EN ISO 6721-2:2019

SLOVENSKI STANDARD
01-september-2019
Nadomešča:
SIST EN ISO 6721-2:2008
Polimerni materiali - Ugotavljanje dinamičnih mehanskih lastnosti - 2. del: Metoda
s torzijskim nihalom (ISO 6721-2:2019)
Plastics - Determination of dynamic mechanical properties - Part 2: Torsion-pendulum
method (ISO 6721-2:2019)
Kunststoffe - Bestimmung dynamisch-mechanischer Eigenschaften - Teil 2:
Torsionspendel-Verfahren (ISO 6721-2:2019)
Plastiques - Détermination des propriétés mécaniques dynamiques - Partie 2: Méthode
au pendule de torsion (ISO 6721-2:2019)
Ta slovenski standard je istoveten z: EN ISO 6721-2:2019
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 6721-2
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2019
EUROPÄISCHE NORM
ICS 83.080.01 Supersedes EN ISO 6721-2:2008
English Version
Plastics - Determination of dynamic mechanical properties
- Part 2: Torsion-pendulum method (ISO 6721-2:2019)
Plastiques - Détermination des propriétés mécaniques Kunststoffe - Bestimmung dynamisch-mechanischer
dynamiques - Partie 2: Méthode au pendule de torsion Eigenschaften - Teil 2: Torsionspendel-Verfahren (ISO
(ISO 6721-2:2019) 6721-2:2019)
This European Standard was approved by CEN on 8 June 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6721-2:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 6721-2:2019) has been prepared by Technical Committee ISO/TC 61 "Plastics"
in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by
NBN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by November 2019, and conflicting national standards
shall be withdrawn at the latest by November 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 6721-2:2008.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 6721-2:2019 has been approved by CEN as EN ISO 6721-2:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 6721-2
Third edition
2019-04
Plastics — Determination of dynamic
mechanical properties —
Part 2:
Torsion-pendulum method
Plastiques — Détermination des propriétés mécaniques
dynamiques —
Partie 2: Méthode au pendule de torsion
Reference number
ISO 6721-2:2019(E)
©
ISO 2019
ISO 6721-2:2019(E)
© 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
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below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 6721-2:2019(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Test apparatus . 3
5.1 Pendulum . 3
5.2 Inertial element . 3
5.2.1 General. 3
5.2.2 Method A (see Figure 1) . 3
5.2.3 Method B (see Figure 2) . 3
5.3 Clamps . 3
5.4 Oscillation-inducing device . 4
5.5 Oscillation-frequency and oscillation-amplitude recording equipment . 4
5.6 Temperature-controlled chamber . 4
5.7 Gas supply . 4
5.8 Temperature-measurement device . 4
5.9 Devices for measuring test-specimen dimensions . 4
6 Test specimens. 4
6.1 General . 4
6.2 Shape and dimensions . 4
6.3 Preparation . 5
7 Number of specimens . 5
8 Conditioning . 5
9 Procedure. 5
9.1 Test atmosphere . 5
9.2 Measurement of specimen cross-section . 5
9.3 Mounting the test specimens . 5
9.4 Varying the temperature . 5
9.5 Performing the test. 5
10 Expression of results . 6
10.1 Symbols and correction factors . 6
10.2 Calculation of logarithmic decrement, Λ . 7
′
10.3 Calculation of torsional storage modulus, G  . 8
to
″
10.4 Calculation of torsional loss modulus, G  . 8
to
11 Precision . 9
12 Test report . 9
Annex A (normative) Influence of longitudinal force, W .10
Annex B (informative) Damping correction factor, F .11
d
Annex C (informative) Dimensional correction factor, F .12
c
Bibliography .13
ISO 6721-2:2019(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.
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 documents 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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
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 5, Physical-
chemical porperties.
This third edition cancels and replaces the second edition (ISO 6721-2:2008), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the document has been revised editorially;
— normative references have been changed to undated.
A list of all parts in the ISO 6721 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 6721-2:2019(E)
Plastics — Determination of dynamic mechanical
properties —
Part 2:
Torsion-pendulum method
1 Scope
This document specifies two methods (A and B) for determining the linear dynamic mechanical
properties of plastics, i.e. the storage and loss components of the torsional modulus, as a function of
temperature, for small deformations within the frequency range from 0,1 Hz to 10 Hz.
NOTE The temperature dependence of these properties, measured over a sufficiently broad range of
temperatures (for example from −50 °C to +150 °C for most commercially available plastics), gives information
on the transition regions (for example the glass transition and the melting transition) of the polymer. It also
provides information concerning the onset of plastic flow.
The two methods described are not applicable to non-symmetrical laminates (see ISO 6721-3). The
methods are not suitable for testing rubbers, for which the user is referred to ISO 4664-2.
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 6721-1, Plastics — Determination of dynamic mechanical properties — Part 1: General principles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6721-1 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
A test specimen of uniform cross-section is gripped by two clamps, one of them fixed and the other
connected to a disc, which acts as an inertial element, by a rod. The end of the specimen connected to the
disc is excited, together with the disc, to execute freely decaying torsional oscillations. The oscillation
mode is that designated IV in ISO 6721-1, and the type of modulus is G as defined in IS
...