ASTM D7253-2006(2011)e1 9375 Standard Test Method for Polyurethane Raw Materials Determination of Acidity as Acid Number for Polyether Polyols《聚氨酯原材料的标准试验方法 聚醚多元醇酸度(酸值)的测定》.pdf
《ASTM D7253-2006(2011)e1 9375 Standard Test Method for Polyurethane Raw Materials Determination of Acidity as Acid Number for Polyether Polyols《聚氨酯原材料的标准试验方法 聚醚多元醇酸度(酸值)的测定》.pdf》由会员分享,可在线阅读,更多相关《ASTM D7253-2006(2011)e1 9375 Standard Test Method for Polyurethane Raw Materials Determination of Acidity as Acid Number for Polyether Polyols《聚氨酯原材料的标准试验方法 聚醚多元醇酸度(酸值)的测定》.pdf(3页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D7253 06 (Reapproved 2011)1Standard Test Method forPolyurethane Raw Materials: Determination of Acidity asAcid Number for Polyether Polyols1This standard is issued under the fixed designation D7253; the number immediately following the designation indicates the year oforiginal adoption
2、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 September 2011.1. Scope1.1 This test method mea
3、sures the acidic constituents inpolyether polyols and reports the results as acid number. Thetypical acid number range is 0-0.1 mg KOH/g sample. (SeeNote 1.)1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard d
4、oes 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.NOTE 1There is no known ISO equiva
5、lent to this standard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: For definitions of terms used in this testmethod see Terminology D883.3
6、.2 Definitions 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 in1gofsample.4. Summary of Test Method4.1 The sample is dissolved in 2-propanol. The resultingsingle-phase solution i
7、s titrated at room temperature with 0.02N methanolic potassium hydroxide solution to an end pointindicated by the color change (pink endpoint) of the addedphenolphthalein.NOTE 2Phenolphthalein is the indicator of choice based on publishedhydroxyl number methods that include an acid number correction
8、. Otherindicators can be chosen if specific acids are of interest. Bromothymolblue (green endpoint) can be used for stronger acids (pKas 7).5. Significance and Use5.1 This test method is suitable for quality control, as aspecification test, and for research. Acid numbers indicate theextent of any ne
9、utralization reaction of the polyol with acids.The results of this method measure batch-to-batch uniformityand are used as correction factors in calculating true hydroxylnumbers.6. Interferences6.1 Samples or constituents that are highly-colored willinterfere with or prevent the use of this test met
10、hod.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 Sept. 1, 2011. Published October 2011. Originallyapproved in 2006. Last previous edition ap
11、proved in 2006 as D7253 - 06.DOI:10.1520/D7253-06R11E01.2For 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.1Copy
12、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Apparatus7.1 Buret, 10 mL, can be manual or automatic.7.2 Graduated cylinder, 10 mL, maximum.7.3 Balance, analytical with sensitivity of at least 60.0001g.7.4 Erlenmeyer flask, at least 2
13、50 mL.7.5 Stirring bars or stirring rods.8. Reagents and Materials8.1 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 suc
14、hspecifications are available.3Other grades can be used pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Phenolphthalein, Indicator Grade.8.3 Phenolphthalein Indicator SolutionDissolve1gofphenolp
15、hthalein in 100 mL of methanol.8.4 Potassium Hydroxide Standard Solution (0.02 N)Prepare and standardize a 0.02 N methanolic potassium hy-droxide solution. (1.32 g KOH pellets (85 % KOH) per 1000mL methanol, standardized with potassium hydrogen phtha-late.)9. Procedure9.1 Add 100 6 20 mL of 2-propan
16、ol and 1 mL of phenol-phthalein indicator solution to an Erlenmeyer flask.9.2 Titrate the stirred solution with 0.02 N KOH solution tothe first faint pink endpoint that persists for 30 seconds.9.3 Weigh 50-60 g of sample into the same Erlenmeyer flaskand record the weight of the sample to the neares
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