ISO 6721-10:2015

INTERNATIONAL ISO
STANDARD 6721-10
Third edition
2015-09-15
Plastics — Determination of dynamic
mechanical properties —
Part 10:
Complex shear viscosity using a
parallel-plate oscillatory rheometer
Plastiques — Détermination des propriétés mécaniques dynamiques —
Partie 10: Viscosité complexe en cisaillement à l’aide d’un rhéomètre
à oscillations à plateaux parallèles
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
5.1 Measurement apparatus . 2
5.2 Temperature-controlled enclosure . 3
5.3 Temperature measurement and control . 3
5.4 Plate/specimen assembly . 4
5.5 Calibration . 4
6 Sampling . 4
7 Procedure. 5
7.1 Test temperature . 5
7.2 Zeroing the gap . 5
7.3 Introducing the test specimen . 5
7.4 Conditioning the test specimen . 5
7.5 Test mode (controlled stress or controlled strain) . 5
7.6 Determination of thermal stability of sample material . 6
7.7 Determination of region of linear-viscoelastic behaviour . 6
7.7.1 In the controlled-strain mode. 6
7.7.2 In the controlled-stress mode . 6
7.7.3 Confirmation of linear-viscoelastic behaviour . 7
7.8 Frequency sweep . 7
7.9 Temperature sweep . 7
7.10 Air entrapment. 7
8 Expression of results . 7
8.1 Symbols used . 7
8.2 Calculation of complex shear modulus and complex shear viscosity . 8
9 Precision .10
10 Test report .11
Annex A (informative) Uncertainty limits .12
Annex B (informative) Verification of rheometer performance .15
Bibliography .19
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
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committee has been established has the right to be represented on that committee. International
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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
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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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.
The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
This third edition cancels and replaces the second edition (ISO 6721-10:1999), which has been technically
revised to include informative guidance on verification of the instruments performance (Annex B).
ISO 6721 consists of the following parts, under the general title Plastics — Determination of dynamic
mechanical properties:
— Part 1: General principles
— Part 2: Torsion-pendulum method
— Part 3: Flexural vibration — Resonance-curve method
— Part 4: Tensile vibration — Non-resonance method
— Part 5: Flexural vibration — Non-resonance method
— Part 6: Shear vibration — Non-resonance method
— Part 7: Torsional vibration — Non-resonance method
— Part 8: Longitudinal and shear vibration — Wave-propagation method
— Part 9: Tensile vibration — Sonic-pulse propagation method
— Part 10: Complex shear viscosity using a parallel-plate oscillatory rheometer
— Part 11: Glass transition temperature
— Part 12: Compressive vibration — Non-resonance method
Annex A and Annex B of this part of ISO 6721 is for information only.
iv © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 6721-10:2015(E)
Plastics — Determination of dynamic mechanical
properties —
Part 10:
Complex shear viscosity using a parallel-plate oscillatory
rheometer
1 Scope
This part of ISO 6721 specifies the general principles of a method for determining the dynamic
-1
rheological properties of polymer melts at angular frequencies typically in the range of 0,01 rad·s to
-1
100 rad·s by means of an oscillatory rheometer with a parallel-plate geometry. Angular frequencies
outside this range can also be used (see Note 1). The method is used to determine values of the following
dynamic rheological properties: complex shear viscosity η*, dynamic shear viscosity η’, the out-of-phase
component of the complex shear viscosity η”, complex shear modulus G*, shear loss modulus G”, and
shear storage modulus G’. It is suitable for measuring complex shear viscosity values typically up to
~10 MPa·s (see Note 2).
NOTE 1 The angular-frequency measurement range is limited by the specification of the measuring instrument
–1
and also by the response of the specimen. When testing using angular frequencies lower than 0,1 rad·s , the test
time can increase significantly as the time taken to obtain a single measurement is proportional to the reciprocal
of the angular frequency. Consequently, when testing at low angular frequencies, degradation or polymerization
of the specimen is more likely to occur and have an effect on the results. At high angular frequencies, the specimen
can distort or fracture at the edge, consequently invalidating the test results.
NOTE 2 The range of complex shear viscosity values that can be measured is dependent on the specimen
dimensions and also the specification of the measuring instrument. For a specimen of given dimensions, the
upper limit of the range is limited by the machine’s torque capacity, angular-displacement resolution, and
compliance. However, correction can be made for compliance effects.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. 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 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
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, ISO 5725-1, ISO 472,
and the following apply.
3.1
controlled-strain mode
testing by applying a sinusoidal angular displacement of constant amplitude
3.2
controlled-stress mode
testing by applying a sinusoidal torque of constant amplitude
3.3
complex shear viscosity
η*
ratio of dynamic stress, given by σ(t) = σ exp iωt, and dynamic rate of strain where the shear strain

γ t is given by γ(t) = γ exp i(ωt - δ), of a viscoelastic material that is subjected to a sinusoidal vibration,
() 0
where σ and γ are the amplitudes of the stress and strain cycles, ω is the angular frequency, δ is the
0 0
phase angle between the stress and strain, and t is time
Note 1 to entry: It is expressed in pascal seconds.
3.4
dynamic shear viscosity
η’
real part of the complex shear viscosity
Note 1 to entry: It is expressed in pascal seconds.
3.5
out-of-phase component of the complex shear viscosity
η”
imaginary part of the complex shear viscosity
Note 1 to entry: It is expressed in pascal seconds.
4 Principle
The specimen is held between two concentric, circular parallel plates (see Figure 1). The thickness of
the specimen is small compared with the diameter
...