1、Designation: D6738 11D6738 15Standard Test Method forPrecipitated SilicaVolatile Content1This standard is issued under the fixed designation D6738; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 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 a procedure to determine the volatile content of precipitated hydrated silicas. These volatiles aregenerally excess w
3、ater adsorbed onto the surface of the silica. This test method does not determine water of hydration of the silica.1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.1.3 This standard does not purport to address all of the safety
4、concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Pre
5、cision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Significance and Use3.1 The volatiles content of a precipitated silica may affect the processing properties of a rubber mixture containing silica andthe properties
6、of the final product.4. Apparatus4.1 Oven, gravity-convection type, capable of maintaining 105 6 5C.4.2 Aluminum Pans, Ground-glass stoppered low-form weighing bottle, oil free.approximately 30 mm in height by 60 mm indiameter.4.3 Analytical Balance, sensitive to 0.1 mg.4.4 Desiccator.NOTE 1It is im
7、portant that the desiccant is very dry, or moisture may be drawn from the desiccant into the sample during cooling.5. Procedure5.1 Weigh an aluminum pan a weighing bottle with stopper to the nearest 0.1 mg and record its weight (W1).5.2 Add approximately 2 g of the silica sample to the pan weighing
8、bottle and reweigh to the nearest 0.1 mg (W2).5.3 Place the pan weighing bottle with the silica sample into the 105C oven for 2 h 6 5 min. Place the stopper nearby theweighing bottle.5.4 Transfer the pan weighing bottle containing the silica sample and closed with the stopper from the oven into a de
9、siccatorand cool for 12 h or until room temperature.5.5 Remove the pan weighing bottle containing the silica sample from the desiccator and reweigh to the nearest 0.1 mg (W3).NOTE 2A ground-glass stoppered low-form weighing bottle (approximately 30 mm in height by 60 mm in diameter) An aluminum pan
10、may be1 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 andProcedures.Current edition approved July 1, 2011Nov. 1, 2015. Published August 2011December 2015. Originally approved in 2001. Last p
11、revious edition approved in 20062011 asD6738 01 (2006).D6738 11. DOI: 10.1520/D6738-11.10.1520/D6738-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards
12、 Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, A
13、STM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1subst
14、ituted for the aluminum weighing dishbottle in this test method. The sample then is dried in the oven and cooled in the dessicator with the stopperremoved, but final weighing would be done with the stopper in the bottle to minimize results are systematically lower due to moisture pick-up from theatm
15、osphere. The thermal transfer of glass differs from that of aluminum, so cooling time may be lengthened using a glass container.shortened using analuminum pan.6. Calculation6.1 The volatile material is given by the following equation:%Volatiles5W2 2W3!/W2 2W1!# 3100 (1)where:W1 = mass of aluminum pa
16、n, g,W2 = mass of aluminum pan and silica sample before heating, g, andW3 = mass of aluminum pan and silica sample after heating, g.W1 = mass of weighing bottle, g,W2 = mass of weighing bottle and silica sample before heating, g, andW3 = mass of weighing bottle and silica sample after heating, g.7.
17、Report7.1 Report the following information:7.1.1 Identification of the sample, and7.1.2 Result reported to the nearest 0.1 %.8. Precision and Bias38.1 The precision of this test method is based on an interlaboratory study of conducted in 2010. Eleven laboratories tested twotypes of silica samples. E
18、very “test result” represents an individual determination. Each laboratory was instructed to report fourreplicate test results for each material. Practice E691 was followed for the design and analysis of the data.8.1.1 Repeatability Limit (r)Two test results obtained within one laboratory shall be j
19、udged not equivalent if they differ bymore than the “r” value for that material; “r” is the interval representing the critical difference between two test results for the samematerial, obtained by the same operator using the same equipment on the same day in the same laboratory.8.1.1.1 Repeatability
20、 limits are listed in Table 1.8.1.2 Reproducibility Limit (R)Two test results shall be judged not equivalent if they differ by more than the “R” value forthat material; “R” is the interval representing the critical difference between two test results for the same material, obtained bydifferent opera
21、tors using different equipment in different laboratories.8.1.2.1 Reproducibility limits are listed in Table 1.8.1.3 The above terms (repeatability limit and reproducibility limit) are used as specified in Practice E177.8.1.4 Any judgment in accordance with statements 8.1.1 and 8.1.2 would have an ap
22、proximate 95 % probability of beingcorrect.8.2 BiasAt the time of the study, there was no accepted reference material suitable for determining the bias for this testmethod, therefore no statement on bias is being made.8.3 The precision statement was determined through statistical examination of 72 r
23、esults, from nine laboratories, on twodifferent precipitated silica samples.3 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D11-1107.TABLE 1 Volatile Content (%)MaterialAverageARepeatabilityStandardDeviationReproducibilityStan
24、dardDeviationRepeatabilityLimitReproducibilityLimitxx sr SR r RSilica A 5.36 0.06 0.22 0.16 0.62Silica B 6.45 0.05 0.24 0.15 0.67A The average of the laboratories calculated averages.D6738 1529. Keywords9.1 precipitated hydrated silica; silica; volatile contentASTM International takes no position re
25、specting 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 entirely their own responsibility.This
26、 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 Intern
27、ational 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 Standards, at the address shown be
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