ASTM_D_6437_-_22.pdf

Designation:D643722Standard Test Method forPolyurethane Raw Materials:Alkalinity in Low-AlkalinityPolyols(Determination of CPR Values of Polyols)1This standard is issued under the fixed designation D6437;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 test method covers measuring alkalinity in low-alkalinity(0.002 meq/g basicity)polyols.This alkalinity isoften expressed as CPR(controlled polymerization rate)ofpolyether polyols.This test method is not applicable toamine-based polyols.1.2 The values stated in SI units are to be regarded asstandard.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,health,and environmental practices and deter-mine the applicability 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 PlasticsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3E456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE2935 Practice for Evaluating Equivalence of Two TestingProcesses3.Terminology3.1 Definitions:3.1.1 Terms used in this standard are defined in accordancewith Terminology D883,unless otherwise specified.For termsrelating to precision and bias and associated issues,the termsused in this standard are defined in accordance with Terminol-ogy E456.3.2 Definitions of Terms Specific to This Standard:3.2.1 CPRcontrolled polymerization rate is expressed asbasicity in milliequivalents per 30 kg of sample(meq/30 kg).4.Summary of Test Method4.1 This test method is a potentiometric titration for samplebasicity in methanol solvent.This test method uses a relativelylarge amount of sample and the titration is performed withdilute acid solution to determine trace quantities of basicity.5.Significance and Use5.1 This test method is suitable for quality control,as aspecification test and for research.The urethane reactionbetween polyols and isocyanates to form polyurethane poly-mers is known to be sensitive to the presence of basicsubstances.This is particularly important in the preparation ofpolyurethane prepolymers which contain isocyanate groupsthat are known to react in the presence of trace amounts ofbasic substances.Since many polyether polyols are often madewith strongly basic catalysts,it is important to have ananalytical method capable of detecting small quantities ofresidual basic substances.This test method is capable ofdetecting ppm levels of base(as KOH).46.Apparatus6.1 Potentiometric Automatic Titrator,capable of detectingmultiple titration end points.6.2 Autotitrator Buret,5 mL(see Note 2).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 March 15,2022.Published March 2022.Originallyapproved in 1999.Last previous edition approved in 2016 as D6437-05(2016)1.DOI:10.1520/D6437-22.2For 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.4H.G.Scholten,J.G.Schuhman,R.E.TenHoor,Journal of Chemical Engineer-ing Data,5,1960,p.396.*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 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.16.3 Buret or Dosing Device,capable of dosing 50 mL.6.4 pH Glass Electrode and Reference Electrode or aCombination Glass Electrode.6.5 Analytical Balance,capable of weighing to the nearest0.01 g.NOTE2A 1-mL titrator buret can be used if available.Due to the lowvolumes of titrant typically required