1、Designation: D 6844 02 (Reapproved 2007)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 D 6844; the number immediately following the d
2、esignation 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers th
3、e characterization 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 as thestandard. The values given in parentheses are for informationonly.1.3
4、 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 applica-bility of regulatory limitations prior to use.2. Referenced Docu
5、ments2.1 ASTM Standards:2D 5297 Test Methods for Rubber Chemical AcceleratorPurity by High Performance Liquid ChromatographyE 682 Practice for Liquid Chromatography Terms and Re-lationships3. Terminology3.1 Definitions:3.1.1 SxBis-(triethoxysilylpropyl)polysulfane or polysul-fide, (EtO)3SiC3H6SxC3H6
6、Si(OEt)33.1.2 S2Bis-(triethoxysilylpropyl)disulfane or disulfide,(EtO)3SiC3H6S2C3H6Si(OEt)33.1.3 S3Bis-(triethoxysilylpropyl)trisulfane or trisulfide,(EtO)3SiC3H6S3C3H6Si(OEt)33.1.4 S3Bis-(triethoxysilylpropyl)tetrasulfane or tetrasul-fide, (EtO)3SiC3H6S4C3H6Si(OEt)33.1.5 S3Bis-(triethoxysilylpropyl
7、)pentasulfane or penta-sulfide, (EtO)3SiC3H6S5C3H6Si(OEt)33.1.6 S3Bis-(triethoxysilylpropyl)hexasulfane or hexasul-fide, (EtO)3SiC3H6S6C3H6Si(OEt)33.1.7 S3Bis-(triethoxysilylpropyl)heptasulfane or hepta-sulfide, (EtO)3SiC3H6S7C3H6Si(OEt)33.1.8 S3Bis-(triethoxysilylpropyl)octasulfane or octasul-fide,
8、 (EtO)3SiC3H6S8C3H6Si(OEt)33.1.9 S3Bis-(triethoxysilylpropyl)nonasulfane or nonasul-fide, (EtO)3SiC3H6S9C3H6Si(OEt)33.1.10 S3Bis-(triethoxysilylpropyl)decasulfane or deca-sulfide, (EtO)3SiC3H6S10C3H6Si(OEt)33.1.11 average sulfur chain lengththe weighted averageof the sulfur bridge in the polysulfide
9、 mixture. Includes S2toS10species.4. Summary of Test Method4.1 A sample of the silane is analyzed by high performanceliquid chromatography to determine amounts of each compo-nent, the average chain length and the amount of dissolvedelemental sulfur.4.2 Two methods are described: Method A with a cons
10、tantcomposition of the mobile phase (isocratic), and Method Busing a gradient. Both methods will give similar chromato-grams.5. Significance and Use5.1 The 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
11、 Detector, operating at 254 nm, InletValve with 5 mm3(L) loop, integrator or data system.6.2 Column C18, 5 m, 4.6 3 250 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
12、.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.20 on Compounding Materialsand Procedures.Current edition approved Nov. 1, 2007. Published January 2008. Originallyapproved in 2002. Last previous edition approved in 2002
13、 as D 6844 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.1Copyright ASTM International, 100 Barr Harbor
14、Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.9 Glass Bottles,5cm3.6.10 Disposable PTFE Filters, 0.20 m,d=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 Tetrabutyla
15、mmoniumbromide.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 (IPA).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 Tetrabutylamm
16、oniumbromide SolutionDissolve 400mg of tetrabutylammoniumbromide in 1000 cm3of deionisedwater.8.2 Mobile Phase:8.2.1 Mobile Phase for Method A (Isocratic)Transfer 180cm3of tetrabutylammoniumbromide solution and 450 cm3ethanol into a 2000 cm3volumetric flask. Make up to the markwith methanol and mix
17、well.NOTE 1Separation between peaks of the silane species and elementalsulfur can be optimized by carefully varying the amount of 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
18、 for Method B (With Gradient)Thecomposition of the mobile phase is variable:Time (min.) IPA (%) AcCN (%) TBAB (0.04 %)02060 2020 50 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
19、 is one of manypossibilities. The specific solvents and ratios used can be determined bythe technician to fit the needs of the lab. 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 th
20、e nearest 0.1 mg into a 20 cm3volumetric flask and makeup to the mark with cyclohexane. Stopper the flask and agitateuntil the solution 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
21、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 withcyclohexane.9. Calibration9.1 Elemental SulfurThe response factor Rsfor convert-ing peak area to weight % sulfur is determined by injecting thesulfur standard into the HPLC
22、 unit and making the followingcalculation:Rs5 ms/ As 100 (1)where:ms= mass of sulfur made up to 50 cm3with cyclohexane,andAs= area of 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 th
23、e mark with cyclohexane, stopper andagitate thoroughly to completely dissolve the sample.NOTE 4If 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 withcyclohexane.10.2 Purge the Hamilton syringe once with the solutionbefore i
24、njecting 100 mm3(L) into the inlet loop. Take carethat no air bubbles are injected.10.3 Turn the inlet loop into the injection position 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
25、 of silane and carbonblack, weigh approximately 320 mg of the sample to thenearest 0.1 mg into a 50 cm3volumetric flask. Make up to themark 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. M
26、ount the PTFE filter on top of the syringe andtransfer 1.5 cm3of the syringe contents into a waste bottle. Thelast 0.5 cm3are filtered 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 Distrib
27、utionCalculations are per-formed utilizing the response factors for the individual silane(sulfur chain length) species contained in the following table:Sulfur ChainLengthMolecular Massg 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
28、.19S10731.4 1.00D 6844 02 (2007)2Si5Ai Ri(i 5 210Ai Ri 100 (2)where:Si= relative amount of silane species with i sulfur atoms in%,Ai= peak area 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 a
29、t retentiontimes higher than the one of the S7species. These peaks, due to oligomers,are not taken into consideration when calculating the sulfur chaindistribution and the average chain length.11.2 Average Chain Length:S 5(i 5 210i Ai Ri/ Mi(i 5 210Ai Ri/ Mi(3)where:S = average sulfur chain length,i
30、 = 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 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
31、.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 1 637 178 0.6S10730 1.00 768 474 768 474 0.3Average Sulfur Chain Length (S-bar) 3.7811.3 Elemental Sulfur:S 5As Rsm(4)where:S = elemental sulfur c
32、ontent in %,As= peak area of elemental sulfur,Rs= response factor for sulfur, andm = mass of silane or admixture in mg in 50 cm3cyclo-hexane.11.4 Examples for Chromatograms:11.4.1 See Fig. 1.11.4.2 See Fig. 2.FIG. 1 Typical Chromatogram for Method A (Isocratic)D 6844 02 (2007)312. Report12.1 Report
33、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 weight %, and12.1.4 Relative amount of silane species with i sulfur atomsin % (optional).ASTM International takes no position respecting the v
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35、ubject 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 Headq
36、uarters. 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 Standards, at the address shown below.This stan
37、dard 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).FIG. 2 Typical Chromatogram for Method B (With Gradient)D 6844 02 (2007)4
