ASTM_D_4662_-_15.pdf

Designation:D466215Standard Test Methods forPolyurethane Raw Materials:Determination of Acid andAlkalinity Numbers of Polyols1This standard is issued under the fixed designation D4662;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 acidic and basic con-stituents in polyols and other materials of high acidity oralkalinity that are soluble in mixtures of toluene and ethylalcohol.These test methods do not apply to polyethers.(SeeNote 1.)1.2 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 PlasticsD1193 Specification for Reagent Water3.Terminology3.1 DefinitionsFor definitions of terms used in these testmethods see Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 acid numberthe quantity of base,expressed in mil-ligrams of potassium hydroxide,that is required to titrate acidicconstituents present in 1 g of sample.3.2.2 alkalinity numberthe quantity of base,expressed asmilligrams of potassium hydroxide,present in 1 g of sample.4.Summary of Test Method4.1 The sample is dissolved in a mixture of toluene andethyl alcohol.The resulting single-phase solution is titrated atroom temperature with alcoholic potassium hydroxidesolution,to the end point indicated by the color change ofadded phenolphthalein.Alkalinity numbers are determined byback-titration after adding excess hydrochloric acid.The end-point of these titrations also can be determined potentiometri-cally.5.Significance and Use5.1 These test methods are suitable for quality control,asspecification tests,and for research.The acid and alkalinitynumbers indicate the extent of a reaction with acids.The resultsare measures of batch-to-batch uniformity and are typicallyused as correction factors in calculating hydroxyl number.6.Reagents and Materials6.1 Purity of ReagentsUse reagent-grade chemicals in alltests.Unless otherwise indicated,it is intended that all reagentsconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society where suchspecifications are available.3Other grades are allowed,pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent water as definedby Type I of Specification D1193.6.3 Ethyl Alcohol,95%.6.4 Hydrochloric Acid(0.1 N)Prepare a 0.1 N solution ofhydrochloric acid(HCl).Standardization is unnecessary.6.5 Phenolphthalein Indicator SolutionDissolve 0.5 g ofphenolphthalein in 100 mL of a mixture of equal volumes ofwater and ethyl alcohol.Add a slight excess of 0.1 N NaOHsolution(pink color)and then just neutralize(colorless)with0.1 N HCl.1These 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.Current edition approved Sept.1,2015.Published September 2015.Originallyapproved in 1987.Last previous edition approved in 2011 as D4662-08(2011)1.DOI:10.1520/D4662-15.2For 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.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.*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 6.6 Potassium Hydroxide,Standard Alcoholic Solution(0.1N)Dissolve 5.61 g of potassium hydroxide(KOH)in 10 mLof carbon dioxide-free water and dilute to 1 L with ethylalcohol.Store the solution in a chemical-resistant dispensingbottle protected by a guard tube containing soda-lime orascarite.Standardize frequently enough to detect changes of0.0005 N,preferably against pure potassium acid phthalate(KHC8H4O4,0.8 to 0.9 g)in about 100 mL of carbondioxide-free water,using phenolphthalein to detect the endpoint.6.7 Sodium Hydroxi