1、Designation: D4671 05(Reapproved 2010)1Standard Test Methods forPolyurethane Raw Materials: Determination of Unsaturationof Polyols1This standard is issued under the fixed designation D4671; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, 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 July 2010.1. Scope1.1 These test methods measure unsaturation in pol
3、yetherpolyols. (See Note 1.)1.1.1 Test Method A, High-Volume Reagent MethodUsesabout 50 mLof 0.1 M mercuric acetate reagent in methanol and15 g or more of sample. These test methods use an indicator forcolorimetric determination of an end point. It is recommendedfor polyols with low values (below 0.
4、01 millequivalents pergram (meq/g) of unsaturation where large sample sizes arerequired.1.1.2 Test Method B, Low-Volume Reagent MethodUses 2mL of ca. 0.05 M mercuric acetate reagent in methanol andabout1gofsample or less. These test methods use apotentiometric determination of an end point.1.2 The v
5、alues stated in SI units are to be regarded asstandard. 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
6、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 PlasticsE180 Practice for Determining the Precision of ASTMMethods for A
7、nalysis and Testing of Industrial and Spe-cialty Chemicals33. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, see Terminology D883.4. Summary of Test Method4.1 Carbon-to-carbon unsaturated compounds in the sampleare reacted with mercuric acetate and methanol in a methan
8、olicsolution to produce acetoxymercuricmethoxy compounds andacetic acid.4The amount of acetic acid released in thisequimolar reaction, which is determined by titration withstandard alcoholic potassium hydroxide, is a measure of theunsaturation originally present. Because the acid cannot betitrated i
9、n the presence of excess mercuric acetate, due to theformation of insoluble mercuric oxide, sodium bromide isadded to convert the mercuric acetate to the bromide, whichdoes not interfere. Inasmuch as these test methods are based onan acidimetric titration, a suitable correction must be applied ifthe
10、 sample is not neutral to phenolphthalein indicator. Takecare to exclude carbon dioxide, which titrates as an acid andgives erroneous results.5. Significance and Use5.1 These test methods are suitable for quality control, asspecification tests, and for research.5.2 Side reactions that form unsaturat
11、ed compounds inpolypropylene oxides produce small amounts of polymers withonly one hydroxyl group per chain. These unsaturated poly-mers lower functionality and molecular weight, while broad-ening the overall molecular-weight distribution.6. Interferences6.1 These test methods do not apply to compou
12、nds in whichthe unsaturation is conjugated with carbonyl, carboxyl, or1These 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. Test Method A was recommended to ASTM bythe S
13、ociety of the Plastics Industry Polyurethane Raw Materials Analysis Commit-tee.Current edition approved July 1, 2010. Published October 2010. Originallyapproved in 1987. Last previous edition approved in 2005 as D4671 - 05. DOI:10.1520/D4671-05R10E01.2For referenced ASTM standards, visit the ASTM we
14、bsite, 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.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Sigia, S. and
15、Hanna, J.G., “Quantitative Organic Analysis via FunctionalGroups,” John Wiley and Sons, New York, 1979.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.nitrile groups. Because water presumably hydrolyzes the reac-tion products to form
16、 basic mercuric salts, quantitative resultsare obtained only when the system is essentially anhydrous.Acetone in low concentrations does not interfere significantly,although its presence can be detrimental to the end point.Inorganic salts, especially halides, must be absent from thesample because ev
17、en small amounts of salts can nullify thereaction of the mercuric acetate with the unsaturated com-pound.TEST METHOD AHIGH-VOLUME REAGENTMETHOD7. Apparatus7.1 Pipet, 50-mL capacity.7.2 Erlenmeyer Flask, 250-mL glass-stoppered.7.3 Balance, 1000-g capacity, 0.1-g sensitivity.7.4 Buret, 50-mL capacity.
18、8. Reagents8.1 Purity of ReagentsUse reagent-grade chemicals in alltests. Unless otherwise indicated, it is intended that all reagentsshall conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications are available.5Other grades are
19、acceptable,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Mercuric Acetate, Methanol Solution (40 g/L)Dissolve 40 g of mercuric acetate (Hg(C2H3O2)2in sufficientmethanol to make 1 L of solution
20、and add sufficient glacialacetic acid to require a blank titration of 1 to 10 mL of 0.1 Nalcoholic KOH solution/50 mL of reagent. Usually 3 or 4 dropsof acid are sufficient. Prepare the reagent fresh weekly andfilter before using.8.3 Sodium Bromide (NaBr).9. Procedure9.1 Add 50 mL of methanol to a s
21、ufficient number of250-mL Erlenmeyer flasks to determine the acidity of eachsample in duplicate. Neutralize to a faint pink end point, usinga few drops of phenolphthalein indicator solution and 0.1 Nalcoholic KOH solution.Add 30 g of the sample weighed to thenearest 0.1 g to each flask and swirl to
22、effect complete solution.Titrate with 0.1 N alcoholic KOH solution to a pink end pointthat persists for at least 15 s and record the volume of titrant asA.9.2 Pipet 50 mL of the Hg(C2H3O2)2solution into each of asufficient number of 250-mL Erlenmeyer flasks to make allblank and sample determinations
23、 in duplicate. Reserve two ofthe flasks for the blank determination. Into each of the otherflasks, introduce 30 g of the sample weighed to the nearest 0.1g and swirl to effect complete solution. Allow the samples tostand together with the blanks at room temperature for 30 min.Swirl the flasks occasi
24、onally. Add 8 to 10 g of NaBr crystals toeach flask and swirl to mix thoroughly. Add approximately 1mL of phenolphthalein indicator solution and titrate immedi-ately with 0.1 N alcoholic KOH solution to a pink end pointthat persists for at least 15 s. Record the volume of titrant usedfor the samples
25、 as D and that used for the blank as E. Thesample titration must not exceed 50 mL of 0.1 N alcoholicKOH solution.10. Calculation10.1 Calculate the acidity, meq/g, of the sample as follows:C 5 A 3 N!/W (1)where:A = 0.1 N alcoholic KOH solution required to neutralizethe sample, mL,N = normality of the
26、 alcoholic KOH solution, andW = sample used, g.10.2 Calculate the unsaturation, meq/g, of the sample asfollows:Total unsaturation 5 D 2 E!N/W 2 C (2)where:D = alcoholic KOH solution required for titration of thesample, mLE = alcoholic KOH solution required for titration of theblank, average mL, andC
27、 = average of results from Eq 1, meq of acidity/g ofsample.11. Precision and Bias11.1 PrecisionAttempts to develop a precision and biasstatement for this test method have not been successful. Forthis reason, data on precision and bias cannot be given.Because this test method does not contain a numer
28、ical preci-sion and bias statement, it shall not be used as a referee testmethod in case of dispute.Anyone wishing to participate in thedevelopment of precision and bias data can contact theChairman, Subcommittee D20.22 (Section D20.22.01),ASTM,100 Barr Harbor Dr., PO Box C700, West Conshohocken, PA
29、19428.11.1.1 It is estimated that duplicate results by the sameanalyst can be considered suspect if they differ by more than0.002.11.2 BiasThe bias for this test method has not yet beendetermined.TEST METHOD BLOW-VOLUME REAGENTMETHOD12. Apparatus12.1 Pipet, 2-mL capacity.12.2 Autotitrator, capable o
30、f determining acidimetric endpoints using a 5-mL buret.12.3 Combination, Glass, pH Electrode, for use with theautotitrator.12.4 Balance, capable of weighing samples to 0.0001 g.5Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on
31、 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 Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D4671 05 (2010)1212.5 Titration Vessels
32、, 50- to 100-mL capacity.13. Reagents13.1 Purity of ReagentsUse reagent-grade chemicals inall tests. Unless otherwise indicated, all reagents shall conformto the specifications of the Committee on Analytical Reagentsof the American Chemical Society, where such specificationsare available.5Other grad
33、es are acceptable, provided it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.13.2 Mercuric Acetate, Methanol Solution (ca. 0.05 M)Dissolve 16 g of mercuric acetate (Hg(C2H3O2)2) into 1 L ofreagent-grade metha
34、nol and add sufficient glacial acetic acid torequire a blank titration of 0.5 to 1 mL of 0.05 N methanolicKOH for a 2-mL aliquot. Usually several drops of acid arerequired. Prepare the reagent fresh weekly and filter beforeusing.13.3 Methanolic Potassium Hydroxide Solution (0.05 N)Prepare a 0.05-N s
35、olution using reagent-grade KOH dissolvedin methanol. Standardize using standard procedures with po-tassium hydrogen phthalate.13.4 Methanolic Hydrochloric Acid Solution (0.05 N)Prepare a 0.05-N solution by successively diluting concen-trated acid into methanol. This will introduce less than 0.5 %wa
36、ter in the titration reagent. Standardize by titrating againstthe 0.05 N methanolic KOH.13.5 Sodium Bromide (NaBr).14. Procedure14.1 Use no more than 0.033 millequivalents (meq) ofunsaturated species for this test. For samples having 0.033meq/g or less, add approximately1gofsample weighed to 0.1mg t
37、o a 100-mL titration flask. If the unsaturation value is notknown for a sample, determine an approximate value by usinga 1-g sample. Use this approximate value to calculate a correctsample size that will contribute no more than 0.033 meq of testsample (See Note 2).NOTE 2This test method requires at
38、least a 2-fold molar excess ofmercury reagent for quantitative reaction of unsaturated species. If toolarge a sample size is selected, this test method will give inaccurate, lowresults as well as reduced precision. Calculate sample size, g, using thefollowing equation:Sample size 5 0.033/test sample
39、 unsaturation (3)14.2 Add 2 mL of mercuric acetate reagent solution andswirl to dissolve the sample completely. Cover with a watchglass and allow to stand for a minimum of 30 min. Add 50 mLof methanol followed by approximately 0.25 g of sodiumbromide crystals.14.3 Titrate using 0.05 N methanolic KOH
40、 to the end pointusing an automatic titrator.14.4 Titrate a blank using the same procedure but withoutadding sample.14.5 To determine the acidity or basicity of the polyol forcorrecting the results, prepare a sample exactly as above, butomit the mercuric acetate reagent. Titrate, as above, with 0.05
41、N methanolic KOH to the potentiometric end point. If thesolution is determined to be already past the acid end point,repeat this procedure, but titrate with 0.05 N methanolic HCl.15. Calculation15.1 Calculate the acidity, meq/g, of the sample as follows:VA3 N KOH! / WA5 A (4)where:VA= 0.05 N KOH req
42、uired to neutralize the sample,mL,N (KOH) = normality of the methanolic KOH solution,meq/mL, andWA= weight of sample used, g.15.2 Calculate the basicity, meq/g, of the sample as follows:VB3 N HCl! / WB5 B (5)where:VB= 0.05 N HCl required to neutralize the sample,mL,N (HCl) = normality of the methano
43、lic HCl, meq/mL, andWB= weight of sample used, g.15.3 Calculate the unsaturation of the sample, meq/g, asfollows:Unsaturation 5 Vs Vb! 3 N KOH! / WA 1 B (6)where:Vs = 0.05 N KOH required for the unsaturation sample,mL,Vb = 0.05 N KOH required for the unsaturation blank, mL,W = weight of sample, g,B
44、= sample basicity, meq/g, andA = sample acidity, meq/g.16. Report16.1 Report the results as the average of duplicates, meq/g,to the nearest 0.001 meq/g.17. Precision and Bias617.1 PrecisionTable 1 is based on a round robin con-ducted in 1997 in accordance with Practice E180, involving sixsamples (se
45、e Table 2 for sample descriptions) tested by sevenlaboratories. Each test result was the average of two individual6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D20-1208.TABLE 1 Round-Robin Unsaturation Data in Accordance withP
46、ractice E180SampleAverage,meq/g SrASRBrCRDnEA 0.0007 0.0011 0.0006 0.0031 0.0017 6B 0.0728 0.0011 0.0033 0.0031 0.0092 6C 0.0362 0.0004 0.0015 0.0011 0.0042 5D 0.0231 0.0008 0.0007 0.0022 0.0020 6E 0.0231 0.0014 0.0126 0.0039 0.0354 6F 0.0350 0.0004 0.0010 0.0011 0.0028 6G 0.1240 0.0018 0.0037 0.005
47、0 0.0104 5ASr= within-laboratory standard deviation of the replicates.BSR= between-laboratory standard deviation of the averages.Cr = within-laboratory repeatability limit = 2.8 3 Sr.DR = between-laboratory reproducibility limit = 2.8 3 SR.En = number of laboratories contributing valid data for this
48、 material.D4671 05 (2010)13determinations obtained on the same day. In each laboratory,test results were obtained for each material and the two testresults for a given material were obtained on two separate days.NOTE 3The explanations of r and R in 17.1.1-17.1.3 are intended onlyto present a meaning
49、ful way of considering the approximate precision ofthis test method. The data in Table 1 must not be rigorously applied to theacceptance or rejection of material, as those data are specific to the roundrobin and are not representative of other lots, conditions, materials andlaboratories. Users of this test method must apply the principles outlinedin Practice E180 to generate data specific to their laboratory and materials,or between specific laboratories. The principles of 17.1.1-17.1.3 wouldthen be valid for such data.17.1.1 Repeatability, rComp
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