1、Designation: D 5044 06Standard Test Method forRubber Compounding MaterialsFree2-Mercaptobenzothiazole (MBT) in Benzothiazyl Disulfide(MBTS)1This standard is issued under the fixed designation D 5044; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the procedure for estimation ofthe acidic impurities in benzothi
3、azyl disulfide (MBTS).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 does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this stan
4、dard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carb
5、on Black ManufacturingIndustries3. Summary of Test Method3.1 A sample of MBTS is dissolved in solvent. Afteraddition of an acetate buffer, water, and starch solution, thesolution is titrated with iodine.3.2 MBTS is sparingly soluble in any organic solvent. MBT,major impurity in MBTS, is very soluble
6、. Stirring thereforewill dissolve MBT, MBTS could stay undissolved.4. Significance and Use4.1 2-Mercaptobenzothiazole (MBT) is usually the majorimpurity in MBTS. Free MBT may be determined by this testmethod.4.2 MBT and MBTS are used for rubber and latex vulcani-zation acceleration. The amount of MB
7、T in MBTS may be ofimportance in predicting performance in rubber compoundsand for raw material purchase and control.4.3 This test method may be used as a quality control tooland for research and development work.5. Apparatus5.1 Erlenmeyer Flask, 300-cm3.5.2 Graduated Cylinders, 10-cm3, 50-cm3, 250-
8、cm3.5.3 Buret, 10-cm3.5.4 Analytical Balance, having a sensitivity of 60.1 mg.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents o
9、f the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, refere
10、ncesto water shall be understood to mean reagent water as definedby Types I, II, or III of Specification D 1193.6.3 Isopropanol, analytical reagent.6.4 Toluene, analytical reagent.6.5 Acetic Acid, 100 % analytical reagent.6.6 Sodium Acetate, analytical reagent.6.7 Water, distilled.6.8 Iodine Solutio
11、n (0.1 N).6.9 Starch Indicator SolutionSlurry2gofsoluble starchwith 10 cm3of water and dilute with 90 cm3of boiling water.6.10 Sodium Acetate SolutionDissolve 60 g of sodiumacetate in water to make 600 cm3of solution.6.11 Acetate-BufferAdd 100 cm3acetic acid (see 6.5)to600 cm3sodium acetate solution
12、 (6.10).1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on Chemical Analysis.Current edition approved Oct. 1, 2006. Published October 2006. Originallyapproved in 1990. Last previous edition approved in 2002 as D 5044
13、02.2For 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.3Reagent Chemicals, American Chemical Society Specificatio
14、ns, 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 Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention,
15、Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.12 SolventMix 5 volumes Isopropanol with 3 volumestoluene.7. Sampling7.1 Sampling shall be at the discretion of the analyst toobtain as representative a samp
16、le as possible of the lot to betested.8. Procedure8.1 Accurately weigh about1gofthetest specimen to thenearest 0.1 mg and carefully transfer to a 300-cm3Erlenmeyerflask.8.2 Add 50 cm3of solvent to the specimen which may notdissolve completely.8.3 With stirring, add the reagents in the following se-q
17、uence: 150 cm3distilled water, 10 cm3acetate buffer, and5cm3starch solution.8.4 Titrate immediately with 0.1 N iodine solution until thecolor change from colorless to light violet is stable for 1 min.(See 3.2)8.5 Obtain a blank titration by proceeding from steps 8.2through 8.4.9. Calculation9.1 Calc
18、ulate the percent free MBT as follows:Percent Free MBT 5A 2 B! 3 N 3 0.1672W3 100 (1)where:A = volume of iodine (see 6.7) required for titrationof the sample, cm3,B = volume of iodine (see 6.7) required for titrationof the blank, cm3,W = mass of the test specimen in g,N = normality of the iodine sol
19、ution, and0.1672 = millimole mass of MBT.10. Report10.1 Report the following information:10.1.1 Proper identification of the sample and10.1.2 Results obtained from two individual determinationsand their average, reported to the nearest 0.1 %.11. Precision and Bias411.1 This precision and bias sectio
20、n has been prepared inaccordance with Practice D 4483. Please refer to this practicefor terminology and other statistical calculation details.11.2 The precision results in this precision and bias sectiongive an estimate of the precision of this test method with thematerials (rubbers, etc.) used in t
21、he particular interlaboratoryprogram as described below. The precision parameters shouldnot be used for acceptance or rejection testing of any group ofmaterials without documentation that the parameters are appli-cable to the particular group of materials and the specifictesting protocols of the tes
22、t method.11.3 A Type 1 interlaboratory test program (ITP) wasconducted in 1997 on a sample of IRM-MBTS. Six laborato-ries participated in the ITP conducting duplicate tests on eachof 2 successive test days.Atest result for free MBT is the valueobtained from one analysis operation. The database gener
23、atedby this ITP was divided into two parts; Part 1 used the first ofthe duplicates on each day and Part 2 used the second of theduplicates. A complete statistical analysis according to D 4483was conducted for each part. The results of each part wherethen combined (averaged) for the final values as g
24、iven in thissection. Thus the precision results pertain to between daysingle determinations for free MBT.11.4 The data of the ITP showed that two laboratories couldnot detect free MBT with good sensitivity reporting only lessthan 0.2 % for all analysis runs. The data for these two weredeleted from t
25、he analysis and thus the reported precision isbased on a four laboratory database. This is an insufficientnumber of laboratories for a reliable assessment of precisionbut it is given as the best effort as of this time.11.5 RepeatabilityThe repeatability r, of this test methodhas been established as
26、the value tabulated in Table 1.Twosingle test results, obtained under normal test method proce-dures, that differ by more than this tabulated r (for any givenlevel) must be considered as derived from different or non-identical sample populations.11.6 ReproducibilityThe reproducibility R, of this tes
27、tmethod has been established as the value tabulated in Table 1.Two single test results obtained in two different laboratories,under normal test method procedures, that differ by more thanthe tabulated R must be considered to have come from differentor non-identical sample populations.11.7 BiasIn tes
28、t method terminology, bias is the differ-ence between an average test value and the reference (or true)test property value. Reference values do not exist for this testmethod since the value (of the test property) is exclusivelydefined by the test method. Bias cannot therefore be deter-mined.12. Keyw
29、ords12.1 mercaptobenzothiazole;mercaptobenzothiazoledisulfide4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D11-1083.TABLE 1 Precision for Free MBT in MBTSAMean Within-Laboratory Between LaboratoryMaterial Value (a) Sr r (r) S
30、R R (R)IRM-MBTS 0.179 0.00604 0.017 9.5 0.0365 0.103 57.4APrecision results for 4 laboratories, mean value for free percent MBT.Sr = repeatability standard deviationSR = reproducibility standard deviationr = repeatability, in measurement unitsR = reproducibility, in measurement units(r) = repeatabil
31、ity (relative) in percent(R) = reproducibility (relative) in percentD5044062ASTM 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 validit
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