ISO 24048:2022

INTERNATIONAL ISO
STANDARD 24048
First edition
2022-11
Plastics — Determination of bound
acrylonitrile content in the continuous
phase of acrylonitrile-butadiene-
styrene (ABS) by Dumas combustion
method
Plastiques — Détermination de la teneur en acrylonitrile lié dans
la phase continue d'acrylonitrile-butadiène-styrène (ABS) par la
méthode de combustion Dumas
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Sampling and preparation of the specimen . 3
7.1 Preparation of cold methanol and settlement of centrifuge . 3
7.2 Sample dispersion . 3
7.3 Centrifuge separation. 3
7.4 Precipitation of continuous phase . 3
7.5 Centrifuge and work-up . 3
8 Procedure .4
8.1 Calibration . 4
8.1.1 General . 4
8.1.2 Instrument set up . 4
8.1.3 Setting up calibration curve. 4
8.2 Measurement . 5
8.3 Calculation . 5
9 Precision . 6
9.1 General . 6
9.2 Repeatability, r. 6
9.3 Reproducibility, R . 6
10 Test report . 6
Annex A (informative) Summary of precision data . 7
Bibliography . 8
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 9,
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INTERNATIONAL STANDARD ISO 24048:2022(E)
Plastics — Determination of bound acrylonitrile content
in the continuous phase of acrylonitrile-butadiene-styrene
(ABS) by Dumas combustion method
1 Scope
This document specifies a method for the determination of bound acrylonitrile content in the continuous
phase of acrylonitrile-butadiene-styrene (ABS) copolymer using Dumas combustion method. This
document is applicable to ABS resin with a mass fraction of bound acrylonitrile content in continuous
phase between 5 % and 50 %.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes the requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 472, Plastics — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
The ABS samples are dispersed in acetone. The dissolved continuous phase is separated from the
dispersed elastomeric phase using a high-speed centrifuge. The separated supernatant is precipitated
by methanol and then washed by n-hexane. The nitrogen content of the precipitate is determined
through Dumas combustion method and the content of acrylonitrile in the continuous phase is
calculated.
5 Reagents
5.1 Reference materials:
Combustible organic compounds with known nitrogen content, purity ≥ 99,99 %.
EXAMPLE Acetanilide, ethylenediaminetetraacetic acid (EDTA), aspartic acid, atropine, etc.
5.2 Oxygen gas, purity ≥ 99,99 % or in accordance with the analyser manufacturer’s instruction.
5.3 Carrier gas, helium, argon or carbon dioxide, purity ≥ 99,995 % or in accordance with the
analyser manufacturer’s instruction.
5.4 Acetone, volume fraction ≥ 99,8 %.
5.5 Methanol, volume fraction ≥ 99,8 %.
5.6 N-hexane, volume fraction ≥ 95 %.
6 Apparatus
6.1 Automatic analyser
The automatic analyser consists of the following components:
a) a combustion unit, capable of complete combustion of the sample in an atmosphere of high-purity
oxygen;
b) an oxygen feeder, capable of feeding enough high purity oxygen for complete combustion;
c) a reduction unit, capable of fully converting liberated nitrogenous compounds to nitrogen gas;
d) an absorber (or another type of separator) of by-products, capable of separating nitrogen from
other combustion products;
NOTE 1 When helium or argon is used as the carrier gas, this unit normally separates nitrogen from
carbon dioxide and water; when carbon dioxide is used as the carrier gas, this unit normally separates
nitrogen from water.
e) a thermal conductivity detector (TCD), capable of detecting nitrogen formed;
f) a microprocessor, capable of calibrating the apparatus with a reference material and of converting
the detector response into the mass of nitrogen in the sam
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