Determination of the flowability and application behaviour of viscoelastic adhesives using the oscillatory rheometry

This document specifies a measuring method for the characterization of rheological properties of structural adhesives using oscillatory rheometry. The advantage of the method in comparison to rotational viscometry measurements lies in the separation of elastic and viscous material properties, thus allowing to define the viscoelastic properties. This enables more precise information concerning the flow behaviour of the materials, thereby resulting in a better understanding of their processing properties.
The method described is particularly suitable for filled and paste-like adhesives. These are frequently processed using automated pump and application systems in industrial applications and shall be set precisely considering their rheological properties. As the rheological behaviour of uncured adhesives is mostly independent of their properties in the cured state, the standard can also serve for the examination of non-structural adhesives.

Bestimmung des Fließ- und Applikationsverhaltens von viskoelastischen Klebstoffen mit Hilfe der Oszillationsrheometrie

Dieses Dokument legt ein Messverfahren zur Charakterisierung der rheologischen Eigenschaften von Strukturklebstoffen mit Hilfe der Oszillationsrheometrie fest. Außerdem kann das Prüfverfahren auch auf das reaktive Gemisch mehrerer Komponenten oder auf die Komponenten eines pastösen Reaktionsklebstoffes angewendet werden. Der Vorteil des Verfahrens gegenüber Rotationsviskosimetrie¬messungen liegt in der Auftrennung von elastischen und viskosen Materialeigenschaften, wodurch die Festlegung der viskoelastischen Eigenschaften ermöglicht wird. Dadurch sind genauere Informationen über das Fließverhalten der Stoffe zugänglich, die zu einem besseren Verständnis ihrer Verarbeitungs¬eigenschaften führen.
Das beschriebene Verfahren eignet sich insbesondere für gefüllte und pastöse Klebstoffe. Diese werden im industriellen Einsatz häufig unter Verwendung automatisierter Pump  und Auftragssysteme verarbeitet, und werden unter Beachtung ihrer rheologischen Eigenschaften präzise eingestellt. Da das rheologische Verhalten ungehärteter Klebstoffe meist unabhängig von ihren Eigenschaften im ausgehärteten Zustand ist, kann das Dokument auch zur Untersuchung nicht struktureller Klebstoffe dienen.

Détermination de l'attitude du fluage et de l'application des adhésifs viscoélastiques avec la méthode de la rhéologie oscillométrique

Le présent document spécifie une méthode de mesure permettant la caractérisation des propriétés rhéologiques des adhésifs structuraux en recourant à la rhéologie oscillométrique. En outre, le mode opératoire d’essai peut être appliqué au mélange réactif de plusieurs composants ou aux composants d’un matériau en pâte se liant par réaction. L'avantage de cette méthode par rapport aux mesurages de la viscosimétrie rotative réside dans la séparation des propriétés élastiques et visqueuses du matériau, permettant ainsi de définir les propriétés viscoélastiques. Ceci permet d'obtenir des informations plus précises concernant le comportement à l'écoulement des matériaux, avec pour résultat une meilleure compréhension de leurs propriétés d'application.
La méthode décrite convient particulièrement aux adhésifs chargés et en pâte. Leur utilisation fait fréquemment intervenir des systèmes automatisés de pompage et d'application dans les applications industrielles ; leur dosage doit être précis et tenir compte de leurs propriétés rhéologiques. Étant donné que le comportement rhéologique des adhésifs non durcis est très largement indépendant de leurs propriétés à l'état durci, le présent document peut également servir à l'examen d'adhésifs non structuraux.

Ugotavljanje sipkosti in uporabnosti viskoelastičnih lepil z uporabo oscilacijske reometrije

General Information

Status
Published
Public Enquiry End Date
11-Sep-2019
Publication Date
20-Sep-2020
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
17-Sep-2020
Due Date
22-Nov-2020
Completion Date
21-Sep-2020

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SLOVENSKI STANDARD
SIST EN 17408:2020
01-november-2020

Ugotavljanje sipkosti in uporabnosti viskoelastičnih lepil z uporabo oscilacijske

reometrije

Determination of the flowability and application behaviour of viscoelastic adhesives using

the oscillatory rheometry

Bestimmung des Fließ- und Applikationsverhaltens von viskoelastischen Klebstoffen mit

Hilfe der Oszillationsrheometrie

Détermination de l'attitude du fluage et de l'application des adhésifs viscoélastiques avec

la méthode de la rhéologie oscillométrique
Ta slovenski standard je istoveten z: EN 17408:2020
ICS:
83.180 Lepila Adhesives
SIST EN 17408:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 17408:2020
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SIST EN 17408:2020
EN 17408
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2020
EUROPÄISCHE NORM
ICS 83.180
English Version
Determination of the flowability and application behaviour
of viscoelastic adhesives using the oscillatory rheometry

Détermination de l'aptitude à l'écoulement et à Bestimmung des Fließ- und Applikationsverhaltens

l'application des adhésifs viscoélastiques avec la von viskoelastischen Klebstoffen mit Hilfe der

méthode de la rhéologie oscillométrique Oszillationsrheometrie
This European Standard was approved by CEN on 3 August 2020.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

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, Turkey 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

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17408:2020 E

worldwide for CEN national Members.
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SIST EN 17408:2020
EN 17408:2020 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

1 Scope .................................................................................................................................................................... 4

2 Normative references .................................................................................................................................... 4

3 Terms and definitions ................................................................................................................................... 4

4 Symbols and units ........................................................................................................................................ 12

5 Test method ................................................................................................................................................... 12

5.1 General ............................................................................................................................................................. 12

5.2 Principle of measurement ........................................................................................................................ 12

5.3 Standard test .................................................................................................................................................. 13

5.4 Extended test ................................................................................................................................................. 13

6 Test equipment ............................................................................................................................................. 13

6.1 Oscillatory rheometer ................................................................................................................................ 13

6.2 Measuring system ........................................................................................................................................ 14

6.3 Temperature controlling system ............................................................................................................ 15

6.4 Inerting ............................................................................................................................................................ 15

7 Sampling and sample preparation ......................................................................................................... 15

8 Implementation ............................................................................................................................................ 15

8.1 General ............................................................................................................................................................. 15

8.2 Setting parameters ...................................................................................................................................... 16

8.3 Standard test .................................................................................................................................................. 16

8.4 Extended test ................................................................................................................................................. 16

9 Interpretation ................................................................................................................................................ 16

10 Test report ...................................................................................................................................................... 18

Bibliography ................................................................................................................................................................. 19

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SIST EN 17408:2020
EN 17408:2020 (E)
European foreword

This document (EN 17408:2020) has been prepared by Technical Committee CEN/TC 193 “Adhesives”,

the secretariat of which is held by UNE.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by March 2021, and conflicting national standards shall

be withdrawn at the latest by March 2021.

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.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: 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, Turkey and the

United Kingdom.

SAFETY WARNING — Persons using this document are expected to be familiar with normal laboratory

practice. This document cannot address all safety problems that could be associated with its

application. It is the responsibility of the user to define measures for health and safety at work and

ensure that these correspond with the European and national regulations.

ENVIRONMENTAL PROTECTION NOTE — The materials approved in this document can have negative

effects on the environment. As soon as technological progress leads to better alternatives to these

materials, they will be removed from the standard as far as possible. At the end of the test, the user is

expected to ensure a suitable disposal of the waste according to regional conditions.

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SIST EN 17408:2020
EN 17408:2020 (E)
1 Scope

This document specifies a measuring method for the characterization of rheological properties of

structural adhesives using oscillatory rheometry. Moreover, the testing procedure can be applied to the

reactive mixture of several components or the components of a reactive bonding paste material. The

advantage of the method in comparison to rotational viscometry measurements lies in the separation of

elastic and viscous material properties, thus allowing the defining of the viscoelastic properties. This

enables more precise information concerning the flow behaviour of the materials, thereby resulting in a

better understanding of their processing properties.

The method described is particularly suitable for filled and paste-like adhesives. These are frequently

processed using automated pump and application systems in industrial applications and will be set

precisely considering their rheological properties. As the rheological behaviour of uncured adhesives is

mostly independent of their properties in the cured state, the document can also serve for the

examination of non-structural adhesives.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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.

EN 923, Adhesives - Terms and definitions
3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 923 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
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SIST EN 17408:2020
EN 17408:2020 (E)
3.1
shear deformation

relation of deflection s to the distance between the plates geometry or gap width H of a sample located

between two plates at linear deflection of the upper plate in accordance with the tangent of the angle of

deflection φ (see Figure 1)
γϕ= s / H = tan (1)
( )

Figure 1 — Deflection s and angle of deflection φ of the test portion in the shear gap H [1]

Note 1 to entry: For a circular deflection in the plate/plate measuring system of a rheometer, this relation only

applies for an infinitesimal surface element. The deflection here depends on the distance to the axis of rotation

and is hence not uniform within the shear gap. The deformation value is, therefore, usually related to the plate

edge (i.e. to r ), sometimes also to a mean distance to the axis of rotation (e.g. 2/3 r ). In this document, the

max max

plate edge is used as a reference value. The cone/plate configuration yields a constant deformation based on the

gap width H raise equivalent to the deflection s increasing outwards in the entire shear gap.

3.2
deformation function
γ (t)

mathematical representation of the sinusoidal change in the deformation during oscillatory tests with

controlled deformation
γγ tt= sin()ω (2)
( )
where
γ (t) is the deformation at the time point t;
γ is the maximum deformation (deformation amplitude);
ω is the angular frequency, in rad/s, with ω = 2 π f.
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SIST EN 17408:2020
EN 17408:2020 (E)
3.3
shear stress function
τ (t)

the deformation as phase-shifted sinusoidal function of the shear stress related to the response of the

sample located in the gap (see Figure 2)
τ ttτ sin ωδ + (3)
( ) ( )
where
τ (t) is the shear stress at the time point t;
τ is the maximum shear stress (shear stress amplitude);
ω is the angular frequency, in rad/s, with ω = 2 π f;
δ is the angle phase shift (loss angle).

Note 1 to entry: In the case of ideal-elastic behaviour (according to Hooke), the loss angle δ is 0°, i.e.

deformation and shear stress are always in the same phase. Maximum shear stress is measured at maximum

deformation. In the case of ideal-viscous behaviour (according to Newton), the loss angle δ = is 90°, i.e. the shear

stress curve is ahead of the deformation curve by 90°. The maximum shear stress at deformation zero results

here, i.e. at highest angular velocity of the test specimen.
Figure 2 — Deformation and shear stress function during oscillation test [3]
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SIST EN 17408:2020
EN 17408:2020 (E)
3.4
storage modulus

calculated from the energy stored during deformation, completely available for recovering after the end

of the deformation process
G′ = cos δ (4)
( )
where
τ is the maximum shear stress (shear stress amplitude);
γ is the maximum deformation (deformation amplitude);
δ is the angle phase shift (loss angle).

Note 1 to entry: The storage modulus represent the elastic portion of the applied energy and describes a typical

solid property (solid like).
3.5
loss modulus
G''

calculated from the energy irreversibly consumed during the deformation, dissipated as heat

G′′ = sin()δ (5)
where
τ is the maximum shear stress (shear stress amplitude);
γ is the maximum deformation (deformation amplitude);
δ is the angle phase shift (loss angle).

Note 1 to entry: The loss modulus represents the viscous (liquid like) portion of the applied energy dissipated

as heat or work.
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SIST EN 17408:2020
EN 17408:2020 (E)
3.6
complex shear modulus
vector sum of storage modulus G' and loss modulus G''
G τγ t / t G′′ + iG · ′ (6)
( ) ( )
* ' 2 '' 2
G GG+ (7)
where
τ (t) is the shear stress at the time point t;
γ (t) is the deformation at the time point t;
G' is the storage modulus;
G'' is the loss modulus;
i is the imaginary part.

Note 1 to entry: When performing oscillatory tests on ideally elastic materials, i.e. completely inflexible, stiff

and rigid solids, Hooke's Law applies, as indicated in Formula (6).

Note 2 to entry: All kinds of materials have a viscoelastic behaviour, this consists of a viscous and an elastic

portion. Their sum is the complex shear modulus G*, represented in the ‘complex plane’ (see Figure 3).

Figure 3 — Vector diagram showing G’, G'' and the resulting vector G*

Note 3 to entry: This plane is spread out using the ‘real axis’ (x-axis) and the ‘imaginary axis’ (y-axis) and the

imaginary unit i −1 is the ‘negative root’ that characterizes the complex number.

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SIST EN 17408:2020
EN 17408:2020 (E)
3.7
loss factor
tan (δ)
calculated as the quotient of loss modulus and storage modulus
tan δ = G"/ G' (8)
( )
where
G' is the storage modulus;
G'' is the loss modulus.

Note 1 to entry: The loss factor corresponds to the ratio between dissipated and reversibly stored deformation

energy.
3.8
complex viscosity

ratio between the time-dependent values of the stress and deformation of shear rate

ητ* = tt/ γ
(9)
( ) ( )
where
τ (t) is the shear stress at the time point t;
is the deformation or shear rate at the time point t.
(t)

Note 1 to entry: The complex viscosity is linked to the amount of the complex shear modulus via a simple

relation as shown in Formula 10.
|η*| Gf* / ω (with ωπ2 )
(10)

Note 2 to entry: Similar to the complex shear modulus, the complex viscosity also comprises an elastic and a

viscous component or better it is a sum of the real part η' and imaginary part η”.

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SIST EN 17408:2020
EN 17408:2020 (E)
3.9
linear-viscoelastic range
LVE range

range of low deformations, in which the amplitudes τ and γ are proportional to one another

A A

Note 1 to entry: The quiescent structure of the substance is extensively retained in this range, and the

deformations are reversible. The functions of G*, G' and G'' (and likewise the viscosity variables linked to this) are

constant and form a plateau value (see Figure 4). For many of the adhesives considered here, this is the case with

deformation values less than or equal to 0,1 %. Besides the material situations, the LVE range also depends on the

temperature and measuring frequency. Strictly speaking, the rheological relations indicated above only apply

exactly in this range. However, the LVE range shall be occasionally departed from to describe the practical

behaviour of adhesives.
Figure 4 — G' and G'' as function of the deformation with the critical value γ
of the linear-viscoelastic range [1]
3.10
stability
structural strength

deformation stability of an adhesive bead in respect to gravity or other external forces

Note 1 to entry: This property also referred to as structural strength is crucially determined by the elastic

material character, which impedes the substance from flowing due to its restoring forces. Contrariwise, viscous

properties play a secondary role, as high viscosity slows, but does not prevent, flow. Permanent stability is only

observed at sufficiently high storage modulus or when G' > G''.

EXAMPLE An adhesive with G' = 100 kPa and G'' = 10 kPa has greater deformation stability than a product

with G' = 10 kPa and G'' = 100 kPa. However, both exhibit the same amount of |G*| and also yield (at identical

deformation and frequency) the same |η*| and τ values.
3.11
yield point
stress measured at the end of the linear-viscoelastic range (see Figure 5)

Note 1 to entry: The yield point τ can be regarded as minimum shear stress at which the structure of a

substance is initially weakened (en: “yield point”). This value is also frequently used for characterization of the

stability. As the LVE range does not end in a sharp point, its limit shall be extrapolated by approximation, e.g. via

tangent method. Many rheometers allow an automatic curve evaluation and the determination of τ using

software.
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SIST EN 17408:2020
EN 17408:2020 (E)
3.12
flow point or flow stress
stress at the intersection of the curves of G' and G'' (see Figure 5)

Note 1 to entry: The flow point τ is approximate for the stress through which a substance is able to flow. This

value can serve for estimating the effort or the pressure that a pump has to apply in order to move material in a

pipe line (“pumping”).
...

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