1、Designation: D6854 12D6854 12aStandard Test Method forSilicaSilica-Oiln-Dibutyl Phthalate Absorption Number1This standard is issued under the fixed designation D6854; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 revision. A number 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 the determination of the n-dibutyl phthalate (DBP) absorption number of silica.1.2 The values stat
3、ed 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 responsibilityof the user of this standard to establish appropriate safety
4、and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1799 Practice for Carbon BlackSampling Packaged ShipmentsD1900 Practice for Carbon BlackSampling Bulk ShipmentsD2414 Test Method for Carbon BlackOil Absorption Numbe
5、r (OAN)E177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Summary of Test Method3.1 In this test method, DBP is added by means of a constant-rate buret to a sample of silica in
6、the mixer chamber of anabsorptometer. As the sample absorbs the DBP, the mixture changes from a free-flowing state to one of a semiplasticagglomeration, with an accompanying increase in viscosity. This increased viscosity is transmitted to the torque-sensing systemof the absorptometer. The test is s
7、topped when a predetermined torque level has been reached. Preferably the torque versus volumeof DBP is recorded by a penwriter or by a data acquisition system allowing a reliable determination of the endpoint. The volumeof DBP per unit mass of silica is the DBP absorption number.4. Significance and
8、 Use4.1 The DBP absorption number of a silica is related to the processing and vulcanizate properties of rubber compoundscontaining the silica.5. Apparatus35.1 Balance, analytical, with 0.001-g sensitivity.5.2 Sieve, 500 m (U.S. standard No. 35), having a 200-mm (8 in.) diameter and 25 mm (1 in.) he
9、ight.5.3 Bottom Receiver Pan.5.4 Oven, gravity-convection type, capable of temperature regulation within 61C at 125C and temperature uniformity within65C.5.5 Spatula, rubber, 100-mm.1 This test method is under the jurisdiction of ASTM Committee D11 on Rubber and is the direct responsibility of Subco
10、mmittee D11.20 on Compounding Materials andProcedures.Current edition approved Jan. 1, 2012Dec. 1, 2012. Published February 2012January 2013. Originally approved in 2003. Last previous edition approved in 20082012 asD6854 03 (2008).D6854 12. DOI: 10.1520/D6854-12.10.1520/D6854-12A.2 For referencedAS
11、TM 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 Document Summary page on the ASTM website.3 All apparatus is to be operated and maintained in accordance with the manufac
12、turers directions for optimum performance.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, AS
13、TM 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 States15.6 Ab
14、sorptometer,4equipped with a constant-rate buret that delivers 4 6 0.024 cm3/min.5.7 Desiccator, with silica gel as desiccant.6. Reagents and Standards6.1 n-Dibutyl Phthalate,5having a density of 1.042 to 1.047 mg/m3 (g/cm3) at 25C.6.2 Silica, commercial grade with a nitrogen surface area of 175 6 1
15、0 m2/g.7. Sampling7.1 Samples shall be taken in accordance with Practices D1799 and D1900.8. Calibration8.1 Absorptometer6 The absorptometer is composed of components that influence calibration: the dynamometer torque springor the load cell, the torque-limit or the indicator set point, the oil dampe
16、r (absorptometers Type E and Type H are equipped withelectronic damping), and the mixer-measuring head.7 It is necessary that each of the components be in good condition or properadjustment to achieve acceptable calibration.NOTE 1Stainless steel mixing chambers8 have been found satisfactory for this
17、 test when they are manufactured to a roughness average (Ra) of 2.56 0.4 m (100 6 15 in.) based upon eight measurements. No single measurement should be greater than 3.6 m (140 in.) or less than 1.5 m (60 in.).Stainless steel bowls purchased with an absorptometer have been pre-polished for 16 h to m
18、inimize bowl surface changes affecting calibration during theirinitial use. It is recommended that new replacement stainless steel bowls should also be pre-polished to minimize the bowl surface effects on calibration(see Annex A1).8.1.1 The torque indicator is the primary component used to correct c
19、alibration. The load cell tension is adjusted by varying thealarm shut-off set point. Proper adjustment on the torque indicator should provide repeatable values for a silica sample dedicatedto internal reference.8.1.2 The maximum torque span is set at 10 000 mNm (10 000 units) torque value. The torq
20、ue-limit alarm is initially set at 5000mNm (5000 units), but for testing silicas it will be necessary to adjust this setting to a lower value in order to obtain reproducibleresults. Use an internal silica sample with a nitrogen surface area of 175 6 10 m2 /g to set the torque limit alarm which shoul
21、dcorrespond to approximately 70 % of the maximum torque developed during the test. After calibration, this setting should not bechanged.NOTE 2It is generally recommended to use the absorptometer in conjunction with a penwriter or preferably with a data acquisition system (see 9.9for further details)
22、.8.1.3 All digital signals are preset at 3 s damping for the torque sensing system.8.1.4 Properly maintain the surface finish of the mixing chamber. If a new mixer chamber is installed, frequently monitor theinstrument for any drift in calibration.8.2 Constant-Rate Buret:8.2.1 The delivery rate of t
23、he buret is to be 4 cm3/min. See Annex A1 for detailed instructions on the procedure for calibrationcheck of the constant-rate buret.9. Procedure9.1 Pass a suitable amount of the sample through Sieve No. 35 (500 m), using a brush in order to deglomerate larger particles.Use 2 g of the sieved materia
24、l to test the moisture content (see 9.2).9.2 Weigh 12.5 g of the sample to the nearest 0.01 g.NOTE 3For silicas with an extraordinary high pour density it may be necessary to increase the sample mass used for the test. This modification hasto be mentioned in the test report.9.3 It is recommended tha
25、t a testing temperature of 2365C be maintained, as measured by a thermocouple in the mixing bowl.If a temperature controllable mixing bowl is not available, keep the bowl temperature below 30C and comply with Note 4 whilerunning the samples.4 Available from C. W. Brabender Instruments, Inc., 50 E. W
26、esley St., Hackensack, NJ 07606, website: , and HITEC Luxembourg, 5 rue de lEglise,L-1458 Luxembourg, website: www.hitec.lu.5 Technical grade has turned out to be suitable for the test, provided that the density is in the specified range.6 Mechanical absorptometers (type A or type B) can be used for
27、 the test; however, they are no longer commercially available. Refer to the instructions of the supplier forcalibration procedure.7 The rotor motor speed is 1.31 rad/s (125 r/min).8 Replacement stainless steel bowls which have been found to be satisfactory are available from Titan Specialties, Inc.,
28、 P.O. Box 2316, Pampa, TX 79066-2316, and C.W. Brabender Instruments, Inc., 50 E. Wesley St., S. Hackensack, NJ 07606, website: , HITEC Luxembourg, 5 rue de lEglise, L-1458 Luxembourg,website: www.hitec.lu, and Titan Specialties, Inc. P.O. Box 2316, Pampa, TX 790662316.D6854 12a2NOTE 4If the absorpt
29、ometer has remained idle for more than 15 min and a temperature controllable bowl is not being used, a 10-min warm-up samplemust be run before beginning a test. It is important that the mixer chamber temperature be kept uniform. Preferably, allow 5 min between the end of onetest and the start of ano
30、ther.9.4 Transfer the sample to the absorptometer mixer chamber and replace the cover.9.5 Place a waste receptacle under the delivery tube. Make sure that the tube is free of air bubbles by delivering approximately1 cm3 of DBP into the waste receptacle.9.6 Verify the drive speed is set to 1.31 rad/s
31、 (125 r/min).9.7 Position the buret delivery tube over the hole in the mixer chamber cover, and set the buret digital counter to zero.9.8 Activate the “start” buttons simultaneously. The apparatus will operate until sufficient torque has developed to activate thetorque-limit switch, which will halt
32、the absorptometer and buret.9.9 Record the volume of DBP used as indicated by the buret digital counter.NOTE 5If a penwriter is used to record the torque curve, deactivate the automatic cut-off by setting the torque limit to 10 000. Stop the test whenthe torque maximum has been recorded unequivocall
33、y. Mark on the curve the DBP volume corresponding to the maximum torque and measure the height(in mm or in.) of the maximum. At the left side of the maximum, identify the point corresponding to a height of 70 % of the maximum of the curve.Measure the distance on the x-axis from the start point to th
34、is point and convert the value to volume of DBP as follows:Volume DBP = delivery rate of buret distance / speed of penwriterNOTE 6If a data acquisition system9 is used, the absorptometer will stop after having recorded the torque maximum, and the test result (in cm3/100g) will be reported automatica
35、lly.9.10 Dismantle the mixer chamber and clean the mixing blades and chamber with a rubber spatula and reassemble.9.11 Determine the amount of moisture in the silica under test by weighing 2 g of the sieved silica (see 9.1) into a dish to thenearest 0.001 g. Place the dish into an oven set at 105C,
36、leave it inside for 2 h, cool in a desiccator and weigh to the nearest 0.001g.10. Calculation10.1 Calculate the moisture content as follows:Moisture,%5100m02m!/m0 (1)where:m0 = mass of the silica before drying, g, andm = mass of the silica after drying, g.10.2 Calculate the DBP absorption number of
37、the sample to the nearest 0.1 10-5m3/kg (cm3/100 g) as follows:DBP absorption number,1025m3/kg5 (2)A/B100/1002Moisture!100where:A = volume of DBP used, cm3, andB = mass of tested sample, g.11. Report11.1 Report the following information:11.1.1 Proper identification of the sample,11.1.2 Sample mass,
38、if different than shown in 9.4, and11.1.3 The result obtained from the individual determination is reported to the nearest 0.1 10-5m3/kg (cm3/100 g).12. Precision and Bias1012.1 The precision of this test method is based on an interlaboratory study conducted in 2010. Five laboratories tested two typ
39、esof silica samples. Every “test result” represents an individual determination. Each laboratory was instructed to report four replicatetest results for each material. Except for the limited number of participating laboratories, Practice E691 was followed for the designand analysis of the data.12.1.
40、1 Repeatability Limit (r)Two test results obtained within one laboratory shall be judged 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 us
41、ing the same equipment on the same day in the same laboratory.9 DBP DataAcquisition Systems are available from C.W. Brabender Instruments, Inc., 50 E. Wesley St., S. Hackensack, NJ 07606, website: , andHITEC Luxembourg, 5 rue de lEglise, L-1458 Luxembourg, website: www.hitec.lu.10 Supporting data ha
42、ve been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D11-1109.D6854 12a312.1.1.1 Repeatability limits are listed in Table 1.12.1.2 Reproducibility Limit (R)Two test results shall be judged not equivalent if they differ by more than the “R” value forth
43、at material; “R” is the interval representing the critical difference between two test results for the same material, obtained bydifferent operators using different equipment in different laboratories.12.1.2.1 Reproducibility limits are listed in Table 1.12.1.3 The above terms (repeatability limit a
44、nd reproducibility limit) are used as specified in Practice E177.12.1.4 Any judgment in accordance with statements 12.1.1 and 12.1.2 would normally have an approximate 95 % probabilityof being correct, however the precision statistics obtained in this ILS must not be treated as exact mathematical qu
45、antities whichare applicable to all circumstances and uses. The limited number of laboratories reporting replicate results guarantees that therewill be times when differences greater than predicted by the ILS results will arise, sometimes with considerably greater or smallerfrequency than the 95 % p
46、robability limit would imply. Consider the repeatability limit and the reproducibility limit as generalguides, and the associated probability of 95 % as only a rough indicator of what can be expected.12.2 BiasAt the time of the study, there was no accepted reference material suitable for determining
47、 the bias for this testmethod, therefore no statement on bias is being made.12.3 The precision statement was determined through statistical examination of 40 results, from five laboratories, on twodifferent precipitated silica samples.13. Keywords13.1 n-dibutyl phthalate; n-dibutyl phthalate absorpt
48、ion number; silicaANNEX(Mandatory Information)A1. CALIBRATION CHECK OF CONSTANT-RATE BURETA1.1 ScopeA1.1.1 The constant-rate buret is an integral part of the absorption measuring system. Failure of the buret to deliver the deliverthe specified amount of reagent to the silica will result in erroneous
49、 absorption readings. This annex provides a method forchecking the delivery rate of the constant-rate buret. One of the reasons for the incorrect absorption values (caused by incorrectreagent delivery by the automatic buret) is entrapped air in the plastic tubing or the delivery tube, especially above the nozzle. Thistrouble source should be checked first.A1.2 ApparatusA1.2.1 Stopwatch.A1.2.2 Beaker, 150-cm3.TABLE 1 Absorption Number (mL 100g)Material AverageARepeatabilityStandar
