ISO 25761:2014

Plastics - Polyols for use in the production of polyurethanes - Determination of basicity (total amine value), expressed as percent nitrogen

The method specified in ISO 25761:2014 measures the basic constituents in polyols that are soluble in glacial acetic acid and reactive with perchloric acid. Samples containing 0,3 % to 10 % of nitrogen have been evaluated by this method. The method is applicable to amine-based polyols, polyether polyols and polyether polyol blends that are used in polyurethane reactions. The results are measures of batch-to-batch uniformity and may be used to estimate reactivity in polyurethane reactions.

Plastiques — Polyalcools utilisés pour la production de polyuréthannes — Détermination de la basicité (valeur totale d'amines) en pourcentage d'azote

General Information

• Status: Published
• Publication Date: 13-Feb-2014
• 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: 9093 - International Standard confirmed
• Start Date: 09-Dec-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 25761:2008 - Plastics - Polyols for use in the production of polyurethanes - Determination of basicity (total amine value), expressed as percent nitrogen
• Effective Date: 26-Jan-2013

Overview

ISO 25761:2014 - "Plastics - Polyols for use in the production of polyurethanes - Determination of basicity (total amine value), expressed as percent nitrogen" - specifies an analytical method to measure the basic (amine) constituents in polyols used for polyurethane production. The method determines the perchloric‑acid‑titrable basicity of polyether and amine‑based polyols (and their blends), reporting results as percent nitrogen (% N) or as total amine value (mg KOH/g). The standard is technically equivalent to ASTM D6979.

Key topics and technical requirements

• Scope and applicability: Validated for samples containing about 0.3% to 10% nitrogen; applicable to amine‑based polyols, polyether polyols and blends used in polyurethane reactions.
• Principle: Dissolve a weighed test portion in glacial acetic acid and titrate potentiometrically (or colorimetrically) with 0.10 mol/L perchloric acid in acetic acid to a potentiometric end point (~600 mV).
• Sampling & apparatus: Requires representative sampling into cleaned borosilicate containers; equipment includes precision balance, one‑mark volumetric flasks, graduated cylinders, and a potentiometric titrator with suitable electrodes.
• Reagents & safety: Use of perchloric acid requires strict safety controls (fume hood approved for perchloric acid, suitable PPE). Reagents should conform to ISO reagent specifications (ISO 6353 series).
• Calculations & reporting: Results calculated as % N from titrant volume, titrant factor, and sample mass. Optionally reported as alkalinity/total amine value in mg KOH/g (conversion factor 5.61 for 0.10 mol/L titrant).
• Precision: Round‑robin precision data provided (repeatability and reproducibility limits) - users are advised to generate laboratory‑specific statistics for acceptance criteria.
• Interferences: Acidic/basic contaminants or buffering substances can bias titration end points.

Applications and who uses it

• Quality control laboratories in polyurethane and polyol manufacturing - for batch‑to‑batch uniformity checks and to estimate polyol reactivity in polyurethane formulations.
• R&D teams developing polyols or formulating polyurethane systems who need quantitative basicity data to predict cure speed and catalyst performance.
• Third‑party testing labs and regulatory/compliance groups verifying product specifications.
• Procurement and specification writers who include analytical acceptance criteria in material datasheets and purchase contracts.

Related standards

• ISO 1042 (volumetric flasks), ISO 4788 (graduated cylinders), ISO 3696 (water for analytical use), ISO 6353‑1/2/3 (reagents).
• ASTM D6979 - method technically equivalent to ISO 25761:2014.

Keywords: ISO 25761:2014, polyols, polyurethanes, basicity, total amine value, percent nitrogen, perchloric acid titration, potentiometric titration, polyether polyols, quality control.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 25761
Second edition
2014-03-01
Plastics — Polyols for use in the
production of polyurethanes —
Determination of basicity (total amine
value), expressed as percent nitrogen
Plastiques — Polyalcools utilisés pour la production de
polyuréthannes — Détermination de la basicité (valeur totale
d’amines) en pourcentage d’azote
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Sampling . 2
6 Apparatus . 2
7 Interference . 2
8 Reagents . 2
9 Procedure. 3
10 Expression of results . 4
11 Precision and bias . 4
11.1 General . 4
11.2 Precision . 5
11.3 Bias . 5
12 Test report
................................................................................................................................................................................................................... 5
Annex A (informative) Determination of the factor F for 0,1 mol/l perchloric acid in acetic acid .6
Bibliography . 7
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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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
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For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information.
The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting
materials.
This second edition cancels and replaces the first edition (ISO 25761:2008), which has been technically
revised.
iv © ISO 2014 – All rights reserved

Introduction
Polyurethanes are produced by the catalysed reaction of isocyanates with polyols. The basicity of the
polyol employed affects the rate of reaction and speed of cure of the product. It is therefore necessary to
determine the basicity in order to predict reactivity and monitor product quality.
INTERNATIONAL STANDARD ISO 25761:2014(E)
Plastics — Polyols for use in the production of
polyurethanes — Determination of basicity (total amine
value), expressed as percent nitrogen
SAFETY STATEMENT — Persons using this document should be familiar with normal laboratory
practice, if applicable. This document does not purport to address all of the safety concerns, 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 regulatory requirements.
1 Scope
The method specified in this International Standard measures the basic constituents in polyols that
are soluble in glacial acetic acid and reactive with perchloric acid. Samples containing 0,3 % to 10 % of
nitrogen have been evaluated by this method. The method is applicable to amine-based polyols, polyether
polyols and polyether polyol blends that are used in polyurethane reactions. The results are measures of
batch-to-batch uniformity and may be used to estimate reactivity in polyurethane reactions.
It is also permissible to express the results in equivalents of base per gram of sample.
NOTE This method is technically equivalent to that in ASTM D 6979.
2 Normative references
The following referenced documents are indispensable for the application 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 1042, Laboratory glassware — One-mark volumetric flasks
ISO 4788, Laboratory glassware — Graduated measuring cylinders
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 6353-1, Reagents for chemical analysis — Part 1: General test methods
ISO 6353-2, Reagents for chemical analysis — Part 2: Specifications — First series
ISO 6353-3, Reagents for chemical analysis — Part 3: Specifications — Second series
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
polyol
polymer based on ethylene oxide and/or propylene oxide which contains two or more hydroxyl groups
3.2
polyurethane
polymer prepared by the reaction of an organic di- or polyisocyanate with a compound containing two
or more hydroxyl groups
3.3
percent nitrogen
quantity of perchloric-acid-titratable base in a sample, expressed as a mass percentage of nitrogen
3.4
alkalinity
quantity of perchloric-acid-titratable base in a sample, expressed as mg of KOH/g of sample
3.5
total amine value
quantity of perchloric-acid-titratable base in a sample, identified only as amines and expressed as mg of
KOH/g of sample
4 Principle
A test portion of the sample is dissolved in glacial acetic acid. The resulting single-phase solution is
titrated at room temperature to a potentiometric end point with a standardized solution of perchloric
acid in acetic acid. The result is reported as percent nitrogen or mg of KOH/g of sample.
5 Sampling
Draw samples from a well-mixed vessel into a thoroughly cleaned and dry borosilicate-glass container
(soft-glass containers are not acceptable). If sampling from a line or valve, flush the line thoroughly with
the product before starting to draw the sample. Seal the sample until analysis.
6 Apparatus
6.1 One-mark volumetric flask, of capaci
...