ASTM D6844 – 02

Designation: D 6844 – 02 Standard Test Method for Silanes Used in Rubber Formulations (bis-(triethoxysilylpropyl)sulfanes): Characterization by High Performance Liquid Chromatography (HPLC)1 This standard is issued under the fixed designation D 6844; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This test method covers the characterization of silanes, or of admixtures of silane and carbon black (see 10.4), of the type bis-(triethoxysilylpropyl)sulfane by high performance liquid chromatography. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility 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 Documents 2.1 ASTM Standards: D 5297 Test Methods for Rubber Chemical Accelerator- Purity by High Performance Liquid Chromatography2 E 682 Practice for Liquid Chromatography Terms and Re- lationships3 3. Terminology 3.1 Definitions: 3.1.1 Sx—Bis-(triethoxysilylpropyl)polysulfane or polysul- fide, (EtO)3SiC3H6SxC3H6Si(OEt)3 3.1.2 S2—Bis-(triethoxysilylpropyl)disulfane or disulfide, (EtO)3SiC3H6S2C3H6Si(OEt)3 3.1.3 S3—Bis-(triethoxysilylpropyl)trisulfane or trisulfide, (EtO)3SiC3H6S3C3H6Si(OEt)3 3.1.4 S3—Bis-(triethoxysilylpropyl)tetrasulfane or tetrasul- fide, (EtO)3SiC3H6S4C3H6Si(OEt)3 3.1.5 S3—Bis-(triethoxysilylpropyl)pentasulfane or penta- sulfide, (EtO)3SiC3H6S5C3H6Si(OEt)3 3.1.6 S3—Bis-(triethoxysilylpropyl)hexasulfane or hexasul- fide, (EtO)3SiC3H6S6C3H6Si(OEt)3 3.1.7 S3—Bis-(triethoxysilylpropyl)heptasulfane or hepta- sulfide, (EtO)3SiC3H6S7C3H6Si(OEt)3 3.1.8 S3—Bis-(triethoxysilylpropyl)octasulfane or octasul- fide, (EtO)3SiC3H6S8C3H6Si(OEt)3 3.1.9 S3—Bis-(triethoxysilylpropyl)nonasulfane or nonasul- fide, (EtO)3SiC3H6S9C3H6Si(OEt)3 3.1.10 S3—Bis-(triethoxysilylpropyl)decasulfane or deca- sulfide, (EtO)3SiC3H6S10C3H6Si(OEt)3 3.1.11 average sulfur chain length—the weighted average of the sulfur bridge in the polysulfide mixture. Includes S2 to S10 species. 4. Summary of Test Method 4.1 A sample of the silane is analyzed by high performance liquid chromatography to determine amounts of each compo- nent, the average chain length and the amount of dissolved elemental sulfur. 4.2 Two methods are described: Method A with a constant composition of the mobile phase (isocratic), and Method B using a gradient. Both methods will give similar chromato- grams. 5. Significance and Use 5.1 The average sulfur chain length is an important param- eter in determining the behavior of the silane in a rubber mixture. 6. Apparatus 6.1 HPLC with UV Detector, operating at 254 nm, Inlet Valve with 5 mm3 (µL) loop, integrator or data system. 6.2 Column C18, 5 µm, 4.6 3 250 mm. 6.3 Column Oven. 6.4 Analytical Balance, accuracy 60.1 mg. 6.5 Hamilton Syringe, 100 mm3 (µL). 6.6 Volumetric Pipet, 5 cm3. 6.7 Volumetric Flasks, 50 and 2000 cm3. 6.8 Syringe, 3 cm3 or 5 cm3. 6.9 Glass Bottles, 5 cm3. 6.10 Disposable PTFE Filters, 0.20 µm, d = 25 mm. 1 This test method is under the jurisdiction of ASTM Committee D11 on Rubber and is the direct responsibility of Subcommittee D11.20 on Compounding Materials and Procedures. Current edition approved Dec. 10, 2002. Published January 2003. Originally approved in 2002. Last previous edition approved in 2002 as D 6844 – 02. 2 Annual Book of ASTM Standards, Vol 09.01. 3 Annual Book of ASTM Standards, Vol 03.06. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. 6.11 Mechanical Flask Shaker. 7. Reagents, AR Grade or Equivalent 7.1 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 (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 Solutions 8.1 Tetrabutylammoniumbromide Solution—Dissolve 400 mg of tetrabutylammoniumbromide in 1000 cm3 of deionised water. 8.2 Mobile Phase: 8.2.1 Mobile Phase for Method A (Isocratic)—Transfer 180 cm3 of tetrabutylammoniumbromide solution and 450 cm3 ethanol into a 2000 cm3 volumetric flask. Make up to the mark with methanol and mix well. NOTE 1—Separation between peaks of the silane species and elemental sulfur can be optimized by carefully varying the amount of water in the mobile 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)—The composition of the mobile phase is variable: Time (min.) IPA (%) AcCN (%) TBAB (0.04 %) 0 20 60 20 20 50 40 10 25 50 40 10 28 80 15 5 30 80 15 5 32 20 60 20 NOTE 2—The combination of solvents will affect the retention times and peak separation efficiency. The above recommendation is one of many possibilities. The specific solvents and ratios used can be determined by the technician to fit the needs of the lab. It is important to maintain the separation of the peaks so they can be unambiguously identified and quantified. 8.3 Sulfur Standard—Weigh approximately 20 mg of sulfur to the nearest 0.1 mg into a 20 cm3 volumetric flask and make up to the mark with cyclohexane. Stopper the flask and agitate until the solution looks homogeneous. Using a volumetric pipet, transfer 5 cm3 of this solution into a 50 cm3 volumetric flask, make up to the mark with cyclohexane and mix well. NOTE 3—If the test shall be run with an internal standard, 100 mm3 (µL) of mesitylene may be added to the 50 cm3 flask prior to making up with cyclohexane. 9. Calibration 9.1 Elemental Sulfur—The response factor Rs for convert- ing peak area to weight % sulfur is determined by injecting the sulfur standard into the HPLC unit and making the following calculation: Rs 5 ms / As · 100 (1) where: ms = mass of sulfur made up to 50 cm3 with cyclohexane, and As = area of sulfur peak. 10. Procedure 10.1 Weigh approximately 160 mg of the silane sample to be analyzed, to the nearest 0.1 mg, into a 50 cm3 volumetric flask. Fill the flask to the mark with cyclohexane, stopper and agitate thoroughly to completely dissolve the sample. NOTE 4—If the test shall be run with an internal standard, 100 mm3 (µL) of mesitylene may be added to the 50 cm3 flask prior to making up with cyclohexane. 10.2 Purge the Hamilton syringe once with the solution before injecting 100 mm3 (µL) into the inlet loop. Take care that no air bubbles are injected. 10.3 Turn the inlet loop into the injection position and start the integrator (or data system) immediately. After 40 min, terminate the run and print the chromatogram, including a peak list. 10.4 When analyzing admixtures of silane and carbon black, weigh approximately 320 mg of the sample to the nearest 0.1 mg into a 50 cm3 volumetric flask. Make up to the mark with cyclohexane, stopper the flask and shake for 20 min to extract the silane from the black. 10.5 Load 2 cm3 of the extract from 10.4 into a 3 cm3- or 5 cm3-syringe. Mount the PTFE filter on top of the syringe and transfer 1.5 cm3 of the syringe contents into a waste bottle. The last 0.5 cm3 are filtered into a small glass bottle from which 100 mm3 (µL) are used to load the injection loop and analyzed as described in 10.2 and 10.3. 11. Calculation 11.1 Sulfur Chain Distribution—Calculations are per- formed utilizing the response factors for the individual silane (sulfur chain length) species contained in the following table: Sulfur Chain Length Molecular Mass g mol-1 Response Factor R S2 474.8 31.3 S3 506.9 8.87 S4 539.0 4.88 S5 571.0 3.24 S6 603.1 2.36 S7 635.2 1.82 S8 667.2 1.46 S9 699.3 1.19 S10 731.4 1.00 D 6844 – 02 2 Si 5 Ai · Ri ( i 5 2 10 Ai · 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, and Ri = response factor of silane species with i sulfur atoms. NOTE 5—Short-chain silanes may exhibit additional peaks at retention times higher than the one of the S7 species. These peaks, due to oligomers, are not taken into consideration when calculating the sulfur chain distribution and the average chain length. 11.2 Average Chain Length: S 5 ( i 5 2 10 i · Ai · Ri / Mi ( i 5 2 10 Ai · Ri / Mi (3) where: S = average sulfur chain length, i = number of sulfur atoms in the silane species, and Mi = molecular mass of silane species with i sulfur atoms. 11.2.1 Example for calculation: Species Mi Rel RF Ri Result Ai Corrected Area % Sx S2 474 31.3 1 407 938 44 068 459 16.8 S3 506 8.87 8 607 037 763 444 189 29.1 S4 538 4.88 12 988 212 63 382 475 24.2 S5 570 3.24 13 083 349 42 390 051 16.2 S6 602 2.36 8 534 198 20 140 707 7.7 S7 634 1.82 5 149 428 9 371 959 3.6 S8 666 1.46 2 815 133 4 110 094 1.6 S9 698 1.19 1 375 780 1 637 178 0.6 S10 730 1.00 768 474 768 474 0.3 Average Sulfur Chain Length (S-bar) 3.78 11.3 Elemental Sulfur: S 5 As · Rs m (4) where: S = elemental sulfur content in %, As = peak area of elemental sulfur, Rs = response factor for sulfur, and m = mass of silane or admixture in mg in 50 cm3 cyclo- 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 3 12. Report 12.1 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 weight %, and 12.1.4 Relative amount of silane species with i sulfur atoms in % (optional). ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of 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 and if not revised, either reapproved or withdrawn. 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FIG. 2 Typical Chromatogram for Method B (With Gradient) D 6844 – 02 4 主营业务范围：ASTMASTMASTMASTM、NASNASNASNAS、NASMNASMNASMNASM、MILMILMILMIL、ISOISOISOISO、ENENENEN、 DINDINDINDIN、JISJISJISJIS等技术 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 翻译；技术 资料 新概念英语资料下载李居明饿命改运学pdf成本会计期末资料社会工作导论资料工程结算所需资料清单 翻译；NADCAPNADCAPNADCAPNADCAP认证 标准资料翻译；国外技术标准中文版优惠低价代购等。 业务 QQQQQQQQ：2298175560229817556022981755602298175560 专业 专注于技术翻译 诚信 实惠 物超所值的服务可靠的质量保证