ASTM D6342-22

Standard Practice for Polyurethane Raw Materials: Determining Hydroxyl Number of Polyols by Near Infrared (NIR) Spectroscopy

SIGNIFICANCE AND USE
5.1 General Utility:  
5.1.1 It is necessary to know the hydroxyl number of polyols in order to formulate polyurethane systems.  
5.1.2 This practice is suitable for research, quality control, specification testing, and process control.  
5.2 Limitations:  
5.2.1 Factors affecting the NIR spectra of the analyte polyols need to be determined before a calibration procedure is started. Chemical structure, interferences, any nonlinearities, the effect of temperature, and the interaction of the analyte with other sample components such as catalyst, water and other polyols needs to be understood in order to properly select samples that will model those effects which cannot be adequately controlled.  
5.2.2 Calibrations are generally considered valid only for the specific NIR instrument used to generate the calibration. Using different instruments (even when made by the same manufacturer) for calibration and analysis can seriously affect the accuracy and precision of the measured hydroxyl number. Procedures used for transferring calibrations between instruments are problematic and are to be utilized with caution following the guidelines in Section 16. These procedures generally require a completely new validation and statistical analysis of errors on the new instrument.  
5.2.3 The analytical results are statistically valid only for the range of hydroxyl numbers used in the calibration. Extrapolation to lower or higher hydroxyl values can increase the errors and degrade precision. Likewise, the analytical results are only valid for the same chemical composition as used for the calibration set. A significant change in composition or contaminants can also affect the results. Outlier detection, as discussed in Practices E1655, is a tool that can be used to detect the possibility of problems such as those mentioned above.
SCOPE
1.1 This standard covers a practice for the determination of hydroxyl numbers of polyols using NIR spectroscopy.  
1.2 Definitions, terms, and calibration techniques are described. Procedures for selecting samples, and collecting and treating data for developing NIR calibrations are outlined. Criteria for building, evaluating, and validating the NIR calibration model are also described. Finally, the procedure for sample handling, data gathering and evaluation are described.  
1.3 The implementation of this standard requires that the NIR spectrometer has been installed in compliance with the manufacturer's specifications.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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 ISO 15063.  
1.6 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-2022
• ICS: 83.080.10 - Thermosetting materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

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: D6342 − 22
Standard Practice for
Polyurethane Raw Materials: Determining Hydroxyl Number
1
of Polyols by Near Infrared (NIR) Spectroscopy
This standard is issued under the fixed designation D6342; 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* D4274 Test Methods for Testing Polyurethane Raw Materi-
als: Determination of Hydroxyl Numbers of Polyols
1.1 This standard covers a practice for the determination of
E131 Terminology Relating to Molecular Spectroscopy
hydroxyl numbers of polyols using NIR spectroscopy.
E168 Practices for General Techniques of Infrared Quanti-
1.2 Definitions, terms, and calibration techniques are de-
tative Analysis
scribed. Procedures for selecting samples, and collecting and
E222 Test Methods for Hydroxyl Groups Using Acetic
treating data for developing NIR calibrations are outlined.
Anhydride Acetylation
Criteria for building, evaluating, and validating the NIR
E1655 Practices for Infrared Multivariate Quantitative
calibration model are also described. Finally, the procedure for
Analysis
sample handling, data gathering and evaluation are described.
E1899 Test Method for Hydroxyl Groups Using Reaction
1.3 The implementation of this standard requires that the with p-ToluenesulfonylIsocyanate(TSI)andPotentiomet-
ric Titration with Tetrabutylammonium Hydroxide
NIR spectrometer has been installed in compliance with the
manufacturer’s specifications. 2.2 ISO Standard:
ISO 15063 Plastics—Polyols for use in the production of
1.4 The values stated in SI units are to be regarded as
polyurethanes—Determination of hydroxyl number by
standard. No other units of measurement are included in this
NIR spectroscopy
standard.
1.5 This standard does not purport to address all of the 3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions—Terminology used in this practice follows
responsibility of the user of this standard to establish appro-
that defined in Terminology D883. For terminology related to
priate safety, health, and environmental practices and deter-
molecular spectroscopy methods, refer to Terminology E131.
mine the applicability of regulatory limitations prior to use.
For terms relating to multivariate analysis, refer to Practice
E1655.
NOTE 1—This standard is equivalent ISO 15063.
1.6 This international standard was developed in accor- 3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
3.2.1 hydroxyl number—the milligrams of potassium hy-
ization established in the Decision on Principles for the droxide equivalent to the hydroxyl content of1gof sample.
Development of International Standards, Guides and Recom-
4. Summary of Practice
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 4.1 Multivariate mathematics is applied to correlate the NIR
absorbance values for a set of calibration samples to the
2. Referenced Documents
respective reference hydroxyl number for each sample. The
2
resultant multivariate calibration model is then applied to the
2.1 ASTM Standards:
analysis of unknown samples to provide an estimate of their
D883 Terminology Relating to Plastics
hydroxyl numbers.
4.2 Multilinear regression (MLR), principal components
1
This practice is under the jurisdiction ofASTM Committee D20 on Plastics and
regression (PCR), and partial least squares regression (PLS)
is the direct responsibility of Subcommittee D20.22 on Cellular Materials - Plastics
and Elastomers.
are the mathematical techniques used for the development of
Current edition approved July 1, 2022. Published July 2022. Originally approved
the calibration model.
ɛ1
in 1998. Last previous edition approved in 2017 as D6342 - 12(2017) . DOI:
10.1520/D6342-22.
4.3 Statistical tests are used to detect outliers during the
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
development of the calibration model. Outliers can include
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
high leverage samples and samples whose hydroxyl numbers
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. are inconsistent with the model.
*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
1

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...

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.
´1
Designation: D6342 − 12 (Reapproved 2017) D6342 − 22
Standard Practice for
Polyurethane Raw Materials: Determining Hydroxyl Number
1
of Polyols by Near Infrared (NIR) Spectroscopy
This standard is issued under the fixed designation D6342; 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
ε NOTE—Reapproved with editorial changes in August 2017.
1. Scope Scope*
1.1 This standard covers a practice for the determination of hydroxyl numbers of polyols using NIR spectroscopy.
1.2 Definitions, terms, and calibration techniques are described. Procedures for selecting samples, and collecting and treating data
for developing NIR calibrations are outlined. Criteria for building, evaluating, and validating the NIR calibration model are also
described. Finally, the procedure for sample handling, data gathering and evaluation are described.
1.3 The implementation of this standard requires that the NIR spectrometer has been installed in compliance with the
manufacturer’s specifications.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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 ISO 15063.
1.6 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
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D4274 Test Methods for Testing Polyurethane Raw Materials: Determination of Hydroxyl Numbers of Polyols
3
D4855 Practice for Comparing Test Methods (Withdrawn 2008)
E131 Terminology Relating to Molecular Spectroscopy
E168 Practices for General Techniques of Infrared Quantitative Analysis
1
This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Materials - Plastics and
Elastomers.
Current edition approved Aug. 1, 2017July 1, 2022. Published August 2017July 2022. Originally approved in 1998. Last previous edition approved in 20122017 as
ɛ1
D6342 - 12.D6342 - 12(2017) . DOI: 10.1520/D6342-12R17E01.10.1520/D6342-22.
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.
*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
1

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D6342 − 22
E222 Test Methods for Hydroxyl Groups Using Acetic Anhydride Acetylation
E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
E456 Terminology Relating to Quality and Statistics
E1655 Practices for Infrared Multivariate Quantitative Analysis
E1899 Test Method for Hydroxyl Groups Using Reaction with p-Toluenesulfonyl Isocyanate (TSI) and Potentiometric Titration
with Tetrabutylammonium Hydroxide
2.2 ISO Standard:
ISO 15063 Plastics—Polyols for use in the production of polyurethanes—Determination of hydroxyl number by NIR
spectroscopy
3. Terminology
3.1 Definitions—Terminology used in this practice follows that defined in Terminology D883. For terminology related to
molecular spectroscopy methods, refer to Terminology E131. For terms relating to multivariate analysis, refer to Practice E1655.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 hydroxyl number—the milligrams of potassium hydroxide equivalent to the hydroxyl content of 1 g of sample.
4. Summary of Practice
4.1 Multivariate mathematics is applied to correlate the NIR absorbance values for a set of calibration samples to the respective
reference hydroxyl number for each sample. The resu
...