1、Designation: D6741 10 (Reapproved 2015)Standard Test Methods forSilanes Used in Rubber Formulations(bis-(triethoxysilylpropyl)sulfanes): Sulfur Content1This standard is issued under the fixed designation D6741; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in 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. Scope1.1 These test methods cover the determination of the sulfurcontent of silanes, or
3、 of admixtures of silane and carbon black,of the type bis-(triethoxysilylpropyl)sulfane. The following testmethods are included:Test Method A: Combustion in an Oxygen Flask and SubsequentTitration of SulfateTest Method B: High-Temperature Combustion with InfraredAbsorption Detection1.2 The values st
4、ated 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 safety a
5、nd health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study t
6、oDetermine the Precision of a Test Method3. Significance and Use3.1 The sulfur content can be used to characterize a silane oran admixture of silane and carbon black. It depends mainly onthe average length of the sulfur chain.Test Method A: Combustion in an Oxygen Flask andSubsequent Titration of Su
7、lfate4. Summary of Test Method4.1 The weighed sample is burned in an oxygen atmo-sphere. The resulting sulfur dioxide and trioxide is absorbed inhydrogen peroxide solution, and the sulfate ions thus generatedare titrated with barium perchlorate solution employing Thorinindicator. Taking into account
8、 the known concentration of theperchlorate solution, the volume consumed, and the samplemass, the sulfur content of the sample can be calculated.5. Apparatus5.1 Analytical Balance, accuracy 60.1 mg.5.2 Combustion Apparatus, according to Schoeniger, with750 cm3flask.5.3 Ultrasonic Bath.5.4 Automatic
9、Titrator.5.5 Photoelectrical Detector, set at 550 nm.5.6 Volumetric Cylinder, 100 cm3.5.7 Volumetric Flask, 100 cm3.5.8 Volumetric Pipet, 10 cm3.5.9 Syringe, 0.5 cm3.5.10 Titration Beakers.5.11 Magnetic Stirrer, with stirring rod.5.12 Filter Paper, for Schoeniger combustion (35 35 70mm).5.13 Glass T
10、ube, attached to a rubber hose.6. Reagents6.1 Purity of ReagentsReagent grade shall be used 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 where1These test methods ar
11、e under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.20 on CompoundingMaterials and Procedures.Current edition approved June 1, 2015. Published September 2015. Originallyapproved in 2001. Last previous edition approved in 2010 as D6741 10. DOI
12、:10.1520/D6741-10R15.2For 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.Copyright ASTM International, 100 Barr H
13、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1such 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.6.2 Purity of Wat
14、erUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D1193.6.3 2-propanol 99 %.6.4 Hydrogen Peroxide Solution, (5 %) as absorbing liquid.6.5 Barium Perchlorate Solution, 0.005 mol/dm3in2-propanol/water.6.6 Thorin Solution, 0.1 % in wat
15、er (Thorin octahydrate).6.7 Sulfuric Acid, as a standard solution (1.000 6 0.002 gSO42-).6.8 Deionized Water.6.9 Oxygen.6.10 Sulfanilic Acid, (certified standard for elemental analy-sis).7. Preparation of ApparatusNOTE 1The flask shall not contain any residues from solvents. Purgewith compressed air
16、 if necessary.NOTE 2Check flask for damages. Do not use flasks having scratchesor cracks.NOTE 3Ignite with safety shield lowered only.NOTE 4After combustion is finished, leave flask in the apparatus for5 min cool-down.7.1 Add 20 cm3of 5 % H2O2solution into the combustionflask by means of a volumetri
17、c cylinder.7.2 Add a magnetic stirring rod.7.3 Purge the flask for 1 min with oxygen gas. Do this bydirecting a gentle stream from the glass tube towards thebottom of the flask.8. Procedure8.1 Preparation of Liquid Samples (Silanes):8.1.1 Place a non-densified cotton wool swab between theplatinum gr
18、ids attached to the glass stopper. The spare placebetween the grids should be filled to23 .8.1.2 Attach the ignition strip in such way that it is incontact with the heating coil.8.1.3 Transfer the stopper onto the balance, add approxi-mately 60 mg of silane and record the mass to the nearest 0.1mg.8
19、.2 Preparation of Solid Samples (Admixtures of CarbonBlack and Silane):8.2.1 Fold the special filter paper as to form a tunnel andtransfer it onto the balance.8.2.2 Add approximately 120 mg of the admixture andrecord the mass to the nearest 0.1 mg.8.2.3 Fold the paper, roll it together and insert it
20、 between theplatinum grids. Make sure the ignition strip is in contact withthe heating coil.8.3 Combustion:8.3.1 Insert the stopper including the sample into the flask.Turn the flask upside down and fix it inside the combustionapparatus.8.3.2 Lower the safety shield and start ignition by pushingthe
21、button.8.3.3 After 5 min take the flask out of the apparatus and stirfor 30 min with a magnetic stirrer.8.3.4 Rinse the platinum grids with approximately 20 cm3of deionized water, while holding it above the combustionflask.8.3.5 Transfer the liquid from the combustion flask to a 100cm3volumetric fla
22、sk, rinse, and make up to the mark withdeionized water.8.4 Titration:8.4.1 Pipet 10 cm3from the volumetric flask into thetitration beaker.8.4.2 Add 40 cm32-propanol and 0.1 cm3Thorin solution.NOTE 5It is important to respect the proportion of water/2-propanol(1:4).8.4.3 Degas in the ultrasonic bath
23、for 5 min.8.4.4 Add barium perchlorate until the color changes fromyellow to pale rose. Preferably use an automatic titratorequipped with photoelectrical detector.8.5 Standardization of the Barium Perchlorate Solution:8.5.1 Pipet 10 cm3of sulfuric acid standard solution into atitration beaker and pr
24、oceed as described in 8.4. Result = V0.NOTE 6Ion chromatography can be used as an alternative method forsulfate determination.9. Calibration9.1 Use sulfanilic acid as a standard for calibration. Carryout the test as described in Sections 7 and 8. The theoreticalsulfur content of sulfanilic acid is 1
25、8.5 %. If this value is notobtained within 60.2 % (absolute), check reagents andapparatus, glassware, and calculation.10. Calculation10.1 Calculate the sulfur content in percentage, according tothe following equation:S 5VF0.1603VtotalmValiquot100 (1)where:V = volume of barium perchlorate solution,F
26、= factor of barium perchlorate solution F =10.41V0(determined using sulfuric acid standard solution),0.1603 = conversion factor from cm30.005 m bariumperchlorate solution to mg S,Vtotal= total volume of sulfate-containing solution (here:100 cm3),Valiquot= aliquot part used for titration, cm3, and3Re
27、agent 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 United States Pharmacopeiaa
28、nd National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D6741 10 (2015)2m = original sample mass, mg.Test Method B: High-Temperature Combustion withInfrared Absorption Detection11. Summary of Test Method11.1 The specimen is burned in a tube furnace at a minimumoperating tempe
29、rature of 1350C in a stream of oxygen tooxidize the sulfur. Moisture and particulates are removed fromthe gas by traps filled with anhydrous magnesium perchlorate.The gas stream is passed through a cell in which sulfur dioxideis measured by an infrared (IR) absorption detector. Sulfurdioxide absorbs
30、 IR energy at a precise wavelength within theIR spectrum. Energy is absorbed as the gas passes through thecell body in which the IR energy is being transmitted. Thus, atthe detector, less energy is received. All other IR energy iseliminated from reaching the detector by a precise wavelengthfilter. T
31、hus, the absorption of IR energy can be attributed onlyto sulfur dioxide whose concentration is proportional to thechange in energy at the detector. One cell is used as both areference and a measurement chamber. Total sulfur as sulfurdioxide is detected on a continuous basis. This test method isempi
32、rical. Therefore, the apparatus shall be calibrated by theuse of a standard reference material.11.2 This test method is for use with commercially availablesulfur analyzers equipped to carry out the preceding operationsautomatically and shall be calibrated using a standard referencematerial (sulfanil
33、ic acid) containing sulfur in the same order ofmagnitude as the samples to be analyzed.12. Apparatus12.1 Measurement Apparatus, equipped to automaticallycombust the specimen.12.2 Combustion Tube, made of mullite, porcelain, orzircon, approximately 40 to 45 mm inside diameter with a3-mm thick wall, a
34、t least 450 mm long with provisions forrouting the gases produced by combustion through the infraredcell.12.3 Boat Puller, rod of a heat-resistant material with a bentor disk end to insert and remove boats from the combustiontube.13. Reagents13.1 Purity of Reagentssee 6.1.13.2 Magnesium Perchlorate.
35、14. Preparation of Apparatus14.1 Assemble the apparatus according to the manufactur-ers instructions. Make a minimum of two determinations tocondition the system prior to calibrating the system.15. Calibration15.1 Carry out four tests with different amounts of sulfanilicacid. Choose the sample mass
36、such that it includes the expectedamount of sulfur present in the silane sample.15.2 Follow the instructions of the manufacturer.16. Procedure16.1 Stabilize and calibrate the analyzer (see 15.1 and 15.2).16.2 Raise the furnace temperature as recommended by themanufacturer to at least 1350C. Weigh th
37、e specimen to thenearest 0.1 mg into a combustion boat and use a boat puller toposition the specimen in the hot zone of the furnace for at least2 min, or until completely combusted.NOTE 7The analytical cycle should begin automatically as soon assulfur is detected.16.3 When the analysis is complete,
38、the instrument shouldindicate the sulfur value. Refer to the manufacturers recom-mended procedure.17. Report17.1 Proper identification of the sample.17.2 Sulfur content to the nearest 0.1 mass %.18. Precision and Bias418.1 The precision of this test method is based on aninterlaboratory study conduct
39、ed in 2008. Six laboratoriesparticipated in this study. Each of the labs reported up to fourreplicate test results for a single material. Every “test result”reported represents an individual determination. Except for theuse of only a single material, Practice E691 was followed forthe design and anal
40、ysis of the data.18.1.1 Repeatability limit (r)Two test results obtainedwithin one laboratory shall be judged not equivalent if theydiffer by more than the “r” value for that material; “r”istheinterval representing the critical difference between two testresults for the same material, obtained by th
41、e same operatorusing the same equipment on the same day in the samelaboratory.18.1.1.1 Repeatability limits are listed in Table 1.18.1.2 Reproducibility limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that material; “R” is the interval representin
42、g the criticaldifference between two test results for the same material,obtained by different operators using different equipment indifferent laboratories.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D11-1101.TABLE 1 Sulfur C
43、ontent (wt %)Material AverageARepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 22.57 1.68 0.21 1.70 0.58 4.78AThe average of the laboratories calculated averages.D6741 10 (2015)318.1.2.1 Reproducibility limits are listed in Table 1.18.1.
44、3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.18.1.4 Any judgment in accordance with statement 18.1.1or 18.1.2 would have an approximate 95 % probability of beingcorrect, however the precision statistics obtained in this ILSmust not be trea
45、ted as exact mathematical quantities which areapplicable to all circumstances and uses. The limited numberof laboratories reporting results guarantees that there will betimes when differences greater than predicted by the ILSresults will arise, sometimes with considerably greater orsmaller frequency
46、 than the 95 % probability limit would imply.As all laboratories did not report the same number ofreplicates, consider the repeatability limit as a general guide,and the associated probability of 95 % as only a rough indicatorof what can be expected.18.2 BiasAt the time of the study, there was no ac
47、ceptedreference material suitable for determining the bias for this testmethod, therefore no statement on bias is being made.18.3 The precision statement was determined through sta-tistical examination of 22 results, from six laboratories, on onematerial. Due to the small number of participating lab
48、s, nooutliers were removed. This material was described as follows:Material A is a commercially available bis-(triethoxysilylpropyl)tetrasulfane.19. Keywords19.1 organosilanes; silanes; sulfurASTM International takes no position respecting the validity of any patent rights asserted in connection wit
49、h any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, 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 revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. You
