ISO 13145:2012
(Main)Rubber — Determination of viscosity and stress relaxation using a rotorless sealed shear rheometer
Rubber — Determination of viscosity and stress relaxation using a rotorless sealed shear rheometer
ISO 13145:2012 describes a method for the determination of the viscosity and stress relaxation of raw or compounded rubber under specified conditions. The viscosity determination consists of a constant strain, temperature and frequency test in which the elastic and the loss components of the complex shear modulus can be determined. The determination of stress relaxation consists of a constant static strain and temperature test in which the torque decrease can be determined.
Caoutchouc — Détermination de la viscosité et de la relaxation de contrainte au moyen d'un rhéomètre à cisaillement sans rotor étanche
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 13145
First edition
2012-09-15
Rubber — Determination of viscosity
and stress relaxation using a rotorless
sealed shear rheometer
Caoutchouc — Détermination de la viscosité et de la relaxation de
contrainte au moyen d’un rhéomètre à cisaillement sans rotor étanche
Reference number
ISO 13145:2012(E)
©
ISO 2012
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ISO 13145:2012(E)
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© ISO 2012
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ii © ISO 2012 – All rights reserved
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ISO 13145:2012(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 3
5.1 General . 3
5.2 Die cavity . 3
5.3 Die closure . 3
5.4 Movement . 3
5.5 Heating and temperature control . 4
5.6 Torque-measuring system . 4
6 Calibration . 6
7 Test piece . 6
7.1 Preparation of the test piece . 6
7.2 Protective films . 6
8 Temperature . 6
9 Procedure. 7
9.1 Testing sequence . 7
9.2 Preparation for the test . 7
9.3 Rheometer loading . 7
10 Reporting of results . 7
10.1 Examples of reporting results . 7
10.2 Basic expression of results . 7
10.3 Additional results . 8
10.4 Stress relaxation test results . 8
11 Precision . 8
12 Test report . 8
Annex A (normative) Calibration schedule .10
Annex B (informative) Precision data .12
Bibliography .14
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ISO 13145:2012(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 13145 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee
SC 2, Testing and analysis.
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ISO 13145:2012(E)
Introduction
The rheological properties of rubbers are related to their structural characteristics and will influence
the behaviour of the rubber during processing and the performance of the final product.
For these reasons, the industrial environment requires instruments that can quickly and easily evaluate
the rheological properties.
As a consequence, this standard test method was formulated using a rotorless sealed shear rheometer
for rheological evaluation under defined conditions.
This test could be an alternative to the Mooney viscometer, still used as standard in many parts of the
rubber industry to measure Mooney viscosity (in accordance with ISO 289-1). The defined conditions
have been selected to provide a shear rate range similar to that used for Mooney viscosity and a good
repeatability level.
This new test procedure should be performed over a short time and preferably in the automatic mode to
optimize test efficiency.
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INTERNATIONAL STANDARD ISO 13145:2012(E)
Rubber — Determination of viscosity and stress relaxation
using a rotorless sealed shear rheometer
WARNING — Persons using this International Standard should be familiar with normal laboratory
practice. This standard does not purport to address all of the safety problems, if any, associated
with its use. It is the responsibility of the user to establish appropriate safety and health practices
and to ensure compliance with any national regulatory conditions.
1 Scope
This International Standard describes a method for the determination of the viscosity and stress
relaxation of raw or compounded rubber under specified conditions.
The viscosity determination consists of a constant strain, temperature and frequency test in which the
elastic and the loss components of the complex shear modulus can be determined.
The determination of stress relaxation consists of a constant static strain and temperature test in which
the torque decrease can be determined.
2 Normative references
The following referenced documents are indispensable for the application 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 1382, Rubber — Vocabulary
ISO 18899:2004, Rubber — Guide to the calibration of test equipment
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 1382 and the following apply.
3.1
rotorless sealed shear rheometer
device consisting of two dies forming a temperature-controlled cavity, one of which is moved relative to
the other to apply a stress or strain to the test piece
3.2
sinusoidal strain
γ(t)
strain produced by the oscillation of the die constituting the test cavity
NOTE It is given by the expression γ(t) = γ sin(ωt), where γ is the maximum amplitude of the applied strain.
0 0
3.3
loss angle
δ
phase angle between the stress and the strain
NOTE This is a measure of the presence and extent of viscous behaviour in a material. For viscoelastic
materials, the phase angle can assume a value between 0° and 90°. 90° is an ideal Newtonian liquid.
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ISO 13145:2012(E)
3.4
complex torque
S*
torque measured by the machine due to application of sinusoidal strain
NOTE The complex torque is a vector which can be represented by a complex number, viz S* = S’ + iS”.
3.5
elastic torque
S’
component of torque that is in phase with the imposed sinusoidal strain
NOTE It is given by the equation S’ = |S*|cosδ.
3.6
loss torque
S”
component of torque that is in quadrature with the imposed sinusoidal strain
NOTE It is given by the equation S” = |S*|sinδ.
3.7
complex shear modulus
G*
ratio of the shear stress to the shear strain, where each is a vector which can be represented by a
complex number
NOTE 1 It is given by the equation G* = G’ + iG”.
NOTE 2 The complex shear modulus is determined by dividing the complex torque S* by the applied strain and
multiplying by a geometric factor related to the cavity shape.
3.8
elastic shear modulus
G’
component of the applied shear stress that is in phase with the shear strain, divided by the strain
NOTE It is given by the equation G’ = |G*|cosδ.
3.9
loss shear modulus
G”
component of the applied shear stress which is in quadrature with the shear strain, divided by the strain
NOTE It is given by the equation G” = |G*|sinδ.
3.10
tangent of the loss angle
tanδ
ratio of the loss modulus to the elastic modulus
4 Principle
The torque generated in a test piece contained in a heated sealed cavity formed by two dies, one of which
can be oscillated through a small amplitude, is measured.
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ISO 13145:2012(E)
5 Apparatus
5.1 General
A rotorless sealed shear rheometer consists of two dies that are heated and closed, under a specified
force, to form a sealed test cavity that contains the test piece. One of the dies oscillates, and a measuring
system records the torque required to produce the relative movement. The elastic torque S’ and the
loss torque S” produced in a test piece by the strain due to the oscillation of the die can be measured at
specified conditions of temperature, frequency and amplitude.
The general arrangement of a rotorless sealed shear rheometer is shown in Figure 1, including typical
machine dimensions.
5.2 Die cavity
The dies shall be manufactured from a stiff material. The surface of the dies shall be treated to minimize
the effect of test piece contamination if protective or carrying film are not used and shall be hard
enough to prevent wear. A minimum Rockwell hardness of 50 HRC, or equivalent, is recommended. The
tolerances necessary on the dimensions of the dies depend on the particular design, but as a general
guide the dimensions of the cavity should be controlled to ±0,2 %.
The top and bottom surfaces of the cavity shall have a pattern of grooves of dimensions sufficient to
prevent slippage of the rubber test piece.
Holes shall be provided in both the upper and lower dies to accommodate temperature sensors. The
positions of the sensors relative to the cavity shall be controlled to ensure a reproducible response.
A seal of suitable low, constant friction shall be provided to prevent material leaking from the cavity.
Suitable means shall be employed, by design of the dies or otherwise, to apply pressure to the test piece
throughout the test to minimize slippage between the disc and the rubber.
5.3 Die closure
The dies shall be closed and held closed during the test by, for example, a pneumatic cylinder.
The closing force required depends on the clearance area; as a general guide, a minimum of 7 kN is
recommended. The contact of the die cavity edges shall be such as to form a perfectly sealed cavity.
5.4 Movement
The moving part in a rotorless instrument is one of the dies. The dies are usually biconical to produce a
substantially uniform shear rate, and this shape is useful to make the test piece loading and unloading
stages easier. The drive linkage shall be sufficiently stiff to prevent significant deformation.
A torsional oscillating movement shall be applied to one of the dies (typically the lower in the cavity) by
means of a motor.
The frequency of oscillation can be varied according to the instrument specification, but in this
International Standard a single frequency is selected.
The oscillation amplitude θ may be varied according to the deformation required. The maximum
is calculated considering the oscillation angle used in the test and the
amplitud
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