EN ISO 6721-1:1996
(Main)Plastics - Determination of dynamic mechanical properties - Part 1: General principles (ISO 6721-1:1994, including Technical Corrigendum 1:1995)
Plastics - Determination of dynamic mechanical properties - Part 1: General principles (ISO 6721-1:1994, including Technical Corrigendum 1:1995)
Kunststoffe - Bestimmung dynamisch-mechanischer Eigenschaften - Teil 1: Allgemeine Grundlagen (ISO 6721-1:1994, einschließlich Technische Korrektur 1:1995)
Diese Internationale Norm legt Verfahren fest zur Bestimmung der dynamisch- mechanischen Eigenschaften von steifen Kunststoffen im Bereich des linear- viskoelastischen Verhaltens. Teil 1 ist ein Einführungsteil, der die Definitionen und alle Gesichtspunkte enthält, die für die einzelnen, in den folgenden Teilen beschrieben Prüfverfahren gemeinsam sind. Unterschiedliche Deformationsarten können Ergebnisse hervorrufen, die nicht direkt vergleichbar sind.
Plastiques - Détermination des propriétés mécaniques dynamiques - Partie 1: Principes généraux (ISO 6721-1:1994, Rectificatif Technique 1:1995 inclus)
Polimerni materiali – Določevanje dinamičnih mehanskih lastnosti – 1. del: Splošna načela (ISO 6721-1:1994, vključno s tehničnim popravkom 1:1995)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 6721-1:1999
01-maj-1999
3ROLPHUQLPDWHULDOL±'RORþHYDQMHGLQDPLþQLKPHKDQVNLKODVWQRVWL±GHO
6SORãQDQDþHOD ,62 YNOMXþQRVWHKQLþQLPSRSUDYNRP
Plastics - Determination of dynamic mechanical properties - Part 1: General principles
(ISO 6721-1:1994, including Technical Corrigendum 1:1995)
Kunststoffe - Bestimmung dynamisch-mechanischer Eigenschaften - Teil 1: Allgemeine
Grundlagen (ISO 6721-1:1994, einschließlich Technische Korrektur 1:1995)
Plastiques - Détermination des propriétés mécaniques dynamiques - Partie 1: Principes
généraux (ISO 6721-1:1994, Rectificatif Technique 1:1995 inclus)
Ta slovenski standard je istoveten z: EN ISO 6721-1:1996
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 6721-1:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST EN ISO 6721-1:1999
---------------------- Page: 2 ----------------------
SIST EN ISO 6721-1:1999
---------------------- Page: 3 ----------------------
SIST EN ISO 6721-1:1999
---------------------- Page: 4 ----------------------
SIST EN ISO 6721-1:1999
INTERNATIONAL ISO
STANDARD 6721-1
First editicn
1994-11-01
- Determination of dynamic
Plastics
mechanical properties -
Part 1:
General principles
- D&ermination des propriet& mkaniques dynamiques -
Plas tiques
Partie 7: Principes g&Waux
Reference number
ISO 6721-1:1994(E)
---------------------- Page: 5 ----------------------
SIST EN ISO 6721-1:1999
ISO 6721=1:1994(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. Esch 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.
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.
International Standard ISO 6721-1 was prepared by Technical Committee
ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical properties.
Together with ISO 6721-2 and ISO 6721-3, it cancels and replaces
ISO 537:i989 and ISO 6721:1983, which have been technically revised.
ISO 6721 consists of the following Parts, under the general title
Plas tics - Determination of dynamic mechanical properties:
- Part 1: General principles
- Part 2: Torsion-pendulum method
- Part 3: Flexural Vibration - Resonance-curve method
- Part 4: Tensile vibra tion - Non-resonance method
- Part 5: Flexural vibra tion - Non-resonance method
- Part 6: Shear Vibration - Non-resonance method
- Part 7: Torsional Vibration - Non-resonance method
Additional Parts are planned.
Annexes A, B and C of this part of ISO 6721 are for information only.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, rncluding photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Gase Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 6 ----------------------
SIST EN ISO 6721-1:1999
0 ISO
ISO 6721=1:1994(E)
Introduction
The methods specified in the various Parts of ISO 6721 tan be used for
determining storage and loss moduli of plastics over a range of tempera-
tures or frequencies by varying the temperature of the specimen or the
frequency of oscillation. Plots of the storage or loss moduli, or both, are
indicative of viscoelastic characteristics of the specimen. Regions of rapid
changes in viscoelastic properties at particular temperatures or fre-
quencies are normally referred to as transition regions. Furthermore, from
the temperature and frequency dependencies of the loss moduli, the
damping of Sound and Vibration of polymer or metal-polymer Systems tan
be estimated.
Apparent discrepancies may arise in results obtained under different ex-
perimental conditions. Without changing the observed data, reporting in
full (as described in the various Parts of ISO 6721) the conditions under
which the data were obtained will enable apparent differentes observed
in different studies to be reconciled.
The definitions of complex moduli apply exactly only to sinusoidal oscilla-
tions with constant amplitude and constant frequency during each
measurement. On the other hand, measurements of small Phase angles
between stress and strain involve some difficulties under these condi-
tions. Because these difficulties are not involved in some methods based
on freely decaying vibrations and/or varying frequency near resonance,
these methods are used frequently (see part 2 and part 3). In these cases,
some of the equations that define the viscoelastic properties are only ap-
proximately valid.
---------------------- Page: 7 ----------------------
SIST EN ISO 6721-1:1999
This page intentionally left blank
---------------------- Page: 8 ----------------------
SIST EN ISO 6721-1:1999
INTERNATIONAL STANDARD 0 ISO
ISO 6721=1:1994(E)
Plastics - Determination of dynamic mechanical
properties -
Part 1:
General principles
Standards indicated below. Members of IEC and ISO
1 Scope
maintain registers of currently valid International
Standards.
The various Parts of ISO 6721 specify methods for the
determination of the dynamic mechanical properties
ISO 291:1977, Plastics
- Standard atmospheres for
of rigid plastics within the region of linear viscoelastic
conditioning and testing.
behaviour. Part 1 is an introductory section which in-
cludes the definitions and all aspects that are com-
ISO 293: 1986, Plastics
- Compression moulding test
mon to the individual test methods described in the
specimens o f thermoplas tic ma terials.
subsequent Parts.
ISO 294:--J, Plastics - Injection moulding of test
Different deformation modes may produce results
specimens o f thermoplas tic ma terials.
that are not directly comparable. For example, tensile
Vibration results in a stress which is uniform across
ISO 295: 1991, Plastics
- Compression moulding of
the whole thickness of the specimen, whereas
test specimens of thermosetting materials.
flexural measurements are influenced preferentially
by the properties of the surface regions of the speci-
ISO 1268: 1974, Plastics
- Preparation of glass fibre
men.
reinforced, resin bonded, low-pressure lamina ted
plates or Panels for test purposes.
Values derived from flexural-test data will be compa-
rable to those derived from tensile-test data only at
ISO 2818:1994, Plastics - Preparation of test speci-
strain levels where the stress-strain relationship is
mens by machining.
linear and for specimens which have a homogeneous
structure.
ISO 4593:1993, Plastics - Film and sheeting - De-
termina tion of thickness by mechanical scanning.
ISO 6721-2:1994, Plastics - Determination of dy-
2 Normative references
namic mechanical proper-Ges - Part 2: Torsion-
pendulum method.
The following Standards contain provisions which,
through reference in this text, constitute provisions
ISO 6721-3:1994, Plastics - Determination of dy-
of this part of ISO 6721. At the time of publication, the
namic mechanical properties - Part 3: Flexural vi-
editions indicated were valid. All Standards are subject
bra tion - ßesonance-curve method.
to revision, and Parties to agreements based on this
part of ISO 6721 are encouraged to investigate the
possibility of applying the most recent editions of the
1) To be published. (Revision of ISO 294:1975)
1
---------------------- Page: 9 ----------------------
SIST EN ISO 6721-1:1999
ISO 672%1:1994(E) 0 ISO
5 The uniaxial-strain modulus L is based upon a load with
3 Definitions
a high hydrostatic-stress component. Therefore values of L,
compensate for the lack of K values, and the “volume
For the purposes of the various Parts of this Inter-
term” 1 - 2~ tan be estimated with sufficient accuracy
national Standard, the following definitions apply.
based upon the modulus pairs (G, L) and (E, L). The pair
(G, L) is preferred, because G is based upon loads without
NOTE 1
Most of the terms defined her-e are also defined
a hydrostatic component.
in ISO 472:1988, Plastics - Vocabuhy. The definitions
given here are not strictly identical with, but are equivalent
6 T ‘he relationships given i
n table 1 are valid for the com-
to, those in ISO 472:1988.
plex moduli as well as their
magnitudes (see 3 .4).
3.1 complex modulus, M*: The ratio of dynamic
7 Most of the relationships for calculating the moduli given
aA exp(i2nft), and dynamic
stress, given by a(t) =
in the other Parts of this International Standard are, to some
strain, given by E(t) = &A exp[i(2Kft - S)], of a visco- extent, approximate. They do not take into account e.g.
“end effects” caused by clamping the specimens, and they
elastic material that is subjected to a sinusoidal vi-
include other simplifications. Using the relationships grven
bration, where aA and &A are the amplitudes of the
in table 1 therefore often requires additional corrections to
stress and strain cycles, f is the frequency, 6 is the
be made. These are given in the Iiterature (see e.g. refer-
Phase angle between stress and strain (see 3.5 and
ences [l] and [2] in the bibliography).
figure 1) and t is time.
8 For linea r-viscoelastic be haviour, the compl ex com-
lt is expressed in Pascals (Pa).
pliance C’ is the reciproca I of the com plex modulu s M*, i.e.
M* = (c*)-’
Depending on the mode of deformation, the complex
. . .
(2)
modulus may be one of several types: E ’, G*, K* or
L* (see table 3).
Thus
C’ - ic”
= M’ + iM”
(see 3.2 and 3.3) . . . (1)
M* M’ + $4” =
. . .
(3)
(cr)’ + (q*
i = (_ l)“* = J- 1
3.2 storage modulus, M ’: The real part of the com-
plex modulus M* [see figure 1 b)].
For the relationships between the different types of
complex modulus, see table 1.
The storage modulus is expressed in Pascals (Pa).
NOTES
lt is proportional to the maximum energy stored dur-
ing a loading cycle and represents the stiffness of a
2 For isotropic viscoelastic materials, only two of the
viscoelastic material.
elastic Parameters G ’, E*, K ’, L’ and p* are independent (p*
is the complex Poisson ’s ratio, given by p* = p’ + iV ”).
The different types of storage modulus, correspond-
ing to different modes of deformation, are: E ’, tensile
3 The most critical term containing Poisson ’s ratio ,U is the
storage modulus, E ’, flexural storage modulus, G ’,
“volume term” 1 - 2~, which has values between 0 and 0,4
for ,Y between 0,5 and 0,3. The relationships in table 1 con- shear storage modulus, G ’,, torsional storage modu-
taining the “volume term” 1 - 2~ tan only be used if this
lus, K’ bulk storage modulus, L ’, uniaxial-strain and
term is known with sufficient accuracy.
L ’, longitudinal-wave storage modulus.
lt tan be seen from table 1 that the volumetric term 1 - 2~
tan only be estimated with any confidence from a know-
3.3 loss modulus, M ”: The imaginary part of the
ledge of the bulk modulus K or the uniaxial-strain modulus
complex modulus [see figure 1 b)].
L and either E or G. This is because K and L measurements
involve deformations when the volumetric strain component
The loss modulus is expressed in Pascals (Pa).
is relatively large.
lt is proportional to the energy dissipated (lost) during
4 Up to now, no measurements of the bulk modulus K,
one loading cycle. As with the storage modulus (see
and only a small number of results relating to relaxation ex-
3.2), the mode of deformation is designated as in ta-
periments measuring K(t), have been described in the liter-
ature. ble3, e.g. E ”, is the tensile loss modulus.
2
---------------------- Page: 10 ----------------------
SIST EN ISO 6721-1:1999
ISO 6721=1:1994(E)
r
a) The Phase shift 6/2nf between the stress d and strain E in a b) The relationship between the storage modutus M ’,
viscoelastic material subjected to sinusoidal oscillation (dA and EA are the loss modulus M ”, the Phase angle 6 and the
the respective amplitudes, f is the frequency). magnitude IM1 of the complex modulus M*.
Figure 1 - Phase angle and complex modulus
Table 1 - Relationships between moduli for uniformly isotropic materials
s
G and p E and p K and p
G and E G and K E and K G and L 1)
Poisson ’s ratio, p
1
3: -- - GIK E
1-2p =2)
1 +G/3K 3K TjE=T
3K(l - 2,~)
E
E
Shear modulus, G =
w +/4 3 - E/3K
31 + P>
3G( 1 - 4G/3L)
3K(l - 24 3G
2w + P)
Tensile modulus, E =
1 +G/3K
1 -G/L
E G
2w + CL)
Bulk modulus, K = 3) -
3(3G/E - 1) L4G 3
31 - a-4 31 - &4
Unaxial-strain or
G(4G/E - 1) K( 1 + E/3K)
2w - l-4 E(l --l-4 Wl -P>
longitudinal-wave modu-
l+P 3G/E - 1 K+F 1 - E/9K
lus, L = 1-2p (1 + /NI - 2P)
1) See note 5.
2) See note 3.
3) See note 4.
3
---------------------- Page: 11 ----------------------
SIST EN ISO 6721-1:1999
0 ISO
ISO 6721=1:1994(E)
tem undergoing freely decaying vibrations (sec
3.4 magnitude IM1 of the complex modulus: The
figure3), given by the equation
root mean Square value of the storage and the loss
moduli as given by the equation
X(t) = X. exp( - ßt) x sin 2n.&t . . .
(6)
. . . (4)
IMl* = (M ’)* + (M,,)* = (oA/JzA)*
where
plitudes of the stress and
where OA and &A are the am
is the magnit ude, at zero time, of the en-
.
the strain cycles, respective XO
IY
velope of the
cycle a mplitudes;
The complex modulus is expressed in Pascals (Pa).
is the frequency of the damped System;
fd
The relationship between the storage modulus M ’, the
is the decay constant (see 3.9).
ß
loss modulus M ”, the Phase angle 6, and the magni-
tude IM1 of the complex modulus is shown in
3.9 decay constant, ß: The coefficient that deter-
figure 1 b). As with the storage modulus, the mode of
mines the time-dependent decay of damped free vi-
deformation is designated as in table3, e.g. IEtl is the
brations, i.e. the time dependence of the amplitude
magnitude of the tensile complex modulus.
X+, of the deformation or deformation rate [see
figure3 and equation (6)].
3.5 Phase angle, 6: The Phase differente between
the dynamic stress and the dynamic strain in a visco-
The decay constant is expressed in reciprocal sec-
elastic material subjected to a sinusoidal oscillation
onds (s- ‘).
(see figure 1).
3.10 logarithmic decrement, A: The natura1 log-
The Phase angle is expressed in radians (r-ad).
arithm of the ratio of two successive amplitudes, in
As with the storage modulus (see 3.2) the mode of
the same direction, of damped free oscillations of a
deformation is designated as in table3, e.g. 6, is the
viscoelastic System (see figure3), given by the
tensile Phase angle.
equation
. . .
A = ‘n(Xy/Xy+ 1) (7)
3.6 loss factor (tan 6): The ratio between the loss
modulus and the storage modulus, given by the
where Xq and X two successive amplitudes of
equation q+l arc
deformati on 0 r deforma tion rate in the s ame direction.
tan 6 = M ”/M, . . .
(5)
The logarithmic decrement is expressed as a
where 6 is the Phase angle (see 3.5) between the
dimensionless number.
stress and the strain.
lt is used as a measure of the damping in a visco-
factor is expressed as a dimensionless
The loss
elastic System.
number.
Expressed in terms of the decay constant ß and the
The loss factor tan 6 is commonly used as a measure
frequency fd, the logarithmic decrement is given by
of the damping in a viscoelastic System. As with the
the equation
storage modulus (see 3.2), the mode of deformation
. . .
A = ß/!fd (8)
is designated as in table3, e.g. tan 6, is the tensile
loss factor.
The loss factor tan 6 is related to the
logarithmic
decrement by the approximate equation
3.7 stress-strain hysteresis loop: The stress ex-
pressed as a function of the strain in a viscoelastic
tan 6 N n/7c . . .
(9)
material subject to sinusoidal vibrations. Provided the
viscoelasticity is linear in nature, this curve is an el-
NOTE 9 Damped freely decaying vibrations are especially
lipse (see figure 2).
suitable for analysing the type of damping in the material
under test (i.e. whether the viscoelastic behaviour is linear
Vibration: The time-d e pendent defor-
3.8 damped
or non-linear) and the friction between moving and fixed
rmation ra te X(t) of a V iscoelast
mation or defo IC sys- components of the apparatus (see annex B).
---------------------- Page: 12 ----------------------
SIST EN ISO 6721-1:1999
ISO 6721=1:1994(E)
b
Dynamit stress-strain hysteresis loop for a linear-viscoelastic material subject to sinusoidal
Figure 2 -
tensile vibrations
5
---------------------- Page: 13 ----------------------
SIST EN ISO 6721-1:1999
ISO 6721=1:1994(E)
%
xo exp k- pt>
XO
l/f,
Damped-Vibration curve for a viscoelastic System undergoing freely decaying vibrations
Figure 3 -
[X is the time-dependent deformation or deformation rate, Xq is the amplitude of the qth cycle and XO and ß
define the envelope of the exponential decay of the cycle amplitudes - see equation (6).]
6
---------------------- Page: 14 ----------------------
SIST EN ISO 6721-1:1999
0 ISO
ISO 6721=1:1994(E)
exhibits high loss. Under these conditions, resonance tests
3.11 resonance curve: The curve representing the
are not suitable.
frequency dependence of the deformation amplitude
D, or deformation-rate amplitude & of an inert visco-
3.13 width of a resonance peak, AA: The differente
elastic System subjected to forced vibrations at con-
between the frequencies fi and f2 of the ith-Order
stant load amplitude LA and at frequencies close to
resonance peak, where the height &, of the reson-
and including resonance (see figure4 and annex A).
ante curve at fI and f2 is related to the peak height
3.12 resonance frequencies, fri: The frequencies of R AMi Of the ith mode by
the peak amplitudes in a resonance curve. The sub-
- 1/2
2 Rp,, = 0,707R~~ . . .
RAh = (10)
script i refers to the Order of the resonance Vibration.
(see figure 4)
Resonance frequencies are expressed in hertz (Hz).
The width AA is expressed in hertz (Hz).
NOTE 10 Resonance frequencies for viscoelastic ma-
terials derived from measurements of displacement ampli-
lt is related to the loss factor tan 6 by the equation
tude will be slightly different from those obtained from
displacement-rate measurements, the differente being
ta n 6 = AJlfii . . .
(11)
larger the greater the loss in the material (see annex A).
Storage and loss moduli are accurately related by simple
If the loss factor does not vary markedly over the
expressions to resonance frequencies obtained from
frequency range defined by Af;, equation (1 1) holds
The use of resonance fre-
displacement-rate curves.
exactly when the resonance curve is based on the
quencies based on displacement measurements leads to a
small error which is only significant when the specimen deformation-rate amplitude (see also annex A).
RAM
RAh
f
fl ri f2 f
Figure 4 - Resonance curve for a viscoelastic System subjected to forced vibrations (Deformation-rate
amplitude RA versus frequency f at constant load amplitude; logarithmic frequency scale)
---------------------- Page: 15 ----------------------
SIST EN ISO 6721-1:1999
ISO 6721=1:1994(E) 0 ISO
natura1 (resonant) or near-resonant. These modes are
4 Principle
described in table 2.
A specimen of known geometry is subjected to
The particular type of modulus depends upon the
mechanical oscillation, described by two character-
mode of deformation (see table 3).
istics: the mode of Vibration and the mode of defor-
mation. Table4 indicates ways in which the various types of
modulus are commonly measured. Table 5 gives a
Four oscillatory modes, I to IV, are possible, depend- summary of the methods covered by the various Parts
of this International Standard.
ing on whether the mode of Vibration is non-reson
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.