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    ASTM D6342 - 12(2017)e1

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

    Active Standard ASTM D6342 | Developed by Subcommittee: D20.22

    Book of Standards Volume: 08.03

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    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.

    1. 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 and health 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 (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D883 Terminology Relating to Plastics

    D4274 Test Methods for Testing Polyurethane Raw Materials: Determination of Hydroxyl Numbers of Polyols

    D4855 Practice for Comparing Test Methods

    E131 Terminology Relating to Molecular Spectroscopy

    E168 Practices for General Techniques of Infrared Quantitative Analysis

    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

    ISO Standard

    ISO 15063

    ICS Code

    ICS Number Code 83.080.10 (Thermosetting materials)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D6342-12R17E01

    Citation Format

    ASTM D6342-12(2017)e1, Standard Practice for Polyurethane Raw Materials: Determining Hydroxyl Number of Polyols by Near Infrared (NIR) Spectroscopy, ASTM International, West Conshohocken, PA, 2017, www.astm.org

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