1、Designation: D6844 10 (Reapproved 2015)Standard Test Method forSilanes Used in Rubber Formulations(bis-(triethoxysilylpropyl)sulfanes): Characterization by HighPerformance Liquid Chromatography (HPLC)1This standard is issued under the fixed designation D6844; the number immediately following the des
2、ignation indicates the year oforiginal adoption or, 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 This test method covers the c
3、haracterization of silanes,or of admixtures of silane and carbon black (see 10.4), of thetype bis-(triethoxysilylpropyl)sulfane by high performanceliquid chromatography.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 Thi
4、s 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 applica-bility of regulatory limitations prior to use.2. Referenced Document
5、s2.1 ASTM Standards:2D5297 Test Methods for Rubber Chemical AcceleratorPurity by High Performance Liquid ChromatographyE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE682 Practice for Liquid Chromatography Terms and Rela-tionshipsE691 Practice for Conducting an Interlaborat
6、ory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 SxBis-(triethoxysilylpropyl)polysulfane orpolysulfide, (EtO)3SiC3H6SxC3H6Si(OEt)33.1.2 S2Bis-(triethoxysilylpropyl)disulfane or disulfide,(EtO)3SiC3H6S2C3H6Si(OEt)33.1.3 S3Bis-(triethoxysilylpropyl)trisulfane or
7、trisulfide,(EtO)3SiC3H6S3C3H6Si(OEt)33.1.4 S3Bis-(triethoxysilylpropyl)tetrasulfane ortetrasulfide, (EtO)3SiC3H6S4C3H6Si(OEt)33.1.5 S3Bis-(triethoxysilylpropyl)pentasulfane orpentasulfide, (EtO)3SiC3H6S5C3H6Si(OEt)33.1.6 S3Bis-(triethoxysilylpropyl)hexasulfane orhexasulfide, (EtO)3SiC3H6S6C3H6Si(OEt
8、)33.1.7 S3Bis-(triethoxysilylpropyl)heptasulfane orheptasulfide, (EtO)3SiC3H6S7C3H6Si(OEt)33.1.8 S3Bis-(triethoxysilylpropyl)octasulfane oroctasulfide, (EtO)3SiC3H6S8C3H6Si(OEt)33.1.9 S3Bis-(triethoxysilylpropyl)nonasulfane ornonasulfide, (EtO)3SiC3H6S9C3H6Si(OEt)33.1.10 S3Bis-(triethoxysilylpropyl)
9、decasulfane ordecasulfide, (EtO)3SiC3H6S10C3H6Si(OEt)33.1.11 average sulfur chain lengththe weighted averageof the sulfur bridge in the polysulfide mixture. Includes S2toS10species.4. Summary of Test Method4.1 A sample of the silane is analyzed by high performanceliquid chromatography to determine a
10、mounts of eachcomponent, the average chain length and the amount ofdissolved elemental sulfur.4.2 Two methods are described: Method A with a constantcomposition of the mobile phase (isocratic), and Method Busing a gradient. Both methods will give similar chromato-grams.5. Significance and Use5.1 The
11、 average sulfur chain length is an important param-eter in determining the behavior of the silane in a rubbermixture.6. Apparatus6.1 HPLC with UV Detector, operating at 254 nm, InletValve with 5 mm3(L) loop, integrator or data system.1This test method is under the jurisdiction of ASTM Committee D11
12、on Rubberand is the direct responsibility of Subcommittee D11.20 on Compounding Materialsand Procedures.Current edition approved June 1, 2015. Published September 2015. Originallyapproved in 2002. Last previous edition approved in 2010 as D6844 10. DOI:10.1520/D6844-10R15.2For referenced ASTM standa
13、rds, 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 Harbor Drive, PO Box C700, West Conshohocken, PA
14、19428-2959. United States16.2 Column C18, 5 m, 4.6 250 mm.6.3 Column Oven.6.4 Analytical Balance, accuracy 60.1 mg.6.5 Hamilton Syringe, 100 mm3(L).6.6 Volumetric Pipet, 5cm3.6.7 Volumetric Flasks, 50 and 2000 cm3.6.8 Syringe, 3cm3or5cm3.6.9 Glass Bottles, 5cm3.6.10 Disposable PTFE Filters, 0.20 m,d
15、=25mm.6.11 Mechanical Flask Shaker.7. Reagents, AR Grade or Equivalent7.1 Reagents for Method A (without gradient):7.1.1 Ethanol, absolute.7.1.2 Methanol.7.1.3 Tetrabutylammoniumbromide.7.1.4 Cyclohexane.7.1.5 Sulfur.7.1.6 Deionised Water.7.2 Reagents for Method B (with gradient):7.2.1 2-Propanol (I
16、PA).7.2.2 Acetonitrile (AcCN).7.2.3 Tetrabutylammoniumbromide.7.2.4 Hexane.7.2.5 Sulfur.7.2.6 Mesitylene.7.2.7 Deionised Water.8. Preparation of Solutions8.1 Tetrabutylammoniumbromide SolutionDissolve 400mg of tetrabutylammoniumbromide in 1000 cm3of deionisedwater.8.2 Mobile Phase:8.2.1 Mobile Phase
17、 for Method A (Isocratic)Transfer 180cm3of tetrabutylammoniumbromide solution and 450 cm3ethanol into a 2000 cm3volumetric flask. Make up to the markwith methanol and mix well.NOTE 1Separation between peaks of the silane species and elementalsulfur can be optimized by carefully varying the amount of
18、 water in themobile phase. In general, higher water content extends retention time,with the silane species being more affected than the elemental sulfur.8.2.2 Mobile Phase for Method B (With Gradient)Thecomposition of the mobile phase is variable:Time (min.) IPA (%) AcCN (%) TBAB (0.04 %)020602020 5
19、0 40 1025 50 40 1028 80 15 530 80 15 532 20 60 20NOTE 2The combination of solvents will affect the retention timesand peak separation efficiency. The above recommendation is one of manypossibilities. The specific solvents and ratios used can be determined bythe technician to fit the needs of the lab
20、. It is important to maintain theseparation of the peaks so they can be unambiguously identified andquantified.8.3 Sulfur StandardWeigh approximately 20 mg of sulfurto the nearest 0.1 mg into a 20 cm3volumetric flask and makeup to the mark with cyclohexane. Stopper the flask and agitateuntil the sol
21、ution looks homogeneous. Using a volumetricpipet, transfer 5 cm3of this solution into a 50 cm3volumetricflask, make up to the mark with cyclohexane and mix well.NOTE 3If the test shall be run with an internal standard, 100 mm3(L)of mesitylene may be added to the 50 cm3flask prior to making up withcy
22、clohexane.9. Calibration9.1 Elemental SulfurThe response factor Rsfor convertingpeak area to weight % sulfur is determined by injecting thesulfur standard into the HPLC unit and making the followingcalculation:Rs5 ms/As100 (1)where:ms= mass of sulfur made up to 50 cm3with cyclohexane,andAs= area of
23、sulfur peak.10. Procedure10.1 Weigh approximately 160 mg of the silane sample tobe analyzed, to the nearest 0.1 mg, into a 50 cm3volumetricflask. Fill the flask to the mark with cyclohexane, stopper andagitate thoroughly to completely dissolve the sample.NOTE 4If the test shall be run with an intern
24、al standard, 100 mm3(L)of mesitylene may be added to the 50 cm3flask prior to making up withcyclohexane.10.2 Purge the Hamilton syringe once with the solutionbefore injecting 100 mm3(L) into the inlet loop. Take carethat no air bubbles are injected.10.3 Turn the inlet loop into the injection positio
25、n and startthe integrator (or data system) immediately. After 40 min,terminate the run and print the chromatogram, including a peaklist.10.4 When analyzing admixtures of silane and carbonblack, weigh approximately 320 mg of the sample to thenearest 0.1 mg into a 50 cm3volumetric flask. Make up to th
26、emark with cyclohexane, stopper the flask and shake for 20 minto extract the silane from the black.10.5 Load 2 cm3of the extract from 10.4 intoa3cm3-or5cm3-syringe. Mount the PTFE filter on top of the syringe andtransfer 1.5 cm3of the syringe contents into a waste bottle. Thelast 0.5 cm3are filtered
27、 into a small glass bottle from which100 mm3(L) are used to load the injection loop and analyzedas described in 10.2 and 10.3.11. Calculation11.1 Sulfur Chain DistributionCalculations are performedutilizing the response factors for the individual silane (sulfurchain length) species contained in the
28、following table:D6844 10 (2015)2Sulfur ChainLengthMolecularMassg mol-1Response FactorRS2474.8 31.3S3506.9 8.87S4539.0 4.88S5571.0 3.24S6603.1 2.36S7635.2 1.82S8667.2 1.46S9699.3 1.19S10731.4 1.00Si5AiRi(i5210AiRi100 (2)where:Si= relative amount of silane species with i sulfur atoms in%,Ai= peak area
29、 of silane species with i sulfur atoms, andRi= response factor of silane species with i sulfur atoms.NOTE 5Short-chain silanes may exhibit additional peaks at retentiontimes higher than the one of the S7species. These peaks, due to oligomers,are not taken into consideration when calculating the sulf
30、ur chaindistribution and the average chain length.11.2 Average Chain Length:S5(i5210iAiRi/Mi(i5210AiRi/Mi(3)where:S= average sulfur chain length,i = number of sulfur atoms in the silane species, andMi= molecular mass of silane species with i sulfur atoms.11.2.1 Example for calculation:Species MiRel
31、RFRiResultAiCorrectedArea% SxS2474 31.3 1 407 938 44 068 459 16.8S3506 8.87 8 607 037 763 444 189 29.1S4538 4.88 12 988 212 63 382 475 24.2S5570 3.24 13 083 349 42 390 051 16.2S6602 2.36 8 534 198 20 140 707 7.7S7634 1.82 5 149 428 9 371 959 3.6S8666 1.46 2 815 133 4 110 094 1.6S9698 1.19 1 375 780
32、1 637 178 0.6S10730 1.00 768 474 768 474 0.3Average Sulfur Chain Length (S-bar) 3.7811.3 Elemental Sulfur:S 5AsRsm(4)where:S = elemental sulfur content in %,As= peak area of elemental sulfur,Rs= response factor for sulfur, andm = mass of silane or admixture in mg in 50 cm3cyclohexane.11.4 Examples f
33、or Chromatograms:11.4.1 See Fig. 1.FIG. 1 Typical Chromatogram for Method A (Isocratic)D6844 10 (2015)311.4.2 See Fig. 2.12. Report12.1 Report the following information:12.1.1 Identification of the silane sample,12.1.2 Average chain length to the nearest 0.01,12.1.3 Sulfur content to the nearest 0.1
34、 weight %, and12.1.4 Relative amount of silane species with i sulfur atomsin % (optional).13. Precision and Bias313.1 The precision of this test method is based on aninterlaboratory study conducted in 2008. Up to ten laboratoriesparticipated in this study. Each of the labs reported fourreplicate tes
35、t results for a variety of analytical parameters, on asingle material. Every “test result” reported represents anindividual determination. Except for the use of only a singlematerial, Practice E691 was followed for the design andanalysis of the data.13.1.1 Repeatability limit (r)Two test results obt
36、ainedwithin 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 the same operatorusing the same equipment on the same day in the same
37、laboratory.13.1.1.1 Repeatability limits are listed in Tables 1-11.13.1.2 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 representing the criticaldifference between two test results for the same
38、material,obtained by different operators using different equipment indifferent laboratories.13.1.2.1 Reproducibility limits are listed in Tables 1-11.13.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.13.1.4 Any judgment in accordance with
39、statement 13.1.1or 13.1.2 would have an approximate 95 % probability of beingcorrect.13.2 BiasAt the time of the study, there was no acceptedreference material utilized for determining the bias for this testmethod, therefore no statement on bias is being made.13.3 The precision statement was determi
40、ned through sta-tistical examination of the reported results from tenlaboratories, on one material. Due to the small number ofparticipating labs, usually no outliers were removed. Howeverin one case, i.e. for elemental sulfur testing one lab was anextreme outlier and had to be removed from the preci
41、sioncalculation. This material was described as follows: MaterialAis a commercially available bis-(triethoxysilylpropyl)tetra sul-fane.14. Keywords14.1 chain length; chain length distribution; elemental sul-fur; organosilane; silane3Supporting data have been filed at ASTM International Headquarters
42、and maybe obtained by requesting Research Report RR:D11-1104.FIG. 2 Typical Chromatogram for Method B (With Gradient)D6844 10 (2015)4TABLE 1 Elemental Sulfur (%)AMaterial AverageBRepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 0.32 0.02
43、 0.02 0.02 0.04 0.06AEight labs reported (one outlier lab excluded from calculations).BThe average of the laboratories calculated averages.TABLE 2 Average Chain LengthAMaterial AverageBRepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 3.6
44、25 0.017 0.007 0.018 0.018 0.051ATen labs reported.BThe average of the laboratories calculated averages.TABLE 3 S2 (relative %)AMaterial AverageBRepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 19.7 0.5 0.2 0.5 0.5 1.4ATen labs reported.
45、BThe average of the laboratories calculated averages.TABLE 4 S3 (relative %)AMaterial AverageBRepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 31.0 0.8 0.1 0.8 0.3 2.1ATen labs reported.BThe average of the laboratories calculated average
46、s.TABLE 5 S4 (relative %)AMaterial AverageBRepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 23.5 0.3 0.09 0.3 0.2 1.0ATen labs reported.BThe average of the laboratories calculated averages.TABLE 6 S5 (relative %)AMaterial AverageBRepeata
47、bilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx SxSrSRrRA 14.5 0.2 0.04 0.2 0.1 0.6ATen labs reported.BThe average of the laboratories calculated averages.D6844 10 (2015)5ASTM International takes no position respecting the validity of any patent rights
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49、e 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. 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 you shouldmake your views known to the ASTM Committee on S
