1、Designation: D7854 13D7854 15Standard 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
2、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 a procedure to measure a carbon black structure property known as Void Volume at mean pressure.Compressed void
3、volumes are obtained by measuring the compressed volume of a weighed sample in a cylindrical chamber as afunction of pressure exerted by a movable piston. A profile of void volume as a function of pressure provides a means to assesscarbon black structure at varying levels of density and aggregate re
4、duction.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.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 est
5、ablish appropriate safety 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
6、 BlackOil Absorption Number (OAN)D3493 Test Method for Carbon BlackOil Absorption Number of Compressed Sample (COAN)D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing IndustriesD4821 Guide for Carbon BlackValidation of Test Method Precision
7、 and BiasD6086 Test Method for Carbon BlackVoid Volume (VV) (Withdrawn 2015)33. Terminology3.1 Refer to Sections 4 and 9 for a more complete understanding 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
8、 a sample mass by a movable piston in a cylindrical chamber, where the loadcell or force measuring system is in contact with the movable piston.3.2.2 compressed volume (carbon black), nthe apparent volume that a specified mass of carbon black occupies when it iscontained in a specified cylindrical c
9、hamber and subjected to a single uniaxial compression at a specified pressure by means ofa movable piston.3.2.3 geometric mean pressure, nthe geometric mean of the applied and transmitted pressures at a specific void volume; thegeometric mean pressure is defined in Eq 1:Geometric Mean PGM 5Pa 3 Pt!0
10、.5 (1)3.2.4 theoretical volume (carbon black), nthe volume that a specific mass of carbon black would occupy if there were no voidspace within the carbon black, and is given by the ratio of mass to skeletal density, where the skeletal density is determined byan accepted test method.3.2.5 transmitted
11、 pressure, nthe resulting pressure transmitted through a sample in a cylindrical chamber, where the load cellor force measuring system is in contact with the sample opposite the movable piston, typically via a stationary second piston.1 This test method is under the jurisdiction ofASTM Committee D24
12、 on Carbon Black and is the direct responsibility of Subcommittee D24.11 on Carbon Black Structure.Current edition approved Nov. 1, 2013June 1, 2015. Published December 2013September 2015. Originally approved in 2013. Last previous edition approved in 2013 asD7854 13. DOI: 10.1520/D7854-13.10.1520/D
13、7854-15.2 For referencedASTM 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 The last approved version of this historical standa
14、rd is referenced on www.astm.org.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, ASTM recomm
15、ends 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 States13.2.6 void volu
16、me (carbon black), na measure of the intra-aggregate void space or occluded volume within the primarystructure of carbon black, characterized by the irregularity and non-sphericity of carbon black aggregate particles, and expressedas the difference (compressed volume minus theoretical volume) as a f
17、unction of specified uniaxial compression pressure, andnormalized to 100 g mass.3.2.6.1 DiscussionCarbon blacks resist packing, compression, and fracture due to aggregate irregularities and entanglements, size distribution, andaggregate strength resulting from particle to-particle necks within aggre
18、gate branches. Compressed void volume is also affectedby reacting forces to the cylinder wall and the piston tip, which in turn depend on factors including sample shape (that is, the ratioof sample height to cylinder diameter) or interfacial area, which can influence the uniformity of the compaction
19、 density. Sincecompressed void volumes as a function of applied pressure are known to be specific to sample mass and cylinder geometry, sucha compressed void volume is biased due to error in the applied pressure relationship. The applied pressure bias is a result of forcelosses due to friction betwe
20、en the sample and cylinder wall interface. There is presently no known technique to properly correctapplied pressure measurements for an instrument design using a single load cell since friction coefficients () are not constant forcarbon black products or applied pressures. For this reason, the most
21、 useful technique for comparing compressed void volumesis based on a numerical technique known as mean compaction force or mean pressure. The mean pressure technique requires aninstrument design consisting of two load cells to enable the measurement of compressed void volume as a function of applied
22、 andtransmitted force or pressure. Such a design allows the computation of void volumes at mean pressures, a method which has beendemonstrated to minimize the effects of carbon black sample mass and cylinder geometry.4. Summary of Test Method4.1 The measured compressed volume (apparent volume) of a
23、weighed dry test sample is obtained in a void volume instrumentas a function of specified pressure. The instrument consists of an apparatus which can apply uniaxial compression to a test samplein a cylindrical sample chamber where applied and transmitted forces (or pressures) are measured. The compr
24、essed void volumeis obtained by subtracting the theoretical volume from the apparent volume, then expressing the result unitized to 100 g mass, asa function of specified mean pressure.5. Significance and Use5.1 The void volume of a carbon black expressed as a function of geometric mean pressure, VVG
25、M, is a carbon black structureproperty. Structure is a generic term that is a function of the shape irregularity and deviation from sphericity of carbon blackaggregates. The greater a carbon black resists compression by having substantial aggregate irregularity and non-sphericity, thegreater the com
26、pressed volume and void volume. Also, the more that a carbon black resists compression, the greater the energyrequired to compress the sample per unit void volume.5.2 Structure is a property that strongly influences the physical properties developed in carbon black-elastomer compounds foruse in tire
27、s, mechanical rubber goods, and other manufactured rubber products. Structure measurements by OAN (Test MethodD2414) and COAN (Test Method D3493), are based on oil absorption.6. Apparatus6.1 Analytical Balance, or equivalent, capable of a weighing sensitivity of 0.1 mg.6.2 Gravity Convection Drying,
28、 Oven, capable of maintaining 125 6 5C.6.3 Weighing Dish, Camel Hair or Similar Brush, to be used for weighing and transferring samples.6.4 Void Volume Instrument, to be used to measure the compressed volume (apparent volume) of carbon blacks as a functionof applied pressure, from which the void vol
29、ume is calculated at specified intervals of geometric mean pressure (that is, geometricmean of applied and transmitted pressures). The void volume instrument or device shall conform to the following genericspecifications and be capable of operating as outlined in Section 9.6.4.1 The instrument shall
30、 have a rigid framework that contains a cylindrical sample chamber. Hysteresis and elasticity in theframework under the range of applied forces should be 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 suffici
31、ent power for the compression forces as required for testing, the piston shallbe capable of being moved to compress the sample.Adevice to record the movement of the piston and measure displacement shallbe provided. The compressed volume of any sample is determined by the distance from the end of the
32、 piston to the end of thecylinder; this is designated as a “height” in the calculations discussed in Section 10. The sample height and cylinder diameter areused to calculate an apparent sample volume.6.4.4 Load cells or other suitable force or pressure measurement devices are used to measure the app
33、lied and transmittedpressures.D7854 1526.4.5 The instrument design shall provide continuous compression at a controlled and constant rate thereby allowing continuousmeasurements of apparent volume and pressures at specified data intervals.6.4.6 The instrument uses an electric motor or hydraulic flui
34、d to operate a linear actuator attached to a piston.6.4.7 The instrument incorporates two load cells to directly measure applied and transmitted forces or pressures.6.4.8 The instrument design shall provide a means to save and store the compression data up to a minimum of 100 MPageometric mean press
35、ure for subsequent analysis.7. Sampling7.1 Samples of candidate carbon blacks shall be taken in accordance with Practice D1799 or D1900.8. Calibration8.1 CalibrationFollow the manufacturers instructions to set up the instrument and to calibrate the The manufacturer willtypically calibrate the instru
36、ment measurement systems. The use of height measurement system is typically calibrated using aphysical standard such as a calibrated steel plug with traceability is recommended to calibrate or verify the height displacementtransducer. A reference load cell plug. Load cells are typically calibrated o
37、r verified using a reference load cell. Traceability isrecommended for all calibration devices. Follow the manufacturers recommendations for calibration frequency and verification-.with traceability is recommended to calibrate or verify the force transducers.9. Procedure9.1 Sample PreparationDry an
38、adequate sample of the carbon black for at least 1 h in a gravity-convection oven set at 1256 5C, in an open container of suitable dimensions, so that the depth of black is no more than 10 mm. Cool to room temperaturein a desiccator before use.9.2 Weigh a mass of sample specified by the instrument m
39、anufacturer, typically 1.000 or 1.000, 2.000 g, or 4.000 g to the nearest0.1 mg.9.3 Define the analysis conditions to include void volume measurements at 50.0, 75.0, and 100.0 MPa geometric mean pressurewith a compression rate of 1 to 2 MPa/s. In practice this is accomplished by defining a scan from
40、 the lowest detection pressureto at least 100 MPa geometric mean pressure.9.4 Transfer the weighed sample to the instrument. Brush the sample pan and funnel to ensure the entire sample is introducedinto the cylinder. Proceed with the test.9.5 At the end of the test insure residual carbon black has b
41、een removed from the cylinder and piston tips.10. Void Volume Calculations10.1 The void volume (VV) is calculated from the apparent compressed volume as follows. The apparent compressed volumeof the sample is evaluated by Eq 2.VA 5h 33.1416 D24 (2)where:VA = the apparent compressed volume of the car
42、bon black sample, cm3, from a single uniaxial compression.h = the “height” of the compressed carbon black in the cylinder, cm, andD = the diameter of the cylinder, cm.10.2 The theoretical volume of the carbon black is evaluated by Eq 3.VT 5mdCB (3)where:VT = the theoretical volume of the carbon blac
43、k sample, cm3,TABLE 1 Precision Parameters for D7854, Void Volume at 50 MPa Mean PressureAMaterial Number ofLabs Unit m3/kgMean Level Sr r (r) SR R (R)SRB 8D 18 24.9 0.20 0.58 1.55 0.29 0.83 2.19SRB 8A 21 46.5 0.25 0.70 1.25 0.39 1.10 2.15SRB 8E 20 50.5 0.22 0.63 2.32 0.38 1.09 3.33SRB 8F 18 61.4 0.
44、34 0.95 1.86 0.48 1.35 2.07SRB 8B 21 70.7 0.31 0.89 1.26 0.56 1.58 2.24SRB 8C 23 73.9 0.49 1.38 1.51 0.54 1.53 2.37Average 54.7Pooled 0.30 0.86 1.63 0.44 1.25 2.39A Precision is based on absolute void volume measurements (non-normalized data) from an inter-laboratory precision program conducted in 2
45、014.D7854 153dCB = 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 (100 g) is given by Eq 4.VV 5VA 2 VT!m 100! (4)where:VV = void volume of carbon black sample, 105m3/kg (cm3/100 g),VA =
46、 the apparent compressed volume of the carbon black sample, cm3, from a single uniaxial compression (Eq 2), andVT = the theoretical volume of the carbon black sample, cm3, (Eq 3).NOTE 1Some carbon blacks have reported skeletal densities of approximately 1.8 to 2.0 g/cm3. The accepted skeletal densit
47、y of rubber carbon blackis 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 0.1 1065m3/kg (0.1 cm3/100g) measured at 50.0, 75.075.0, and 100.0 MPaGeometric mean pressures.11.1.3 Sample mass in grams weighed to nearest
48、 0.1 mg.11.1.4 Cylinder diameter to the nearest 0.001 mm.12. Precision and Bias412.1 These precision statements have been prepared in accordance with Practice D4483-99. Refer to this practice forterminology and other statistical details.12.2 Precision and BiasA precision and bias statement has not b
49、een developed as of this time.The precision results in thisprecision and bias section give an estimate of the precision of this test method with the materials used in the particularinterlaboratory program described below. The precision parameters should not be used for acceptance or rejection testing of anygroup of materials without documentation that they are applicable to those particular materials and the specific testing protocolsof the test method.12.3 A type 2 inter-laboratory precision program was conducted in 2014 as detailed in Tables 1-3.
