ISO 16565:2013
(Main)Rubber — Determination of 5-ethylidenenorbornene (ENB) or dicyclopentadiene (DCPD) in ethylene-propylene-diene (EPDM) terpolymers
Rubber — Determination of 5-ethylidenenorbornene (ENB) or dicyclopentadiene (DCPD) in ethylene-propylene-diene (EPDM) terpolymers
ISO 16565:2013 specifies the methods to be used to determine the content of 5 ethylidenenorbornene (ENB) or dicyclopentadiene (DCPD) in ethylene-propylene-diene (EPDM) terpolymers in the 0,1 % to 10 % range. ENB and DCPD are dienes introduced into ethylene-propylene rubbers to generate specific cure properties. Since high precision for diene content determination is important, a Fourier transform infrared spectroscopic (FT IR) method is utilized.
Caoutchouc — Détermination du 5-éthylidènenorbornène (ENB) ou du dicyclopentadiène (DCPD) dans les terpolymers d'éthylène-propylène-diène (EPDM)
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 16565
Third edition
2013-05-15
Rubber — Determination of
5-ethylidenenorbornene (ENB) or
dicyclopentadiene (DCPD) in ethylene-
propylene-diene (EPDM) terpolymers
Caoutchouc — Détermination du 5-éthylidènenorbornène (ENB)
ou du dicyclopentadiène (DCPD) dans les terpolymers d’éthylène-
propylène-diène (EPDM)
Reference number
ISO 16565:2013(E)
©
ISO 2013
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ISO 16565:2013(E)
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ii © ISO 2013 – All rights reserved
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ISO 16565:2013(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Principle . 1
3 Apparatus . 1
4 Test specimen preparation . 2
4.1 Primary method . 2
4.2 Alternative method . 2
4.3 Alternative method for liquid polymer film preparation . 2
5 Acquisition of spectra . 3
5.1 With a specimen shuttle . 3
5.2 Without a specimen shuttle . 3
6 Calibration of the spectrophotometer . 3
7 Diene determination . 4
7.1 Preparation . 4
7.2 Single absorbance spectrum . 4
7.3 Determination of film thickness . 4
7.4 Determination of diene content . 4
8 Precision . 8
9 Test report . 9
Annex A (normative) Procedure for spectral subtraction of water vapour .10
Annex B (informative) Precision and bias .12
Bibliography .14
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ISO 16565:2013(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. 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. 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.
The committee responsible for this document is ISO/TC 45, Rubber and rubber products, Subcommittee
SC 2, Testing and analysis.
This third edition cancels and replaces the second edition (ISO 16565:2008), of which it constitutes a
minor revision. The main changes are: a correction to the Scope concerning the range of termonomer
content (either ENB or DCPD) to be determined and the locations of points A and B on Figure 1.
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INTERNATIONAL STANDARD ISO 16565:2013(E)
Rubber — Determination of 5-ethylidenenorbornene
(ENB) or dicyclopentadiene (DCPD) in ethylene-propylene-
diene (EPDM) terpolymers
WARNING — Persons using this International Standard should be familiar with normal laboratory
practice. This International Standard does not purport to address all of the safety concerns, if
any, associated with its use. It is the responsibility of the user of this International Standard to
establish appropriate safety and health practices and to ensure compliance with any national
regulatory conditions.
1 Scope
This International Standard specifies the methods to be used to determine the content of
5-ethylidenenorbornene (ENB) or dicyclopentadiene (DCPD) in ethylene-propylene-diene (EPDM)
terpolymers in the 0,1 % to 10 % range.
ENB and DCPD are dienes introduced into ethylene-propylene rubbers to generate specific cure
properties. Since high precision for diene content determination is important, a Fourier transform
infrared spectroscopic (FT-IR) method is utilized.
NOTE The procedures for the mass fraction of ENB and the mass fraction of DCPD differ only in the location
in the infrared (IR) of the peak being quantified.
2 Principle
A test specimen is moulded between two PTFE-coated aluminium or mylar sheets. The ENB content is
−1 −1
determined from its infrared absorbance at 1 681 cm to 1 690 cm (a measure of the exocyclic double
−1 −1
bond in ENB). The DCPD content is determined from its infrared absorbance at 1 605 cm to 1 610 cm
(a measure of the monocyclic double bond in DCPD).
The second derivative of the absorbance is calculated and ratioed to an internal standard. For ENB, the
−1
resulting second-derivative peak near 1 690 cm is related to the ENB mass fraction by calibrating
the instrument with known EPDM standards. For DCPD, the resulting second-derivative peak near
−1
1 610 cm is related to the DCPD mass fraction in the same way.
For oil-extended polymers, the oil shall be extracted before the diene content is determined.
3 Apparatus
3.1 Carver-type press, capable of compressing films at 150 °C and 10 MPa.
3.2 Mould.
3.2.1 The mould primarily used is made of a stainless-steel strip 400 µm thick with an opening, which
gives a specimen of the appropriate size for the specimen-film holder described in 3.4 (2 cm by 2 cm). The
mould shall have approximately the same dimensions as the press platens.
3.2.2 Alternatively, a thinner mould plate may be used. However, precision can be adversely affected
at low diene levels. The precision of the method shall be determined when thinner films are utilized.
For example, 127 µm-thick stainless-steel foil with a 15 mm by 35 mm opening may be used for the
simultaneous determination of ethylene and diene.
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ISO 16565:2013(E)
3.2.3 For liquid EPDMs, a ring washer of 22 mm outer diameter by 16 mm inner diameter and 400 µm-
thick is used as a spacer between salt plates (NaBr, NaCl) to set a fixed path length. The spacer is sized to
cover only the outer edge of the salt plates.
3.3 PTFE-coated aluminium moulding sheets, type A, 36 µm thick, or silicone release sheeting.
3.4 Specimen-film holders: films may be moulded, cut out and transferred to a film holder. Magnetic-
film holders are ideal. Alternatively, a mould sized to fit in the spectrophotometer specimen compartment,
with an appropriate-sized opening, may be used to support the film without removal after compressing. A
standard salt plate support is used for liquid samples prepared between salt plates.
3.5 Infrared Fourier transform spectrophotometer, capable of measuring absorbances in the
−1 −1
range of 4 000 cm to 600 cm with a transmittance specification (accuracy) of ±1 % T or better. The
−1
instrument shall be capable of spectral resolution of 2 cm . A deuterated triglycine sulfate (DTGS) or, as
an alternative, a mercury cadmium telluride (MCT) detector shall be used.
[1]
NOTE A specification for the evaluation of the analysis of infrared spectra is given in Reference.
The instrument shall be capable of spectral accumulation, averaging and subtracting. Water is the
primary source of interference in this method. Methods, physical and electronic, which minimize the
moisture level and moisture-level variation are required to obtain the highest precision. The preferred
method is to use an instrument equipped with a dry-gas purge and specimen shuttle, which permits
alternating and repetitive collection of single-beam specimen and background spectra (see Clause 5).
Alternatively, should a specimen shuttle be unavailable, careful purging of the specimen compartment
with dry nitrogen can yield satisfactory results. High precision of calibration-standard data is indicative
of adequate purging. When moisture interference is not removed by purging, spectral subtraction of
water vapour may be used. A procedure for further development of the method is described in Annex A.
4 Test specimen preparation
4.1 Primary method
Place 0,20 g ± 0,05 g of the material to be analysed between two sheets (see 3.3) in the mould (see 3.2.1).
Place the mould between the press platens heated to 125 °C ± 5 °C and apply 4 MPa pressure for 60 s ± 10 s.
Should the material be highly viscous, the mould may be heated to 175 °C ± 5 °C.
Cool the material to ambient temperature. Cut out a piece of film of approximately 15 mm by 50 mm.
Detach the specimen film from the sheets (see 3.3), and position it on the spectrophotometer specimen
compartment window.
4.2 Alternative method
When using the thinner mould described in 3.2.2, place a small piece (0,04 g to 0,06 g) of the material
to be analysed in the mould opening between two sheets (see 3.3) and compress as in 4.1. Remove the
mould from the press, turn it over and compress it again. Then, remove the mould from the press and
allow it to cool to ambient temperature. When cool, carefully remove the sheets (see 3.3), allowing the
specimen film to remain attached to the mould.
4.3 Alternative method for liquid polymer film preparation
Place a washer (see 3.2.3) on top of a salt plate. Place a small amount (about 0,3 g) of the liquid EPDM
polymer to be analysed in the centre of the washer, filling the hole completely. Place a second salt plate
on top of the filled washer. Gently place a 1 kg weight on top of the salt plate/washer assembly and allow
the weighted assembly to sit for 2 min to 3 min. (For viscous samples, it may be necessary to warm the
sample prior to compressing.) Remove the 1 kg weight and, if necessary, allow to cool. Wipe off any
excess material that might have been pressed out of the assembly. Hold the assembly up to the light and
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ISO 16565:2013(E)
inspect for bubbles and/or voids. Should there be imperfections, repeat the preparation with a larger
amount of material.
5 Acquisition of spectra
5.1 With a specimen shuttle
5.1.1 The data-acquisition parameters shall be:
−1
— resolution: 2 cm ;
— scans/scan time: total scan time, split between specimen scans and background scans, about 90 s.
5.1.2 Place the test specimen in the specimen compartment, allow purge to be re-established and,
in alternating fashion, collect single-beam specimen and empty specimen compartment spectra. Eight
passes of the shuttle shall be made (eight specimen and eight empty-compartment collections), collecting
four scans at each position.
5.1.3 Calculate the specimen absorbance spectrum as −log of the ratio of the accumulated single-
10
beam specimen to the empty-compartment spectrum using Formula (1):
A = −log (P/P )
10 0
(1)
where
A is the absorbance of the specimen at a given wavelength;
P is the empty specimen compartment light-beam intensity at that wavelength;
0
P is the single-beam specimen light-beam intensity at that wavelength.
5.2 Without a specimen shuttle
5.2.1 The data-acquisition parameters shall be:
−1
— resolution: 2 cm ;
— scans/scan time: background scans: 32 scans, 120 s total; specimen scans: 32 scans, 120 s total.
5.2.2 Establish a dry atmosphere inside the empty specimen compartment and coll
...
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