ASTM D4671-21

Standard Test Method for Polyurethane Raw Materials: Determination of Unsaturation of Polyols

SIGNIFICANCE AND USE
5.1 This test method is suitable for quality control, as specification tests, and for research.  
5.2 Side reactions that form unsaturated compounds in polypropylene oxides produce small amounts of polymers with only one hydroxyl group per chain. These unsaturated polymers lower functionality and molecular weight, while broadening the overall molecular-weight distribution.
SCOPE
1.1 This test method measures unsaturation in polyether polyols. (See Note 1.) It uses 2 mL of ca. 0.05 M mercuric acetate reagent in methanol and about 1 g of sample or less. This test method uses a potentiometric determination of an end point.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by law.  
1.4 This 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 standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: This standard is equivalent to ISO 17710.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Jun-2021
• ICS: 83.040.30 - Auxiliary materials and additives for plastics
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM E2935-17 - Standard Practice for Conducting Equivalence Testing in Laboratory Applications
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM E2935-16 - Standard Practice for Conducting Equivalence Testing in Laboratory Applications
• Effective Date: 15-Nov-2016
• Refers: ASTM E2935-15 - Standard Practice for Conducting Equivalence Testing in Laboratory Applications
• Effective Date: 01-Oct-2015

Overview

ASTM D4671-21, "Standard Test Method for Polyurethane Raw Materials: Determination of Unsaturation of Polyols," establishes a procedure for measuring unsaturation in polyether polyols-key raw materials in the production of polyurethane. Unsaturation in polyols results from side reactions during the synthesis of polypropylene oxides, producing polymers with only one hydroxyl group per chain. Elevated levels of unsaturation can lower the functionality and molecular weight of polyols, which impacts polyurethane performance and consistency.

This ASTM method uses a potentiometric titration involving mercuric acetate reagent in methanol, providing reliable results for quality control, specification testing, and research applications. The standard is closely aligned with ISO 17710, ensuring international applicability.

Key Topics

• Determination of Unsaturation in Polyols

  • Measures the presence of carbon-to-carbon double bonds in polyether polyols using potentiometric titration.
  • Unsaturation is an important quality attribute affecting polyurethane properties.

• Sampling and Reagents

  • Typically requires about 1 g of sample or less.
  • Utilizes approximately 2 mL of 0.05 M mercuric acetate in methanol as a reagent.
  • Potentiometric end point is determined using an autotitrator and pH electrode.

• Significance of Results

  • Monitoring unsaturation helps manufacturers maintain specification limits and ensures consistent material quality.
  • Detects variability resulting from process side reactions, which impact product performance.

• Precision and Quality Control

  • Widely used for quality assurance in manufacturing and for verifying supplier specifications.
  • Featuring defined repeatability and reproducibility criteria.

• Safety and Compliance

  • Emphasizes careful handling of mercury and adherence to all relevant health, safety, and environmental regulations.
  • Users must consult relevant Safety Data Sheets (SDS) and be aware of legal restrictions on mercury-containing products.

Applications

• Quality Control in Polyurethane Manufacturing

  • Used routinely to test incoming polyol batches for unsaturation, ensuring raw material quality before use in polyurethane foam, elastomers, coatings, and adhesives.

• Specification Testing

  • Allows suppliers and manufacturers to certify polyol shipments against contractual specifications and industry standards.

• Research and Product Development

  • Supports development of new polyols and formulation adjustments by providing critical data on polymer characteristics.

• Ensuring Regulatory Compliance

  • Facilitates adherence to national and international quality standards for polyurethane materials, supporting exports and supply chain transparency.

• Process Optimization

  • Enables manufacturers to monitor and optimize production processes, minimizing undesirable side reactions that lead to increased unsaturation.

Related Standards

• ISO 17710: Plastics – Polyols for Use in the Production of Polyurethane – Determination of Degree of Unsaturation by Microtitration. This standard is noted as equivalent to ASTM D4671-21 for global harmonization.
• ASTM D883: Terminology Relating to Plastics, providing reference definitions used within ASTM D4671-21.
• ASTM E2935: Practice for Evaluating Equivalence of Two Testing Processes, useful for laboratories comparing test methods.
• ASTM E456: Terminology Relating to Quality and Statistics, aiding in understanding terms related to precision and bias.

Keywords: unsaturation in polyols, polyurethane raw materials, ASTM D4671-21, polyether polyol testing, potentiometric titration, quality control, polyurethane manufacturing, mercury reagent safety, ISO 17710 equivalent.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4671 − 21
Standard Test Method for
Polyurethane Raw Materials: Determination of Unsaturation
of Polyols
This standard is issued under the fixed designation D4671; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method measures unsaturation in polyether
D883 Terminology Relating to Plastics
polyols. (See Note 1.) It uses 2 mL of ca. 0.05 M mercuric
E180 Practice for Determining the Precision of ASTM
acetate reagent in methanol and about1gof sample or less.
Methods for Analysis and Testing of Industrial and Spe-
This test method uses a potentiometric determination of an end
cialty Chemicals (Withdrawn 2009)
point.
E456 Terminology Relating to Quality and Statistics
1.2 The values stated in SI units are to be regarded as
E2935 Practice for Evaluating Equivalence of Two Testing
standard. No other units of measurement are included in this
Processes
standard.
2.2 ISO Standards:
1.3 Mercury has been designated by many regulatory agen- ISO 17710 Plastics—Polyols for Use in the Production of
Polyurethane—Determination of Degree of Unsaturation
cies as a hazardous substance that can cause serious medical
issues. Mercury, or its vapor, has been demonstrated to be by Microtitration
hazardous to health and corrosive to materials. Caution should
3. Terminology
be taken when handling mercury and mercury containing
products. See the applicable product Safety Data Sheet (SDS) 3.1 Definitions—Terms used in this standard are defined in
for additional information. Users should be aware that selling accordance with Terminology D883, unless otherwise speci-
mercury and/or mercury containing products into your state or fied. For terms relating to precision and bias and associated
country may be prohibited by law. issues,thetermsusedinthisstandardaredefinedinaccordance
with Terminology E456.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
4.1 Carbon-to-carbon unsaturated compounds in the sample
priate safety, health, and environmental practices and deter-
arereactedwithmercuricacetateandmethanolinamethanolic
mine the applicability of regulatory limitations prior to use.
solution to produce acetoxymercuricmethoxy compounds and
NOTE 1—This standard is equivalent to ISO 17710.
acetic acid. The amount of acetic acid released in this
equimolar reaction, which is determined by titration with
1.5 This international standard was developed in accor-
standard alcoholic potassium hydroxide, is a measure of the
dance with internationally recognized principles on standard-
unsaturation originally present. Because the acid cannot be
ization established in the Decision on Principles for the
titrated in the presence of excess mercuric acetate, due to the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
These test methods are under the jurisdiction of ASTM Committee D20 on The last approved version of this historical standard is referenced on
Plastics and are the direct responsibility of Subcommittee D20.22 on Cellular www.astm.org.
Materials - Plastics and Elastomers. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
Current edition approved July 1, 2021. Published July 2021. Originally approved 4th Floor, New York, NY 10036, http://www.ansi.org.
in 1987. Last previous edition approved in 2016 as D4671 - 16. DOI: 10.1520/ Sigia, S. and Hanna, J.G., “Quantitative Organic Analysis via Functional
D4671-21. Groups,” John Wiley and Sons, New York, 1979.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4671 − 21
formation of insoluble mercuric oxide, sodium bromide is KOH for a 2-mL aliquot. Usually several drops of acid are
added to convert the mercuric acetate to the bromide, which required. Prepare the reagent fresh weekly and filter before
does not interfere. Inasmuch as these test methods are based on using.
an acidimetric titration, a suitable correction must be applied if
8.3 Methanolic Potassium Hydroxide Solution (0.05 N)—
the sample is not neutral to phenolphthalein indicator. Take
Prepare a 0.05-N solution using reagent-grade KOH dissolved
care to exclude carbon dioxide, which titrates as an acid and
in methanol. Standardize using standard procedures with po-
gives erroneous results.
tassium hydrogen phthalate.
8.4 Methanolic Hydrochloric Acid Solution (0.05 N)—
5. Significance and Use
Prepare a 0.05-N solution by successively diluting concen-
5.1 This test method is suitable for quality control, as
trated acid into methanol. This will introduce less than 0.5 %
specification tests, and for research.
water in the titration reagent. Standardize by titrating against
5.2 Side reactions that form unsaturated compounds in the 0.05 N methanolic KOH.
polypropylene oxides produce small amounts of polymers with
8.5 Sodium Bromide (NaBr).
only one hydroxyl group per chain. These unsaturated poly-
mers lower functionality and molecular weight, while broad- 9. Procedure
ening the overall molecular-weight distribution.
9.1 Use no more than 0.033 millequivalents (meq) of
unsaturated species for this test. For samples having 0.033
6. Interferences
meq/g or less, add approximately1gof sample weighed to 0.1
6.1 This test method does not apply to compounds in which mg to a 100-mL titration flask. If the unsaturation value is not
the unsaturation is conjugated with carbonyl, carboxyl, or known for a sample, determine an approximate value by using
nitrile groups. Because water presumably hydrolyzes the reac- a 1-g sample. Use this approximate value to calculate a correct
tion products to form basic mercuric salts, quantitative results sample size that will contribute no more than 0.033 meq of test
are obtained only when the system is essentially anhydrous. sample (See Note 2).
Acetone in low concentrations does not interfere significantly,
NOTE 2—This test method requires at least a 2-fold molar excess of
although its presence can be detrimental to the end point.
mercury reagent for quantitative reaction of unsaturated species. If too
Inorganic salts, especially halides, must be absent from the
large a sample size is selected, this test method will give inaccurate, low
results as well as reduced precision. Calculate sample size, g, using the
sample because even small amounts of salts can nullify the
following equation:
reaction of the mercuric acetate with the unsaturated com-
pound.
Sample size 5 0.033/test sample unsaturation (1)
9.2 Add2mLofmercuricacetatereagentsolutionandswirl
7. Apparatus
to dissolve the sample
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4671 − 16 D4671 − 21
Standard Test Method for
Polyurethane Raw Materials: Determination of Unsaturation
of Polyols
This standard is issued under the fixed designation D4671; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method measures unsaturation in polyether polyols. (See Note 1.) It uses 2 mL of ca. 0.05 M mercuric acetate reagent
in methanol and about 1 g of sample or less. This test method uses a potentiometric determination of an end point.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues.
Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken when
handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional
information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be
prohibited by law.
1.4 This 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 standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—This standard is equivalent to ISO 17710.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
(Withdrawn 2009)
E456 Terminology Relating to Quality and Statistics
E2935 Practice for Evaluating Equivalence of Two Testing Processes
These test methods are under the jurisdiction of ASTM Committee D20 on Plastics and are the direct responsibility of Subcommittee D20.22 on Cellular Materials -
Plastics and Elastomers.
Current edition approved April 1, 2016July 1, 2021. Published April 2016July 2021. Originally approved in 1987. Last previous edition approved in 20102016 as
ɛ1
D4671 - 05 (2010)D4671 - 16. . DOI: 10.1520/D4671-16.10.1520/D4671-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4671 − 21
2.2 ISO Standards:
ISO 17710 Plastics—Polyols for Use in the Production of Polyurethane—Determination of Degree of Unsaturation by
Microtitration
3. Terminology
3.1 Definitions—For definitions of terms used in these test methods, see Terms used in this standard are defined in accordance with
Terminology D883, unless otherwise specified. For terms relating to precision and bias and associated issues, the terms used in
this standard are defined in accordance with Terminology E456.
4. Summary of Test Method
4.1 Carbon-to-carbon unsaturated compounds in the sample are reacted with mercuric acetate and methanol in a methanolic
solution to produce acetoxymercuricmethoxy compounds and acetic acid. The amount of acetic acid released in this equimolar
reaction, which is determined by titration with standard alcoholic potassium hydroxide, is a measure of the unsaturation originally
present. Because the acid cannot be titrated in the presence of excess mercuric acetate, due to the formation of insoluble mercuric
oxide, sodium bromide is added to convert the mercuric acetate to the bromide, which does not interfere. Inasmuch as these test
methods are based on an acidimetric titration, a suitable correction must be applied if the sample is not neutral to phenolphthalein
indicator. Take care to exclude carbon dioxide, which titrates as an acid and gives erroneous results.
5. Significance and Use
5.1 This test method is suitable for quality control, as specification tests, and for research.
5.2 Side reactions that form unsaturated compounds in polypropylene oxides produce small amounts of polymers with only one
hydroxyl group per chain. These unsaturated polymers lower functionality and molecular weight, while broadening the overall
molecular-weight distribution.
6. Interferences
6.1 This test method does not apply to compounds in which the unsaturation is conjugated with carbonyl, carboxyl, or nitrile
groups. Because water presumably hydrolyzes the reaction products to form basic mercuric salts, quantitative results are obtained
only when the system is essentially anhydrous. Acetone in low concentrations does not interfere significantly, although its presence
can be detrimental to the end point. Inorganic salts, especially halides, must be absent from the sample because even small amounts
of salts can nullify the reaction of the mercuric acetate with the unsaturated compound.
7. Apparatus
7.1 Pipet, 2-mL capacity.
7.2 Autotitrator, capable of determining acidimetric end points using a 5-mL buret.
7.3 Combination, Glass, pH Electrode, for use with the autotitrator.
7.4 Balance, capable of weighing samples to 0.0001 g.
7.5 Titration Vessels, 50- to 100-mL 50 mL to 100 mL capacity.
8. Reagents
8.1 Purity of Reagents—Use reagent-grade chemicals in all tests. Unless otherwise indicated, all reagents shall conform to the
specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Sigia, S. and Hanna, J.G., “Quantitative Organic Analysis via Functional Groups,” John Wiley and Sons, New York, 1979.
D4671 − 21
available. Other grades are acceptable, provided it is first ascertained that the reagent is of sufficiently high purity to permit its
use without lessening the accuracy of the determination.
8.2 Mercuric Acetate, Methanol Solution (ca. 0.05 M)—Dissolve 16 g of mercuric acetate (Hg(C H O ) ) into 1 L of reagent-grade
2 3 2 2
methanol and add sufficient glacial acetic acid to require a blank titration of 0.5 to 1 mL of 0.05 N methanolic KOH for a 2-mL
aliquot. Usually several drops of acid are required. Prepare the reagent fresh weekly and filter before using.
8.3 Methanolic Potassium Hydroxide Solution (0.05 N)—Prepare a 0.05-N solution using reagent-grade KOH dissolved in
methanol. Standardize using standard procedures with potassium hydrogen phthalate.
8.4 Methanolic Hydrochloric Acid Solution (0.05 N)—Prepare a 0.05-N solution by successively diluting concentrated acid into
methanol. This will introduce less than 0.5 % water in the titration reagent. Standardize by titrating against the 0.05 N methanolic
KOH.
8.5 Sodium Bromide (NaBr).
9. Procedure
9.1 Use no more than 0.033 millequivalents (meq) of unsaturate
...