1、Designation: D 6739 01 (Reapproved 2006)Standard Test Method forSilicapH Value1This standard is issued under the fixed designation D 6739; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in paren
2、theses 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 is used to measure the pH of a 5 %silica/water suspension or mechanical dispersion and is indica-tive of the relative acidity or alk
3、alinity of the silica.1.2 The values stated 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 stan
4、dard 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:2E70 Test Method for pH of Aqueous Solutions With theGlass Electrode3. Significance and Use3.1 The pH level of silica, as measu
5、red by this test method,is known to affect the vulcanization of some rubber com-pounds. Refer to Test Method E70for a fuller understandingof pH and a more detailed procedure for making pH measure-ments.4. Apparatus4.1 pH Meter, (digital is recommended), having an accuracyof 60.05 pH and equipped wit
6、h a combination electrode.4.2 Mortar and Pestle.4.3 Beaker, glass, 150 cm3with watch glass.4.4 Magnetic Stirring Bar and Stirrer.5. Reagents5.1 Degassed, Neutral Water. Boil a container of eitherdistilled or deionized water for 10 min, cover, and allow to coolto room temperature, or purge the water
7、with nitrogen gas for20 min using a fritted bubbler.5.2 Buffer Solutions, pH of 4.00, 7.00, and 10.00.6. Procedure6.1 Pulverize pelleted or granulated silica to a fine powder,using a mortar and pestle.6.2Weigh5gofsilica to the nearest 0.1 g into a 150 cm3glass beaker.6.3 Add 100 cm3of degassed, neut
8、ral water.6.4 Cover the glass beaker with a watch glass and stir themixture for 5 min at room temperature.6.5 Standardize the pH meter with two buffer solutions thatbracket the expected pH value of the silica. Rinse the electrodewith distilled water and wipe clean after each test.6.6 Place the elect
9、rode in the silica/water mixture, continu-ing to stir with the magnetic stirrer. When a constant pH isobtained, record the pH to the nearest 0.05 pH unit.6.7 Rinse the electrode with distilled water. Store electrodein accordance with manufacturers instructions when not inuse.7. Report7.1 Report the
10、following information:7.1.1 Identification of the sample, and7.1.2 Result obtained, reported to the nearest 0.1 unit.8. Precision and Bias8.1 No precision and bias study has been performed for thismethod.9. Keywords9.1 pH; silica1This test method is under the jurisdiction of ASTM Committee D11 on Ru
11、bberand is the direct responsibility of Subcommittee D11.20 on Compounding Materialsand Procedures.Current edition approved Oct. 1, 2006. Published November 2006. Originallyapproved in 2001. Last previous edition approved in 2001 as D 6739 01.2For referenced ASTM standards, visit the ASTM website, w
12、ww.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 Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.AST
13、M International takes no position respecting the validity of any patent rights asserted in connection with 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 en
14、tirely 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 standardsa
15、nd 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
16、on Standards, at the address shown below.This standard 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).D 6739 01 (2006)2
