ASTM_D_7252_-_17.pdf

Designation:D725217Standard Test Method forPolyurethane Raw Materials:Determination of Monomer andIsomers in Isocyanates1This standard is issued under the fixed designation D7252;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.Scope1.1 This test method determines the percent by weight ofmonomeric isomers and total monomer in crude or modifiedisocyanates.The test method is applicable to methylene di(phe-nylisocyanate)(MDI)and polymeric(methylene phenylisocya-nate)(PMDI).(See Note 1.)1.2 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.3 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.NOTE1There is no known ISO equivalent to this standard.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE682 Practice for Liquid Chromatography Terms and Rela-tionshipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 For definitions of terms used in these test methods seeTerminology D883.4.Summary of Test Method4.1 The sample is reacted(derivatized)with methanol toform a mixture of methyl urethanes.The urethanes mixture isthen separated by normal phase high performance liquidchromatography(HPLC).The separated,derivatized isomersare quantified through the use of an internal standard.5.Significance and Use5.1 This test method is used for research or for qualitycontrol to characterize isocyanates used in polyurethane prod-ucts.6.Apparatus6.1 High Performance Liquid Chromatograph,consistingof:6.1.1 Binary(or greater)solvent pump,capable of main-taining a pulse-free flow rate of 1-3 milliliters per minute6.1.2 Sample injector,automatic or manual,capable ofreproducibly injecting a 2 microliter volume6.1.3 Column heater,capable of maintaining a temperatureof 30 6 0.2C6.1.4 UV detector,capable of measurements at 235 nm.6.1.5 Chart recorder or Data system,capable of peak areaintegration.6.2 HPLC analytical column,250 mm by 4.6 mm by 5 mcyano stationary phase.NOTE2Other chromatographic columns are used provided it isascertained that similar chromatographic performance is obtained.6.3 Magnetic Stirring Hotplate.7.Reagents and Materials7.1 Purity of ReagentsReagent-grade chemicals are to beused in all tests.Unless otherwise indicated,it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society,wheresuch specifications are available.Other grades are used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.1.1 Acetanilide,99.9%purity,to be used as an internalstandard.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials-Plastics and Elastomers.Current edition approved April 15,2017.Published May 2017.Originallyapproved in 2006.Last previous edition approved in 2011 as D7252-06(2011)1.DOI:10.1520/D7252-17.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 7.1.2 Acetonitrile,dry.Dry this and reagents below overmolecular sieve for twenty-four hours.7.1.3 Ethanol,dry.Use of ethanol denatured with methanol(such as SDA-30)is used if more readily available.7.1.4 Hexane,dry.7.1.5 Methanol,dry.7.1.6 Eluent solution,Mix 1:1 by volume of dry methanoland ethanol.7.1.7 Internal Standard and derivatization solution,Dis-solve 0.20 g of acetanilide in 1 L of dry methanol.8.Sampling8.1 Since organic isocyanates react with atmosphericmoisture,take