ISO 16014-2:2019

Plastics - Determination of average molecular weight and molecular weight distribution of polymers using size-exclusion chromatography - Part 2: Universal calibration method

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.

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

General Information

• Status: Published
• Publication Date: 14-May-2019
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 61/SC 5 - Physical-chemical properties
• Drafting Committee: ISO/TC 61/SC 5/WG 11 - Analytical methods
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Jun-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 16014-2:2012 - Plastics - Determination of average molecular mass and molecular mass distribution of polymers using size-exclusion chromatography - Part 2: Universal calibration method
• Effective Date: 15-Dec-2017

Overview - ISO 16014-2:2019 (Universal calibration method)

ISO 16014-2:2019 is the ISO standard for determining the average molecular weight and molecular weight distribution of polymers using size-exclusion chromatography (SEC) with the universal calibration approach. Published as Part 2 of the ISO 16014 series (third edition, 2019), the standard specifies how to build and use a universal calibration curve - plotting lg([η]·M) versus elution time or volume - and how to convert SEC elution data into near-absolute molecular-weight values using the Mark–Houwink–Sakurada relationship ([η] = K·M^a).

Note: ISO 16014-2 is classed as a relative method (see ISO 16014-1) but, according to Annex A, typically yields average molecular weights and distributions equal or very close to absolute values.

Key topics and technical requirements

• Universal calibration curve: prepare using narrow-distribution polymer standards (e.g., polystyrene, PMMA); plot lg([η]·M) vs elution time (t) or volume (V = t·Q).
• Intrinsic viscosity and Mark–Houwink–Sakurada equation: use [η] = K·M^a to compute intrinsic viscosity or use directly measured [η] under the same elution conditions.
• Calculation steps:
  • Build universal calibration curve from standards.
  • Determine [η] or use K and a values to compute [η] for sample fractions.
  • Calculate molecular weight M at each elution time and compute average molecular weights, polydispersity, and differential/cumulative distributions per Clauses 9.2–9.4.
• Data acquisition & processing: follows procedures in ISO 16014-1 (baseline correction, signal intensity H at each t).
• Limitations and applicability: method assumes no specific interaction with column packing and that K and a are reasonably constant. It can be unreliable for strongly interacting polymers or extensively long-chain branched materials (see Annex A).
• Documentation: include calibration curve, standard information, apparatus and measurement parameters, and results in the test report (Clauses 11.2–11.4).

Applications and who uses this standard

• Laboratories performing polymer characterization by SEC seeking more universal / near-absolute molecular-weight results.
• R&D and QC teams in plastics, polymer manufacturing, coatings, adhesives, and materials science.
• Instrument vendors and service labs validating SEC systems and calibration procedures.
• Academic researchers comparing polymer architectures (linear vs branched) and seeking consistent inter-laboratory results.

Related standards

• ISO 16014-1 - General principles for SEC molecular-weight determination
• ISO 16014-3 - Low-temperature SEC method
• ISO 16014-4 - High-temperature SEC method
• ISO 472 - Plastics - Vocabulary

Keywords: ISO 16014-2:2019, universal calibration, size-exclusion chromatography, SEC, molecular weight distribution, intrinsic viscosity, Mark–Houwink–Sakurada, polymer characterization.

Standards Content (Sample)

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
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
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Website: www.iso.org
Published in Switzerland
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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.org/iso/foreword .html.
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
complete listing of these bodies can be found at www .iso .org/members .html.
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 “
...