ISO 16014-2:2012
(Main)Plastics — Determination of average molecular mass and molecular mass distribution of polymers using size-exclusion chromatography — Part 2: Universal calibration method
Plastics — Determination of average molecular mass and molecular mass distribution of polymers using size-exclusion chromatography — Part 2: Universal calibration method
ISO 16014-2:2012 specifies a method for determining the average molecular mass and the molecular mass distribution of polymers using size-exclusion chromatography (SEC). The average molecular mass and the molecular mass distribution are calculated using a universal calibration curve instead of the conventional calibration curve.
Plastiques — Détermination de la masse moléculaire moyenne et de la distribution des masses moléculaires de polymères par chromatographie d'exclusion stérique — Partie 2: Méthode d'étalonnage universelle
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16014-2
Second edition
2012-07-01
Plastics — Determination of average
molecular mass and molecular mass
distribution of polymers using size-
exclusion chromatography —
Part 2:
Universal calibration method
Plastiques — Détermination de la masse moléculaire moyenne
et de la distribution des masses moléculaires des polymères par
chromatographie d’exclusion stérique —
Partie 2: Méthode d’étalonnage universelle
Reference number
ISO 16014-2:2012(E)
©
ISO 2012
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ISO 16014-2:2012(E)
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ii © ISO 2012 – All rights reserved
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ISO 16014-2:2012(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle of universal calibration method . 2
5 Reagents . 3
6 Apparatus . 3
7 Procedure . 3
8 Data acquisition and processing . 3
9 Expression of results . 4
9.1 Preparation of universal calibration curve . 4
9.2 Calculation of average molecular mass . 4
9.3 Differential molecular mass distribution curve . 6
9.4 Cumulative molecular mass distribution curve . 6
10 Precision . 6
11 Test report . 7
11.1 General . 7
11.2 Apparatus and measurement parameters . 7
11.3 Calibration of the system . 7
11.4 Results . 7
Annex A (informative) Supplementary information . 8
Annex B (informative) K and a in the Mark-Houwink-Sakurada equation . 11
Bibliography .12
© ISO 2012 – All rights reserved iii
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ISO 16014-2:2012(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.
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 16014-2 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This second edition cancels and replaces the first edition (ISO 16014 2:2003). The main changes are as follows:
a) the scope has been editorially revised;
b) the normative references have been updated.
ISO 16014 consists of the following parts, under the general title Plastics — Determination of average molecular
mass and molecular mass distribution of polymers using size-exclusion chromatography:
— Part 1: General principles
— Part 2: Universal calibration method
— Part 3: Low-temperature method
— Part 4: High-temperature method
— Part 5: Method using light-scattering detection
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INTERNATIONAL STANDARD ISO 16014-2:2012(E)
Plastics — Determination of average molecular mass and
molecular mass distribution of polymers using size-exclusion
chromatography —
Part 2:
Universal calibration method
1 Scope
This part of ISO 16014 specifies a method for determining the average molecular mass and the molecular
mass distribution of polymers using size-exclusion chromatography (SEC). The average molecular mass and
the molecular mass distribution are calculated using a universal calibration curve instead of the conventional
calibration curve.
A list of documents related to this part of ISO 16014 is given in the Bibliography.
NOTE The concept of the universal calibration method is based on a relationship by which the retention time in SEC
depends on the size of the polymer molecule (the hydrodynamic volume) or on the product of the intrinsic viscosity [η] and
the molecular mass M. Many polymers classified as random-coil polymers (regardless of their chemical structure, degree
of branching, composition or tacticity) have been experimentally confirmed as following this relationship. The universal
calibration curve is prepared by plotting the logarithm of [η]M against the elution time t or elution volume V using polymer
standards such as polystyrene with narrow molecular mass distributions. The molecular mass M of an unknown polymer
i
sample can then be calculated from the value of [η]M at each retention time using the universal calibration curve and [η] or
a a+1
K and a in the Mark-Houwink-Sakurada equation ([η] = KM → [η]M = KM ), where K is a constant and a is an exponent
depending on the experimental conditions. Therefore this test method is classified as a relative method as described in
ISO 16014-1, but the average molecular masses and molecular mass distributions calculated by the method are equal to,
or nearly equal to, the absolute values.
2 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 472, Plastics — Vocabulary
ISO 16014-1:2012, Plastics — Determination of average molecular mass and molecular mass distribution of
polymers using size-exclusion chromatography — Part 1: General principles
ISO 16014-3:2012, Plastics — Determination of average molecular mass and molecular mass distribution of
polymers using size-exclusion chromatography — Part 3: Low-temperature method
ISO 16014-4:2012, Plastics — Determination of average molecular mass and molecular mass distribution of
polymers using size-exclusion chromatography — Part 4: High-temperature method
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ISO 16014-2:2012(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and in ISO 16014-1 apply. The
definitions of the various types of average molecular mass are reproduced here for convenience.
Four types of average molecular mass are defined by the following equations, where N is the number of
i
molecules of species i of molecular mass M and a is the exponent of the Mark-Houwink-Sakurada equation.
i
NOTE Although the definitions are the same as in ISO 16014-1, the values of M in the equations are calculated by
i
using a universal calibration curve as described in Clause 4.
3.1
number-average molecular mass
M
n
∞
()NM×
∑ ii
i=1
M = (1)
n
∞
N
∑ i
i=1
3.2
mass-average molecular mass
M
w
∞
2
()NM×
∑ ii
i=1
M = (2)
w
∞
()NM×
∑ ii
i=1
3.3
z-average molecular mass
M
z
∞
3
()NM×
∑ ii
i=1
M = (3)
z
∞
2
()NM×
∑ ii
i=1
3.4
viscosity-average molecular mass
M
v
1/a
∞
a+1
()NM×
∑ ii
i=1
M = (4)
v
∞
()NM×
∑ ii
i=1
4 Principle of universal calibration method
In this part of ISO 16014, the experimental SEC procedures are the same as in ISO 16014-1, ISO 16014-3 and
ISO 16014-4, but the molecular mass M at each elution time is calculated based on the universal calibration
i
method. According to the theory, this method provides values for the average molecular mass and the molecular
mass distribution that are equal to, or nearly equal to, the absolute values.
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ISO 16014-2:2012(E)
According to theory, the size of a polymer in solution, the hydrodynamic volume V , is proportional to the
h
product of the intrinsic viscosity [η] and the molecular mass M as given by Equation (5):
[]ηη∝→VM/[ ]MV∝ (5)
hh
In SEC, many random-coil polymers, regardless of their chemical structure, degree of branching, composition
or tacticity, follow the same relationship, in which the retention time is proportional to the product of [η] and
M under the specific experimental conditions, including the column system, solvent and temperature. The
relationship between the logarithm of [η]M and the elution time is called the “universal calibration curve”, and
the SEC technique for the determination of average molecular masses and molecular mass distributions using
this calibration curve is called the “universal calibration method”.
As a first step, the universal calibration curve, retention time t versus the logarithm of [η]M, is prepared using
polymer standards with narrow molecular mass distributions and the Mark-Houwink-Sakurada equation:
a
s
[]η =KM (6)
ss s
where the subscript “s” denotes “polymer standard”.
Direct measurement of [η] is also possible.
s
In the next step, the molecular mass M at each retention time t is calculated using the universal calibration
i i
curve and the Mark-Houwink-Sakurada equation for the polymer sample:
a
[]η =KM (7)
a+1
[]ηηMM==[] KM (8)
s,iis, ii i
Again, direct measurement of [η] is possible.
Lastly, the average molecular mass and the molecular mass distribution are calculated from the molecular
mass M and peak height H at each retention time, using the equations given in 9.2, 9.3 and 9.4.
...
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