ASTM_D_4671_-_05_2010e1.pdf

Designation:D467105(Reapproved 2010)1Standard Test Methods forPolyurethane Raw Materials:Determination of Unsaturationof Polyols1This standard is issued under the fixed designation D4671;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.1NOTEReapproved with editorial changes in July 2010.1.Scope1.1 These test methods measure unsaturation in polyetherpolyols.(See Note 1.)1.1.1 Test Method A,High-Volume Reagent MethodUsesabout 50 mLof 0.1 M mercuric acetate reagent in methanol and15 g or more of sample.These test methods use an indicator forcolorimetric determination of an end point.It is recommendedfor polyols with low values(below 0.01 millequivalents pergram(meq/g)of unsaturation where large sample sizes arerequired.1.1.2 Test Method B,Low-Volume Reagent MethodUses 2mL of ca.0.05 M mercuric acetate reagent in methanol andabout 1 g of sample or less.These test methods use apotentiometric determination of an end point.1.2 The values stated in SI units are to be regarded asstandard.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.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)33.Terminology3.1 DefinitionsFor definitions of terms used in these testmethods,see Terminology D883.4.Summary of Test Method4.1 Carbon-to-carbon unsaturated compounds in the sampleare reacted with mercuric acetate and methanol in a methanolicsolution to produce acetoxymercuricmethoxy compounds andacetic acid.4The amount of acetic acid released in thisequimolar reaction,which is determined by titration withstandard alcoholic potassium hydroxide,is a measure of theunsaturation originally present.Because the acid cannot betitrated in the presence of excess mercuric acetate,due to theformation of insoluble mercuric oxide,sodium bromide isadded to convert the mercuric acetate to the bromide,whichdoes not interfere.Inasmuch as these test methods are based onan acidimetric titration,a suitable correction must be applied ifthe sample is not neutral to phenolphthalein indicator.Takecare to exclude carbon dioxide,which titrates as an acid andgives erroneous results.5.Significance and Use5.1 These test methods are suitable for quality control,asspecification tests,and for research.5.2 Side reactions that form unsaturated compounds inpolypropylene oxides produce small amounts of polymers withonly one hydroxyl group per chain.These unsaturated poly-mers lower functionality and molecular weight,while broad-ening the overall molecular-weight distribution.6.Interferences6.1 These test methods do not apply to compounds in whichthe unsaturation is conjugated with carbonyl,carboxyl,or1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.22 on CellularMaterials-Plastics and Elastomers.Test Method A was recommended to ASTM bythe Society of the Plastics Industry Polyurethane Raw Materials Analysis Commit-tee.Current edition approved July 1,2010.Published October 2010.Originallyapproved in 1987.Last previous edition approved in 2005 as D4671-05.DOI:10.1520/D4671-05R10E01.2For 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.4Sigia,S.and Hanna,J.G.,“Quantitative Organic Analysis via FunctionalGroups,”John Wiley and Sons,New York,1979.*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 nitrile groups.Because water presumably hydrolyzes the reac-tion products to form basic mercuric salts,quantitative resultsare 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 thesample because even small amounts of salts can nullify thereaction of the mercuric acetate with the unsaturated com-pound.TEST METHOD AHIGH-VOLUME REAGENTMETHOD7.Apparatus7.1 Pipet,50-mL capacity.7.2 Erlenmeyer Flask,250-m