ISO 16564:2004
(Main)Rubber, raw natural — Determination of average molecular mass and molecular-mass distribution by size exclusion chromatography (SEC)
Rubber, raw natural — Determination of average molecular mass and molecular-mass distribution by size exclusion chromatography (SEC)
ISO 16564:2004 specifies a method of determining the average molecular mass and the molecular-mass distribution of raw natural rubber dissolved in tetrahydrofuran. A set of polystyrene standards is used for calibration purposes (i.e. the method is a relative one). An alternative method, using cyclohexane as solvent and polyisoprene standards, is included in an informative annex.
Caoutchouc naturel brut — Détermination de la masse moléculaire moyenne et de la répartition des masses moléculaires par chromatographie d'exclusion stérique (SEC)
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16564
First edition
2004-10-01
Rubber, raw natural — Determination of
average molecular mass and molecular-
mass distribution by size exclusion
chromatography (SEC)
Caoutchouc naturel brut — Détermination de la masse moléculaire
moyenne et de la répartition des masses moléculaires par
chromatographie d'exclusion stérique (SEC)
Reference number
ISO 16564:2004(E)
©
ISO 2004
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ISO 16564:2004(E)
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ii © ISO 2004 – All rights reserved
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ISO 16564:2004(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Principle . 1
3 Materials. 1
4 Apparatus . 2
5 Procedure . 2
6 Calibration . 3
7 Expression of results. 5
8 Precision . 5
9 Test report . 5
Annex A (informative) SEC analysis of natural rubber using cyclohexane as solvent and
polyisoprene standards. 6
Bibliography . 7
© ISO 2004 – All rights reserved iii
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ISO 16564:2004(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.
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 16564 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee
SC 2, Testing and analyses.
iv © ISO 2004 – All rights reserved
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INTERNATIONAL STANDARD ISO 16564:2004(E)
Rubber, raw natural — Determination of average molecular
mass and molecular-mass distribution by size exclusion
chromatography (SEC)
WARNING — Persons using this International Standard should be familiar with normal laboratory
practice. This standard 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 limitations prior to use.
1 Scope
This International Standard specifies a method of determining the average molecular mass and the molecular-
mass distribution of raw natural rubber dissolved in tetrahydrofuran. A set of polystyrene standards is used for
calibration purposes (i.e. the method is a relative one).
An alternative method, using cyclohexane as solvent and polyisoprene standards, is included in an informative
annex.
2 Principle
Dried natural rubber is dissolved in tetrahydrofuran at room temperature. The solution is filtered to remove
“gel” (slightly crosslinked rubber) and other insoluble materials. The filtrate is used to determine the molecular
[1]
mass by size exclusion chromatography . From the chromatogram, the number-average molecular mass
(M ), the mass-average molecular mass (M ) and a polydispersity value (M /M ) are calculated.
n w w n
3 Materials
3.1 The recommended solvent is HPLC-grade tetrahydrofuran (THF). If analytical-grade THF is used, 0,5 %
of butylated hydroxytoluene (BHT) shall be added to the solvent as an antioxidant. The BHT is strongly
retained and acts as a marker for the end of the chromatogram. It also allows minor variations in run time to
be corrected, as well as indicating when a serious change in the column conditions has occurred.
3.2 The solvent is filtered through a polytetrafluoroethylene (PTFE) membrane (4.2) before use.
3.3 A set of polystyrene standards with proper traceability shall be used, typically covering an M range
w
3 7
from 6,5 × 10 to 1,06 × 10 . An example of a suitable set of polystyrene standards is given in Table 1.
Table 1 — Polystyrene standards
No. of standard M M /M
p w n
5
1 3,55 × 10 1,08
5
2 7,06 × 10 1,12
6
3 2,89 × 10 1,36
6
4 3,84 × 10 1,30
6
5 4,48 × 10 1,47
6
6 5,48 × 10 1,40
6
7 6,77 × 10 1,37
6
8 8,42 × 10 1,33
© ISO 2004 – All rights reserved 1
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ISO 16564:2004(E)
4 Apparatus
4.1 Size exclusion chromatograph: Suitable high-performance liquid chromatography equipment
consisting of the components specified in 4.1.1 to 4.1.7.
4.1.1 Solvent reservoir, large enough to hold an adequate quantity of solvent (see 3.1). About 3 l of
solvent is recommended for a complete analysis. Refilling can result in variations in dissolved air and the
inclusion of impurities. When fresh solvent is added, it takes a long time to obtain a stable baseline.
4.1.2 Automatic on-line degassing system, to prevent the formation of bubbles in the mobile phase and
to ensure a stabilized liquid feed flow.
4.1.3 Pump with temperature-control equipment, capable of delivering the solvent at
...
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