SIST EN ISO 22007-2:2012

Plastics - Determination of thermal conductivity and thermal diffusivity - Part 2: Transient plane heat source (hot disc) method (ISO 22007-2:2008)

ISO 22007-2:2008 specifies a method for the determination of the thermal conductivity and thermal diffusivity, and hence the specific heat capacity per unit volume, of plastics. The experimental arrangement can be designed to match different specimen sizes. Measurements can be made in gaseous and vacuum environments at a range of temperatures and pressures.
This method is suitable for testing homogeneous and isotropic materials, as well as anisotropic materials with a uniaxial structure. In general, the method is suitable for materials having values of thermal conductivity, λ, in the approximate range 0,01 Wm-1K-1 < λ < 500 Wm-1K-1 and values of thermal diffusivity, α, in the range 5 x 10-8 m2s-1 ≤ α ≤ 10-4 m2s-1, and for temperatures, T, in the approximate range 50 K < T < 1 000 K.
The thermal-transport properties of liquids can also be determined, provided care is taken to minimize thermal convection.

Kunststoffe - Bestimmung der Wärmeleitfähigkeit und der Temperaturleitfähigkeit - Teil 2: Transientes Flächenquellenverfahren (Hot-Disk-Verfahren) (ISO 22007-2:2008)

Der vorliegende Teil von ISO 22007 legt ein Verfahren zur Bestimmung der Wärmeleitfähigkeit und Temperaturleitfähigkeit und somit der spezifischen Wärmekapazität je Volumeneinheit von Kunststoffen fest. Die experimentelle Anordnung kann so ausgeführt werden, dass Messungen an Probekörpern verschiedener Größe möglich sind. Die Messungen können in gasförmigen Umgebungen und unter Vakuum bei verschie-denen Temperaturen und verschiedenem Druck durchgeführt werden.
1.2   Dieses Verfahren eignet sich für die Prüfung von homogenen und isotropen Materialien sowie von anisotropen Materialien mit einer einachsigen Struktur. Im Allgemeinen ist das Verfahren für Materialien geeignet, die Wärmeleitfähigkeitswerte  im annähernden Bereich 0,01 Wm–1K–1 <  < 500 Wm–1K–1 und Temperaturleitfähigkeitswerte  im Bereich 5  10–8 m2s–1    10–4 m2s–1 aufweisen, sowie für Tempera-turen T im annähernden Bereich 50 K < T < 1 000 K.
ANMERKUNG   Die spezifische Wärmekapazität je Volumeneinheit C kann erhalten werden, indem die Wärme-leitfähigkeit  durch die Temperaturleitfähigkeit  dividiert wird, d. h. C = /, und liegt im annähernden Bereich von 0,2 MJm–3K–1 < C < 5 MJm–3K–1. Diese wird auch als volumenspezifische Wärmekapazität bezeichnet.
1.3   Die Wärmetransporteigenschaften von Flüssigkeiten können ebenfalls bestimmt werden, voraus¬gesetzt, dass die Wärmekonvektion auf ein Minimum reduziert wird.

Plastiques - Détermination de la conductivité thermique et de la diffusivité thermique - Partie 2: Méthode de la source plane transitoire (disque chaud) (ISO 22007-2:2008)

L'ISO 22007-2:2008 spécifie une méthode pour déterminer la conductivité thermique et la diffusivité thermique, et de ce fait la chaleur massique par unité de volume, des plastiques. Le dispositif expérimental peut être conçu pour s'accorder à différentes tailles d'éprouvette. Les mesurages peuvent être effectués dans des environnements gazeux et sous vide sur une plage de températures et de pressions.
Cette méthode est appropriée aux essais de solides homogènes, isotropes et anisotropes ayant une structure uniaxiale. En général, cette méthode est appropriée aux matériaux ayant des valeurs de conductivité thermique, λ, comprises dans la plage approximative 0,01 Wm-1K-1 < λ < 500 Wm-1K-1 et des valeurs de diffusivité thermique, α, comprises dans la plage 5 x 10-8 m2s-1 ≤ α ≤ 10-4 m2s-1, et pour des températures, T, dans la plage approximative de 50 K < T < 1 000 K.
Les propriétés de transmission thermique des liquides peuvent être déterminées à condition que des précautions soient prises pour minimiser la convection thermique.

Polimerni materiali - Ugotavljanje toplotne prevodnosti in toplotne razprševalnosti - 2. del: Metoda s tranzientnim ploskovnim toplotnim virom (vroči disk) (ISO 22007-2:2008)

Ta del standarda ISO 22007 določa metodo za ugotavljanje toplotne prevodnosti in toplotne razprševalnosti ter posledično posebno toplotno kapaciteto polimernih materialov na enoto prostornine. Eksperimentalna ureditev je lahko oblikovana tako, da ustreza različnim velikostim vzorca. Meritve je mogoče opravljati v plinskem in vakuumskem okolju pri različni temperaturi in tlaku.

General Information

• Status: Withdrawn
• Publication Date: 06-Feb-2012
• Withdrawal Date: 02-Sep-2015
• ICS: 83.080.01 - Plastics in general
• Technical Committee: IPMA - Polimer materials and products
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 03-Sep-2015
• Due Date: 26-Sep-2015
• Completion Date: 03-Sep-2015
• Ref Project: EN ISO 22007-2:2012 - Plastics - Determination of thermal conductivity and thermal diffusivity - Part 2: Transient plane heat source (hot disc) method (ISO 22007-2:2008)

Relations

• Replaced By: SIST EN ISO 22007-2:2015 - Plastics - Determination of thermal conductivity and thermal diffusivity - Part 2: Transient plane heat source (hot disc) method (ISO 22007-2:2015)
• Effective Date: 01-Oct-2015

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 22007-2:2012
01-marec-2012
3ROLPHUQLPDWHULDOL8JRWDYOMDQMHWRSORWQHSUHYRGQRVWLLQWRSORWQHUD]SUãHYDOQRVWL
GHO0HWRGDVWUDQ]LHQWQLPSORVNRYQLPWRSORWQLPYLURPYURþLGLVN,62

Plastics - Determination of thermal conductivity and thermal diffusivity - Part 2: Transient
plane heat source (hot disc) method (ISO 22007-2:2008)
Kunststoffe - Bestimmung der Wärmeleitfähigkeit und der Temperaturleitfähigkeit - Teil 2:
Transientes Flächenquellenverfahren (Hot-Disk-Verfahren) (ISO 22007-2:2008)
Plastiques - Détermination de la conductivité thermique et de la diffusivité thermique -
Partie 2: Méthode de la source plane transitoire (disque chaud) (ISO 22007-2:2008)
Ta slovenski standard je istoveten z: EN ISO 22007-2:2012
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 22007-2:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 22007-2:2012

---------------------- Page: 2 ----------------------

SIST EN ISO 22007-2:2012


EUROPEAN STANDARD
EN ISO 22007-2

NORME EUROPÉENNE

EUROPÄISCHE NORM
January 2012
ICS 83.080.01
English Version
Plastics - Determination of thermal conductivity and thermal
diffusivity - Part 2: Transient plane heat source (hot disc)
method (ISO 22007-2:2008)
Plastiques - Détermination de la conductivité thermique et Kunststoffe - Bestimmung der Wärmeleitfähigkeit und der
de la diffusivité thermique - Partie 2: Méthode de la source Temperaturleitfähigkeit - Teil 2: Transientes
plane transitoire (disque chaud) (ISO 22007-2:2008) Flächenquellenverfahren (Hot-Disk-Verfahren) (ISO 22007-
2:2008)
This European Standard was approved by CEN on 24 December 2011.

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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 22007-2:2012: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 22007-2:2012
EN ISO 22007-2:2012 (E)
Contents Page
Foreword .3

2

---------------------- Page: 4 ----------------------

SIST EN ISO 22007-2:2012
EN ISO 22007-2:2012 (E)
Foreword
The text of ISO 22007-2:2008 has been prepared by Technical Committee ISO/TC 61 “Plastics” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 22007-2:2012 by
Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by NBN.
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 July 2012, and conflicting national standards shall be withdrawn at the
latest by July 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations 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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 22007-2:2008 has been approved by CEN as a EN ISO 22007-2:2012 without any
modification.

3

---------------------- Page: 5 ----------------------

SIST EN ISO 22007-2:2012

---------------------- Page: 6 ----------------------

SIST EN ISO 22007-2:2012

INTERNATIONAL ISO
STANDARD 22007-2
First edition
2008-12-15
Corrected version
2009-02-15



Plastics — Determination of thermal
conductivity and thermal diffusivity —
Part 2:
Transient plane heat source (hot disc)
method
Plastiques — Détermination de la conductivité thermique et de la
diffusivité thermique —
Partie 2: Méthode de la source plane transitoire (disque chaud)




Reference number
ISO 22007-2:2008(E)
©
ISO 2008

---------------------- Page: 7 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.


COPYRIGHT PROTECTED DOCUMENT


©  ISO 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2008 – All rights reserved

---------------------- Page: 8 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Principle.3
5 Apparatus .3
6 Test specimens.5
6.1 Bulk specimens.5
6.2 Anisotropic bulk specimens.6
6.3 Slab specimens.6
6.4 Thin-film specimens .6
7 Procedure .7
8 Calculation of thermal properties .9
8.1 Bulk specimens.9
8.2 Anisotropic bulk specimens.12
8.3 Slab specimens.13
8.4 Thin-film specimens .14
9 Calibration and verification .14
9.1 Calibration of apparatus .14
9.2 Verification of apparatus.14
10 Precision and bias .15
11 Test report .16
Bibliography .17

© ISO 2008 – All rights reserved iii

---------------------- Page: 9 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(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 22007-2 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
ISO 22007 consists of the following parts, under the general title Plastics — Determination of thermal
conductivity and thermal diffusivity:
⎯ Part 1: General principles
⎯ Part 2: Transient plane heat source (hot disc) method
⎯ Part 3: Temperature wave analysis method
⎯ Part 4: Laser flash method
In this corrected version of ISO 22007-2:2008, Figure 3 has been amended to remove a horizontal line
running between ∆U and the earth connection.
iv © ISO 2008 – All rights reserved

---------------------- Page: 10 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
Introduction
A significant increase in the development and application of new and improved materials for broad ranges of
physical, chemical, biological and medical applications has necessitated better performance data from
methods of measurement of thermal-transport properties. The introduction of alternative methods that are
relatively simple, fast and of good precision would be of great benefit to the scientific and engineering
[1]
communities .
A number of measurement techniques described as contact transient methods have been developed and
several have been commercialized. These are being widely used and are suitable for testing many types of
[2],[3]
material. In some cases, they can be used to measure several properties separately or simultaneously .
A further advantage of some of these methods is that it has become possible to measure the true bulk
properties of a material. This feature stems from the possibility of eliminating the influence of the thermal
contact resistance (see 8.1.1) that is present at the interface between the probe and the specimen
[1],[3],[4],[5],[6]
surfaces .

© ISO 2008 – All rights reserved v

---------------------- Page: 11 ----------------------

SIST EN ISO 22007-2:2012

---------------------- Page: 12 ----------------------

SIST EN ISO 22007-2:2012
INTERNATIONAL STANDARD ISO 22007-2:2008(E)

Plastics — Determination of thermal conductivity and thermal
diffusivity —
Part 2:
Transient plane heat source (hot disc) method
1 Scope
1.1 This part of ISO 22007 specifies a method for the determination of the thermal conductivity and thermal
diffusivity, and hence the specific heat capacity per unit volume, of plastics. The experimental arrangement
can be designed to match different specimen sizes. Measurements can be made in gaseous and vacuum
environments at a range of temperatures and pressures.
1.2 This method is suitable for testing homogeneous and isotropic materials, as well as anisotropic
materials with a uniaxial structure. In general, the method is suitable for materials having values of thermal
−1 −1 −1 −1
conductivity, λ, in the approximate range 0,01 W⋅m ⋅K < λ < 500 W⋅m ⋅K and values of thermal
−8 2 −1 −4 2 −1
diffusivity, α, in the range 5 × 10 m⋅s u α u 10 m⋅s , and for temperatures, T, in the approximate
range 50 K < T < 1 000 K.
NOTE The specific heat capacity per unit volume, C, can be obtained by dividing the thermal conductivity, λ, by the
−3 −1 −3 −1
thermal diffusivity, α, i.e. C = λ/α, and is in the approximate range 0,2 MJ⋅m ⋅K < C < 5 MJ⋅m ⋅K . It is also referred to
as the volumetric heat capacity.
1.3 The thermal-transport properties of liquids can also be determined, provided care is taken to minimize
thermal convection.
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 472, Plastics — Vocabulary
ISO 22007-1, Plastics — Determination of thermal conductivity and thermal diffusivity — Part 1: General
principles
© ISO 2008 – All rights reserved 1

---------------------- Page: 13 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and ISO 22007-1 and the
following apply.
3.1
penetration depth
∆p
pen
measure of how far into the specimen, in the direction of heat flow, a heat wave has travelled
NOTE 1 For this method, the penetration depth is given by
∆=ptκα⋅
pen tot
where
t is the total measurement time for the transient recording;
tot
α is the thermal diffusivity of the specimen material;
κ is a constant dependent on the sensitivity of the temperature recordings.
NOTE 2 It is expressed in metres (m).
3.2
probing depth
∆p
prob
measure of how far into the specimen, in the direction of heat flow, a heat wave has travelled during the time
window used for calculation
NOTE 1 The probing depth is given by
∆=ptκα⋅
prob max
where t is the maximum time of the time window used for calculating the thermal-transport properties.
max
NOTE 2 It is expressed in metres (m).
NOTE 3 A typical value in hot-disc measurements is κ = 2, which is assumed throughout this document.
3.3
sensitivity coefficient
β
q
coefficient defined by the equation
∂∆⎡⎤Tt
()
⎣⎦
β = q
q
∂q
where
q is the thermal conductivity, λ, the thermal diffusivity, α, or the volumetric specific heat capacity, C;
∆T(t) is the mean temperature increase of the probe
NOTE 1 Different sensitivity coefficients are defined for thermal conductivity, thermal diffusivity and specific heat per
[8]
unit volume .
2 © ISO 2008 – All rights reserved

---------------------- Page: 14 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
NOTE 2 To define the time window that is used to determine both the thermal conductivity and diffusivity from one
single experiment, the theory of sensitivity coefficients is used. Through this theory, which deals with a large number of
experiments and considers the constants, q, as variables, it has been established that
2
0,30 u t ⋅α/r u 1,0
max
where r is the mean radius of the outermost spiral of the probe.
Assuming κ = 2, this expression can be rewritten as
1,1r u ∆p u 2,0r
prob
4 Principle
A specimen containing an embedded hot-disc probe of negligible heat capacity is allowed to equilibrate at a
given temperature. A heat pulse in the form of a stepwise function is produced by an electrical current through
the probe to generate a dynamic temperature field within the specimen. The increase in the temperature of the
probe is measured as a function of time. The probe operates as a temperature sensor unified with a heat
source (i.e. a self-heated sensor). The response is then analysed in accordance with the model developed for
the specific probe and the assumed boundary conditions.
5 Apparatus
5.1 A schematic diagram of the apparatus is shown in Figure 1.
2
3
1
5
6 7
4
8

Key
1 specimen with probe 5 bridge circuit
2 chamber 6 voltmeter
3 vacuum pump 7 voltage source
4 thermostat 8 personal computer
Figure 1 — Basic layout of the apparatus
5.2 A typical hot-disc probe is shown in Figure 2. Convenient probes can be designed with diameters from
4 mm to 100 mm, depending on the specimen size and the thermal-transport properties of the material to be
tested. The probe is constructed as a bifilar spiral etched out of a (10 ± 2) µm thick metal foil and covered on
both sides by thin (from 7 µm to 100 µm) insulating film. It is recommended that nickel or molybdenum be
used as the heater/temperature-sensing metal foil due to their relatively high temperature coefficient of
electrical resistivity and stability over a wide temperature range. It is recommended that polyimide, mica,
aluminum nitride or aluminum oxide be used as the insulating film, depending on the ultimate temperature of
use. The arms of the bifilar spiral forming an essentially circular probe shall have a width of (0,20 ± 0,03) mm
for probes with an overall diameter of 15 mm or less and a width of (0,35 ± 0,05) mm for probes of larger
diameter. The distance between the edges of the arms shall be the same as the width of the arms.
© ISO 2008 – All rights reserved 3

---------------------- Page: 15 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)

Figure 2 — Probe with bifilar spiral as heating/sensing element
(Sensor diameters, D, from 4 mm to 100 mm can be used, depending on available specimen size)

5.3 An electrical bridge shall be used to record the transient increase in resistance of the probe. Through
the bridge, which is initially balanced, the successive increases in resistance of the probe shall be followed by
recording the imbalance of the bridge with a sensitive voltmeter (see Figure 3). With this arrangement, the
probe is placed in series with a resistor which shall be designed in such a way that its resistance is kept
strictly constant throughout the transient. These two components are combined with a precision
potentiometer, the resistance of which shall be about 100 times larger than the sum of the resistances of the
probe and the series resistor. The bridge shall be connected to a power supply which can supply 20 V and a
current of up to 1 A. The digital voltmeter by which the difference voltages are recorded shall have a resolution
corresponding to 6,5 digits at an integration time of 1 power line cycle. The resistance of the series resistor,
R , shall be close to the initial resistance of the probe with its leads, R + R , in order to keep the power output
S 0 L
of the probe as constant as possible during the measurement.
4 © ISO 2008 – All rights reserved

---------------------- Page: 16 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)

Key
1 potentiometer
2 probe
3 probe leads
Figure 3 — Diagram of bridge for recording the resistance increase of the probe
R is the series resistance, R is the total resistance of the probe leads, R is the resistance of the probe
S L 0
before initiating the transient heating, ∆R is the increase in resistance of the probe during the transient heating
and ∆U is the voltage imbalance created by the increase in the resistance of the probe.
NOTE This experimental arrangement allows the determination of temperature deviations from the iterated straight
line (see treatment of experimental data in 8.1) down to or better than 50 µK.
5.4 A constant-temperature environment controlled to ± 0,1 K or better for the duration of a measurement
shall be established. The chamber need only be evacuated when working with slab specimens (see 6.3).
6 Test specimens
6.1 Bulk specimens
6.1.1 For bulk specimens, the requirement for specimen thickness depends on the thermal properties of the
material from which the specimen is made. The expression for the probing depth contains the diffusivity, which
is not known prior to the measurement. This means that the probing depth has to be calculated after an initial
experiment has been completed. If, with this new information, the probing depth is outside the limits given in
8.1.3, the test shall be repeated, with an adjusted total measurement time, until the required conditions are
fulfilled.
The shape of the specimen can be cylindrical, square or rectangular. Machining to a certain shape is not
necessary, as long as a flat surface (see 6.1.4) of each of the two specimen halves faces the sensor and the
requirements on the sensor size given in 8.1.3 are fulfilled.
6.1.2 The thickness of the specimen shall be at least 20 times the characteristic length of the components
making up the material or of any inhomogeneity in the material, e.g. the average diameter of the particles if
the specimen is a powder.
6.1.3 The specimen dimensions shall be chosen to minimize the effect that its outer surfaces will have on
the measurement. The specimen size shall be such that the distance from any part of the bifilar spiral of the
hot-disc probe to any part of the outside boundary of the specimen is larger than the overall mean radius of
the bifilar spiral (see 5.2). An increase in this distance beyond the size of the diameter of the spiral does not
improve the accuracy of the results.
© ISO 2008 – All rights reserved 5

---------------------- Page: 17 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
6.1.4 Specimen surfaces which are in contact with the sensor shall be plane and smooth. The specimen
halves shall be clamped on to both sides of the hot-disc probe.
NOTE Heat sink contact paste is not recommended since:
a) it is difficult to obtain a sufficiently thin layer of paste which will actually improve the thermal contact;
b) the paste obviously increases the heat capacity of the insulating layer and delays the development of the constant
temperature difference between the sensing material and the specimen surface;
c) it is difficult to obtain exactly the same thickness of paste on both sides of the probe and achieve a strictly
symmetrical flow of heat from the heating/sensing material through the insulation into the two specimen halves.
6.1.5 For liquids, suitable containment vessels with adequate seals are necessary and air bubbles and
evaporation shall be avoided.
Storage and conditioning of the liquid may affect its properties, e.g. by absorbtion of water or gas. It may be
necessary to pretreat the specimen prior to testing, e.g. by degassing. However, pretreatment procedures
shall not be used when they could detrimentally affect the material to be tested, e.g. through degradation.
6.1.6 For materials with which significant dimensional changes may occur, e.g. when making
measurements over large temperature ranges, due to thermal expansion, a change of state, a phase
transition or other causes, care shall be taken to ensure that, when placing the hot-disc probe in contact with
the specimen, the applied load does not affect the properties of the specimen.
With soft materials, the clamping pressure shall not compress the specimen and thus change its thermal-
transport properties.
6.1.7 The specimen shall be conditioned in accordance with the standard specification which applies to the
type of material and its particular use.
6.2 Anisotropic bulk specimens
6.2.1 If a material is anisotropic, specimens shall be cut (or otherwise prepared) so that the probe can be
oriented in the main directions (e.g. the fibre directions in reinforced plastics, the main directions in layered
[4],[7]
structures or the principal axes in crystals) . The hot-disc method is limited to materials in which the
thermal properties along two of the orthogonal and principal axes are the same, but are different from those
along the third axis.
6.2.2 The size of anisotropic specimens shall be chosen so that the requirements of 8.1.3 are fulfilled along
the principal axes.
6.3 Slab specimens
The so-called slab method is used with sheet-formed specimens extending in two dimensions, but with a
[9]
limited and well-defined thickness in the range from 1 mm to 10 mm . The slab specimen thickness shall be
known to an accuracy of 0,01 mm. When two equally thick slabs of a material are clamped around a probe
and thermally insulated on the outer sides, it is possible to measure the thermal conductivity and diffusivity of
such specimens. The condition related to the probing depth (see 3.2) has to be fulfilled in the plane of the
probe but not in the through-thickness direction. This method is particularly suited to studies of materials
−1 −1
having thermal conductivities higher than 10 W⋅m ⋅K but can also be used for materials with thermal
−1 −1
conductivities as low as 1 W⋅m ⋅K , provided good thermal insulation of the slabs can be arranged (for
instance by performing the measurements in a vacuum).
6.4 Thin-film specimens
The so-called thin-film method is used with specimens such as paper, textiles, polymer films or deposited thin-
[10]
film layers (such as ceramic coatings) with thicknesses ranging from 0,01 mm to 1,0 mm . The thickness of
thin-film specimens (placed on both sides of the probe) shall be known to an accuracy of ± 1 µm.
6 © ISO 2008 – All rights reserved

---------------------- Page: 18 ----------------------

SIST EN ISO 22007-2:2012
ISO 22007-2:2008(E)
NOTE 1 When making a measurement on a material with a high thermal conductivity, the temperature undergoes a
rapid increase at the very beginning of the transient followed by a much more gradual increase. The insulating layer,
between which the sensing spiral is sandwiched, causes this rapid increase. It has been shown both experimentally and in
computer simulations that the temperature difference across the insulating layer becomes constant within a very short time
and remains constant throughout the measurement. The reason is that the total power output, the area of the sensing
material and the thickness of the insulating layer are constant in the test.
If thin films of a material are placed between the probe and a high-conductivity background material (in the
form of an “infinite” solid), it is possible to measure the thermal conductivity of the film material, provided that
the thermal conductivity of the insulating layer with which the probe is covered has been determined in a
[10]
separate experiment .
NOTE 2 It might be necessary to make measurements on films of different thicknesses or with different clamping
pressures to eliminate mathematically the influence of thermal contact resistances.
The t
...