1、Designation: D7854 13Standard Test Method forCarbon Black-Void Volume at Mean Pressure1This standard is issued under the fixed designation D7854; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n 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 measure a carbonblack structure property known as Void Volume at meanpressure. Compressed void volumes a
3、re obtained by measuringthe compressed volume of a weighed sample in a cylindricalchamber as a function of pressure exerted by a movable piston.A profile of void volume as a function of pressure provides ameans to assess carbon black structure at varying levels ofdensity and aggregate reduction.1.2
4、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 standard to establish appro-pr
5、iate safety and health practices and determine the 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 Ab
6、sorptionNumber (OAN)D3493 Test Method for Carbon BlackOil AbsorptionNumber of Compressed Sample (COAN)D4821 Guide for Carbon BlackValidation of Test MethodPrecision and BiasD6086 Test Method for Carbon BlackVoid Volume (VV)3. Terminology3.1 Refer to Sections 4 and 9 for a more complete under-standin
7、g of the use of these terms in this test method.3.2 Definitions of Terms Specific to This Standard:3.2.1 applied pressure, nthe pressure exerted on a samplemass by a movable piston in a cylindrical chamber, where theload cell or force measuring system is in contact with themovable piston.3.2.2 compr
8、essed volume (carbon black), nthe apparentvolume that a specified mass of carbon black occupies when itis contained in a specified cylindrical chamber and subjected toa single uniaxial compression at a specified pressure by meansof a movable piston.3.2.3 geometric mean pressure, nthe geometric mean
9、ofthe applied and transmitted pressures at a specific void volume;the geometric mean pressure is defined in Eq 1:Geometric Mean PGM5 Pa3 Pt!0.5(1)3.2.4 theoretical volume (carbon black), nthe volume thata specific mass of carbon black would occupy if there were novoid space within the carbon black,
10、and is given by the ratio ofmass to skeletal density, where the skeletal density is deter-mined by an accepted test method.3.2.5 transmitted pressure, nthe resulting pressure trans-mitted through a sample in a cylindrical chamber, where theload cell or force measuring system is in contact with thesa
11、mple opposite the movable piston, typically via a stationarysecond piston.3.2.6 void volume (carbon black), na measure of theintra-aggregate void space or occluded volume within theprimary structure of carbon black, characterized by the irregu-larity and non-sphericity of carbon black aggregate part
12、icles,and expressed as the difference (compressed volume minustheoretical volume) as a function of specified uniaxial com-pression pressure, and normalized to 100 g mass.3.2.6.1 DiscussionCarbon blacks resist packing,compression, and fracture due to aggregate irregularities andentanglements, size di
13、stribution, and aggregate strength result-ing from particle to-particle necks within aggregate branches.Compressed void volume is also affected by reacting forces tothe cylinder wall and the piston tip, which in turn depend onfactors including sample shape (that is, the ratio of sampleheight to cyli
14、nder diameter) or interfacial area, which caninfluence the uniformity of the compaction density. Sincecompressed void volumes as a function of applied pressure areknown to be specific to sample mass and cylinder geometry,1This test method is under the jurisdiction of ASTM Committee D24 on CarbonBlac
15、k and is the direct responsibility of Subcommittee D24.11 on Carbon BlackStructure.Current edition approved Nov. 1, 2013. Published December 2013. DOI:10.1520/D7854-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
16、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1such a compressed void volume is biased due to error in theapplied pressure rel
17、ationship. The applied pressure bias is aresult of force losses due to friction between the sample andcylinder wall interface. There is presently no known techniqueto properly correct applied pressure measurements for aninstrument design using a single load cell since frictioncoefficients () are not
18、 constant for carbon black products orapplied pressures. For this reason, the most useful techniquefor comparing compressed void volumes is based on a numeri-cal technique known as mean compaction force or meanpressure. The mean pressure technique requires an instrumentdesign consisting of two load
19、cells to enable the measurementof compressed void volume as a function of applied andtransmitted force or pressure. Such a design allows the com-putation of void volumes at mean pressures, a method whichhas been demonstrated to minimize the effects of carbon blacksample mass and cylinder geometry.4.
20、 Summary of Test Method4.1 The measured compressed volume (apparent volume) ofa weighed dry test sample is obtained in a void volumeinstrument as a function of specified pressure. The instrumentconsists of an apparatus which can apply uniaxial compressionto a test sample in a cylindrical sample cham
21、ber where appliedand transmitted forces (or pressures) are measured. The com-pressed void volume is obtained by subtracting the theoreticalvolume from the apparent volume, then expressing the resultunitized to 100 g mass, as a function of specified meanpressure.5. Significance and Use5.1 The void vo
22、lume of a carbon black expressed as afunction of geometric mean pressure, VVGM, is a carbon blackstructure property. Structure is a generic term that is a functionof the shape irregularity and deviation from sphericity ofcarbon black aggregates. The greater a carbon black resistscompression by havin
23、g substantial aggregate irregularity andnon-sphericity, the greater the compressed volume and voidvolume. Also, the more that a carbon black resistscompression, the greater the energy required to compress thesample per unit void volume.5.2 Structure is a property that strongly influences thephysical
24、 properties developed in carbon black-elastomer com-pounds for use in tires, mechanical rubber goods, and othermanufactured rubber products. Structure measurements byOAN (Test Method D2414) and COAN (Test Method D3493),are based on oil absorption.6. Apparatus6.1 Analytical Balance, or equivalent, ca
25、pable of a weighingsensitivity of 0.1 mg.6.2 Gravity Convection Drying, Oven, capable of maintain-ing 125 6 5C.6.3 Weighing Dish, Camel Hair or Similar Brush, to be usedfor weighing and transferring samples.6.4 Void Volume Instrument, to be used to measure thecompressed volume (apparent volume) of c
26、arbon blacks as afunction of applied pressure, from which the void volume iscalculated at specified intervals of geometric mean pressure(that is, geometric mean of applied and transmitted pressures).The void volume instrument or device shall conform to thefollowing generic specifications and be capa
27、ble of operating asoutlined in Section 9.6.4.1 The instrument shall have a rigid framework thatcontains a cylindrical sample chamber. Hysteresis and elastic-ity in the framework under the range of applied forces shouldbe accounted for in the displacement measurement.6.4.2 The cylinder shall have a u
28、niform diameter.6.4.3 By means of a suitable mechanism with sufficientpower for the compression forces as required for testing, thepiston shall be capable of being moved to compress the sample.A device to record the movement of the piston and measuredisplacement shall be provided. The compressed vol
29、ume ofany sample is determined by the distance from the end of thepiston to the end of the cylinder; this is designated as a “height”in the calculations discussed in Section 10. The sample heightand cylinder diameter are used to calculate an apparent samplevolume.6.4.4 Load cells or other suitable f
30、orce or pressure measure-ment devices are used to measure the applied and transmittedpressures.6.4.5 The instrument design shall provide continuous com-pression at a controlled and constant rate thereby allowingcontinuous measurements of apparent volume and pressures atspecified data intervals.6.4.6
31、 The instrument uses an electric motor or hydraulicfluid to operate a linear actuator attached to a piston.6.4.7 The instrument incorporates two load cells to directlymeasure applied and transmitted forces or pressures.6.4.8 The instrument design shall provide a means to saveand store the compressio
32、n data up to a minimum of 100 MPageometric mean pressure for subsequent analysis.7. Sampling7.1 Samples of candidate carbon blacks shall be taken inaccordance with Practice D1799 or D1900.8. Calibration8.1 CalibrationFollow the manufacturers instructions toset up the instrument and to calibrate the
33、measurement sys-tems. The use of a physical standard such as a calibrated steelplug with traceability is recommended to calibrate or verify theheight displacement transducer. A reference load cell withtraceability is recommended to calibrate or verify the forcetransducers.9. Procedure9.1 Sample Prep
34、arationDry an adequate sample of thecarbon black for at least1hinagravity-convection oven set at125 6 5C, in an open container of suitable dimensions, so thatthe depth of black is no more than 10 mm. Cool to roomtemperature in a desiccator before use.9.2 Weigh a mass of sample specified by the instr
35、umentmanufacturer, typically 1.000 or 2.000 g, to the nearest 0.1 mg.D7854 1329.3 Define the analysis conditions to include void volumemeasurements at 50.0, 75.0, and 100.0 MPa geometric meanpressure with a compression rate of 1 to 2 MPa/s. In practicethis is accomplished by defining a scan from the
36、 lowestdetection pressure to at least 100 MPa geometric meanpressure.9.4 Transfer the weighed sample to the instrument. Brushthe sample pan and funnel to ensure the entire sample isintroduced into the cylinder. Proceed with the test.9.5 At the end of the test insure residual carbon black hasbeen rem
37、oved from the cylinder and piston tips.10. Void Volume Calculations10.1 The void volume (VV) is calculated from the apparentcompressed volume as follows. The apparent compressedvolume of the sample is evaluated by Eq 2.VA5 h 33.1416 D24 (2)where:VA= the apparent compressed volume of the carbon black
38、sample, cm3, from a single uniaxial compression.h = the “height” of the compressed carbon black in thecylinder, cm, andD = the diameter of the cylinder, cm.10.2 The theoretical volume of the carbon black is evaluatedby Eq 3.VT5 mdCB(3)where:VT= the theoretical volume of the carbon black sample,cm3,d
39、CB= accepted true (skeletal) density of the carbon black =1.90 g/cm3, andm = mass of the carbon black sample, g.10.3 The void volume of a carbon black per unit mass (100g) is given by Eq 4.VV 5 VA2 VT!m 100! (4)where:VV = void volume of carbon black sample, 105m3/kg (cm3/100 g),VA= the apparent comp
40、ressed volume of the carbon blacksample, cm3, from a single uniaxial compression (Eq2), andVT= the theoretical volume of the carbon black sample,cm3,(Eq 3).NOTE 1Some carbon blacks have reported skeletal densities ofapproximately 1.8 to 2.0 g/cm3. The accepted skeletal density of rubbercarbon black
41、is 1.90 g/cm3.11. Report11.1 Report the following information:11.1.1 Sample Identification.11.1.2 Void volume expressed to the nearest 106m3/kg (0.1cm3/100g) measured at 50.0, 75.0 and 100.0 MPa Geometricmean pressures.11.1.3 Sample mass in grams weighed to nearest 0.1 mg.11.1.4 Cylinder diameter to
42、 the nearest 0.001 mm.12. Precision and Bias12.1 Precision and BiasA precision and bias statementhas not been developed as of this time.13. Keywords13.1 apparent volume; geometric mean pressure; structure;theoretical volume; void volumeASTM International takes no position respecting the validity of
43、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 standard is subject to r
44、evision 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 International Headquarters. Yo
45、ur 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 below.This standard is cop
46、yrighted 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7854 133
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