ISO 22768:2017

INTERNATIONAL ISO
STANDARD 22768
Second edition
2017-08
Rubber, raw — Determination of
the glass transition temperature by
differential scanning calorimetry (DSC)
Caoutchouc brut — Détermination de la température de transition
vitreuse par analyse calorimétrique différentielle (DSC)
Reference number
ISO 22768:2017(E)
©
ISO 2017

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ISO 22768:2017(E)

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ISO 22768:2017(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus and materials. 2
6 Test specimen . 2
7 Conditioning . 2
8 Calibration . 2
9 Procedure. 2
9.1 Gas flow rate . 2
9.2 Loading the test specimen . 2
9.3 Temperature scan . 3
10 Expression of results . 3
11 Test report . 4
12 Precision . 5
Annex A (informative) Precision . 6
Bibliography . 9
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ISO 22768:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry.
This second edition cancels and replaces the first edition (ISO 22768:2006), which has been technically
revised with the following changes:
— additional description on placing an empty pan (crucible) as reference;
— general DSC thermogram inserted to show an inflection point which should be T ;
g
— move of the content of the clause on precision data to an informative Annex A.
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INTERNATIONAL STANDARD ISO 22768:2017(E)
Rubber, raw — Determination of the glass transition
temperature by differential scanning calorimetry (DSC)
WARNING — Persons using this document should be familiar with normal laboratory practice.
This document 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 document specifies a method using a differential scanning calorimeter to determine the glass
transition temperature of raw rubber.
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.
ISO 1407, Rubber — Determination of solvent extract
ISO 11357-1:2016, Plastics — Differential scanning calorimetry (DSC) — Part 1: General principles
ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical test methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11357-1 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 http:// www .iso .org/ obp
3.1
glass transition
reversible change in an amorphous polymer, or in amorphous regions of a partially crystalline polymer,
from (or to) a rubbery or viscous condition to (or from) a glassy or hard condition
3.2
glass transition temperature
T
g
approximate midpoint of the temperature range over which the glass transition (3.1) takes place
Note 1 to entry: For the purposes of this document, the glass transition temperature is defined as the point of
inflection of the DSC curve which has been obtained at a heating rate of 20 °C/min (see A.3).
4 Principle
The change in specific heat capacity of the rubber as a function of temperature under a specified
inert atmosphere is measured using a differential scanning calorimeter (DSC). The glass transition
temperature is determined from the curve thus produced.
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ISO 22768:2017(E)

5 Apparatus and materials
5.1 Differential scanning calorimeter, in accordance with ISO 11357-1:2016, 5.1.
The calorimeter should be operated in a room held at standard laboratory temperature. It should be
protected from draughts, direct sunlight and sudden temperature changes.
5.2 Specimen pans (crucibles), in accordance with ISO 11357-1:2016, 5.2.
5.3 Gas supply, analytical grade, usually nitrogen or helium.
5.4 Balance, capable of measuring the specimen mass to an accuracy of ±0,000 1 g.
6 Test specimen
The test specimen shall be as representative as possible of the sample being examined and shall have a
mass between 0,01 g and 0,02 g.
To determine T of polymers, extract raw rubber in accordance with ISO 1407.
g
7 Conditioning
Condition the sample to be examined and the test specimen in accordance with ISO 23529.
8 Calibration
Calibrate the calorimeter according to the manufacturer’s instructions.
The use of suitable analytical grade substances is recommended to check t
...