4 With the oven at 25 °C� 5 °C, introduce a fresh test portion of carbon black, of mass as specified in the
manufacturer’s instructions, into the balance pan and close the apparatus.
6.1.5 Record the time t , switch over to nitrogen gas flow, set the oven temperature to increase to 650 °Cata
1
rate of 10 °C/min and then hold the temperature constant.
6.1.6 Observe the thermogravimetric analyser mass trace and, when this no longer indicates a mass loss with
time, note the time t .
2
NOTE As a check, the pan should still contain carbon black since the mass loss should be constant if not all the carbon
black has burned off during the heating time.
6.1.7 The purge time t , which is the time required to purge all oxygen from the system, is given by the following
p
equation:
t = t – t
p 2 1
6.2 Discrimination between carbon black and calcium carbonate
6.2.1 Calcium carbonate will decompose to calcium oxide when heated to 800 °C. Carbon black is thermally
stable up to this temperature in a nitrogen atmosphere. In air or oxygen, however, carbon black will be oxidized to
carbon dioxide at 800 °C.
6.2.2 Provided that nitrogen having an low enough concentration of oxygen is used, that purging is carried out for
a time greater than the purge time determined in 6.1, that there are no leaks in the apparatus, and that the oven
design and gas flow rate ensure that all carbon dioxide is swept out from the sample chamber, there should be no
problem in distinguishing between, and measuring separately, black and whiting (calcium carbonate). To check the
operation of the thermogravimetric analyser, carry out the following procedure:
6.2.3 Grind together equal (to within 1 %) masses of analytical-grade calcium carbonate and the purest grade of
carbon black available.
6.2.4 Purge the apparatus with nitrogen for 10
...
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