1、Designation: D7854 18cStandard 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
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 measure a carbonblack structure property by Void Volume at mean pressure.Compressed void volumes are ob
3、tained by measuring thecompressed 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. For the
4、purposes of standard-ized testing a single value of void volume is reported at 50 MPamean pressure.1.2 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 a
5、ny, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internatio
6、nally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1799 Prac
7、tice for Carbon BlackSampling PackagedShipmentsD1900 Practice for Carbon BlackSampling Bulk Ship-mentsD2414 Test Method for Carbon BlackOil AbsorptionNumber (OAN)D3493 Test Method for Carbon BlackOil AbsorptionNumber of Compressed Sample (COAN)D4483 Practice for Evaluating Precision for Test MethodS
8、tandards in the Rubber and Carbon Black ManufacturingIndustries3. Terminology3.1 Refer to Sections 4 and 9 for a more complete under-standing 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
9、 by a movable piston in a cylindrical chamber, where theload cell or force measuring system is in contact with themovable piston.3.2.2 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
10、 thesample opposite the movable piston, typically via a stationarysecond piston.3.2.3 compressed 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 specifi
11、ed pressure by meansof a movable piston.3.2.4 geometric mean pressure, nthe geometric mean 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)3.2.5 theoretical volume (carbon black), nthe volume thata spec
12、ific mass of carbon black would occupy if there were novoid space within the carbon black, and is given by the ratio ofmass to skeletal density, where the skeletal density is deter-mined by an accepted test method.3.2.6 void volume (carbon black), na measure of theintra-aggregate void space or occlu
13、ded volume within theprimary structure of carbon black, characterized by the irregu-larity and non-sphericity of carbon black aggregate particles,and expressed as the difference (compressed volume minustheoretical volume) as a function of specified uniaxial com-pression pressure, and normalized to 1
14、00 g mass. pressure, andnormalized to 100 g mass. The void volume of a carbon black1This test method is under the jurisdiction of ASTM Committee D24 on CarbonBlack and is the direct responsibility of Subcommittee D24.11 on Carbon BlackStructure.Current edition approved Dec. 1, 2018. Published Januar
15、y 2019. Originallyapproved in 2013. Last previous edition approved in 2018 as D7854 18b. DOI:10.1520/D7854-18C.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 s
16、tandards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the
17、Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1expressed as a function of geometric mean pressure, VV, is acarbon black structure property.3.2.6.1 DiscussionCarbon bl
18、acks resist packing,compression, and fracture due to aggregate irregularities andentanglements, size distribution, 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
19、 tip, which in turn depend onfactors including sample shape (that is, the ratio of sampleheight to cylinder 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 mas
20、s and cylinder geometry,such a compressed void volume is biased due to error in theapplied pressure relationship. 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 press
21、ure measurements for aninstrument design using a single load cell since frictioncoefficients () are not 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
22、force or meanpressure. The mean pressure technique requires an instrumentdesign consisting of two load 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
23、 whichhas been demonstrated to minimize the effects of carbon blacksample mass and cylinder geometry.4. 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 instrumentcon
24、sists of an apparatus which can apply uniaxial compressionto a test sample in a cylindrical sample chamber 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 resul
25、tunitized to 100 g mass, as a function of specified meanpressure.5. Significance and Use5.1 The greater a carbon black resists compression byhaving substantial aggregate irregularity and non-sphericity,the greater the compressed volume and void volume. Also, themore that a carbon black resists compr
26、ession, the greater theenergy required to compress the sample per unit void volume.5.2 Structure is a property that strongly influences thephysical properties developed in carbon black-elastomer com-pounds for use in tires, mechanical rubber goods, and othermanufactured rubber products. Structure by
27、 void volume isbased on compression while structure measurements by OAN(Test Method D2414) and COAN (Test Method D3493) arebased on oil absorption.6. Apparatus6.1 Analytical Balance, or equivalent, capable of a weighingsensitivity of 0.1 mg.6.2 Gravity Convection Drying, Oven, capable of maintain-in
28、g 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 carbon blacks as afunction of applied pressure, from which the void volume iscalculated at specified
29、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 capable of operating asoutlined in Section 9.6.4.1 The instrument shall have a rigid framework thatconta
30、ins 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 uniform diameter.6.4.3 By means of a suitable mechanism with sufficientpower for the compression forc
31、es 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 volume ofany sample is determined by the distance from the end of thepiston to the end of the cylinder;
32、 this is designated as a “height”in the calculations discussed in Section 11. The sample heightand cylinder diameter are used to calculate an apparent samplevolume.6.4.4 Load cells or other suitable force or pressure measure-ment devices are used to measure the applied and transmittedpressures.6.4.5
33、 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 The instrument uses an electric motor or hydraulicfluid to operate a linear actuator attached to a
34、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 compression data up to a minimum of 50 MPageometric mean pressure for subsequent analysis.7. Sampling7.1 Sampl
35、es of candidate carbon blacks shall be taken inaccordance with Practice D1799 or D1900.8. Calibration8.1 CalibrationThe manufacturer will typically calibratethe instrument measurement systems. The height measurementsystem is typically calibrated using a physical standard such asa calibrated steel pl
36、ug. Load cells are typically calibrated orverified using a reference load cell. Traceability is recom-mended for all calibration devices. Follow the manufacturersrecommendations for calibration frequency and verification.D7854 18c29. Procedure9.1 Sample PreparationDry an adequate sample of thecarbon
37、 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 instrumentmanufacturer, typically 1.000, 2.000
38、g, or 4.000 g to the nearest0.1 mg.9.3 Define the analysis conditions to include a void volumemeasurement at 50.0 MPa geometric mean pressure with acompression rate of 1 to 2 MPa/s. In practice this is accom-plished by defining a scan from the lowest detection pressure toat least 50 MPa geometric me
39、an pressure.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 removed from the cylinder and piston tips.10. Normalization
40、using Standard Reference Blacks(SRB)10.1 Test the six ASTM Standard Reference Blacks (SRBs)in duplicate to establish the average measured value. Addi-tional values are added periodically.10.2 An optimum normalization test frequency has not yetbeen established.10.3 The rolling average of the measured
41、 values is com-puted from the latest four values.10.4 Void volume normalization should include all sixSRBs. There is only one normalization curve required for allcarbon black products.10.5 All six SRBs should be from the same series (ex-ample: series-8).10.6 Perform a regression analysis using the s
42、tandard valueof the standard (y value) and the rolling average measuredvalue (x value).10.7 Normalize the values of all subsequent samples usingthe regression equation as follows:Normalized value 5 measured value*slope!1intercept (2)10.8 For normalized values of the SRBs that are consis-tently outsi
43、de 3-sigma x-chart limits, the instrument calibrationin Section 8 should be reviewed.11. Void Volume Calculations11.1 The void volume (VV) is calculated from the apparentcompressed volume as follows. The apparent compressedvolume of the sample is evaluated by Eq 3.VA5 h 33.1416 D24 (3)where:VA= the
44、apparent compressed volume of the carbon blacksample, cm3, from a single uniaxial compression.h = the “height” of the compressed carbon black in thecylinder, cm, andD = the diameter of the cylinder, cm.11.2 The theoretical volume of the carbon black is evaluatedby Eq 4.VT5 mdCB(4)where:VT= the theor
45、etical volume of the carbon black sample,cm3,dCB= accepted true (skeletal) density of the carbon black =1.90 g/cm3, andm = mass of the carbon black sample, g.11.3 The void volume of a carbon black per unit mass (100g) is given by Eq 5.VV 5 VA2 VT!m 100! (5)where:VV = void volume of carbon black samp
46、le, 105m3/kg (cm3/100 g),VA= the apparent compressed volume of the carbon blacksample, cm3, from a single uniaxial compression (Eq3), andVT= the theoretical volume of the carbon black sample,cm3,(Eq 4).NOTE 1Some carbon blacks have reported skeletal densities ofapproximately 1.8 to 2.0 g/cm3. The ac
47、cepted skeletal density of rubbercarbon black is 1.90 g/cm3.12. Report12.1 Report the following information:12.1.1 Sample Identification.TABLE 1 Precision Parameters for D7854, Void Volume at 50 MPa Mean PressureAMaterialNumber ofLabsUnit m3/kgMean LevelSr r (r) SR R (R)SRB 8D 12 23.9 0.13 0.36 1.51
48、 0.17 0.47 1.98SRB 8A 12 45.5 0.15 0.43 0.95 0.25 0.72 1.58SRB 8A2 11 46.6 0.15 0.43 0.91 0.17 0.48 1.03SRB 8E 11 49.4 0.16 0.46 0.94 0.22 0.62 1.25SRB 8F2 11 54.5 0.16 0.45 0.83 0.23 0.64 1.17SRB 8F 12 60.3 0.21 0.58 0.97 0.33 0.94 1.55SRB 8B2 11 67.6 0.26 0.74 1.10 0.35 0.99 1.47SRB 8B 11 69.7 0.2
49、6 0.73 1.05 0.32 0.91 1.30SRB 8C 9 72.8 0.27 0.75 1.03 0.26 0.73 1.01Average 54.5Pooled 0.19 0.55 1.03 0.25 0.72 1.37APrecision is based on normalized void volume measurements from an inter-laboratory precision program conducted in 2017.D7854 18c312.1.2 Normalized void volume expressed to the nearest 0.1105m3/kg (0.1 cm3/100 g) measured at 50.0 MPa Geometricmean pressure.12.1.3 Sample mass in grams weighed to nearest 0.1 mg.12.1.4 Cylinder diameter to the nearest 0.001 mm.13. Precision and Bias313.1 These precision statements have been prepared inaccor
