ASTM_D_6342_-_12.pdf

Designation:D634212Standard Practice forPolyurethane Raw Materials:Determining Hydroxyl Numberof Polyols by Near Infrared(NIR)Spectroscopy1This standard is issued under the fixed designation D6342;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This standard covers a practice for the determination ofhydroxyl numbers of polyols using NIR spectroscopy.1.2 Definitions,terms,and calibration techniques are de-scribed.Procedures for selecting samples,and collecting andtreating data for developing NIR calibrations are outlined.Criteria for building,evaluating,and validating the NIRcalibration model are also described.Finally,the procedure forsample handling,data gathering and evaluation are described.1.3 The implementation of this standard requires that theNIR spectrometer has been installed in compliance with themanufacturers specifications.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1This standard is equivalent ISO 15063.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD4274 Test Methods for Testing Polyurethane Raw Materi-als:Determination of Hydroxyl Numbers of PolyolsD4855 Practice for Comparing Test Methods(Withdrawn2008)3E131 Terminology Relating to Molecular SpectroscopyE168 Practices for General Techniques of Infrared Quanti-tative AnalysisE222 Test Methods for Hydroxyl Groups Using AceticAnhydride AcetylationE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible SpectrophotometersE456 Terminology Relating to Quality and StatisticsE1655 Practices for Infrared Multivariate QuantitativeAnalysisE1899 Test Method for Hydroxyl Groups Using Reactionwith p-Toluenesulfonyl Isocyanate(TSI)and Potentiomet-ric Titration with Tetrabutylammonium Hydroxide2.2 ISO Standard:ISO 15063 PlasticsPolyols for use in the production ofpolyurethanesDetermination of hydroxyl number byNIR spectroscopy3.Terminology3.1 DefinitionsTerminology used in this practice followsthat defined in Terminology D883.For terminology related tomolecular spectroscopy methods,refer to Terminology E131.For terms relating to multivariate analysis,refer to PracticeE1655.3.2 Definitions of Terms Specific to This Standard:3.2.1 hydroxyl numberthe milligrams of potassium hy-droxide equivalent to the hydroxyl content of 1 g of sample.4.Summary of Practice4.1 Multivariate mathematics is applied to correlate the NIRabsorbance values for a set of calibration samples to therespective reference hydroxyl number for each sample.Theresultant multivariate calibration model is then applied to theanalysis of unknown samples to provide an estimate of theirhydroxyl numbers.4.2 Multilinear regression(MLR),principal componentsregression(PCR),and partial least squares regression(PLS)are the mathematical techniques used for the development ofthe calibration model.4.3 Statistical tests are used to detect outliers during thedevelopment of the calibration model.Outliers can include1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.22 on Cellular Materials-Plasticsand Elastomers.Current edition approved Aug.1,2012.Published September 2012.Originallyapproved in 1998.Last previous edition approved in 2008 as D6342-08.DOI:10.1520/D6342-12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 high leverage samples and samples whose hydroxyl numbersare inconsistent with the model.4.4 Validation of the calibration model is performed byusing the model to analyze a set of validation samples.Thehydroxyl number estimates for the validation set are statisti-cally compared to the reference hydroxyl number for this set totest for agreement of the model with the reference method.4.5 Statistical expressions are given for calculating theprecision and bias of the NIR method relative to the referencemethod.5.Significance and Use5.1 General Utility:5.1.1 It is necessary to know the hydroxyl number ofpolyols in order to formulate