1、Designation: D4662 15Standard 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 revis
2、ion, 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
3、 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
4、 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:2D883 Terminology Relating to PlasticsD1193 Specification for Reagent Water3.
5、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 in1gofsa
6、mple.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 potas
7、sium 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
8、 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
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 are allo
10、wed, 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
11、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
12、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.
13、 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
14、 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
15、 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, W
16、est Conshohocken, PA 19428-2959. United States16.6 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
17、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 Hydroxide, Standard So
18、lution (0.1 N)Prepareand standardize a 0.1 N solution of sodium 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 soli
19、dification. Unless the material is a finelyground solid, it is necessary 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 t
20、he sampling.TEST METHOD AACID NUMBER8. Procedure8.1 Into a 250-mL 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).N
21、OTE 2For samples with an acid number of less than 7.0, use 6 to 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 nece
22、ssary. Weigh samples exceeding 1.0 g to the nearest 1mg. Weigh smaller 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
23、the KOH solution dropwise whenapproaching the end point. Consider 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 0.1
24、N KOH solution required to reach the phenolphthalein endpoint.9. Calculation9.1 Calculate the acid number, in milligrams of KOH/gramof sample, as follows:Acid number 5 A 2 B!N 356.1#/Wwhere:A = KOH solution required for titration of the sample, mL,B = KOH solution required for titration of the blank
25、, mL,N = normality of the KOH solution, andW = sample used, g.10. Report10.1 For acid and alkalinity numbers below 7.0, report thevalue to the nearest 0.01.10.2 For acid or alkalinity numbers of 7.0 or over, report thevalue to the nearest 0.1.11. Precision and Bias411.1 PrecisionAttempts to develop
26、a precision and biasstatement for these test methods have not been successful. Forthis reason, data on precision and bias cannot 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
27、 to participate inthe development of precision and bias data should contact theChairman, Subcommittee D20.22 (Section D20.22.01), ASTMInternational, 100 Barr Harbor Drive, West Conshohocken, PA19428.11.1.1 A limited round robin was run with three laborato-ries. It is estimated that duplicate results
28、 by the same analystshould be considered suspect if they differ by more than thefollowing amounts:Acid or Alkalinity Number Repeatabilityless than 7.0 0.1 number7.0 and over 1 %11.2 BiasThe bias for these test methods has not yet beendetermined.12. Keywords12.1 acidity; acid number; alkalinity numbe
29、r; polyolsTEST METHOD BALKALINITY NUMBER13. Procedure13.1 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
30、 buret. Titrate a blank containing the same amount ofadded 0.1 N HCl.14. Calculation14.1 Calculate the alkalinity number, in milligrams of KOH/gram of sample, as follows:Alkalinity number 5 B 2 A!N 356.1#/Wwhere the terms are defined as in Section 9.4Supporting data are available from ASTM Headquart
31、ers. Request RR:D20-1089.D4662 15215. Report15.1 For acid and alkalinity numbers below 7.0, report thevalue to the nearest 0.01.15.2 For acid or alkalinity numbers of 7.0 or over, report thevalue to the nearest 0.1.16. Precision and Bias416.1 PrecisionAttempts to develop a precision and biasstatemen
32、t for these test methods have not been successful. Forthis reason, data on precision and bias cannot 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 develo
33、pment of precision and bias data should contact theChairman, Subcommittee D20.22 (Section D20.22.01), ASTMInternational, 100 Barr Harbor Drive, West Conshohocken, PA19428.16.1.1 A limited round robin was run with three laborato-ries. It is estimated that duplicate results by the same analystshould b
34、e considered suspect if they differ by more than thefollowing amounts:Acid or Alkalinity Number Repeatabilityless than 7.0 0.1 number7.0 and over 1 %16.2 BiasThe bias for these test methods has not yet beendetermined.17. Keywords17.1 acidity; acid number; alkalinity number; polyolsSUMMARY OF CHANGES
35、Committee D20 has identified the location of selected changes to this standard since the last issue(D4662 - 08(2011)1) that may impact the use of this standard. (September 1, 2015)(1) Removed non-mandatory language from 5.1 and 6.1.ASTM International takes no position respecting the validity of any
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38、omments 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 is copyrig
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