1、Designation: D 4662 08Standard Test Methods forPolyurethane Raw Materials: Determination of Acid andAlkalinity Numbers of Polyols1This standard is issued under the fixed designation D 4662; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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. Scope1.1 These test methods measure the acidic and basic con-stituents in polyols and other materials of hig
3、h 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 t
4、o establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1193 Specification for Reagent Water
5、3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods see Terminology D 883.3.2 Descriptions of Terms Specific to This Standard:3.2.1 acid numberthe quantity of base, expressed inmilligrams of potassium hydroxide, that is required to titrateacidic constituents present in1go
6、fsample.3.2.2 alkalinity numberthe quantity of base, expressed asmilligrams of potassium hydroxide, present in1gofsample.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 po
7、tassium hydroxide solu-tion, to the end point indicated by the color change of the addedphenolphthalein. Alkalinity numbers are determined by back-titration after adding excess hydrochloric acid. The endpoint ofthese titrations also can be determined potentiometrically.5. Significance and Use5.1 The
8、se 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 may be used ascorrection factors in calculating hydroxyl number.6. Reagents
9、 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 may be u
10、sed 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 D
11、 1193.6.3 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
12、of 0.1 N NaOHsolution (pink color) and then just neutralize (colorless) with0.1 N HCl.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-res
13、istant dispensingbottle protected by a guard tube containing soda-lime orascarite. Standardize frequently enough to detect changes of0.0005 N, preferably against pure potassium acid phthalate1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibi
14、lity of Subcommittee D20.22 on CellularMaterials - Plastics and Elastomers.Current edition approved Aug. 1, 2008. Published September 2008. Originallyapproved in 1987. Last previous edition approved in 2003 as D 4662 - 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
15、t 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 r
16、eagents 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO
17、 Box C700, West Conshohocken, PA 19428-2959, United States.(KHC8H4O4, 0.8 to 0.9 g) in about 100 mL of carbondioxide-free water, using phenolphthalein to detect the endpoint.6.7 Sodium Hydroxide, Standard Solution (0.1 N)Prepareand standardize a 0.1 N solution of sodium hydroxide (NaOH).6.8 Titratio
18、n SolventMix equal volumes of toluene andethyl alcohol.7. Sampling7.1 Polyesters usually contain molecules covering an appre-ciable range of molecular weights. These have a tendency tofractionate during solidification. Unless the material is a finelyground solid, it is necessary to melt (using as lo
19、w a temperatureas necessary) and mix the resin well before removing a samplefor analysis. Because many polyols are hygroscopic, one musttake care to provide minimum exposure to atmospheric mois-ture during the sampling.TEST METHOD AACID NUMBER8. Procedure8.1 Into a 250-mL Erlenmeyer flask, introduce
20、 a weighedquantity of the sample (Note 2). Add 50 mL of the titrationsolvent and 0.5 mL of the indicator solution, and swirl until thesample is completely dissolved (heat only if necessary, and donot boil).NOTE 2For samples with an acid number of less than 7.0, use 6 to 8g of sample. If the acid num
21、ber is expected to exceed 7.0, choose anamount of sample that will contain 0.7 to 0.9 meq of acid. If the sampleis not sufficiently soluble to enable use of the above amounts, decrease thesample size as necessary. Weigh samples exceeding 1.0 g to the nearest 1mg. Weigh smaller samples to the nearest
22、 0.1 mg.8.2 Titrate immediately with 0.1 N KOH solution at atemperature below 30C, using a 10-mL buret to add the KOHsolution and using phenolphthalein as the indicator. Swirl thesolution vigorously and add the KOH solution dropwise whenapproaching the end point. Consider the end point definite ifth
23、e color change persists for 15 s.8.3 Make a blank determination on 50 mL of the titrationsolvent and 0.5 mL of the indicator solution, in the samemanner as the sample was titrated. Record the quantity of 0.1N KOH solution required to reach the phenolphthalein endpoint.9. Calculation9.1 Calculate the
24、 acid number, in milligrams of KOH/gramof sample, as follows:Acid number 5 A 2 B!N 3 56.1/Wwhere:A = KOH solution required for titration of the sample, mL,B = KOH solution required for titration of the blank, mL,N = normality of the KOH solution, andW = sample used, g.TEST METHOD BALKALINITY NUMBER1
25、0. Procedure10.1 Proceed as directed in Section 8. If the sample solutionis alkaline to phenolphthalein, add 0.1 N HCl from a 10-mLburet until the solution is colorless; then add 1.0 mL excess.Back-titrate to the end point with 0.1 N NaOH solution from a10-mL buret. Titrate a blank containing the sa
26、me amount ofadded 0.1 N HCl.11. Calculation11.1 Calculate the alkalinity number, in milligrams of KOH/gram of sample, as follows:Alkalinity number 5 B 2 A!N 3 56.1/Wwhere the terms are defined as in Section 9.12. Report12.1 For acid and alkalinity numbers below 7.0, report thevalue to the nearest 0.
27、01.12.2 For acid or alkalinity numbers of 7.0 or over, report thevalue to the nearest 0.1.13. Precision and Bias413.1 PrecisionAttempts to develop a precision and biasstatement for these test methods have not been successful. Forthis reason, data on precision and bias cannot be given.Because these t
28、est methods do not contain numerical precisionand bias statements, they shall not be used as referee testmethods in case of dispute. Anyone wishing to participate inthe development of precision and bias data should contact theChairman, Subcommittee D20.22 (Section D20.22.01), ASTMInternational, 100
29、Barr Harbor Drive, West Conshohocken, PA19428.13.1.1 A limited round robin was run with three laborato-ries. It is estimated that duplicate results by the same analystshould be considered suspect if they differ by more than thefollowing amounts:Acid or Alkalinity Number Repeatabilityless than 7.0 0.
30、1 number7.0 and over 1 %13.2 BiasThe bias for these test methods has not yet beendetermined.14. Keywords14.1 acidity; acid number; alkalinity number; polyols4Supporting data are available from ASTM Headquarters. Request RR: D20-1089.D 4662 082ASTM International takes no position respecting the valid
31、ity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subje
32、ct to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquart
33、ers. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard
34、 is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 4662 083
