SIST-TP CEN ISO/TR 20659-2:2025
(Main)Rheological test methods - Fundamentals and interlaboratory comparisons - Part 2: Determination of the time-dependent structural change (thixotropy) (ISO/TR 20659-2:2024)
Rheological test methods - Fundamentals and interlaboratory comparisons - Part 2: Determination of the time-dependent structural change (thixotropy) (ISO/TR 20659-2:2024)
This document gives information on an interlaboratory comparison for the determination of the time-dependent structural change (thixotropy) using rheological test methods. Thixotropy is the reversible, time-dependent decrease of shear viscosity η at a constant shear rate or shear stress τ.
This document provides examples of fields of application, in which important material properties can be characterized by the thixotropy. These fields of application include:
— effectiveness of rheological additives and thixotropic agents, respectively;
— stability of the structure at rest (e.g. behaviour when starting to pump);
— wet film thickness after processing;
— levelling and sagging behaviour (e.g. without brushmarks or sag formation);
— orientation of effect pigments.
Rheologische Prüfverfahren - Grundlagen und Ringversuch - Teil 2: Thixotropie (ISO/TR 20659-2:2024)
Méthodes d'essai rhéologiques - Principes fondamentaux et comparaisons interlaboratoires - Partie 2: Détermination de la variation structurelle dans le temps (thixotropie) (ISO/TR 20659-2:2024)
Reološke preskusne metode - Osnovni principi in medlaboratorijske primerjave - 2. del: Določanje spremembe strukture v odvisnosti od časa (tiksotropija) (ISO/TR 20659-2:2024)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2025
Reološke preskusne metode - Osnovni principi in medlaboratorijske primerjave -
2. del: Določanje spremembe strukture v odvisnosti od časa (tiksotropija) (ISO/TR
20659-2:2024)
Rheological test methods - Fundamentals and interlaboratory comparisons - Part 2:
Determination of the time-dependent structural change (thixotropy) (ISO/TR 20659-
2:2024)
Rheologische Prüfverfahren - Grundlagen und Ringversuch - Teil 2: Thixotropie (ISO/TR
20659-2:2024)
Méthodes d'essai rhéologiques - Principes fondamentaux et comparaisons
interlaboratoires - Partie 2: Détermination de la variation structurelle dans le temps
(thixotropie) (ISO/TR 20659-2:2024)
Ta slovenski standard je istoveten z: CEN ISO/TR 20659-2:2024
ICS:
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN ISO/TR 20659-2
TECHNICAL REPORT
RAPPORT TECHNIQUE
October 2024
TECHNISCHER REPORT
ICS 87.040
English Version
Rheological test methods - Fundamentals and
interlaboratory comparisons - Part 2: Determination of the
time-dependent structural change (thixotropy) (ISO/TR
20659-2:2024)
Méthodes d'essai rhéologiques - Principes Rheologische Prüfverfahren - Grundlagen und
fondamentaux et comparaisons interlaboratoires - Ringversuch - Teil 2: Thixotropie (ISO/TR 20659-
Partie 2: Détermination de la variation structurelle 2:2024)
dans le temps (thixotropie) (ISO/TR 20659-2:2024)
This Technical Report was approved by CEN on 6 October 2024. It has been drawn up by the Technical Committee CEN/TC 139.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye 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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TR 20659-2:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (CEN ISO/TR 20659-2:2024) has been prepared by Technical Committee ISO/TC 35
"Paints and varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes”
the secretariat of which is held by DIN.
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.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
Endorsement notice
The text of ISO/TR 20659-2:2024 has been approved by CEN as CEN ISO/TR 20659-2:2024 without any
modification.
Technical
Report
ISO/TR 20659-2
First edition
Rheological test methods —
2024-03
Fundamentals and interlaboratory
comparisons —
Part 2:
Determination of the time-
dependent structural change
(thixotropy)
Méthodes d'essai rhéologiques — Principes fondamentaux et
comparaisons interlaboratoires —
Partie 2: Détermination de la variation structurelle dans le temps
(thixotropie)
Reference number
ISO/TR 20659-2:2024(en) © ISO 2024
ISO/TR 20659-2:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
ISO/TR 20659-2:2024(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measuring technique for the determination of thixotropy . 1
4.1 Conditions for the measuring technique .1
4.2 Flow curves, with evaluation of the hysteresis area (rotational test) .3
4.2.1 Specification of the measuring profile .3
4.2.2 Evaluation .5
4.3 Step test with recovery, as a rotational test with controlled shear rate .7
4.3.1 Specification of the measuring programme .7
4.3.2 Evaluation .8
4.4 Step test with recovery, as a rotational test with alternating controlled shear stress
and shear rate .9
4.4.1 Specification of the measuring programme .9
4.4.2 Evaluation .10
4.5 Step test with recovery, as a combined oscillatory and rotational test with controlled
shear strain and shear rate, respectively .10
4.5.1 Specification of the measuring programme .10
4.5.2 Evaluation . .11
5 Comparative testing programme . 14
5.1 Aim of the comparative testing programme.14
5.2 Performance of the tests .14
5.2.1 Preliminary test .14
5.2.2 Comparative testing programme . 15
5.3 Evaluation . 15
6 Result.16
6.1 General .16
6.2 Measurement of the Newtonian reference sample .17
6.2.1 Flow curve .17
6.3 Step test with specification of the shear rate in measuring segments 1 and 3 .17
6.4 Step test with controlled shear stress in measuring segments 1 and 3 .18
6.5 Step test as oscillatory test in measuring segments 1 and 3 .18
7 Analysis . .18
Annex A (informative) Details of the comparative testing programme .20
Annex B (informative) Explanatory notes .34
Bibliography .36
iii
ISO/TR 20659-2:2024(en)
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
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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)
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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.
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This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9,
General test methods for paints and varnishes.
A list of all parts in the ISO 20659 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
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SIST-TP C
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