1、Designation: D6979 18Standard Test Method forPolyurethane Raw Materials: Determination of Basicity inPolyols, Expressed as Percent Nitrogen1This standard is issued under the fixed designation D6979; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se 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.1. Scope*1.1 This test method measures the basic constituents inpolyols that are soluble in glacial ac
3、etic acid and reactive withperchloric acid. Samples containing 0.3 10 % nitrogen havebeen evaluated by this method. This test method is applicableto polyether polyols and polyether polyol blends that are usedin urethane reactions. (See Note 1.)1.2 The values stated in SI units are to be regarded ass
4、tandard. No other units of measurement are included in thisstandard.1.3 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 establish appro-priate safety, health, and environmental practices and
5、 deter-mine the applicability of regulatory limitations prior to use.NOTE 1This standard is equivalent to ISO 25761:08.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopm
6、ent of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Te
7、sting of Industrial and Spe-cialty Chemicals (Withdrawn 2009)3E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standards:4ISO 25761 PlasticsPolyols for use in the production ofpolyurethanesDetermination of basicity (total aminevalue), expressed
8、as percent nitrogen3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod see Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 percent nitrogenthe quantity of perchloric acid-titratable base, expressed as a weight percentage of nitrogen ina sample.4. S
9、ummary of Test Method4.1 The sample is dissolved in glacial acetic acid. Theresulting single-phase solution is titrated at room temperatureto a potentiometric end point with a standardized solution ofperchloric acid in acetic acid. Results are reported as percentnitrogen.5. Significance and Use5.1 T
10、his test method is suitable for quality control, as aspecification test, and for research. The results are measures ofbatch-to-batch uniformity and are useful in estimating reactiv-ity.5.1.1 The percent nitrogen can be used to characterize apolyol or indicate amounts of certain components in a polyo
11、lblend.5.1.2 It is permissible to also express the results in equiva-lents of base per gram of sample, if desired.6. Apparatus6.1 Potentiometric Automatic Titrator6.2 Autotitrator Buret with Dosing Device, 20-mL6.3 pH Glass Electrode and Reference Electrode or aCombination Glass Electrode1This test
12、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 Aug. 1, 2018. Published August 2018. Originallyapproved in 2003. Last previous edition approved in 2013 as
13、 D6979 - 13. DOI:10.1520/D6979-18.2For 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
14、of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive
15、, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issu
16、ed by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.4 Analytical Balances, capable of weighing to the nearest0.01g and 0.0001 g6.5 Magnetic Stirrer/Hotplate7. Reagents and Materials7.1 Purity of ReagentsUse reagent-grade chemicals in alltests. Unless otherwise indicated
17、, it is intended that all reagentsconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society where suchspecifications are available.5It is permissible to use othergrades provided it is first ascertained that the reagent is ofsufficiently high purity to perm
18、it its use without lessening theaccuracy of the determination.7.2 Acetic Acid, Glacial7.3 Acetic Anhydride7.4 Perchloric Acid, (70 % nominal)7.5 Perchloric acid in Acetic Acid (0.10 N)Prepare 0.10 Nperchloric acid in acetic acid. For example, in a 1000-mLvolumetric flask dissolve 8.7 mL of perchlori
19、c acid in 500 mLof glacial acetic acid; add 25 mL of acetic anhydride and diluteto volume with glacial acetic acid.NOTE 2Perchloric Acidis extremely irritating to the skin, eyes andmucous membrane; highly toxic via oral and inhalation routes; and canform explosive mixtures when mixed with carbonaceo
20、us material orallowed to dry. Concentrated material shall only be used in a hoodapproved for perchloric acid use. Skin contactwash with soap and water.Eye contactflush with copious amounts of water for 15 minutes.Inhalation - move victim to an uncontaminated area. Ingestiondo notinduce vomiting. For
21、 all exposures seek professional medical advice.8. Procedure8.1 Weigh the appropriate amount of sample, W into asuitable container. Calculate the target weight of sample to beanalyzed as follows:W 5 2/P (1)where:W = the target weight of the sample to be analyzed ingrams, andP = the expected percent
22、nitrogen content of the sample.NOTE 3For sample weights below 10.0 g, record the weight to thenearest 0.1 mg; for sample weights greater than 10.0 g, record the weightto the nearest 0.01g.8.2 Add 100 mL of glacial acetic acid and gently stir untilthe sample dissolves completely.NOTE 4If necessary, t
23、he mixture is heated gently until the sample iscompletely dissolved.8.3 Titrate the sample solution potentiometrically with 0.10N perchloric acid through the end point which occurs at ca. 600mV.9. Calculation9.1 Calculate the basicity in the sample, as percent nitrogenas follows:% N 5S 3N 314.00W 31
24、0003100% (2)where:S = the volume of titrant used to reach the end point ofthe sample solution titration in milliliters,N = the normality of the 0.10 N perchloric acid solutionin milliequivalents per milliliter,W = the weight of the sample in grams,14.00 = the equivalent weight of nitrogen in milligr
25、ams permilliequivalent, and1000 = the factor for converting milligrams to gramsNOTE 5It is permissible to also report the results as alkalinity inmilligrams of potassium hydroxide per gram of sample as follows:Alkalinity, mg KOH/g! 5S 3N 356.10Wwhere:the variables have the same meaning as in 9.1 abo
26、ve and 56.10 is theequivalent weight of KOH in mg per meq.10. Report10.1 For samples containing 1 % nitrogen or less, reportresults no more precisely than the nearest 0.0001 %.10.2 For samples containing between 1 and 10 %, reportresults no more precisely than the nearest 0.001 %.11. Precision and B
27、ias611.1 Table 1 is based on a round robin involving sevenlaboratories and conducted in 2002 in accordance with PracticeE180. All labs used potentiometric titration for the generationof the data used in this study. All the samples were prepared atone source, but the individual specimens were prepare
28、d at thelaboratories that tested them. Each test result was the averageof two individual determinations. Each laboratory made dupli-cate determinations on each material on each of two days.(WarningThe explanation of r and R (11.2.1 11.2.3) areonly intended to present a meaningful way of considering
29、the5Reagent 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 LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmac
30、opeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D20-1239. The precision estimatesare based on an interlaboratory study performed in 2002 on fo
31、ur samples of polyolor polyol blend. Seven industrial laboratories participated in the test methodevaluation.TABLE 1 Round-Robin Percent Nitrogen Data in Accordance withPractice E180AMaterial Average SrBSRCrDREdfFA 0.317 0.0007 0.0018 0.0020 0.0050 5B 2.51 0.0046 0.0053 0.0129 0.0148 5C 5.86 0.0079
32、0.0139 0.0221 0.0392 5D 9.45 0.0220 0.0217 0.0616 0.0618 5AValues in units of percent nitrogen.BSr= within-laboratory standard deviation of the replicates.CSR= between-laboratories standard deviation of the average.Dr = within-laboratory repeatability limit = 2.8Sr.ER = between-laboratories reproduc
33、ibility limit = 2.8SR.Fdf = degrees of freedom in the data.D6979 182approximate precision of this test method. Do not apply thedata in Table 1 to acceptance or rejection of material, as thesedata apply only to the materials tested in the round robin andare unlikely to be rigorously representative of
34、 other lots,formulations, conditions, materials, or laboratories. Users ofthis test method need to apply the principles outlined inPractice E180 or E691 to generate data specific to theirmaterials and laboratory (or between specific laboratories). Theprinciples of 11.2.1 11.2.3 would then be valid f
35、or such data.)11.2 Precision11.2.1 RepeatabilityPrecision under repeatability condi-tions.11.2.2 ReproducibilityPrecision under reproducibilityconditions.11.2.3 Any judgment in accordance with 11.2.1 and 11.2.2would have an approximate 95 % (0.95) probability of beingcorrect.11.2.4 Repeatability Lim
36、itThe value below which theabsolute difference between two individual test results obtainedunder repeatability conditions may be expected to occur with aprobability of approximately 0.95 (95 %). For the data gener-ated above, the maximum expected differences between twotest results for the same mate
37、rial, obtained by the sameoperator using the same equipment on the same day in the samelaboratory due solely to the method is r.11.2.5 Reproducibility LimitThe value below which theabsolute difference between two individual test results obtainedunder reproducibility conditions may be expected to occ
38、ur witha probability of approximately 0.95 (95 %). For the datagenerated above, the maximum expected differences betweentwo test results for the same material, obtained by differentoperators using different equipment in different laboratoriesdue solely to the method is R.11.3 There are no recognized
39、 standards by which to estimatethe bias of this test method.12. Keywords12.1 alkalinity; nitrogen; polyols; polyurethane; raw mate-rials; test method; titrationSUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D6979-13)that may imp
40、act the use of this standard. (August 1, 2018)(1) Added ISO 25761 as a reference.(2) Subsection 8.2, Note 4: Removed non-mandatory language.(3) Changed Precision and Bias section to comply with D4968.ASTM International takes no position respecting the validity of any patent rights asserted in connec
41、tion 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 subject to revision at any time by the responsib
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43、sideration 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 copyrighted by ASTM International, 100
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