ISO 23673:2021

INTERNATIONAL ISO
STANDARD 23673
First edition
2021-05
Plastics — Elasticity index —
Determination of elastic property of
melts
Plastiques — Indice d'élasticité — Détermination de la propriété
élastique à l’état fondu
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
5.1 Measurement apparatus . 1
5.2 Temperature-controlled enclosure . 2
5.3 Temperature measurement and control . 2
5.4 Plate/specimen assembly . 2
5.5 Calibration . 2
6 Sampling . 2
7 Procedure. 2
7.1 Test temperature . 2
7.2 Zeroing the gap . 2
7.3 Introducing the test specimen . 2
7.4 Conditioning the test specimen . 2
7.5 Test mode (controlled stress or controlled strain) . 2
7.6 Determination of thermal stability of sample material . 3
7.7 Determination of region of linear-viscoelastic behaviour . 3
7.7.1 In the controlled-strain mode. 3
7.7.2 In the controlled-stress mode . 3
7.7.3 Confirmation of linear-viscoelastic behaviour . 3
7.8 Air entrapment. 3
8 Expression of results . 3
9 Test report . 4
Bibliography . 5
Foreword
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
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iv © ISO 2021 – All rights reserved

Introduction
Many thermoplastic materials show similar viscosities, but elastic properties can vary significantly,
which can lead to inappropriate applications.
The definition of an elasticity index describing the elastic properties of resins in a similar way as the
viscosity is indicated by the melt flow rate opens a possibility to designate the elastic properties using
a simple characteristic number.
Selecting G' at a particular frequency as elasticity index can no longer describe the complete behaviour
of materials with varying frequency. But considering the success MFR/MVR (see ISO 1133-1 and
ISO 1133-2) as characteristic numbers of viscosity the elasticity index provides a similar useful
characteristic number for the elasticity of materials.
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