1、Designation: D4569 06 (Reapproved 2012)Standard Test Method forRubber Compounding MaterialsDetermination of Acidity inSulfur1This standard is issued under the fixed designation D4569; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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 covers the determination of the acidmaterial, which disassociates in distilled water, th
3、at is presentin sulfur. The acidity is determined by an electrometric orvisual titration.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, assoc
4、iated with its use. It is theresponsibility of the user of this standard 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:2D4483 Practice for Evaluating Precision for Test MethodSta
5、ndards in the Rubber and Carbon Black ManufacturingIndustries3. Significance and Use3.1 This test method provides a means of determining theacidity of sulfur and may be used for quality control, researchand development, or for any other reason for which such adetermination is required. A low acidity
6、 value indicates to theuser that the sulfur used should not adversely affect thevulcanization system.4. Apparatus4.1 pH Meter, equipped with a glass measuring electrodeand calomel reference electrode, operated according to themanufacturers directions for optimum performance.4.2 10 cm3Burette, with 0
7、.05 cm3graduations.4.3 Laboratory Glassware, suitable for carrying out theprocedure as written.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical R
8、eagents of the American Chemical Society wheresuch specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Bromothymol BlueDissolve 0.1 g of 38,39-d
9、ibromothymolsulfonphthalein in 100 cm3of 20 % methanolor use commercical preparations.5.3 Sodium Hydroxide, 0.01 N.6. Procedure6.1 Weigh 10.0 g of sulfur into a 500-cm2beaker, and wetthe sample with 25 cm3of alcohol.6.2 Add 200 cm3of distilled water, and stir the wetted sulfurthoroughly.6.3 Place th
10、e pH meter electrode in the solution and titratewith 0.01 N NaOH to a pH of 7.0. Stir the mixture constantlywhile titrating. When nearing the end of the titration, wait untilthe pH reading has reached equilibrium before adding addi-tional NaOH solution to prevent overshooting the end point.6.4 If a
11、pH meter is unavailable, add 10 drops of bromo-thymol blue indicator and titrate as above.6.5 Important: Titrate a blank (no sulfur) using the sameamounts of alcohol and water to a pH 7.0 end point. Subtractthe amount used for the blank from the amount used to titratea sulfur sample in order to dete
12、rmine the acidity of the sulfursample.7. Calculation7.1 Calculate the percent acidity, A, (as H2SO4) in accor-dance with the following equation:A 5 4.9 3 V 3 N/W (1)1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on C
13、hemical Analysis.Current edition approved May 1, 2012. Published June 2012. Originallyapproved in 1986. Last previous edition approved in 2006 as D4569 06. DOI:10.1520/D4569-06R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org
14、. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary 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
15、 Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
16、59, United States.where:V = volume of NaOH for sample-volume NaOH forblank, cm3,N = normality of NaOH solution, andW = sample mass, g.8. Report8.1 Report the following information:8.1.1 Percent acidity as H2SO4.8.1.2 If the pH of the sulfur solution is greater than 7.0 andno titrant is needed, repor
17、t the result as basic.9. Precision and Bias49.1 This precision and bias section has been prepared inaccordance with Practice D4483. Refer to Practice D4483 forterminology and other statistical details.9.2 The precision results in this precision and bias sectiongive an estimate of the precision of th
18、is test method with thematerials (rubbers) used in the particular interlaboratory pro-grams as described below. The precision parameters should notbe used for acceptance/rejection testing of any group ofmaterials without documentation that they are applicable tothose particular materials and the spe
19、cific testing protocols thatinclude this test method.9.3 A Type 1 (interlaboratory) precision was evaluated in1986. Both repeatability and reproducibility are short term. Aperiod of a few days separates replicate test results.Atest resultis the mean value, as specified by this test method, obtained
20、ontwo determinations or measurements of the property or param-eter in question.9.4 Three different materials were used in the interlabora-tory program. These were tested in seven laboratories on twodifferent days.9.5 The results of the precision calculations for repeatabilityand reproducibility are
21、given in Table 1, in ascending order ofmaterial average or level, for each of the materials evaluated.NOTE 1The percent acidity values have been multiplied by 100 toavoid leading zeros in Table 1. The values of S, r, S, and R are influencedby this multiplication factor, that is, S (percent ash 3 100
22、)/100 = S (actualor true percent basis).9.6 The precision of this test method may be expressed inthe format of the following statements which use an “appro-priate value” of r, R, (r),or(R), that is, that value to be used indecisions about test results (obtained with the test method).The appropriate
23、value is that value of r or R associated with amean level in Table 1 closest to the mean level underconsideration at any given time, for any given material inroutine testing operations.9.7 RepeatabilityThe repeatability, r, of this test methodhas been established as the appropriate value tabulated i
24、nTable 1. Two single test results, obtained under normal testmethod procedures, that differ by more than this tabulated r(for any given level) must be considered as derived fromdifferent or nonidentical sample populations.9.8 ReproducibilityThe reproducibility, R, of this testmethod has been establi
25、shed as the appropriate value tabulatedin Table 1. Two single test results obtained in two differentlaboratories, under normal test method procedures, that differby more than the tabulated R (for any given level) must beconsidered to have come from different or nonidentical samplepopulations.NOTE 2T
26、he values of r and R are relatively large, whereas the averageor mean test level is small (close to zero). This is typical for this type ofprecision measurement process. This should be kept in mind whenever useis made of r and R.9.9 The relative repeatability (r) and reproducibility (R)have been omi
27、tted from Table 1 since the level of values testedwas extremely low and approached the limits of sensitivity ofthe test method. Under these circumstances, the relative valuesbecome trivial.9.10 BiasIn test method terminology, bias is the differ-ence between an average test value and the reference (o
28、r true)test property value. Reference values have not been evaluatedfor this test method. Bias, therefore, cannot be determined.10. Keywords10.1 acidity; oil-treated sulfur; sulfur4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:
29、D11-1046.TABLE 1 Type 1 Precision ResultsAcidity, % 3 100Material AverageWithin LaboratoryABetween LaboratoryASrrSRROil Treated, 90 %Insoluble SulfurA0.21 0.2315 0.6551 0.2419 0.6847Oil Treated, 90 %Insoluble SulfurB0.36 0.3505 0.9920 0.3505 0.9920General PurposeGround Sulfur3.73 0.3266 0.9243 0.013
30、7 2.3027Pooled ValuesB1.43 0.3062 0.8665 0.5793 1.6394ASr= repeatability standard deviation.r = repeatability = 2.83 3 the square root of the repeatability variance.SR= reproducibility standard deviation.R = reproducibility = 2.83 3 the square root of the reproducibility variance.BNo values omitted.
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