1、Designation:D643705(Reapproved 2010)1Standard 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
2、 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 November 2010.1.Scope1.1 This test method c
3、overs 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 as thestandard.1.3 This
4、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
5、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Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3E691 Practice for Conducting an Interlaboratory Study
6、toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 The terminology in this test method is in accordancewith the standard terminology defined in Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 CPRcontrolled polymerization rate is expressed asbasicit
7、y 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 sample and titration with dilute acid solution to determinetrace quantities of basicity.5.Sig
8、nificance 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 preparat
9、ion 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 ofresid
10、ual 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).6.3 Buret or Dosing Device,capable of dosing 50 mL.6.4 pH Glass Electrod
11、e 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(0 to 0.5 mL),larger burets will giveless precise results.1This test method
12、 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 Nov.1,2010.Published March 2011.Originallyapproved in 1999.Last previous edition approved in 2005 as D6437-05.DOI
13、:10.1520/D6437-05R10E01.2For 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 histori
14、cal 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Reagents and Materials7.1 HCl Aqueous,0.01 NStandardize
15、to detect changes of0.0001 N.7.2 Methanol,reagent grade8.Procedure8.1 Set up the autotitrator to find multiple end points with amaximum volume of 5 mL.8.2 Place 50 6 0.1 mL of methanol solvent in a 100-mLtitration cup and titrate a blank using 0.01 N aqueous HCl.8.3 Weigh 30 6 1.00 g of sample into
16、a titration cup.Add50 6 0.1 mL of reagent grade methanol,stir to mix well,andtitrate with 0.01 N aqueous HCl.There will be as many as threeend points(breaks)in these titrations.Use the volume to thelast end point for calculation.NOTE3If the viscosity of the sample appears too high,use 100 mL ofmethanol to dissolve the sample.9.Calculation9.1 Calculate the CPR as meq/30 kg of the polyol asfollows:CPR5Vsam2 Vblk!N30000/W(1)where:Vsam=volume of titrant to the last break in sampletitration,mLVblk=vo
