ISO 13226:1999

Rubber — Standard reference elastomers (SREs) for characterizing the effect of liquids on vulcanized rubbers

Caoutchouc — Élastomères de référence normalisés (SRE) pour la caractérisation de l'effet des liquides sur les caoutchoucs vulcanisés

General Information

• Status: Withdrawn
• Publication Date: 01-Dec-1999
• Withdrawal Date: 01-Dec-1999
• ICS: 83.060 - Rubber
• Technical Committee: ISO/TC 45/SC 2 - Testing and analysis
• Drafting Committee: ISO/TC 45/SC 2/WG 3 - Degradation tests
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 07-Nov-2005

Relations

• Revised: ISO 13226:2005 - Rubber — Standard reference elastomers (SREs) for characterizing the effect of liquids on vulcanized rubbers
• Effective Date: 15-Apr-2008
• Consolidated By: ISO 22088-4:2006 - Plastics — Determination of resistance to environmental stress cracking (ESC) — Part 4: Ball or pin impression method
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13226
First edition
1999-12-01
Rubber — Standard reference elastomers
(SREs) for characterizing the effect of
liquids on vulcanized rubbers
Caoutchouc — Élastomères de référence normalisés (SRE) pour la
caractérisation de l'effet des liquides sur les caoutchoucs vulcanisés
A Reference number
ISO 13226:1999(E)

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ISO 13226:1999(E)
Contents
Page
1 Scope .1
2 Normative references .1
3 Composition.2
4 Preparation.2
5 Description .2
6 Test sheet properties.2
7 Designation .2
8 Storage.2
Annex A (normative) Acrylic rubbers: SRE-ACM/1 and SRE-ACM/1X.3
Annex B (normative) Acrylonitrile-butadiene rubbers: SRE-NBR 28/P and SRE-NBR 28/PX.5
Annex C (normative) Acrylonitrile-butadiene rubbers: SRE-NBR 28/S, SRE-NBR 28/SX, SRE-NBR 34/S
and SRE-NBR 34/SX .8
Annex D (normative) Acrylonitrile-butadiene rubbers: SRE-NBR/M.12
Annex E (normative) Acrylonitrile-butadiene rubbers: SRE-NBR/L.13
Annex F (normative) Chlorobutyl rubbers: SRE-CIIR/1.14
Annex G (normative) Chloroprene rubbers: SRE-CR/1.15
Annex H (normative) Ethylene-propylene rubbers: SRE-EPM/1.16
Annex I (normative) Fluoropolymer rubbers: SRE-FKM/1 .17
Annex J (normative) Fluoropolymer rubbers: SRE-FKM/2X.18
Annex K (normative) Hydrogenated acrylonitrile-butadiene rubbers: SRE-HNBR/1 and SRE-HNBR/1X.21
(normative)
Annex L Natural rubbers: SRE-NR/1.24
Annex M (normative) Silicone rubbers: SRE-MQ/1.25
Annex N (normative) Silicone rubbers: SRE-VMQ1 and SRE-VMQ/1X .26
©  ISO 1999
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 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
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© ISO ISO 13226:1999(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 3.
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 ISO 13226 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Physical and degradation tests.
Annexes A to N form a normative part of this International Standard.
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ISO 13226:1999(E) © ISO
Introduction
The materials covered by this International Standard are specified in annexes A to N. The following standard
elastomers are included:
a) Acrylic rubbers:
— SRE-ACM/1 and SRE-ACM/1X
b) Acrylonitrile-butadiene rubbers:
— SRE-NBR 28/P and SRE-NBR 28/PX
— SRE-NBR 28/S, SRE-NBR 28/SX, SRE-NBR 34/S and SRE-NBR 34/SX
— SRE-NBR/M
— SRE-NBR/L
c) Chlorobutyl rubbers:
— SRE-CIIR/1
d) Chloroprene rubbers:
— SRE-CR/1
e) Ethylene-propylene rubbers:
— SRE-EPM/1
f) Fluoropolymer rubbers:
— SRE-FKM/1
— SRE-FKM/2X
g) Hydrogenated acrylonitrile-butadiene rubbers:
— SRE-HNBR/1 and SRE-HNBR/1X
h) Natural rubbers:
— SRE-NR/1
i) Silicone rubbers:
— SRE-MQ/1
— SRE-VMQ/1 and SRE-VMQ/1X
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INTERNATIONAL STANDARD  © ISO ISO 13226:1999(E)
Rubber — Standard reference elastomers (SREs) for
characterizing the effect of liquids on vulcanized rubbers
WARNING — Persons using this International Standard should be familiar with normal laboratory practice.
This standard 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 International Standard specifies requirements for vulcanized rubbers in sheet form for use as standards in
characterizing the effect of test liquids and service fluids. Details of the individual standard reference elastomers are
listed in the annexes.
The compounding and preparation ensure that the property profile agrees sufficiently with that of the material group
represented, while the simple formulation ensures reliable reproducibility.
The specified property changes of the SRE when in contact with a fluid under specified conditions may be included
as supplementary data in specifications for the fluid concerned.
This International Standard is not designed to provide formulations of elastomeric-product compositions for actual
service.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 37:1994, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties.
ISO 48:1994, Rubber, vulcanized or thermoplastic — Determination of hardness (hardness between 10 IRHD and
100 IRHD).
ISO 1817:1999, Rubber, vulcanized — Determination of the effect of liquids.
1)
ISO 2230:— , Vulcanized rubber — Specification for controlled storage.
ISO 2393:1994, Rubber test mixes — Preparation, mixing and vulcanization — Equipment and procedures.
ISO 2781:1988, Rubber, vulcanized — Determination of density.
ISO 4648:1991, Rubber, vulcanized or thermoplastic — Determination of dimensions of test pieces and products for
test purposes.
ISO 7619:1997, Rubber — Determination of indentation hardness by means of pocket hardness meters.

1)
  To be published. (Revision of ISO 2230:1973)
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ISO 13226:1999(E) © ISO
3 Composition
The materials shall be homogeneous mixes of the ingredients shown in the relevant annex, in the proportions
shown, weighed to the accuracy required in ISO 2393.
All ingredients shall be of recognized rubber quality.
The identification of proprietary materials as suitable ingredients does not exclude the use of other materials that
can be shown to meet the requirements of the standard.
If necessary, the quantity of carbon black or silica may be adjusted from one consignment of rubber to another to
give properties within the limits specified in the annexes. If the filler content is adjusted, the details shall be declared.
4 Preparation
The mixing of compounds and the vulcanization of test sheets shall be carried out in accordance with ISO 2393 as
modified by detailed conditions and procedures given in the annexes.
If a mould release agent is needed, dry PTFE mould lubricant shall be used.
5 Description
The vulcanized test sheets shall be 2 mm ± 0,2 mm thick when measured in accordance with ISO 4648, free from
surface defects and from internal voids when viewed with normally corrected vision.
A "lot" of sheets is those sheets made from a single batch of rubber mix vulcanized under the same conditions. A
"pressing" is the quantity of sheets produced at the same time in a single moulding operation.
6 Test sheet properties
The test sheets shall be characterized by one or more physical properties in accordance with the relevant ISO
standard test method. Properties and tolerances for individual materials are given in the annexes.
All sheets shall be tested for compliance with the requirements of clause 5. A sample sheet from each lot shall be
tested for the properties of interest for compliance with the tolerances given in the appropriate annex. The actual
values obtained shall be reported.
The test pieces necessary for determining material properties shall be taken from the test sheets in such a way that
a minimum distance from the edge of the sheets is maintained. Bar-shaped test pieces shall be taken with their
longitudinal axis parallel to the direction of milling of the moulding blank.
7 Designation
Each elastomer shall be designated as ISO 13226 SRE-A/B where ISO 13226 is this International Standard, SRE is
the abbreviation for standard reference elastomer and, after the hyphen, A is set of code-letters designating the
polymer type and B is a descriptor identifying the particular compound. Some designations end with the letter X to
signify that additional test requirements apply.
8 Storage
Test sheets shall be stored in accordance with ISO 2230. After one year, they shall be retested or disposed of. If the
sheets still meet the test requirements, they may be stored and used for a further year.
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© ISO
ISO 13226:1999(E)
Annex A
(normative)
Acrylic rubbers: SRE-ACM/1 and SRE-ACM/1X
A.1  Purpose
These SREs are representative of ACM materials such as are used, for instance, for parts in contact with petroleum
products in the mechanical-engineering and automobile sectors.
They are used for the characterization of service fluids such as mineral oils, fuels, lubricants, hydraulic fluids,
coolants and refrigerants with regard to their effect on vulcanized acrylic rubbers.
The changes in mass, volume, hardness, tensile strength and elongation at break of the SRE when in contact with
the service fluid under specified conditions may be included as supplementary data in specifications for the fluid
concerned.
A.2  Composition
Table A.1 — Composition of the SRE
Ingredients Parts by mass
a
Acrylic rubber 100,0
Stearic acid 1,0
b
Pentaerythrite stearate 2,0
c
Octylated diphenylamine (ODPA) 2,0
Carbon black, N 550 65,0
Sodium stearate 4,0
d
Quaternary ammonium salts 2,0
Total 176,0
a 
 HyTemp 4051 from Zeon Corp., or equivalent.
b 
 Struktol WB 222 from Schill & Seilacher, or equivalent.
c 
 Vulkanox OCD/SG from Bayer AG, or equivalent.
d 
 HyTemp NPC-50 from Zeon Corp., or equivalent.
A.3  Recommended mixing procedure
Mix on a two-roll mill (see clause A.6).
A.4  Vulcanization
Condition the sheeted compound at ambient temperature for 12 h to 48 h.
Press-cure at 180 °C ± 2 °C for 10 min ± 1 min.
Post-cure at 175 °C ± 2 °C for 4 h ± 0,5 h.
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ISO 13226:1999(E) © ISO
A.5  Test sheet properties
Material SRE-ACM/1 shall fulfil the basic property given in Table A.2. Additional properties may be specified (see
Table A.3).
Material SRE-ACM/1X shall fulfil both the basic and the additional properties.
Table A.2 — Basic property
Property Unit Requirement Test method
Increase in mass in test liquid B for % 26 to 29 ISO 1817, 3 type 2 dumb-bell test
a
fuels, as in ISO 1817 pieces immersed for 22 h ± 0,5 h at
23 °C ± 2 °C
Test piece/test liquid volume ratio:
1/(30 ± 5)
a
 As specified in ISO 37.
Table A.3 — Additional properties
Property Unit Requirement Test method
Tensile strength MPa 12 to 16 ISO 37, 5 type 2 dumb-bell test pieces
Elongation at break % 140 to 220
Hardness Shore A 69 to 74 ISO 7619, 3 type 2 dumb-bell test
a
pieces , 3 plies
a
IRHD 69 to 74
ISO 48, 3 type 2 dumb-bell test pieces ,
3 plies
3
Density 1,30 to 1,34 ISO 2781:1988, method A, 3 test pieces
Mg/m
a
 As specified in ISO 37.
A.6  Mixing procedures
The following mixing procedure can be used to produce SRE-ACM/1X material:
Roll diameter: 200 mm
Working width: 395 mm
–1
Speed of rolls: 18/22 min
Surface temperature of rolls: 70 °C ± 5 °C
Mass of rubber: 650 g
Mixing step Elapsed time, minutes Nip opening, mm
Band rubber 0
2,0 ± 0,5
Add stearic acid, pentaerythrite stearate, ODPA and carbon black 1
Make 3/4 cuts (4 from each side) 11
a
13
Add sodium stearate and quaternary ammonium salts
2,2 ± 0,5
17
Make 3/4 cuts (6 from each side)
19
Turn the rolled sheet (3 times)
21
Sheet off
Final temperature of sheet: approx. 75 °C
a
 It is recommended that some of the final cuts are made during the addition of the sodium stearate to finalize the mixing procedure so
that the sheet is taken off not later than 6 min ± 1 min after the accelerator has been added.
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© ISO
ISO 13226:1999(E)
Annex B
(normative)
Acrylonitrile-butadiene rubbers: SRE-NBR 28/P and SRE-NBR 28/PX
B.1  Purpose
These SREs are representative of peroxide-cured NBR materials such as are used, for instance, for parts in contact
with petroleum products in the mechanical-engineering and automobile sectors.
They are used for the characterization of service fluids such as mineral oils, fuels, lubricants, hydraulic fluids,
coolants and refrigerants with regard to their effect on vulcanized nitrile rubbers.
The changes in mass, volume, hardness, tensile strength and elongation at break of the SRE when in contact with
the service fluid under specified conditions may be included as supplementary data in specifications for the fluid
concerned.
B.2  Composition
Table B.1 — Composition of the SRE
Ingredients Parts by mass
a
NBR with (28 ± 0,5) % by mass of acrylonitrile 100,0
b
N-(1,3 dimethylbutyl)-N-phenyl-p-phenylenediamine (6PPD) 0,5
c
Zinc oxide, precipitated 5,0
Carbon black, N 550 70,0
d
Dicumyl peroxide (40 % by mass) 3,0
Total 178,5
a


Perbunan NT 2845 from Bayer AG, or equivalent.
b 
 Vulkanox 4020 from Bayer AG, or equivalent.
c 
 Zinkoxyd aktiv from Bayer AG, or equivalent.
d 
 Perkadox BC 40 from Akzo-Nobel Chemicals BV, or equivalent.
B.3  Recommended mixing procedure
Prepare a masterbatch without the peroxide in an internal mixer followed by homogenizing and addition of peroxide
on a two-roll mill (see B.6.1).
Alternatively, mix completely on a two-roll mill (see B.6.2).
B.4  Vulcanization
Condition the sheeted compound at ambient temperature for 20 h to 24 h.
Press-cure at 170 °C ± 2 °C for 20 min ± 1 min.
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ISO 13226:1999(E) © ISO
B.5  Test sheet properties
SRE-NBR 28/P material shall fulfil the basic property given in Table B.2. Additional properties may be specified (see
Table B.3).
SRE-NBR 28/PX material shall fulfil both the basic and the additional properties.
Table B.2 — Basic property
Property Unit Requirement Test method
Increase in mass in test liquid B for % 25 to 28 ISO 1817, 3 type 2 dumb-bell test
a
fuels, as in ISO 1817 pieces immersed for 22 h ± 0,5 h at
23 °C ± 2 °C
Test piece/test liquid volume ratio:
1/(30 ± 5)
a
 As specified in ISO 37.
Table B.3 — Additonal properties
Property Unit Requirement Test method
Tensile strength MPa 20 to 25 ISO 37, 5 type 2 dumb-bell test pieces
% 170 to 220
Elongation at break
Hardness Shore A 79 to 84 ISO 7619, 3 type 2 dumb-bell test
a
pieces , 3 plies
a
IRHD 79 to 84 ISO 48, 3 type 2 dumb-bell test pieces ,
3 plies
3
Density Mg/m 1,21 to 1,25 ISO 2781:1988, method A, 3 test pieces
a
 As specified in ISO 37.
B.6  Mixing procedures
The following mixing procedures can be used to produce SRE-NBR 28/PX material:
B.6.1  Internal mixer and subsequent two-roll mill
Example of a mixing procedure for preparation of a masterbatch without peroxide, using an internal mixer fitted with
intermeshing blades:
a 3
Mixing-chamber volume : 4,6 dm
b
Chamber filled to: (65 ± 5) %
c –1
Speed : 30 min
Mass of rubber: 2 000 g
Mixing step Elapsed time, minutes
Add rubber 0
Add zinc oxide and 6PPD 2
Add carbon black 3
Dump 8
Final temperature of masterbatch: approx. 120 °C
a
 Determined by means of wheat grains.
b
 When using a mixer fitted with non-intermeshing blades, fill the chamber to (80 ± 5) %.
c
 With cooling fully operative.
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© ISO
ISO 13226:1999(E)
Example of a mixing procedure for homogenization of masterbatch and addition of peroxide using a two-roll mill:
Roll diameter: 250 mm
Working width: 410 mm
Speed of rolls:
–1
0 min to 13 min: 12/18 min
–1
14 min to 25 min: 12/12 min
Surface temperature of rolls: 50 °C ± 5 °C
Mixing step Elapsed time, minutes Nip opening, mm
Band hot masterbatch 0
Make 3/4 cuts (14 from each side) 1
Turn the rolled sheet (8 times) 8
Make 3/4 cuts (2 from each side) 13
3,0 0,5
Add peroxide 14 ±
Make 3/4 cuts (5 from each side) 16
Turn the rolled sheet (4 times) 19
Make 3/4 cuts (5 from each side) 21
Turn the rolled sheet (4 times) 23
1,5 ± 0,5
Sheet off 25
Final temperature of sheet: approx. 75 °C
B.6.2  Mixing using a two-roll mill
Roll diameter: 200 mm
Working width: 395 mm
–1
Speed of rolls: 20/24 min
Surface temperature of rolls: 50 °C ± 5 °C
Mass of rubber: 1 000 g
Mixing step Elapsed time, minutes Nip opening, mm
Band rubber 0
Add zinc oxide and 6PPD 3 2,0 ± 0,5
Make 3/4 cuts (3 from each side) 4
Add carbon black 6
Set stepwise to
3,2 ± 0,5
Add peroxide 17
Make 3/4 cuts (6 from each side) 19
3,2 ± 0,5
Turn the rolled sheet (4 times) 23
Sheet off 26 1,5 ± 0,5
Final temperature of sheet: approx. 90 °C
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ISO 13226:1999(E) © ISO
Annex C
(normative)
Acrylonitrile-butadiene rubbers: SRE-NBR 28/S, SRE-NBR 28/SX,
SRE-NBR 34/S and SRE-NBR 34/SX
C.1  Purpose
These SREs are representative of low-sulfur-cured NBR materials such as are used, for instance, for parts in
contact with petroleum products in the mechanical-engineering and automobile sectors.
They are used for the characterization of service fluids such as mineral oils, fuels, lubricants, hydraulic fluids,
coolants and refrigerants with regard to their effect on vulcanized nitrile rubbers.
In order to cover a wide range of service fluids, two different acrylonitrile (ACN) contents and thus a different
swelling behaviour of the SREs are specified as follows:
ISO 13226 SRE-NBR 28/S and SRE-NBR 28/SX (ACN content 28 %);
ISO 13226 SRE-NBR 34/S and SRE-NBR 34/SX (ACN content 34 %).
The changes in mass, volume, hardness, tensile strength and elongation at break of the SRE when in contact with
the service fluid under specified conditions may be included as supplementary data in specifications for the fluid
concerned.
C.2  Composition
Table C.1 — Composition of the SRE
Ingredients Parts by mass
28/S 34/S
28/SX 34/SX
a
NBR (ACN content 28 %) 100,0 —
b
NBR (ACN content 34 %) — 100,0
c
Polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ) 2,0 2,0
d
Zinc oxide, precipitated 5,0 5,0
Stearic acid 1,0 1,0
Carbon black, N 550 65,0 65,0
e
Tetramethylthiuram disulfide (TMTD) 2,5 2,5
f
N-cyclohexylbenzothiazyl-2-sulfenamide (CBS) 1,5 1,5
Sulfur 0,2 0,2
177,2 177,2
Total
a 
 Perbunan NT 2845 from Bayer AG, or equivalent.
b 
 Perbunan NT 3445 from Bayer AG, or equivalent.
c 
 Vulkanox HS/LG from Bayer AG, or equivalent.
d 
 Zinkoxyd aktiv from Bayer AG, or equivalent.
e 
 Vulkacit Thiuram/C from Bayer AG, or equivalent.
f 
 Vulkacit CZ/C from Bayer AG, or equivalent.
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© ISO
ISO 13226:1999(E)
C.3  Recommended mixing procedures
Prepare a masterbatch without the TMTD, CBS and sulfur in an internal mixer followed by homogenizing and
addition of curing agents on a two-roll mill (see C.6.1).
To obtain good sulfur dispersion, use about 10 % of the rubber to make a sulfur masterbatch.
Alternatively, mix completely on a two-roll mill. Prepare a sulfur masterbatch and store it for between 30 min and
24 h before proceeding with the main mix (see C.6.2).
C.4  Vulcanization
Condition the sheeted compound at ambient temperature for 2 h to 24 h.
Press-cure at 160 °C ± 2 °C for 20 min ± 1 min.
C.5  Test sheet properties
SRE-NBR 28/S and SRE-NBR 34/S materials shall fulfil the basic property given in Table C.2. Additional properties
may be specified (see Table C.3).
SRE-NBR 28/SX and SRE-NBR 34/SX materials shall fulfil both the basic and the additional properties.
Table C.2 — Basic property
Property Unit Requirement Test method
28/S 34/S
28/SX 34/SX
Increase in mass in test liquid B for % 26 to 29 17 to 20 ISO 1817, 3 type 2 dumb-bell test
a
fuels, as in ISO 1817 pieces immersed for 22 h ± 0,5 h at
23 °C ± 2 °C
Test piece/test liquid volume ratio:
1/(30 ± 5)
a
 As specified in ISO 37.
Table C.3 — Additonal properties
Property Unit Requirement Test method
28/SX 34/SX
Tensile strength MPa 20 to 25 20 to 25 ISO 37, 5 type 2 dumb-bell test pieces
Elongation at break % 300 to 400 300 to 400
Hardness Shore A 76 to 81 77 to 82 ISO 7619, 3 type 2 dumb-bell test
a
pieces , 3 plies
a
IRHD 76 to 81 77 to 82 ISO 48, 3 type 2 dumb-bell test pieces ,
3 plies
3
Density Mg/m 1,19 to 1,23 1,20 to 1,24 ISO 2781:1988, method A, 3 test pieces
a
 As specified in ISO 37.
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ISO 13226:1999(E) © ISO
C.6  Mixing procedures
The following mixing procedures can be used to produce SRE-NBR 28/SX and SRE-NBR 34/SX materials:
C.6.1  Internal mixer and subsequent two-roll mill
Use an internal mixer to prepare a masterbatch, without the vulcanizing ingredients, e.g. as specified in Table C.4.
Homogenize using a two-roll mill and add the vulcanizing ingredients, e.g. as specified in Table C.5.
To achieve good sulfur dispersion, which is essential for good tensile characteristics, take about 10 % of the rubber
and mix a sulfur batch in accordance with Table C.6 (with properly adjusted working width and/or nip opening). Add
this batch on the two-roll mill after step 2, as specified in Table C.5.
Table C.4 — Mixing procedure for preparation of a masterbatch without vulcanizing
ingredients using an internal mixer fitted with intermeshing blades (example)
a 3
Mixing-chamber volume : 4,6 dm
b
Chamber filled to: (65 ± 5) %
c –1
Speed : 30 min
Mass of rubber: 2 000 g
Mixing step Elapsed time, minutes
Add rubber 0
Add zinc oxide and TMQ 2
Add carbon black and stearic acid 3
Dump 8
Final temperature of masterbatch: approx. 120 °C
a
 Determined by means of wheat grains.
b
 When using a mixer fitted with non-intermeshing blades, fill the chamber to (80 ± 5) %.
c
 With cooling fully operative.
Table C.5 — Mixing procedure for homogenization of masterbatch and addition of vulcanizing ingredients,
using a two-roll mill (example)
Roll diameter: 250 mm
Working width: 410 mm
Speed of rolls:
–1
0 min to 13 min: 12/18 min
–1
14 min to 25 min: 12/12 min
Surface temperature of rolls: 50 °C ± 5 °C
Mixing step Elapsed time, minutes Nip opening, mm
Band hot masterbatch 0
Make 3/4 cuts (14 from each side) 1
Turn the rolled sheet (8 times) 8
Make 3/4 cuts (2 from each side) 13
Add sulfur, TMDT and CBS 14 3,0 ± 0,5
Make 3/4 cuts (5 from each side) 16
Turn the rolled sheet (4 times) 19
Make 3/4 cuts (5 from each side) 21
Turn the rolled sheet (4 times) 23
Sheet off 25 1,5 ± 0,5
Final temperature of sheet: approx. 90 °C. To ensure homogenous sulfur distribution, the final temperature shall not be
less than 90 °C. Increase the surface temperature of the rolls if necessary.
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© ISO
ISO 13226:1999(E)
C.6.2  Mixing using a two-roll mill
To ensure good sulfur distribution, prepare a sulfur batch (masterbatch) at a roll surface temperature of
80 °C ± 5 °C, e.g. as specified in Table C.6.
Store the sulfur batch for at least 30 min, but no longer than 24 h.
Continue the preparation of the mix at a roll surface temperature of 50 °C ± 5 °C, e.g. as specified in Table C.7.
Table C.6 — Mixing procedure for preparation of a sulfur batch (example)
Roll diameter: 200 mm
Working width: 395 mm
–1
Speed of rolls: 20/24 min
Surface temperature of rolls: 80 °C ± 5 °C
Rubber mass: 1 000 g
Mixing step Elapsed time, minutes Nip opening, mm
Pass the rubber twice 0 < 1
Band rubber 1
Add sulfur 2
2,5 ± 0,5
Make 3/4 cuts (3 from each side) 4
Sheet off 7
Final temperature of sheet: approx. 90 °C. To ensure homogenous sulfur distribution, the final temperature shall not
be less than 90 °C. Increase the surface temperature of the rolls if necessary.
Table C.7 — Mixing procedure for preparation of mix with sulfur batch (see Table C.6) (example)
Roll diameter: 200 mm
Working width: 395 mm
–1
Speed of rolls: 20/24 min
Surface temperature of rolls: 50 °C ± 5 °C
Mixing step Elapsed time, minutes Nip opening, mm
Pass sulfur batch between rolls 0
Add antioxidant 1
Make 3/4 cuts (2 from each side) 2,5 2,5 ± 0,5
Add zinc oxide 3
Make 3/4 cuts (2 from each side) 5
Add carbon black and stearic acid 6 Set stepwise to
3,2 ± 0,5
Make 3/4 cuts (4 from each side) 24
Add TMDT and CBS 26
3,2 ± 0,5
Make 3/4 cuts (6 from each side) 28
Turn the rolled sheet (4 times) 30
Sheet off 31 1,5 ± 0,5
Final temperature of sheet: approx. 90 °C
11

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ISO 13226:1999(E) © ISO
Annex D
(normative)
Acrylonitrile-butadiene rubbers: SRE-NBR/M
D.1  Purpose
Representative of a medium-nitrile-content acrylonitrile-butadiene rubber.
D.2  Composition
Table D.1 — Composition of the SRE
Ingredients Parts by mass
a
Medium acrylonitrile-butadiene rubber (ACN content 33 %) 100
Stearic acid 1,5
Zinc oxide 5,0
Carbon black, N 550 55 (nominal)
b
Sulfur masterbatch 1,9
c
Dibenzothiazyl disulfide masterbatch (MBTS) 2,0
Total 165,4
a
 Medium-nitrile-content, hot-polymerized Breon N33H80 from Zeon Corp. has been found to be suitable.
b
 Masterbatch containing 80 % sulfur and 20 % of an ethylene-propylene rubber.
c
 Masterbatch containing 75 % active accelerator and 25 % of an ethylene-propylene rubber.
D.3  Vulcanization
Press-cure for 20 min ± 15 s at 155 °C ± 2 °C.
D.4  Test sheet properties
SRE-NBR/M material shall fulfil the basic property given in Table D.2.
Table D.2 — Basic property
Property Unit Requirement Test method
Increase in mass in test liquid 101, % 19 to 22 ISO 1817, 3 test pieces
as in ISO 1817 0
immersed for 48 h at
( )-1
100 °C ± 1 °C
No additional properties are specified.
12

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© ISO
ISO 13226:1999(E)
Annex E
(normative)
Acrylonitrile-butadiene rubbers: SRE-NBR/L
E.1  Purpose
Representative of a low-nitrile-content acrylonitrile-butadiene rubber.
E.2  Composition
Table E.1 — Composition of the SRE
Ingredients Parts by mass
a
Low acrylonitrile-butadiene rubber (ACN content 18 %) 100
Stearic acid 1,5
Zinc oxide 5,0
Carbon black, N 550 67 (nominal)
b
Sulfur masterbatch 1,9
c
Dibenzothiazyl disulfide masterbatch (MBTS) 2,0
Total 177,4
a
 Low-nitrile-content Paracril 18.80 from Uniroyal Chemical has been found to be suitable.
b
 Masterbatch containing 80 % sulfur and 20 % of an ethylene-propylene rubber.
c
 Masterbatch containing 75 % active accelerator and 25 % of an ethylene-propylene rubber.
E.3  Vulcanization
Press-cure for 30 min ± 15 s at 155 °C ± 2 °C.
E.4  Test sheet properties
SRE-NBR/L material shall fulfil the basic property given in Table E.2.
Table E.2 — Basic property
Property Unit Requirement Te
...