1、Designation: D4671 05(Reapproved 2010)1D4671 16Standard Test MethodsMethod 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
2、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.1 NOTEReapproved with editorial changes in July 2010.1. Scope Scope*1.1 TheseThis test methods m
3、easuremethod measures unsaturation in polyether polyols. (See Note 1.) It uses 2 mL of ca. 0.05M mercuric acetate reagent in methanol and about 1 g of sample or less. This test method uses a potentiometric determination ofan end point.1.1.1 Test Method A, High-Volume Reagent MethodUses about 50 mL o
4、f 0.1 M mercuric acetate reagent in methanol and 15g or more of sample. These test methods use an indicator for colorimetric determination of an end point. It is recommended forpolyols with low values (below 0.01 millequivalents per gram (meq/g) of unsaturation where large sample sizes are required.
5、1.1.2 Test Method B, Low-Volume Reagent MethodUses 2 mL of ca. 0.05 M mercuric acetate reagent in methanol and about1 g of sample or less. These test methods use a potentiometric determination of an end point.1.2 The values stated in SI units are to be regarded as standard. No other units of measure
6、ment are included in this standard.1.3 Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues.Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken whenhandling mercur
7、y and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additionalinformation. Users should be aware that selling mercury and/or mercury containing products into your state or country may beprohibited by law.1.4 This standard does not purport to address all of the s
8、afety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.NOTE 1There is no known ISO equivalent to this standard.This standard is eq
9、uivalent to ISO 17710.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)32.2 ISO Standards:ISO 17710 PlasticsPolyols for Use in the
10、Production of PolyurethaneDetermination of Degree of Unsaturation byMicrotitration43. Terminology3.1 DefinitionsFor definitions of terms used in these test methods, see Terminology D883.1 These test methods are under the jurisdiction of ASTM Committee D20 on Plastics and are the direct responsibilit
11、y of Subcommittee D20.22 on Cellular Materials -Plastics and Elastomers. Test Method A was recommended to ASTM by the Society of the Plastics Industry Polyurethane Raw Materials Analysis Committee.Current edition approved July 1, 2010April 1, 2016. Published October 2010April 2016. Originally approv
12、ed in 1987. Last previous edition approved in 20052010 asD4671 - 05.D4671 - 05 (2010)1. DOI: 10.1520/D4671-05R10E01.10.1520/D4671-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume inform
13、ation, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document
14、 is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appr
15、opriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Sta
16、tes14. Summary of Test Method4.1 Carbon-to-carbon unsaturated compounds in the sample are reacted with mercuric acetate and methanol in a methanolicsolution to produce acetoxymercuricmethoxy compounds and acetic acid.5 The amount of acetic acid released in this equimolarreaction, which is determined
17、 by titration with standard alcoholic potassium hydroxide, is a measure of the unsaturation originallypresent. Because the acid cannot be titrated in the presence of excess mercuric acetate, due to the formation of insoluble mercuricoxide, sodium bromide is added to convert the mercuric acetate to t
18、he bromide, which does not interfere. Inasmuch as these testmethods are based on an acidimetric titration, a suitable correction must be applied if the sample is not neutral to phenolphthaleinindicator. Take care to exclude carbon dioxide, which titrates as an acid and gives erroneous results.5. Sig
19、nificance and Use5.1 TheseThis test methods aremethod is suitable for quality control, as specification tests, and for research.5.2 Side reactions that form unsaturated compounds in polypropylene oxides produce small amounts of polymers with only onehydroxyl group per chain. These unsaturated polyme
20、rs lower functionality and molecular weight, while broadening the overallmolecular-weight distribution.6. Interferences6.1 TheseThis test methods domethod does not apply to compounds in which the unsaturation is conjugated with carbonyl,carboxyl, or nitrile groups. Because water presumably hydrolyze
21、s the reaction products to form basic mercuric salts, quantitativeresults are 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
22、 absent from the samplebecause even small amounts of salts can nullify the reaction of the mercuric acetate with the unsaturated compound.TEST METHOD AHIGH-VOLUME REAGENT METHOD7. Apparatus7.1 Pipet, 50-mL capacity.7.2 Erlenmeyer Flask, 250-mL glass-stoppered.7.3 Balance, 1000-g capacity, 0.1-g sens
23、itivity.7.4 Buret, 50-mL capacity.8. Reagents8.1 Purity of ReagentsUse reagent-grade chemicals in all tests. Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where suchspecificati
24、ons are available.5 Other grades are acceptable, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.8.2 Mercuric Acetate, Methanol Solution (40 g/L)Dissolve 40 g of mercuric acetate (Hg(C2H3O2)2 in suf
25、ficient methanol tomake 1 L of solution and add sufficient glacial acetic acid to require a blank titration of 1 to 10 mL of 0.1 N alcoholic KOHsolution/50 mL of reagent. Usually 3 or 4 drops of acid are sufficient. Prepare the reagent fresh weekly and filter before using.8.3 Sodium Bromide (NaBr).9
26、. Procedure9.1 Add 50 mL of methanol to a sufficient number of 250-mL Erlenmeyer flasks to determine the acidity of each sample induplicate. Neutralize to a faint pink end point, using a few drops of phenolphthalein indicator solution and 0.1 N alcoholic KOHsolution. Add 30 g of the sample weighed t
27、o the nearest 0.1 g to each flask and swirl to effect complete solution. Titrate with 0.1N alcoholic KOH solution to a pink end point that persists for at least 15 s and record the volume of titrant as A.9.2 Pipet 50 mL of the Hg(C2H3O2)2 solution into each of a sufficient number of 250-mL Erlenmeye
28、r flasks to make all blankand sample determinations in duplicate. Reserve two of the flasks for the blank determination. Into each of the other flasks,introduce 30 g of the sample weighed to the nearest 0.1 g and swirl to effect complete solution.Allow the samples to stand togetherwith the blanks at
29、 room temperature for 30 min. Swirl the flasks occasionally. Add 8 to 10 g of NaBr crystals to each flask andswirl to mix thoroughly. Add approximately 1 mL of phenolphthalein indicator solution and titrate immediately with 0.1 N5 Sigia, S. and Hanna, J.G., “Quantitative Organic Analysis via Functio
30、nal Groups,” John Wiley and Sons, New York, 1979.Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poo
31、le, Dorset, U.K., and the United States Pharmacopeia and National Formulary,U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D4671 162alcoholic KOH solution to a pink end point that persists for at least 15 s. Record the volume of titrant used for the samples as Dand that used for the blank
32、 as E. The sample titration must not exceed 50 mL of 0.1 N alcoholic KOH solution.10. Calculation10.1 Calculate the acidity, meq/g, of the sample as follows:C 5A 3N!/W (1)where:A = 0.1 N alcoholic KOH solution required to neutralize the sample, mL,N = normality of the alcoholic KOH solution, andW =
33、sample used, g.10.2 Calculate the unsaturation, meq/g, of the sample as follows:Total unsaturation5D 2E!N/W# 2C (2)where:D = alcoholic KOH solution required for titration of the sample, mLE = alcoholic KOH solution required for titration of the blank, average mL, andC = average of results from Eq 1,
34、 meq of acidity/g of sample.11. Precision and Bias11.1 PrecisionAttempts to develop a precision and bias statement for this test method have not been successful. For thisreason, data on precision and bias cannot be given. Because this test method does not contain a numerical precision and biasstatem
35、ent, it shall not be used as a referee test method in case of dispute. Anyone wishing to participate in the development ofprecision and bias data can contact the Chairman, Subcommittee D20.22 (Section D20.22.01), ASTM, 100 Barr Harbor Dr., POBox C700, West Conshohocken, PA 19428.11.1.1 It is estimat
36、ed that duplicate results by the same analyst can be considered suspect if they differ by more than 0.002.11.2 BiasThe bias for this test method has not yet been determined.TEST METHOD BLOW-VOLUME REAGENT METHOD7. Apparatus7.1 Pipet, 2-mL capacity.7.2 Autotitrator, capable of determining acidimetric
37、 end points using a 5-mL buret.7.3 Combination, Glass, pH Electrode, for use with the autotitrator.7.4 Balance, capable of weighing samples to 0.0001 g.7.5 Titration Vessels, 50- to 100-mL capacity.8. Reagents8.1 Purity of ReagentsUse reagent-grade chemicals in all tests. Unless otherwise indicated,
38、 all reagents shall conform to thespecifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications areavailable.6 Other grades are acceptable, provided it is first ascertained that the reagent is of sufficiently high purity to permit itsuse without l
39、essening the accuracy of the determination.8.2 Mercuric Acetate, Methanol Solution (ca. 0.05 M)Dissolve 16 g of mercuric acetate (Hg(C2H3O2)2) into 1 L ofreagent-grade methanol and add sufficient glacial acetic acid to require a blank titration of 0.5 to 1 mL of 0.05 N methanolic KOHfor a 2-mL aliqu
40、ot. Usually several drops of acid are required. Prepare the reagent fresh weekly and filter before using.8.3 Methanolic Potassium Hydroxide Solution (0.05 N)Prepare a 0.05-N solution using reagent-grade KOH dissolved inmethanol. Standardize using standard procedures with potassium hydrogen phthalate
41、.8.4 Methanolic Hydrochloric Acid Solution (0.05 N)Prepare a 0.05-N solution by successively diluting concentrated acid intomethanol. This will introduce less than 0.5 % water in the titration reagent. Standardize by titrating against the 0.05 N methanolicKOH.8.5 Sodium Bromide (NaBr).9. Procedure9.
42、1 Use no more than 0.033 millequivalents (meq) of unsaturated species for this test. For samples having 0.033 meq/g or less,add approximately 1 g of sample weighed to 0.1 mg to a 100-mLtitration flask. If the unsaturation value is not known for a sample,D4671 163determine an approximate value by usi
43、ng a 1-g sample. Use this approximate value to calculate a correct sample size that willcontribute no more than 0.033 meq of test sample (See Note 2).NOTE 2This test method requires at least a 2-fold molar excess of mercury reagent for quantitative reaction of unsaturated species. If too large asamp
44、le size is selected, this test method will give inaccurate, low results as well as reduced precision. Calculate sample size, g, using the followingequation:Sample size50.033/test sample unsaturation (1)9.2 Add 2 mL of mercuric acetate reagent solution and swirl to dissolve the sample completely. Cov
45、er with a watch glass andallow to stand for a minimum of 30 min. Add 50 mL of methanol followed by approximately 0.25 g of sodium bromide crystals.9.3 Titrate using 0.05 N methanolic KOH to the end point using an automatic titrator.9.4 Titrate a blank using the same procedure but without adding samp
46、le.9.5 To determine the acidity or basicity of the polyol for correcting the results, prepare a sample exactly as above, but omit themercuric acetate reagent. Titrate, as above, with 0.05 N methanolic KOH to the potentiometric end point. If the solution isdetermined to be already past the acid end p
47、oint, repeat this procedure, but titrate with 0.05 N methanolic HCl.10. Calculation10.1 Calculate the acidity, meq/g, of the sample as follows:VA 3N KOH!/WA 5A (2)where:VA = 0.05 N KOH required to neutralize the sample, mL,N (KOH) = normality of the methanolic KOH solution, meq/mL, andWA = weight of
48、 sample used, g.10.2 Calculate the basicity, meq/g, of the sample as follows:VB 3N HCl!/WB 5B (3)where:VB = 0.05 N HCl required to neutralize the sample, mL,N (HCl) = normality of the methanolic HCl, meq/mL, andWB = weight of sample used, g.10.3 Calculate the unsaturation of the sample, meq/g, as fo
49、llows:Unsaturation5Vs2Vb! 3N KOH!/W# 2A1B (4)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 = sample basicity, meq/g, andA = sample acidity, meq/g.11. Report11.1 Report the results as the average of duplicates, meq/g, to the nearest 0.001 meq/g.12. Precision and Bias712.1 PrecisionTable 1 is based on a round robin conducted in 1997 in accordance with Practice E180, involving six samples(see Table 2 for sample descriptions) tested by seven laboratories.
