1、Designation: D 4662 03Standard 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 (e) 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 h
3、igh 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
4、 to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1193 Specification for Reagent Water3. Terminolo
5、gy3.1 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 in1gofsample.3.2.
6、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 potassium hydr
7、oxide 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 These test meth
8、ods 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 and Materia
9、ls6.1 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 used pro-vide
10、d 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 1193.6.3 Et
11、hyl 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 NaO
12、Hsolution (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-resistant dispe
13、nsingbottle 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 responsibility of Subc
14、ommittee D20.22 on CellularPlastics.Current edition approved November 1, 2003. Published January 2004. Originallyapproved in 1987. Last previous edition approved in 1998 as D 4662 - 98.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceast
15、m.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 Che
16、mical 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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Internation
17、al, 100 Barr Harbor Drive, PO 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
18、hydroxide (NaOH).6.8 Titration 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 n
19、ecessary to melt (using as low 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-m
20、L Erlenmeyer flask, introduce 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
21、8g of sample. If the acid number 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 s
22、maller samples to the nearest 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. Conside
23、r the end point definite ifthe 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.
24、 Calculation9.1 Calculate the 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.TE
25、ST METHOD BALKALINITY NUMBER10. 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. Titr
26、ate a blank containing the same 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, repo
27、rt thevalue to the nearest 0.01.12.2 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 ca
28、nnot be given.Because these test 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
29、.01), ASTMInternational, 100 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
30、Repeatabilityless than 7.0 0.1 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 032SUMMARY OF CHANGESThis secti
31、on identifies the location of selected changes to this test method. For the convenience of the user,Committee D20 has highlighted those changes that may impact the use of this test method. This section may alsoinclude descriptions of the changes or reasons for the changes, or both.D 4662 03:(1) Corr
32、ected note reference in 8.1 to accurately point to Note2.D 4662 98:(1) Section 1.1Modified the scope to refer to only materialsof high acid or alkalinity number.(2) Section 4.1Added provision for use of potentiometric endpoint determination.(3) Section 5.1Editorial changes concerning use of theresul
33、ts in correcting hydroxyl number determinations.(4) Section 6.6Editorial change concerning description ofbottle for reagent storage.(5) Section 7.1Deleted the reference to polyethers (thesenormally have much lower levels than the scope allows for).(6) Section 8.1Corrected an error in numbering of No
34、te 2.(7) Section 8.2Deleted reference to the second method ofdetermining colorimetric end point.(8) Section 13.1.1Editorial correction to wording of repeat-ability criterion.(9) Changed keyword list to include alkalinity number anddelete hydroxyl number.ASTM International takes no position respectin
35、g the validity 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 standa
36、rd is subject 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 Internationa
37、l Headquarters. 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.Th
38、is standard 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 033
