1、Designation: D6854 15Standard Test Method forSilica-Oil 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 revision. A number in parentheses
2、 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 then-dibutyl phthalate (DBP) absorption number of silica.1.2 The values stated in SI units are to be regarded a
3、s thestandard. The values given in parentheses are for informationonly.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 standard to establish appro-priate safety and health practices and determine th
4、e applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1799 Practice for Carbon BlackSampling PackagedShipmentsD1900 Practice for Carbon BlackSampling Bulk Ship-mentsD2414 Test Method for Carbon BlackOil AbsorptionNumber (OAN)E177 Practice for Use of the
5、Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Summary of Test Method3.1 In this test method, DBP is added by means of aconstant-rate buret to a sample of silica in the mixer chamberof an absorptometer. A
6、s the sample absorbs the DBP, themixture changes from a free-flowing state to one of a semi-plastic agglomeration, with an accompanying increase inviscosity. This increased viscosity is transmitted to the torque-sensing system of the absorptometer. The test is stopped whena predetermined torque leve
7、l has been reached. Preferably thetorque versus volume of DBP is recorded by a penwriter or bya data acquisition system allowing a reliable determination ofthe endpoint. The volume of DBP per unit mass of silica is theDBP absorption number.4. Significance and Use4.1 The DBP absorption number of a si
8、lica is related to theprocessing 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.) height.5.3 Bottom Receiver Pan.5.4 Oven, grav
9、ity-convection type, capable of temperatureregulation within 61C at 125C and temperature uniformitywithin 65C.5.5 Spatula, rubber, 100-mm.5.6 Absorptometer,4equipped with a constant-rate buret thatdelivers 4 6 0.024 cm3/min.5.7 Desiccator, with silica gel as desiccant.6. Reagents and Standards6.1 n-
10、Dibutyl Phthalate,5having a density of 1.042 to 1.047mg/m3(g/cm3) at 25C.6.2 Silica, commercial grade with a nitrogen surface area of175 6 10 m2/g.7. Sampling7.1 Samples shall be taken in accordance with PracticesD1799 and D1900.1This 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 June 1, 2015. Published July 2015. Originally approvedin 2003. Last previous edition approved in 2012 as D6854 12a. DOI: 10.1520/D6854-15.2For referenced ASTM standards, visit
12、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 page onthe ASTM website.3All apparatus is to be operated and maintained in accordance with themanufacturers directions for
13、optimum performance.4Available from C. W. Brabender Instruments, Inc., 50 E. Wesley St.,Hackensack, NJ 07606, website: , and HITEC Luxembourg,5 rue de lEglise, L-1458 Luxembourg, website: www.hitec.lu.5Technical grade has turned out to be suitable for the test, provided that thedensity is in the spe
14、cified range.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States18. Calibration8.1 Absorptometer6 The absorptometer is composed ofcomponents that influence calibration: the dynamometer torquespring or the load cell, the torque-limit or th
15、e indicator setpoint, the oil damper (absorptometers Type E and Type H areequipped with electronic damping), and the mixer-measuringhead.7It is necessary that each of the components be in goodcondition or proper adjustment to achieve acceptable calibra-tion.NOTE 1Stainless steel mixing chambers8have
16、 been found satisfactoryfor this test when they are manufactured to a roughness average (Ra) of2.5 6 0.4 m (100 6 15 in.) based upon eight measurements. No singlemeasurement should be greater than 3.6 m (140 in.) or less than 1.5 m(60 in.). Stainless steel bowls purchased with an absorptometer haveb
17、een pre-polished for 16 h to minimize bowl surface changes affectingcalibration during their initial use. It is recommended that new replace-ment stainless steel bowls should also be pre-polished to minimize thebowl surface effects on calibration (see Annex A1).8.1.1 The torque indicator is the prim
18、ary component used tocorrect calibration. The load cell tension is adjusted by varyingthe alarm shut-off set point. Proper adjustment on the torqueindicator should provide repeatable values for a silica samplededicated to internal reference.8.1.2 The maximum torque span is set at 10 000 mNm(10 000 u
19、nits) torque value. The torque-limit alarm is initiallyset at 5000 mNm (5000 units), but for testing silicas it will benecessary to adjust this setting to a lower value in order toobtain reproducible results. Use an internal silica sample witha nitrogen surface area of 175 6 10 m2/g to set the torqu
20、e limitalarm which should correspond to approximately 70 % of themaximum torque developed during the test. After calibration,this setting should not be changed.NOTE 2It is generally recommended to use the absorptometer inconjunction with a penwriter or preferably with a data acquisition system(see 9
21、.10 for further details).8.1.3 All digital signals are preset at 3 s damping for thetorque sensing system.8.1.4 Properly maintain the surface finish of the mixingchamber. If a new mixer chamber is installed, frequentlymonitor the instrument for any drift in calibration.8.2 Constant-Rate Buret:8.2.1
22、The delivery rate of the buret is to be 4 cm3/min. SeeAnnex A1 for detailed instructions on the procedure forcalibration check 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 largerparticles. Use2gofth
23、esieved material to test the moisturecontent (see 9.3).9.2 Determine the amount of moisture in the silica undertest by weighing 2 g of the sieved silica (see 9.1) into a dish tothe nearest 0.001 g. Place the dish into an oven set at 105C,leave it inside for 2 h, cool in a desiccator and weigh to the
24、nearest 0.001 g. See Section 10 (Calculation) for details ofmoisture calculation.9.3 Weigh 12.5 g of the sample to the nearest 0.01 g.NOTE 3For silicas with an extraordinary high pour density it may benecessary to increase the sample mass used for the test. This modificationhas to be mentioned in th
25、e test report.9.4 It is recommended that a testing temperature of 23 65C be maintained, as measured by a thermocouple in themixing bowl. If a temperature controllable mixing bowl is notavailable, keep the bowl temperature below 30C and complywith Note 4 while running the samples.NOTE 4If the absorpt
26、ometer has remained idle for more than 15 minand a temperature controllable bowl is not being used, a 10-min warm-upsample must be run before beginning a test. It is important that the mixerchamber temperature be kept uniform. Preferably, allow 5 min betweenthe end of one test and the start of anoth
27、er.9.5 Transfer the sample to the absorptometer mixer chamberand replace the cover.9.6 Place a waste receptacle under the delivery tube. Makesure that the tube is free of air bubbles by delivering approxi-mately 1 cm3of DBP into the waste receptacle.9.7 Verify the drive speed is set to 1.31 rad/s (1
28、25 r/min).9.8 Position the buret delivery tube over the hole in themixer chamber cover, and set the buret digital counter to zero.9.9 Activate the “start” buttons simultaneously. The appa-ratus will operate until sufficient torque has developed toactivate the torque-limit switch, which will halt the
29、 absorptom-eter and buret.9.10 Record the volume of DBP used as indicated by theburet digital counter.NOTE 5If a penwriter is used to record the torque curve, deactivate theautomatic cut-off by setting the torque limit to 10 000. Stop the test whenthe torque maximum has been recorded unequivocally.
30、Mark on the curvethe DBP volume corresponding to the maximum torque and measure theheight (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 ofthe curve. Measure the distance on the x-axis from the start point to thispoi
31、nt and convert the value to volume of DBP as follows:Volume DBP = delivery rate of buret distance speed of penwriterNOTE 6If a data acquisition system9is used, the absorptometer willstop after having recorded the torque maximum, and the test result (incm3/100 g) will be reported automatically.9.11 D
32、ismantle the mixer chamber and clean the mixingblades and chamber with a rubber spatula and reassemble.9.12 Determine the amount of moisture in the silica undertest by weighing 2 g of the sieved silica (see 9.1) into a dish tothe nearest 0.001 g. Place the dish into an oven set at 105C,leave it insi
33、de for 2 h, cool in a desiccator and weigh to thenearest 0.001 g.6Mechanical absorptometers (typeAor type B) can be used for the test; however,they are no longer commercially available. Refer to the instructions of the supplierfor calibration procedure.7The rotor motor speed is 1.31 rad/s (125 r/min
34、).8Replacement stainless steel bowls which have been found to be satisfactory areavailable from Titan Specialties, Inc., P.O. Box 2316, Pampa, TX 79066-2316, andC. W. Brabender Instruments, Inc., 50 E. Wesley St., S. Hackensack, NJ 07606,website: , HITEC Luxembourg, 5 rue de lEglise, L-1458Luxembour
35、g, website: www.hitec.lu, and Titan Specialties, Inc. P.O. Box 2316,Pampa, TX 790662316.9DBP Data Acquisition Systems are available from C.W. BrabenderInstruments, Inc., 50 E. Wesley St., S. Hackensack, NJ 07606, website: www.cw-, and HITEC Luxembourg, 5 rue de lEglise, L-1458 Luxembourg,website: ww
36、w.hitec.lu.D6854 15210. Calculation10.1 Calculate the moisture content as follows:Moisture, % 5 100m02 m!/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 the sample tothe nearest 0.1 10-5m3/kg (cm3/100 g) as fo
37、llows:DBP absorption number, 1025m3/kg5 (2)A/B100/100 2 Moisture!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, if different than shown in 9.5, and11.1.3 The result o
38、btained from the individual determina-tion 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 aninterlaboratory study conducted in 2010. Five laboratoriestested two types of silica samples. Every “test result” repre-sents a
39、n individual determination. Each laboratory was in-structed to report four replicate test results for each material.Except for the limited number of participating laboratories,Practice E691 was followed for the design and analysis of thedata.12.1.1 Repeatability Limit (r)Two test results obtainedwit
40、hin 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 for the same material, obtained by the same operatorusing the same equipment on the same day in the samelaborato
41、ry.12.1.1.1 Repeatability limits are listed in Table 1.12.1.2 Reproducibility Limit (R)Two test results shall bejudged not equivalent if they differ by more than the “R” valuefor that material; “R” is the interval representing the criticaldifference between two test results for the same material,obt
42、ained by different operators using different equipment indifferent laboratories.12.1.2.1 Reproducibility limits are listed in Table 1.12.1.3 The above terms (repeatability limit and reproduc-ibility limit) are used as specified in Practice E177.12.1.4 Any judgment in accordance with statements 12.1.
43、1and 12.1.2 would normally have an approximate 95 % prob-ability of being correct, however the precision statistics ob-tained in this ILS must not be treated as exact mathematicalquantities which are applicable to all circumstances and uses.The limited number of laboratories reporting replicate resu
44、ltsguarantees that there will be times when differences greaterthan predicted by the ILS results will arise, sometimes withconsiderably greater or smaller frequency than the 95 %probability limit would imply. Consider the repeatability limitand the reproducibility limit as general guides, and the as
45、so-ciated probability of 95 % as only a rough indicator of what canbe expected.12.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for this testmethod, therefore no statement on bias is being made.12.3 The precision statement was determined th
46、rough sta-tistical examination of 40 results, from five laboratories, on twodifferent precipitated silica samples.13. Keywords13.1 n-dibutyl phthalate; n-dibutyl phthalate absorptionnumber; silica10Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Re
47、search Report RR:D11-1109.TABLE 1 Absorption Number (mL 100g)Material AverageARepeatabilityStandardDeviationReproducibilityStandardDeviationRepeatabilityLimitReproducibilityLimitx srsRrRSilica A 207.18 0.81 2.48 2.26 6.94Silica B 230.40 1.81 5.64 5.07 15.78AThe average of the laboratories calculated
48、 averages.D6854 153ANNEX(Mandatory Information)A1. CALIBRATION CHECK OF CONSTANT-RATE BURETA1.1 ScopeA1.1.1 The constant-rate buret is an integral part of theabsorption measuring system. Failure of the buret to deliver thedeliver the specified amount of reagent to the silica will resultin erroneous
49、absorption readings. This annex provides amethod for checking the delivery rate of the constant-rateburet. One of the reasons for the incorrect absorption values(caused by incorrect reagent delivery by the automatic buret) isentrapped air in the plastic tubing or the delivery tube,especially above the nozzle. This trouble source should bechecked first.A1.2 ApparatusA1.2.1 Stopwatch.A1.2.2 Beaker, 150-cm3.A1.3 ProcedureA1.3.1 Ensure that all seals and tubing are in good condi-tion.A1.3.
