ASTM_D_4274_-_11.pdf

Designation:D427411Standard Test Methods for TestingPolyurethane Raw Materials:Determination of HydroxylNumbers of Polyols1This standard is issued under the fixed designation D4274;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 These test methods measure the hydroxyl groups inpolyester and polyether polyols containing primary and sec-ondary hydroxyl groups.They also apply to many otherhydroxyl-containing substances.1.1.1 Test Method AAcetic Anhydride Pressure Bottle,recommended for polyesters.1.1.2 Test Method BPhthalic Anhydride Pressure Bottle,recommended for polyethers and polyesters.1.1.3 Test Method CPhthalic Anhydride Reflux,recom-mended for polyethers and polyesters.1.1.4 Test Method DImidazoleCatalyzed Phthalic Anhy-dride Pressure Bottle,recommended for polyethers,polyesters,polymer polyols,and amine-initiated polyols.1.1.5 Test Method EImidazole-Catalyzed Pyromellitic Di-anhydride Esterification,recommended for polyols used forflexible and rigid polyurethane foams and urethane elastomers.It is recommended for polyester polyols,polyether polyols,amine-started polyols,and polymer polyols(polyacrylonitrile/copolystyrene-based).1.2 Another ASTM test method for measuring hydroxylgroups is Test Method E222.1.3 The values stated in SI units are to be regarded as thestandard.1.4 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 and ISO 6796 address the same subject matter,but differ in technical content.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1193 Specification for Reagent WaterE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3E200 Practice for Preparation,Standardization,and Storageof Standard and Reagent Solutions for Chemical AnalysisE203 Test Method for Water Using Volumetric Karl FischerTitrationE222 Test Methods for Hydroxyl Groups Using AceticAnhydride AcetylationE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2ISO Standard:4ISO 6796 Polyglycols for Industrial UseDetermination ofHydroxyl NumberPhthalic Anhydride EsterificationMethod3.Terminology3.1 DefinitionsThe terminology in these test methodsfollows the standard terminology defined in TerminologyD883.3.2 Definitions of Terms Specific to This StandardThereare no terms in these test methods that require new or otherthan dictionary definitions.4.Summary of Test Methods4.1 Test Method AThe sample is acetylated with a solutionof acetic anhydride in pyridine in a pressure bottle at 98C.Theexcess reagent is hydrolyzed with water and the acetic acid istitrated with standard sodium hydroxide solution.The hydroxylcontent is calculated from the difference in titration of the1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.22 on CellularMaterials-Plastics and Elastomers.Current edition approved Feb.1,2011.Published March 2011.Originallyapproved in 1988.Last previous edition approved in 2005 as D4274-05.DOI:10.1520/D4274-11.2For 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.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.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 blank and sample solutions.(WarningAcetic anhydride andpyridine are toxic and flammable.In addition,acetic anhydrideis corrosive.Proper precautions must be taken in handlingthese reagents.).4.2 Test Method BThe hydroxyl group is esterified with asolution of phthalic anhydride in pyridine in a pressure bottleat 98C.The excess reagent is titrated with standard sodiumhydroxide solution.4.3 Test Method CThe hydroxyl group is esterified with asolution of phthalic anhydride in pyridine under reflux condi-tions at 115C.The excess reagent is titrated with standardsodium hydroxide solution.4.4 Test Method DThe hydroxyl group is esterified byreaction with phthalic anhydride in a pyridine medium atapproximately 100C.The esterification reaction is catalyzedby imidazole.The excess anhydride is hy