EN ISO 11358:1997

SLOVENSKI STANDARD
01-maj-1999
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Plastics - Thermogravimetry (TG) of polymers - General principles (ISO 11358:1997)
Kunststoffe - Thermogravimetrie (TG) von Polymeren - Allgemeine Grundlagen (ISO
11358:1997)
Plastiques - Thermogravimétrie (TG) des polymeres - Principes généraux (ISO
11358:1997)
Ta slovenski standard je istoveten z: EN ISO 11358:1997
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
IS0
STANDARD
First edition
1997-04- 15
Plastics - Thermogravimetry (TG) of
polymers - General principles
Plastiques - Thermogravim&rie (TG) des polymkes -
Principes g&&aux
Reference number
IS0 11358:1997(E)
IS0 11358:1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
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 IS0 11358 was prepared by Technical Committee
ISO/TC 61, Plastics, Subcommittee SC 5, Physical-chemical properfies.
Annex A of this International Standard is for information only.
0 IS0 1997
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 the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet central @ iso.ch
x.400
c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
INTERNATIONAL STANDARD @ IS0 IS0 11358:1997(E)
Plastics - Thermogravimetry (TG) of polymers -
General principles
1 Scope
1.1 This International Standard specifies the general conditions for the analysis of polymers using
thermogravimetric techniques.
1.2 It is applicable to liquids or solids. Solid materials may be in the form of pellets, granules or powders.
Fabricated shapes reduced to appropriate specimen size may also be analysed by this method.
1.3 Thermogravimetry can be used to determine the temperature(s) and rate(s) of decomposition of polymers, and
to measure at the same time the amounts of volatile matter, additives and/or fillers they contain.
1.4 The thermogravimetric measurements may be carried out in a dynamic mode (mass change versus
) or an isothermal mode (mass change versus time at constant
temperature or time under programmed conditions
temperature).
2 Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the edition indicated was valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent edition of the standard indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
- Standard atmospheres for conditioning and testing.
IS0 291 :-‘I, Plastics
3 Definitions
For the purposes of this International Standard, the following definitions apply:
3.1 thermogravimetry (TG): A technique in which the mass of a test specimen is measured as a function of
temperature or time, while the test specimen is subjected to a controlled temperature programme.
3.2 dynamic mass-change determination: A technique for obtaining a record of the variation of the mass of a
test specimen with temperature T which is changing at a programmed rate.
3.3 isothermal mass-change determination: A technique for obtaining a record of the variation of the mass of a
test specimen with time t at constant temperature T.
1) To be published. (Revision of IS0 291:1977)

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IS0 11358: 1997(E)
3.4 TG curve: A curve drawn in thermogravimetry by plotting the mass of a test specimen as the ordinate (y-axis)
and the temperature T, or time t, as the abscissa (x-axis).
3.5 differential scanning calorimetry (DSC): A technique in which the difference in heat flux (power) into a test
specimen and a reference specimen is measured as a function of temperature and/or time while the test specimen
and the reference specimen are subjected to a controlled temperature programme.
3.6 differential thermal analysis (DTA): A technique in which the difference in temperature between a test
specimen and a reference specimen is measured as a function of temperature and/or time while the test specimen
and the reference specimen are subjected to a controlled temperature programme.
3.7 Curie temperature: The temperature at which a ferromagnetic material passes from the ferromagnetic state
to the paramagnetic state or vice versa.
3.8 sample: A small part or portion of a bulk material or batch of products intended to be representative of the
whole.
3.9 test specimen: A complete product or single piece taken from a sample and used to carry out a test. In the
case of bulk materials such as pellets, powders and granules: a portion taken from a sample and used to carry out a
test.
4 Principle
4.1 A test specimen is heated at a constant rate with a controlled temperature programme, and the change in
mass is measured as a function of temperature. Alternatively, the specimen is kept at a given constant temperature
and the change in mass is measured as a function of time over a given period.
In general, the reactions which cause the mass of a test specimen to change are decomposition or oxidation
reactions or the volatilization of a component. The change in mass is recorded as a TG curve.
4.2 The change in mass of a material as a function of temperature and the extent of this change are indicators of
the thermal stability of the material. TG data can therefore be used to evaluate the relative thermal stability of
polymers of the same generic family and polymer-polymer or polymer-additive interactions, using measurements
made under the same test conditions.
4.3 TG data may be used for process control, process development and material evaluation. Long-term thermal
stability is a complex function of service and environmental conditions. TG data alone will not describe the long-term
thermal stability of a polymer.
5 Apparatus
instruments suitab lie for the rmog ravimetric measurements are available. The basic
A number of co mmercial
apparatus compo nents con sist of the fol owing:
5.1 Thermobalance, of the null or deflection type. Where the mass of the test specimen is less than 50 mg, the
thermobalance shall be capable of measuring the mass with an accuracy of + 0,020 mg. The thermobalance shall
be constructed so that gas flows around the test specimen and permits heat transfer to it at a constant rate.
5.2 Furnace, with a housing of low thermal mass to allow rapid or slow heating and cooling (generally at least
50 “C/min) over a temperature range of ambient to about 1 000 “C.
5.3 Temperature sensor, capable of measuring the temperature of the test specimen. It shall be located as close
as possible to the test specimen.
0 IS0 IS0 11358: 1997(E)
5.4 Temperature programmer, capable of providing a linear rate of scanning over a predetermined temperature
range.
5.5 Recording device, capable of recording the specimen mass and temperature and/or time in a way that the
relation between mass loss and temperature or time is illustrated. An X-Y recorder is suitable for this purpose.
5.6 Specimen holder, of shape and dimensions sufficient for a mass of at least 5 mg and made of a material
capable of withstanding the maximum temperature to be used.
5.7 Purge gas: dry air or oxygen (oxidizing conditions) or a suitable inert gas with an oxygen content of
0,001 % (V/V) or less (non-oxidizing conditions). In either case, the water content of the purge gas shall be less than
0,001 % (m/m).
5.8 Flowmeter, capable of measuring gas-flow rates of 50 mI/min to 150 mI/min.
5.9 Balance, capable of measuring the initial mass of the specimen with an accuracy of 0,Ol mg.
6 Test specimen preparation
Test specimens may be liquids or solids. The latter may be in the form of powders, pellets, granules or cut pieces.
For finished products, the test specimen shall be in the form normally found in use.
6.1 Test specimens from finished products
Cut the test specimen to an appropriate size for the specimen holder. Microtomes or razor blades are suitable for
this purpose.
Test specimen size and shape will generally be dependent on the sample holder. Surface area will affect the overall
NOTE -
results. For instance, in comparing a test specimen of large surface area with a test specimen of smaller surface area, both
having the same mass, the smaller surface area test specimen normally changes at a slower rate.
6.2 Test specimen conditioning
Unless otherwise specified, test specimens shall be conditioned, prior to measurement, at 23 “C + 2 “C and
(50 + 5) % relative humidity in accordance with IS0 291, or by any other method specified by agreement between
the interested parties.
6.3 Test specimen mass
The mass of the test specimen shall be greater than 10 mg unless only smaller quantities of material are available.
7 Calibration
7.1 Mass calibration
Without any gas flow through the thermobalance (to prevent any disturbance through buoyancy and/or convection
effects), calibrate the thermobalance as follows, using calibrated weights in the range 10 mg to 100 mg:
Zero the thermobalance. Place the calibration weight on the thermobalance and measure the corresponding mass
change. If necessary, adjust the thermobalance so that the measured mass is equal to the mass of the calibration
weight.
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IS0 11358: 1997(E)
7.2 Temperature calibration
Position the temperature sensor, usually a thermocouple, to provide the most accurate reading of the test specimen
temperature. This position may differ for each instrument.
Carry out the temperature calibration using the same atmosphere, rate of gas flow and heating rate as will be used
in the actual determination (see clause 8).
If the thermobalance is used alone, use the following procedure:
a) Choose two or more standard reference materials from the set of five standards comprising GM761, selecting
reference materials with a Curie temperature near the temperature range to be examined. If possible, choose
the reference materials in such a way that the temperature range to be examined lies between the Curie
temperatures of two of them.
b) Start heating at the same heating rate as will be used in the actual determination and carry out a calibration
based on the start temperature TA, mid-point temperature TC and end temperature TB for the Curie temperature
transition.
NOTE - GM761 is specified as a range of Curie (magnetic transition) temperature standards by the International
Confederation for Thermal Analysis (ICTA) and the National Institute of Standards and Technology (NIST) (see annex A).
Nickel of 99,99 % or higher purity can also be used for the calibration.
If the thermobalance is combined with a DSC or DTA detector, it is recommended that the thermobalance is
temperature-calibrated using standard reference materials (NIST or ICTA) developed for DSC or DTA calibration.
See annex A for a list of some of the standard calibration materials.
NOTES
1 The melting point of a standard refe rence materi al is defined as the intercept of the extrapolated baseline and the tangent to
of inflection of the curve (the so-called onset temperature).
the slope of the endotherm at the point
2 Calibration is the most critical stage in obtaining reliable thermogravimetry data; the relationship between the temperature
sensor, specimen geometry and type of atmosphere, including the rate of gas flow, will affect the calibration of the
measurement system.
3 The rate of mass loss is dependent upon the rate of oxidation of the test specimen, and therefore dependent in part upon
the atmosphere and rate of gas flow to which it is exposed. It is therefore important to use the same atmosphere and rate of
gas flow in the calibration as in the actual determination.
8 Procedure
The procedu re has to be adapted to the instrument that is used and to the test cond itions. Two modes can be used:
temperature scanni (see 8.1) and isothermal (see 8.2).
@I
NOTE - A change in buoyancy and convection occurs in the thermobalance when the gas flow is operating. Even if there is
no actual change in mass, an apparent change in mass is observed and the accuracy of mass measurement is reduced. It is
recommended that a preliminary run without the test specimen is carried out at the same heating rate and gas-flow rate as in
the actual test in order to observe the apparent change in mass The precision of the mass measurement cannot be better than
that obtained from the preliminary test.
8.1 Temperature-scanning mode
8.1.1 Weigh the test specimen.
8.1.2 Adjust the zero point of the thermobalance.
the test specimen on the thermobala rice. Select the gas-flow rate, start
8.1.3 Place the sample holder containing
the gas flow and record the initial mass, unl ess the following paragraph applies:

@ IS0 IS0 11358:1997(E)
For investigations under a strictly
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