1、Designation: D 6979 08Standard Test Method forPolyurethane Raw Materials: Determination of Basicity inPolyols, Expressed as Percent Nitrogen1This standard is issued under the fixed designation D 6979; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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. Scope1.1 This test method measures the basic constituents inpolyols that are soluble in glacial a
3、cetic 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 as
4、standard. 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 and health practices and determine the
5、applica-bility of regulatory limitations prior to use.NOTE 1This standard is equivalent to ISO 25761:082. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Ch
6、emicalsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod see Terminology D 883.3.2 Definitions of Terms Specific to This Standard:3.2.1 percent nitrogenthe quantity of perchlo
7、ric acid-titratable base, expressed as a weight percentage of nitrogen ina sample.4. Summary 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 aci
8、d in acetic acid. Results are reported as percentnitrogen.5. Significance and Use5.1 This test method is suitable for quality control, as aspecification test, and for research. The results are measures ofbatch-to-batch uniformity and may be useful in estimatingreactivity.5.1.1 The percent nitrogen c
9、an be used to characterize apolyol or indicate amounts of certain components in a polyolblend.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.
10、3 pH Glass Electrode and Reference Electrode or aCombination Glass Electrode6.4 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, it
11、 is intended that all reagentsconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society where suchspecifications are available.3It is permissible to use othergrades provided it is first ascertained that the reagent is ofsufficiently high purity to permit i
12、ts use without lessening theaccuracy of the determination.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 Aug. 1, 2008. Published September 200
13、8. Originallyapproved in 2003. Last previous edition approved in 2003 as D 6979 - 03.2For 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
14、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 LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the
15、United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.2 Acetic Acid, Glacial7.3 Acetic Anhydride7.4 Perchloric Acid, (70 % nominal
16、)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 perchloric acid in 500 mLof glacial acetic acid; add 25 mL of acetic anhydride and diluteto volume with glacial acetic acid.NOTE 2Perchloric Acidis e
17、xtremely irritating to the skin, eyes andmucous membrane; highly toxic via oral and inhalation routes; and canform explosive mixtures when mixed with carbonaceous material orallowed to dry. Concentrated material shall only be used in a hoodapproved for perchloric acid use. Skin contactwash with soap
18、 and water.Eye contactflush with copious amounts of water for 15 minutes.Inhalation - move victim to an uncontaminated area. Ingestiondo notinduce vomiting. For all exposures seek professional medical advice.8. Procedure8.1 Weigh the appropriate amount of sample, W into asuitable container. Calculat
19、e 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 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 tha
20、n 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, the mixture can be heated gently until the sampleis completely dissolved.8.3 Titrate the sample solution potentiometrically with 0.10N perchl
21、oric 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 3 N 3 14.00W 3 10003 100 % (2)where:S = the volume of titrant used to reach the end point ofthe sample solution titration in millilitres,N = the norm
22、ality of the 0.10 N perchloric acid solutionin milliequivalents per millilitre,W = the weight of the sample in grams,14.00 = the equivalent weight of nitrogen in milligrams permilliequivalent, and1000 = the factor for converting milligrams to gramsNOTE 5It is permissible to also report the results a
23、s alkalinity inmilligrams of potassium hydroxide per gram of sample as follows:Alkalinity, mg KOH/g! 5S 3 N 3 56.10Wwhere:the variables have the same meaning as in 9.1 above and 56.10 is theequivalent weight of KOH in mg per meq.10. Report10.1 For samples containing 1 % nitrogen or less, reportresul
24、ts 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 Bias411.1 Table 1 is based on a round robin involving sevenlaboratories and conducted in 2002 in accordance with PracticeE 180. Al
25、l 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 prepared at thelaboratories that tested them. Each test result was the averageof two individual determinations. Each laboratory made du
26、pli-cate determinations on each material on each of two days.11.2 PrecisionWarningThe following explanations of r and R (11.2.1-11.2.3) are intended only to present a meaningful way ofconsidering the approximate precision of this test method. Donot apply rigorously the data in Table 1 to the accepta
27、nce orrejection of material, as those data are specific to the roundrobin and may not be representative of other lots, conditions,materials, or laboratories. Users of this test method shouldapply the principles outlined in Practice E 180 or E 691 togenerate data specific to their laboratory and mate
28、rials orbetween specific laboratories. The principles of 11.2.1-11.2.3then would be valid for such data.11.2.1 Repeatability, (r)Comparing two replicates for thesame material, obtained by the same operator, using the sameequipment on the same day. The two replicate results shall bejudged not equival
29、ent if they differ by more than the r value forthat material.11.2.2 Reproducibility, (R)Comparing two results, eachthe mean of replicates, for the same material, obtained bydifferent operators, using different equipment in differentlaboratories on different days. The two test results shall bejudged
30、not equivalent if they differ by more than the R valuefor that material.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D201239. The precision estimatesare based on an interlaboratory study performed in 2002 on four samples of
31、polyolor polyol blend. Seven industrial laboratories participated in the test methodevaluation.TABLE 1 Round-Robin Percent Nitrogen Data in Accordancewith Practice E 180AMaterial 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 0.0139 0.0221
32、 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 reproducibility limit
33、 = 2.8SR.Fdf = degrees of freedom in the data.D697908211.2.3 Any judgment in accordance with 11.2.1 and 11.2.2would have an approximate 95 % (0.95) probability of beingcorrect.11.3 There are no recognized standards by which to estimatethe bias of this test method.12. Keywords12.1 alkalinity; polyols
34、; polyurethane; raw materials; testmethod; titrationASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rig
35、hts, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for
36、 revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments 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
37、 you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D6979083
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