1、Designation: D6738 11Standard 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 in pare
2、ntheses 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 thevolatile content of precipitated hydrated silicas. These volatilesare generally excess water adso
3、rbed onto the surface of thesilica. This test method does not determine water of hydrationof the silica.1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.3 This standard does not purport to address all of thesafety concerns, if
4、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 Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and
5、 Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Significance and Use3.1 The volatiles content of a precipitated silica may affectthe processing properties of a rubber mixture containing silicaand the properties of the final
6、product.4. Apparatus4.1 Oven, gravity-convection type, capable of maintaining105 6 5C.4.2 Aluminum Pans, oil free.4.3 Analytical Balance, sensitive to 0.1 mg.4.4 Desiccator.NOTE 1It is important that the desiccant is very dry, or moisture maybe drawn from the desiccant into the sample during cooling
7、5. Procedure5.1 Weigh an aluminum pan to the nearest 0.1 mg andrecord its weight (W1).5.2 Add approximately2gofthesilica sample to the panand reweigh to the nearest 0.1 mg (W2).5.3 Place the pan with the silica sample into the 105C ovenfor2h6 5 min.5.4 Transfer the pan containing the silica sample
8、from theoven into a desiccator and cool for1horuntil roomtemperature.5.5 Remove the pan containing the silica sample from thedesiccator and reweigh to the nearest 0.1 mg (W3).NOTE 2Aground-glass stoppered low-form weighing bottle (approxi-mately 30 mm in height by 60 mm in diameter) may be substitut
9、ed for thealuminum weighing dish in this test method. The sample then is dried inthe oven and cooled in the dessicator with the stopper removed, but finalweighing would be done with the stopper in the bottle to minimizemoisture pick-up from the atmosphere. The thermal transfer of glassdiffers from t
10、hat of aluminum, so cooling time may be lengthened usinga glass container.6. Calculation6.1 The volatile material is given by the following equation:% Volatiles 5 W2 W3!/W2 W1!# 3 100 (1)where:W1= mass of aluminum pan, g,W2= mass of aluminum pan and silica sample beforeheating, g, andW3= mass of alu
11、minum pan and silica sample after heat-ing, g.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 July 1, 2011. Published August 2011. Originallyapproved in
12、2001. Last previous edition approved in 2006 as D6738 01 (2006).DOI: 10.1520/D6738-11.2For 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
13、 page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. 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 pr
14、ecision of this test method is based on aninterlaboratory study of conducted in 2010. Eleven laboratoriestested two types of silica samples. Every “test result” repre-sents an individual determination. Each laboratory was in-structed to report four replicate test results for each material.Practice E
15、691 was followed for the design and analysis of thedata.8.1.1 Repeatability Limit (r)Two test results obtainedwithin 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
16、 for the same material, obtained by the same operatorusing the same equipment on the same day in the samelaboratory.8.1.1.1 Repeatability limits are listed in Table 1.8.1.2 Reproducibility Limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that mater
17、ial; “R” is the interval representing the criticaldifference between two test results for the same material,obtained by different operators using different equipment indifferent laboratories.8.1.2.1 Reproducibility limits are listed in Table 1.8.1.3 The above terms (repeatability limit and reproduci
18、bil-ity limit) are used as specified in Practice E177.8.1.4 Any judgment in accordance with statements 8.1.1and 8.1.2 would have an approximate 95 % probability ofbeing correct.8.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for this testme
19、thod, therefore no statement on bias is being made.8.3 The precision statement was determined through statis-tical examination of 72 results, from nine laboratories, on twodifferent precipitated silica samples.9. Keywords9.1 precipitated hydrated silica; silica; volatile contentASTM International ta
20、kes 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 entirely their own r
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23、he 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 (p
24、hone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).3Supporting data have been filed at ASTM International Headquarters and maybe obtained by
25、 requesting Research Report RR:D11-1107.TABLE 1 Volatile Content (%)MaterialAverageARepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx srSRrRSilica A 5.36 0.06 0.22 0.16 0.62Silica B 6.45 0.05 0.24 0.15 0.67AThe average of the laboratories calculated averages.D6738 112
