ISO 16014-2:2019

INTERNATIONAL ISO
STANDARD 16014-2
Third edition
2019-05
Plastics — Determination of average
molecular weight and molecular
weight 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 de polymères par
chromatographie d'exclusion stérique —
Partie 2: Méthode d'étalonnage universelle
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle of universal calibration method . 1
5 Reagents . 2
6 Apparatus . 2
7 Procedure. 2
8 Data acquisition and processing . 3
9 Expression of results . 3
9.1 Preparation of universal calibration curve . 3
9.2 Calculation of average molecular weight . 3
9.3 Differential molecular weight distribution curve . 4
9.4 Cumulative molecular weight distribution curve . 4
10 Precision . 4
11 Test report . 4
11.1 General . 4
11.2 Apparatus and measurement parameters . 4
11.3 Calibration of the system . 5
11.3.1 Information on the molecular weight standards . 5
11.3.2 Calibration curve . 5
11.4 Results . 5
Annex A (informative) Supplementary information . 6
Annex B (informative) K and a in the Mark-Houwink-Sakurada equation .9
Bibliography .10
Foreword
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This third edition cancels and replaces the second edition (ISO 16014-2:2012), which has been
technically revised. The main changes compared to the previous edition are as follows:
— publication dates of references have been removed;
— molecular mass has been change to molecular weight according to IUPAC rule.
A list of all parts in the ISO 16014 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 16014-2:2019(E)
Plastics — Determination of average molecular weight
and molecular weight distribution of polymers using size-
exclusion chromatography —
Part 2:
Universal calibration method
1 Scope
This document specifies a method for determining the average molecular weight and the molecular
weight distribution of polymers using size-exclusion chromatography (SEC). The average molecular
weight and the molecular weight distribution are calculated using a universal calibration curve instead
of the conventional calibration curve.
NOTE This test method is classified as a relative method as described in ISO 16014-1, but the average
molecular weights and molecular weight distributions calculated by the method are equal to, or nearly equal to,
the absolute values. For details, see the Annex A.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes 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
ISO 16014-1, Plastics — Determination of average molecular weight and molecular weight distribution of
polymers using size-exclusion chromatography — Part 1: General principles
ISO 16014-3, Plastics — Determination of average molecular weight and molecular weight distribution of
polymers using size-exclusion chromatography — Part 3: Low-temperature method
ISO 16014-4, Plastics — Determination of average molecular weight and molecular weight distribution of
polymers using size-exclusion chromatography — Part 4: High-temperature method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and in ISO 16014-1 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 http: //www .electropedia .org/
4 Principle of universal calibration method
In ISO 16014-2, the experimental SEC procedures are the same as in ISO 16014-1, ISO 16014-3 and
ISO 16014-4, but the molecular weight M at each elution time is calculated based on the universal
i
calibration method. According to the theory, this method provides values for the average molecular
weight and the molecular weight distribution that are equal to, or nearly equal to, the absolute values.
According to theory, the size of a polymer in solution, the hydrodynamic volume, V , is proportional to
h
the product of the intrinsic viscosity [η] and the molecular weight M as given by Formula (1):
ηη∝→VM/  MV∝ (1)
  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 weights
and molecular weight 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 weight distributions and the Mark-Houwink-Sakurada
equation shown in Formula (2):
a
s
η =KM (2)
  ss
s
where the subscript “s” denotes “polymer standard”.
Direct measurement of [η] is also possible.
s
In the next step, the molecular weight M at each retention time t is calculated using the universal
i i
calibration curve shown in Formula (3) and the Mark-Houwink-Sakurada equation shown in Formula (4)
for the polymer sample:
a
η =KM (3)
 
 
a+1
ηη MM=  =KM (4)
  s,i   ii
s,i i
Again, direct measurement of [η] is possible.
Lastly, the average molecular weight and the molecular weight distribution are calculated from the
molecular weight M and peak height H at each retention time, using the formulae given in 9.2, 9.3
i i
and 9.4.
For additional information on the universal calibration curve and the use of a conventional calibration
curve based on universal calibration theory, see 9.1 and A.2.1.
For additional information on the intrinsic viscosity [η], see A.2.2.
The values of K and a in the Mark-Houwink-Sakurada equation for several polymers are given in
Annex B.
5 Reagents
According to ISO 16014-1.
6 Apparatus
According to ISO 16014-1.
7 Procedure
According to ISO 16014-1.
2 © ISO 2019 – All rights reserved

8 Data acquisition and processing
According to ISO 16014-1.
9 Expression of results
9.1 Preparation of universal calibration curve
The universal calibration curve is prepared by plotting the logarithm of [η] M against the elution time
s s
for a number of polymer standards. The value of [η] for each polymer standard may be calculated using
s
the Mark-Houwink-Sakurada equation or measured directly under the specific elution conditions.
For information on the molecular weights of commercially available polymer standards, see ISO 16014-1.
For the expression of the universal calibration curve, polynomials containing terms up to t are widely
used. The addition of subsequent higher-power terms might improve the fit of the calibration curve. See
Formulae (5) and (6).
lg η MA=+At (5)
 
()s 01
 
s
2 3
lg η MA=+At ++At At (6)
()
  s 01 2 3
s
where
[η] is the intrinsic viscosity of the po
...