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
Standards Content (Sample)
(NBR) — Evaluation procedure
Caoutchouc acrylonitrile-butadiène (NBR) — Méthode d'évaluation
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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
© ISO 2020 – All rights reserved iii
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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
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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
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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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 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
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
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
ISO 6502-3, Rubber — Measurement of vulcanization characteristics using curemeters — Part 3: Rotorless
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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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.
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
Table 1 — Standard test formulation for evaluation on NBRs
Material Parts by mass
Zinc oxide 3,00
Stearic acid 1,00
Carbon black 40,00
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,
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
2 © ISO 2020 – All rights reserved
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6.2 Equipment and procedure
Equipment and the procedure for preparation, mixing and vulcanization shall be in accordance with
6.3 Mixing procedures
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
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.
188.8.131.52 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