ISO 20463:2018

INTERNATIONAL ISO
STANDARD 20463
First edition
2018-04
Rubber and rubber products —
Determination of combustion energy
and carbon dioxide emission from
biobased and non-biobased materials
Élastomères et produits à base d'élastomères — Méthode de
détermination de l'énergie de combustion et de l'émission de CO des
matériaux biosourcés et non biosourcés
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Sampling . 3
6 Determination of the combustion energy of biobased and non-biobased materials .3
6.1 General . 3
6.2 Reagents and materials . 3
6.3 Apparatus . 3
6.4 Procedure . 6
6.5 Calculation method of biobased and non-biobased combustion energy . 7
7 Determination of the amount of carbon dioxide emission from biobased and non-
biobased materials . 7
7.1 General . 7
7.2 Apparatus . 7
7.3 Reagents. 8
7.4 Procedure . 8
7.4.1 Verification of the measurement . 8
7.4.2 Transfer of the combustion gas to a gas sampling bag from bomb . 9
7.4.3 Measurement of carbon dioxide concentration by GC . 9
7.4.4 Determination of the total volume of the combustion gas .10
7.4.5 Measurement of the room temperature and the atmospheric pressure .11
7.4.6 Calculation of the amount of carbon dioxide emission .11
7.5 Calculation of biobased and non-biobased carbon dioxide emission .12
8 Precision .12
9 Test report .12
Annex A (informative) Calculation of net calorific value for combustion energy.13
Annex B (informative) Examples of determination of combustion energy of biobased and
non-biobased materials .15
Annex C (normative) Saturated water vapour pressure .16
Annex D (informative) Determination of the amount of carbon dioxide emission from
biobased and non-biobased materials .17
Annex E (informative) Precision .18
Bibliography .20
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.
The procedures used to develop this document and those intended for its further maintenance are
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
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
iv © ISO 2018 – All rights reserved

Introduction
To reduce the use of exhaustible fossil resources such as petroleum, coal, or natural gas, as well as the
amount of carbon dioxide emission from those during rubber production process or waste disposal, it is
very important to shift the raw materials from fossil-based resources to “biomass” resources. Biomass
includes starch, cellulose, hemicellulose or lignin which living plants photosynthesize converting the
carbon dioxide in the atmosphere. It is preferred to utilize inedible biomass such as agricultural waste
or food-industries’ wastes rather than using edible biomass. Using biobased resources instead of fossil-
based ones will benefit to make sustainable social systems and to preserve the global environment.
Products that are produced fully or partially from biomass resources are “biobased” products. Many
rubber products today include natural rubber as component, so there are many biobased products in the
rubber market already. That is a great advantage for the rubber industry to contribute to sustainable
social systems.
Recycling chemical products is an important act to preserve limited resources, and basically there are
two ways to recycle end-of-life rubber products, i.e. “material recycling” and “thermal recycling”. It is
useful to develop concrete indices to evaluate the effect of thermal recycling.
This document specifies how to determine the biobased combustion energy and the amount of biobased
carbon dioxide emission hoping to promote rubber-product waste as an alternative fuel.
This document introduces the idea of biobased combustion energy as an index to examine the degree
of contribution of thermal recycling of rubber wastes. At the same time, the amount of biobased carbon
dioxide emission from the thermal recycling process will act as a direct comparison to the fossil-based
carbon dioxide emission.
INTERNATIONAL STANDARD ISO 20463:2018(E)
Rubber and rubber products — Determination of
combustion energy and carbon dioxide emission from
biobased and non-biobased materials
WARNING 1 — 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
determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document might involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies the measuring methods of the combustion energy (i.e. gross calorific value)
and the carbon dioxide emission amount from biobased and non-biobased materials in rubber or rubber
products.
This document applies to rubber and rubber products (including polyurethane) such as raw materials,
materials and final products.
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 1382, Rubber — Vocabulary
ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures
ISO 1928, Solid mineral fuels — Determination of gross calorific value by the bomb calorimetric method
and calculation of net calorific value
ISO 4661-2, Rubber, vulcanized — Preparation of samples and test pieces — Part 2: Chemical tests
ISO 19984-2, Rubber and rubber products — Determination of biobased content — Part 2: Biobased
carbon content
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1382 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
3.1
biobased component
biobased part of a biobased constituent which is wholly or partly from biomass resource(s)
[SOURCE: ISO 19984-1:2017, 3.2]
3.2
biobased carbon content
biobased component(s) (3.1) in a product expressed by carbon% to total carbon
[SOURCE: ISO 19984-1:2017, 3.4]
3.3
biomass
material of biological origin excluding material embedded in geological formations and/or fossilized
[SOURCE: ISO 19984-1:2017, 3.6]
3.4
biobased combustion energy
energy obtained from the combustion of the biobased carbon contained in rubber or a rubber product
Note 1 to entry: The combustion energy is measured as gross calorific value or net calorific value.
Note 2 to entry: The biobased combustion energy is expressed in J/g, or calorific value (joules, J) per sample
mass (g).
3.5
biobased carbon dioxide emission
amount of carbon dioxide emitted from the biobased carbon contained in rubber or a rubber product
Note 1 to entry: The biobased carbon dioxide emission is expressed in g/g, or emitted carbon dioxide amount (g)
per sample mass (g).
3.6
gross calorific value
absolute value of the specific energy of combustion, for unit mass of rubber or rubber-product sample
burned in oxygen in a calorimetric bomb under specified conditions
Note 1 to entry: The products of combustion are assumed to consist of gaseous oxygen, nitrogen, carbon dioxide
and sulfur dioxide, of liquid water (in equilibrium with its vapour) saturated with carbon dioxide under the
conditions of the bomb reaction, and of solid ash, all at the reference temperature.
Note 2 to entry: The gross calorific value is expressed in J/g.
3.7
net calorific value
absolute value of the specific energy of combustion, for unit mass of rubber or rubber-product sample
burned in oxygen in a calorimetric bomb under such conditions that all the water of the reaction
products remains as water vapour, the other products being as for the gross calorific value (3.6), all at
the reference temperature
Note 1 to entry: The net calorific value is expressed in J/g.
4 Principle
A sample from rubber or a rubber product is completely combusted in a pressure-proof sealed vessel
(bomb) with high pressure oxygen gas settled in an insulated area. The combustion energy of the
sample is calculated from the increased heat in the insulated area. The carbon dioxide emission amount
is determined by measuring both the combustion gas volume collected from the used bomb and its
carbon dioxide concentration.
The biobased combustion energy and the biobased carbon dioxide emission can be calculated in
proportion by multiplying the obtained values by the biobased carbon content.
NOTE There are two kinds of combustion energies, i.e. gross calorific value and net calorific value (see
Annex A for information). This document specifies the determination of gross calorific value of rubber and
rubber products.
2 © ISO 2018 – All rights reserved

5 Sampling
For raw rubber, carry out sampling in accordance with ISO 1795. For vulcanized rubber, carry out
sampling in accordance with ISO 4661-2.
6 Determination of the combustion energy of biobased and non-biobased
materials
6.1 General
This method specifies how to determine the combustion energy of rubber or a rubber product using
a bomb calorimeter. A high-pressure proof sealed bomb is used as a measuring vessel. A test sample
is placed in the bomb filled with high-pressure oxygen with an ignition wire contacting the sample.
The bomb is then placed in a water vessel the temperature of which is accurately controlled and
measured. The test sample is combusted by igniting the wire and the calorific value is determined by
the temperature increase, the volume of water in the water vessel (or the heat capacity of calorimeter)
and the heat capacity of the bomb.
The combustion system is calibrated by combusting the calorimetric standard, i.e. certified benzoic acid.
If the carbon dioxide emission amount is to be measured in the later process, the combustion gas in the
bomb shall be collected and used for the determination.
6.2 Reagents and materials
6.2.1 Oxygen, at a pressure high enough to fill the bomb to 3 MPa, pure, with an assay of at least 99,5 %
volume fraction, and free from combustible matter.
NOTE Oxygen made by the electrolytic process can contain up to 4 % volume fraction of hydrogen.
6.2.2 Benzoic acid, of calorimetric-standard quality, certified by (or traceable to) a recognized
standardizing authority.
6.3 Apparatus
6.3.1 Bomb calorimeter
The calorimeter (see Figure 1) consists of the assembled combustion bomb, the calorimeter can (with or
without a lid), the calorimeter stirrer, water, temperature sensor and leads with connectors inside the
calorimeter can required for ignition of the sample or as part of temperature measurement or control
circuits. The calorimeter shall conform to ISO 1928 or provide the equivalent test results. During
measurements, the calorimeter is enclosed in a thermostat. The manner in which the thermostat
temperature is controlled defines the working principle of the instrument and, hence, the strategy for
evaluating the corrected temperature rise.
Key
1 thermostat lid 4 calorimeter can
2 ignition leads 5 thermostat
3 thermometer 6 stirrer
Figure 1 — Classical-type combustion-bomb calorimeter with thermostat
6.3.2 Combustion bomb, capable of withstanding safely the pressures developed during combustion;
see Figures 1 and 2.
The material of construction shall resist corrosion by the acids produced in the combustion of rubber
or a rubber product. A suitable internal volume of the bomb is from 250 ml to 350 ml and it is preferred
that the bomb is equipped with a relief valve or a bursting disc.
WARNING — Bomb parts shall be inspected regularly for wear and corrosion; particular
attention shall be paid to the condition of the threads of the main closure. Manufacturers’
instructions regarding the safe handling and use of the bomb shall be observed. When more
than one bomb of the same design is used, it is imperative to use each bomb as complete unit.
Colour coding is recommended. Swapping of parts can lead to a serious accident.
4 © ISO 2018 – All rights reserved

Key
1 valve cover 4 closure ring
2 valve housing 5 sealing ring
3 cap 6 vessel body
Figure 2 — Typical calorimeter bomb
6.3.3 Fuse
6.3.3.1 Ignition wire, of nickel-chromium 0,10 mm to 0,20 mm in diameter, platinum 0,05 mm to
0,10 mm in diameter, or another suitable conducting wire with well characterized thermal behaviour
during combustion.
6.3.3.2 Cotton fuse, of white cellulose cotton, or equivalent.
6.3.4 Pressure regulator, to control the filling of the bomb with oxygen.
6.3.5 Pressure gauge (e.g. 0 MPa to 6 MPa), to indicate the pressure in the bomb with a resolution of
0,05 MPa.
6.3.6 Relief valve or bursting disc, operating at 3,5 MPa, and installed in the filling line, to prevent
overfilling the bomb.
CAUTION — Equipment for high-pressure oxygen shall be kept free from oil and grease. Do not
test or calibrate the pressure gauge with hydrocarbon fluid.
6.3.7 Balance, capable of weighing the sample, ignition wire, etc., with a resolution of at least 0,1 mg.
6.4 Procedure
6.4.1 Preparation of test sample
Weigh out 0,3 g to 0,8 g of the sample to the nearest 0,1 mg. Block, sheet, powder or liquid sample can be
used. The amount of sample shall correspond to the measurable energy range of the calorimeter used.
6.4.2 Calibration of calorimeter
Weigh approximately 1 g of benzoic acid pellet certified for combustion energy measurement and place
it on a combustion dish in the bomb. Settle an ignition wire so that it touches this pellet and connects to
the ignition electrode of the ignition circuit. Close the vessel body and tighten the closure ring firmly.
Connect the pipe from the oxygen pressure regulator to the valve of the combustion bomb. The pipe shall
be certified to perform under 3,5 MPa pressure and have a branched purge line with an on-off valve.
Open the bomb valve and control the regulator to gradually fill oxygen in the bomb. When the pressure
reaches 2,5 MPa to 3,0 MPa, close both the bomb valve and the regulator valve, and remove the pipe
from the bomb.
Immerse the sealed, assembled bomb in the water vessel. Watch for babbles in water and make sure
there is no oxygen leak.
When the water temperature has become stable, combust the benzoic acid pellet by applying voltage to
the ignition wire.
Adjust the obtained combustion energy as 26 460 J/g of benzoic acid. Repeat the same procedure for
another pellet until two consecutive measured values fall within 26 460 J/g ± 80 J/g.
6.4.3 Measurement of combustion energy
Place the accurately weighed test sample (6.4.1) on the combustion dish in the bomb. Settle the ignition
wire so that it touches the sample and connects to the ignition electrode of the ignition circuit. Close the
vessel body and tighten the closure ring firmly.
Connect the pipe from the oxygen pressure regulator to the valve of the combustion bomb. The pipe shall
be certified to perform under 3,5 MPa pressure and have a branched purge line with an on-off valve.
When the amount of carbon dioxide emission is to be measured afterwards (see Clause 7), purge the
inside air with oxygen. To do that, connect an oxygen bottle, introduce ca. 0,2 MPa oxygen and evacuate
the oxygen and the inside air together either by removing the pipe or by using the branched purge line.
Repeat the process at least twice.
Open the bomb valve and control the regulator to gradually fill oxygen in the bomb. When the pressure
reaches 2,5 MPa to 3,0 MPa, close both the bomb valve and the regulator valve, and remove the pipe (if
a purge line is equipped, release oxygen before removing the pipe).
Immerse the sealed, assembled bomb in the water vessel. Watch for babbles in water and make sure
there is no oxygen leak.
When the water temperature has become stable, combust the test sample by applying voltage to the
ignition wire. Read the measured value for combustion energy.
Repeat the measurement procedure for the same test sample and compare the results. When the difference
falls into ±160 J/g, finish the measurement and take the mean value as the total combustion energy.
6.4.4 Measurement of biobased carbon content
To determine the biobased combustion energy (E ) of the test sample, information on its biobased
B
carbon content (x ) is indispensable. If the sample's chemical formulation and the resource of each
B
6 © ISO 2018 – All rights reserved

component (i.e. the biobased carbon content of each component) is available, the biobased carbon
content of the sample can be calculated in accordance w
...