ISO 4504:2023

INTERNATIONAL ISO
STANDARD 4504
First edition
2023-06
Plastics — Polyethylene (PE) —
Determination of co-monomer
content by solution state C-NMR
spectrometry
Plastiques — polyéthylène (PE) — Détermination de la teneur en co-
monomères par spectroscopie RMN du carbone 13
Reference number
© ISO 2023
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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols . 2
3.3 Abbreviated terms . 2
4 Principle . 2
5 Reagents and materials . 2
6 Apparatus . 3
7 Preparation and preservation of test samples . 3
8 Method A — Inverse gated decoupling method . 3
8.1 Sample preparation . 3
8.2 Procedure . 4
8.3 Calculation . 4
9 Method B — Insensitive nuclei enhanced by polarization transfer method .5
9.1 Sample preparation . 5
9.2 Procedure . 5
9.3 Calculation . 6
10 Expression of results . 6
11 Precision . 7
12 Test report . 7
Annex A (normative) Spectral integration method and integration limits outlines .8
Annex B (normative) Summary of formulae .10
Annex C (informative) Calculation example of method A .12
Annex D (informative) Calculation example of method B .14
Annex E (informative) Reference longitudinal relaxation time(T ) values .16
Annex F (informative) Chemical shift region of branch CH-carbon of different co-monomers .19
Annex G (informative) Summary of precision data .20
Annex H (informative) Introduction to pulse program.22
Annex I (informative) Consistency validation between method A and method B .24
Bibliography .25
iii
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 9,
Thermoplastic materials.
Any feedback or questions on this document should be directed to the user’s national standards body.
A complete
iv
INTERNATIONAL STANDARD ISO 4504:2023(E)
Plastics — Polyethylene (PE) — Determination of co-
monomer content by solution state C-NMR spectrometry
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the user’s responsibility to establish appropriate safety and health practices.
1 Scope
This document specifies two methods for the determination of co-monomer contents of polyethylene
products by solution state C-NMR spectrometry (nuclear magnetic resonance spectrometry):
— method A: inverse gated decoupling method.
— method B: insensitive nuclei enhanced by polarization transfer method;
This document is applicable to copolymers of ethylene having a content of other 1-olefinic monomers of
less than a mass fraction of 50 %.
This document is not applicable to ethylene homopolymers or copolymers in which ethylene is
polymerized with two or more type 1-olefin comonomers.
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 648, Laboratory glassware — Single-volume pipettes
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and the following apply.
ISO and IEC maintain terminology 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/
3.1.1
insensitive nuclei enhanced by polarization transfer
INEPT
C NMR method in which magnetisation is transferred from sensitive nuclei to directly linked
insensitive nuclei enhanced by polarisation transfer
Note 1 to entry: See Reference [4].
3.1.2
refocused INEPT
INEPT pulse program with a pair of refocus delay and π inversion pulse in both sensitive and insensitive
nuclei resonance channels
3.2 Symbols
T Longitudinal relaxation time
T longest T of atom nuclei
1, max 1
C Carbon 13
H Hydrogen 1
T polarization transfer time
p
T refocusing time
R
3.3 Abbreviated terms
NMR nuclear magnetic resonance
C-NMR carbon 13 nuclear magnetic resonance
PFT-NMR pulse Fourier transform nuclear magnetic resonance spectrometer
LOQ limit of quantitation
LOD limit of detection
SNR signal-to-noise ratio
SW sweep width
4 Principle
4.1 Polyethylene samples are dissolved in the deuterated solvent and put in the magnetic field. Radio
pulses are applied to excite the nuclei, and a set of resonance signals are generated from nuclei with
different chemical circumstances. With proper excitation pulse or pulses combination, the intensities
of a resonance signal are proportional to the molar fractions of nuclei with identical or similar chemical
circumstances. A linear relationship is established between the carbon molar content of different
chemical shifts and the comonomer content. In this document, two methods with different NMR pulse
programs are established to acquire C NMR spectra. Method A utilizes the “single pulse with inverse
[4] 13
gated proton decoupling” . NMR pulse program to excite the C nuclei directly. Method B excites the
[5][6]
proton initially by the “Refocused INEPT with proton decoupling” . NMR Pulse program to enhance
the signal sensitivity of C nuclei. The principles of two different NMR spectrometer pulse programs
are shown in Annex H.
5 Reagents and materials
5.1 Deuterated reagents, deuterated ortho-dichlorobenzene, or para-dichlorobenzene (o-DCB-d4 or
p-DCB-d4), or 1,1,2,2-tetrachloroethane-d2 (TCE-d2), analytical grade.
5.2 Relaxation reagents, chromium (III) acetylacetonate, analytical grade.
6 Apparatus
6.1 PFT-NMR spectrometer, with a minimum magnet field strength of 7,05 Tesla (equivalent proton
resonance frequency at 300 MHz, or C nuclei resonance frequency at 75 MHz), capable of being
maintained at 120 °C ± 1 °C.
6.2 Analytical balance, accurate to 1 mg.
6.3 Sample tube, capped NMR tube with 5 mm or 10 mm outer diameter.
6.4 Adjustable pipette, 5 ml capacity, meet the requirement of Class A defined in ISO 648.
6.5 Supplementary heating equipment, capable of uniformly heating the samples to 130 C ± 1 °C. It
can ensure that the sample tube is kept in a vertical position during the heating process.
7 Preparation and preservation of test samples
Test samples can be obtained from materials in the form of powders, pellets, or moulded parts. To
ensure the required accuracy of sample mass, large samples should be cut into smaller pieces. It is
important that the laboratory receive a sample which is representative and has not been damaged or
c
...