Acrylonitrile-butadiene rubber (NBR) — Evaluation procedure

This document specifies, for acrylonitrile-butadiene rubbers (NBRs): — physical and chemical tests on raw rubbers; — standard materials, a standard test formulation, equipment and processing methods for evaluating the vulcanization characteristics. The mixing preferred method is the single stage mixing with LIM (laboratory internal mixer).

Caoutchouc acrylonitrile-butadiène (NBR) — Méthode d'évaluation

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Status
Published
Publication Date
10-Aug-2020
Current Stage
6060 - International Standard published
Start Date
11-Aug-2020
Completion Date
11-Aug-2020
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INTERNATIONAL ISO
STANDARD 4658
Fourth edition
2020-08
Acrylonitrile-butadiene rubber
(NBR) — Evaluation procedure
Caoutchouc acrylonitrile-butadiène (NBR) — Méthode d'évaluation
Reference number
ISO 4658:2020(E)
ISO 2020
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ISO 4658:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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ii © ISO 2020 – All rights reserved
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ISO 4658:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Sampling and sample preparation .................................................................................................................................................... 2

5 Physical and chemical tests on raw rubber .............................................................................................................................. 2

5.1 Mooney viscosity ................................................................................................................................................................................... 2

5.2 Volatile matter ......................................................................................................................................................................................... 2

5.3 Ash ..................................................................................................................................................................................................................... 2

6 Preparation of the test mix for evaluation ................................................................................................................................ 2

6.1 Standard test formulation ............................................................................................................................................................. 2

6.2 Equipment and procedure ............................................................................................................................................................ 3

6.3 Mixing procedures ............................................................................................................................................................................... 3

6.3.1 General...................................................................................................................................................................................... 3

6.3.2 LIM mixing for methods A1 and A2 ................................................................................................................. 3

6.3.3 Method B — Mill mixing ........................................................................................................................................... . 5

7 Evaluation of vulcanization characteristics by a curemeter test ....................................................................... 6

7.1 E valuation using an oscillating-disc curemeter .......................................................................................................... 6

7.2 E valuation using a rotorless curemeter............................................................................................................................. 6

8 E valuation of tensile stress-strain properties of vulcanized test mixes .....................................................7

9 Precision ....................................................................................................................................................................................................................... 7

10 Test report ................................................................................................................................................................................................................... 7

Annex A (informative) Precision ............................................................................................................................................................................... 8

Bibliography .............................................................................................................................................................................................................................10

© ISO 2020 – All rights reserved iii
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ISO 4658:2020(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.

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 of 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 www .iso .org/

iso/ foreword .html.

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 fourth edition cancels and replaces the third edition (ISO 4658:1999), which has been technically

revised. It also incorporates the Amendment ISO 4658:1999/Amd.1:2004.
The main changes compared to the previous edition are as follows:
— Clause 2 has been updated;

— the mixing procedure has been specified: method A1 for single stage mixing with LIM is the preferred

method; method A2 is for two stages mixing using a LIM for initial mixing and mill mixing for final

mixing; method B deals with mill mixing;
— the precision data have been moved to Annex A.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
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INTERNATIONAL STANDARD ISO 4658:2020(E)
Acrylonitrile-butadiene rubber (NBR) — Evaluation
procedure
1 Scope
This document specifies, for acrylonitrile-butadiene rubbers (NBRs):
— physical and chemical tests on raw rubbers;

— standard materials, a standard test formulation, equipment and processing methods for evaluating

the vulcanization characteristics.

The mixing preferred method is the single stage mixing with LIM (laboratory internal mixer).

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 37, Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties

ISO 247-1, Rubber — Determination of ash — Part 1: Combustion method

ISO 247-2, Rubber — Determination of ash — Part 2: Thermogravimetric analysis (TGA)

ISO 248-1, Rubber, raw — Determination of volatile-matter content — Part 1: Hot-mill method and

oven method

ISO 248-2, Rubber, raw — Determination of volatile-matter content — Part 2: Thermogravimetric methods

using an automatic analyser with an infrared drying unit

ISO 289-1, Rubber, unvulcanized — Determinations using a shearing-disc viscometer — Part 1:

Determination of Mooney viscosity

ISO 1795, Rubber, raw natural and raw synthetic — Sampling and further preparative procedures

ISO 2393, Rubber test mixes — Preparation, mixing and vulcanization — Equipment and procedures

ISO 6502-2, Rubber — Measurement of vulcanization characteristics using curemeters — Part 2: Oscillating

disc curemeter

ISO 6502-3, Rubber — Measurement of vulcanization characteristics using curemeters — Part 3: Rotorless

curemeter

ISO 23529, Rubber — General procedures for preparing and conditioning test pieces for physical test methods

3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2020 – All rights reserved 1
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ISO 4658:2020(E)
4 Sampling and sample preparation

4.1 Take a sample of mass approximately 1,5 kg by the method described in ISO 1795.

4.2 Prepare the test portion in accordance with ISO 1795.
5 Physical and chemical tests on raw rubber
5.1 Mooney viscosity

Determine the Mooney viscosity in accordance with ISO 289-1, on a test portion prepared as indicated

in 4.2. Record the result as M (1+4) at 100 °C.
5.2 Volatile matter

Determine the volatile matter content by the method specified in ISO 248-1 or ISO 248-2.

5.3 Ash
Determine the ash in accordance with ISO 247-1 or ISO 247-2.
6 Preparation of the test mix for evaluation
6.1 Standard test formulation
The standard test formulation is given in Table 1.

The materials shall be national or international standard reference materials, unless no standard

reference materials are available in which case the materials to be used shall be agreed between the

interested parties.
Table 1 — Standard test formulation for evaluation on NBRs
Material Parts by mass
NBR 100,00
Zinc oxide 3,00
Sulfur 1,50
Stearic acid 1,00
Carbon black 40,00
TBBS 0,70
Total 146,20
Class B1a (see ISO 9298:2017, Annex D).
See ISO 8332.
See ISO 8312.

The current industry reference black (IRB), or an equivalent national or international standard reference material,

is used.

N-tert-Butyl-2-benzothiazole sulfenamide. This is supplied in powder form having an initial insoluble-matter

content, determined in accordance with ISO 11235. The material is stored at room temperature in a closed container and

the insoluble-matter content is checked every 6 months. If this is found to exceed 0,75 %, the material is discarded or

recrystallized.
2 © ISO 2020 – All rights reserved
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ISO 4658:2020(E)
6.2 Equipment and procedure

Equipment and the procedure for preparation, mixing and vulcanization shall be in accordance with

ISO 2393.
6.3 Mixing procedures
6.3.1 General
The three following alternative mixing procedures are specified:

— method A1: single stage mixing with LIM (laboratory internal mixer) which is the preferred method;

— method A2: two stage mixing using a LIM for initial mixing and mill mixing for final mixing;

— method B: mill mixing.
6.3.2 LIM mixing for methods A1 and A2
6.3.2.1 General

The mixing technique in each method may be modified to achieve a good dispersion of all the

ingredients. The LIM conditions shall be the same during the preparation of a series of identical mixes

for each batch mixed. At the beginning of each series of test mixes, a machine-conditioning batch shall

be mixed using the same formulation as the mixes under test. The LIM shall be allowed to cool down to

60 °C between the end of one test batch and the start of the next. Temperature control condition shall

not be altered during the mixing of a series of test.
6.3.2.2 Method A1 — Single stage mixing with LIM

The final temperature of the batch discharged after mixing shall not exceed 120 °C. If necessary, adjust

the batch mass, head temperature or rotors speed, so that this condition is met.

Compounding materials other than rubber, carbon black and oil may be added to LIM batches more

precisely and with greater ease if they are previously blended together in the proportions required by

the formulation. Such blends may be made using a mortar and pestle, by mixing for 10 min in a biconical

blender with intensifier bar turning, or by mixing in a b
...

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