ISO 14897:2002

Plastics — Polyols for use in the production of polyurethane — Determination of water content

ISO 14897 specifies methods used to measure the water content of polyols employed as polyurethane raw materials. Method A is a manual amperometric method which has been included to better define the principles of the Karl Fischer measurement. Amperometric methods are applicable to a wide range of polyols, including those which have enough colour to obscure a visual end-point. Method B includes an automated amperometric procedure and an automated coulometric procedure. The coulometric procedure is an absolute method that does not require calibration and gives improved sensitivity compared with amperometric methods.

Plastiques — Polyols pour la production du polyuréthanne — Dosage de l'eau

General Information

• Status: Withdrawn
• Publication Date: 12-Jun-2002
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: ISO/TC 61/SC 12 - Thermosetting materials
• Drafting Committee: ISO/TC 61/SC 12 - Thermosetting materials
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 22-Jun-2023

Relations

• Revised: ISO 14897:2023 - Plastics — Polyols for use in the production of polyurethanes — Determination of water content
• Effective Date: 17-Sep-2022
• Revises: ISO 14897:2000 - Plastics — Polyols for use in the production of polyurethane — Determination of water content
• Effective Date: 15-Apr-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 14897
Second edition
2002-06-15

Plastics — Polyols for use in the
production of polyurethane —
Determination of water content
Plastiques — Polyols pour la production du polyuréthanne — Dosage de
l'eau




Reference number
ISO 14897:2002(E)
©
ISO 2002

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ISO 14897:2002(E)
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ISO 14897:2002(E)
Contents Page
Foreword.iv
1 Scope .1
2 Normative references.1
3 Terms and definitions .1
4 Principle.2
5 Application .2
6 Interferences .2
7 Reagents.2
8 Apparatus .3
9 Sampling.4
10 Standardization of reagent .5
11 Procedure .5
12 Expression of results .6
13 Precision and bias.6
14 Test report .7
Annex A (informative) Interlaboratory precision studies.8

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ISO 14897:2002(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.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14897 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting
materials.
This second edition cancels and replaces the first edition (ISO 14897:2000), which has been technically revised.
The principal technical change is the incorporation of significantly improved precision data.
The standard is based on ASTM D 4672, Standard Test Methods for Polyurethane Raw Materials — Determination
of Water Content of Polyols.


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INTERNATIONAL STANDARD ISO 14897:2002(E)

Plastics — Polyols for use in the production of polyurethane —
Determination of water content
CAUTION — 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 of this standard to establish appropriate safety and health practices and to
ensure compliance with any national regulatory conditions prior to use.
1 Scope
This International Standard specifies methods used to measure the water content of polyols employed as
polyurethane raw materials. Method A is a manual amperometric method which has been included to better define
the principles of the Karl Fischer measurement. Amperometric methods are applicable to a wide range of polyols,
including those which have enough colour to obscure a visual end-point. Method B includes an automated
amperometric procedure and an automated coulometric procedure. The coulometric procedure is an absolute
method that does not require calibration and gives improved sensitivity compared with amperometric methods.
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 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 6353-1:1982, Reagents for chemical analysis — Part 1: General test methods
ISO 6353-2:1983, Reagents for chemical analysis — Part 2: Specifications — First series
ISO 6353-3:1987, Reagents for chemical analysis — Part 3: Specifications — Second series
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
polyol
an organic compound containing two or more hydroxyl groups suitable for reaction with isocyanates
3.2
polyurethane
a polymer prepared by the reaction of an organic di- or polyisocyanate with compounds containing two or more
hydroxyl groups
NOTE Polyurethanes may be thermosetting, thermoplastic, rigid or soft and flexible, cellular or non-cellular.
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ISO 14897:2002(E)
4 Principle
4.1 Methods A and B are based on amperometric or coulometric titrations with Karl Fischer reagent. The sulfur
dioxide in the reagent first reacts with the alcohol to form an ester which is neutralized by the base present in the
reagent. The anion of the alkyl sulfurous acid is the reactive component. The titration of water present constitutes
the oxidation of the alkyl sulfite to alkyl sulfate by the iodine, which consumes the water. The reaction can be
1)
formulated as follows:
ROH + SO + R¢N → (R¢NH)SO R
2 3
H O + I + (R¢NH)SO R + 2R¢N → (R¢NH)SO R + 2(R¢NH)I
2 2 3 4
4.2 To determine water, Karl Fischer reagent [a solution of iodine, sulfur dioxide, ethylene glycol monomethyl
ether (HOCH CH OCH ) and pyridine or a pyridine substitute] is added to a solution of the test portion in methanol
2 2 3
or another alcohol until all of the water present has been consumed. In an amperometric titration, this is evidenced
by a current-measuring device that indicates the depolarization of a pair of platinum electrodes. In coulometric
titrations, the iodine reagent is generated electrically, thus eliminating the need for standardization of the reagent.
5 Application
These test methods are suitable for quality control, as a specification test for products, and for research. The water
content of a polyol is important because water reacts with isocyanates to form carbon dioxide and an amine which
consumes additional isocyanate.
NOTE The description of the manual system presented below is principally for reference purposes and has been included
in order to better define the principles of the Karl Fischer measurement. Commercially available automated Karl Fischer titrators
of the type described in Method B are used extensively. Additional details and diagrams are available in ISO 760:1978,
Determination of water — Karl Fischer method (General method).
6 Interferences
6.1 Oxides, hydroxides and strongly basic compounds react with Karl Fischer reagent, producing an equivalent
amount of water, thus giving falsely high results. Therefore, this method shall not be used for crude polyols
containing KOH or other highly basic products unless corrections are made for the excess water produced.
6.2 Amine-based polyols may shift the pH of the Karl Fischer system into the alkaline range, causing incorrect
results. This problem may be circumvented by adding salicylic or benzoic acid in greater than stoichiometric
amounts before carrying out the titration. Tests should be run to determine the suitability of the procedure for a
particular polyol type.
7 Reagents
7.1 Purity of reagents
Reagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall
conform to the specifications of ISO 6353-1, ISO 6353-2 and ISO 6353-3. Other grades may be used, provided that
it is first determined that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of
the determination.

1)
Scholz, Eugen: Karl Fischer Titration, Springer-Verlag, Berlin, Heidelberg, New York, 1984.
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ISO 14897:2002(E)
7.2 Purity of water
Unless otherwise indicated, references to water shall be understood to mean grade 3 water as defined in
ISO 3696.
7.3 Reagents for Method A (manual titration)
7.3.1 Karl Fischer reagent, equivalent to 2,5 mg to 3,5 mg of water/ml. Dilute commercially available stabilized
Karl Fischer reagent (6 mg of water/ml) with an equal volume of anhydrous ethylene glycol monomethyl ether
(containing less than 0,1 % of water).
NOTE Improved, pyridine-free Karl Fischer reagents have been made available and are highly recommended as a
replacement for the previous reagents.
7.3.2 Titration solvent (anhydrous methanol): Unless the methanol is extremely dry, it will require a large
amount of dilute Karl Fischer reagent to react with its residual water. For this reason, dry the solvent further by
adding undiluted Karl Fischer reagent (6 mg of water/ml) to a bottle of methanol until a light red-brown colour
persists. Then add methanol until the solution is a pale yellow. A 100 ml portion of the treated solvent should
require 1 ml to 10 ml of dilute Karl Fischer reagent.
7.4 R
...