1、Designation: D7854 16D7854 18Standard 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 by Void Volume at meanpressure. Compressed vo
3、id volumes are obtained by measuring the compressed volume of a weighed sample in a cylindricalchamber as a function of pressure exerted by a movable piston.Aprofile of void volume as a function of pressure provides a meansto assess carbon black structure at varying levels of density and aggregate r
4、eduction. For the purposes of standardized testing asingle value of void volume is reported at 50 MPa mean pressure.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 s
5、afety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standard was developed
6、in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1
7、 ASTM Standards:2D1799 Practice for Carbon BlackSampling Packaged ShipmentsD1900 Practice for Carbon BlackSampling Bulk ShipmentsD2414 Test Method for Carbon BlackOil Absorption Number (OAN)D3493 Test Method for Carbon BlackOil Absorption Number of Compressed Sample (COAN)D4483 Practice for Evaluati
8、ng Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries3. 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 pr
9、essure exerted on 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 transmitted pressure, nthe resulting pressure transmitted through a sample in a cylindrical chamber, where the load cellor force meas
10、uring system is in contact with the sample opposite the movable piston, typically via a stationary second piston.3.2.3 compressed volume (carbon black), nthe apparent volume that a specified mass of carbon black occupies when it iscontained in a specified cylindrical chamber and subjected to a singl
11、e uniaxial compression at a specified pressure by means ofa movable piston.3.2.4 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!0.5 (1)3.2.5 theoretical volume
12、(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.1 This test method is under the jurisdiction ofA
13、STM Committee D24 on Carbon Black and is the direct responsibility of Subcommittee D24.11 on Carbon Black Structure.Current edition approved Jan. 1, 2016March 1, 2018. Published February 2016April 2018. Originally approved in 2013. Last previous edition approved in 20152016 asD7854 15.D7854 16. DOI:
14、 10.1520/D7854-16.10.1520/D7854-18.2 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.This document is not an AS
15、TM 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 recommends that users consult prior editions as appropriate. In a
16、ll 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 States13.2.5 transmitted pressure, nthe resulting pressure transmitted through a
17、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.3.2.6 void volume (carbon black), na measure of the intra-aggregate void space or occluded volume within the primarystruct
18、ure 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 function of specified uniaxial compression pressure, andnormalized to 100 g mass. pressure, and normalized t
19、o 100 g mass. The void volume of a carbon black expressed as a functionof geometric mean pressure, VV, is a carbon black structure property.3.2.6.1 DiscussionCarbon blacks resist packing, compression, and fracture due to aggregate irregularities and entanglements, size distribution, andaggregate str
20、ength resulting from particle to-particle necks within aggregate 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 interfacia
21、l area, which can influence the uniformity of the compaction 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 pr
22、essure bias is a result of forcelosses due to friction between 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 bl
23、ack products or applied pressures. For this reason, the most 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 me
24、asurement of compressed void volume as a function of applied 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 Meth
25、od4.1 The measured compressed volume (apparent volume) of a 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 a
26、nd transmitted forces (or pressures) are measured. The compressed 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 b
27、lack expressed as a function of geometric mean pressure, VVGM, 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 a
28、ggregate irregularity and non-sphericity, thegreater the compressed 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
29、developed in carbon black-elastomer compounds foruse in tires, mechanical rubber goods, and other manufactured rubber products. Structure by void volume is based on compressionwhile structure measurements by OAN (Test Method D2414) and COAN (Test Method D3493),) are based on oil absorption.6. Appara
30、tus6.1 Analytical Balance, or equivalent, capable of a weighing sensitivity of 0.1 mg.6.2 Gravity Convection Drying, 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 measur
31、e the compressed volume (apparent volume) of carbon blacks as a functionof applied pressure, from which the void volume 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
32、 the following genericspecifications and be capable of operating as outlined in Section 9.6.4.1 The instrument shall 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 displacem
33、ent measurement.6.4.2 The cylinder shall have a uniform diameter.6.4.3 By means of a suitable mechanism with sufficient 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
34、displacement shallbe provided. The compressed volume of any sample is determined by the distance from the end of the 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 apparen
35、t sample volume.D7854 1826.4.4 Load cells or other suitable force or pressure measurement devices are used to measure the applied and transmittedpressures.6.4.5 The instrument design shall provide continuous compression at a controlled and constant rate thereby allowing continuousmeasurements of app
36、arent volume and pressures at specified data intervals.6.4.6 The instrument uses an electric motor or hydraulic fluid 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 instrumen
37、t design shall provide a means to save and store the compression data up to a minimum of 10050 MPageometric mean pressure for subsequent analysis.7. Sampling7.1 Samples of candidate carbon blacks shall be taken in accordance with Practice D1799 or D1900.8. Calibration8.1 CalibrationThe manufacturer
38、will typically calibrate the instrument measurement systems. The height measurementsystem is typically calibrated using a physical standard such as a calibrated steel plug. Load cells are typically calibrated or verifiedusing a reference load cell. Traceability is recommended for all calibration dev
39、ices. Follow the manufacturers recommendationsfor calibration frequency and verification.9. Procedure9.1 Sample PreparationDry an 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
40、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 manufacturer, typically 1.000, 2.000 g, or 4.000 g to the nearest 0.1mg.9.3 Define the analysis conditions to include a void volume measurements at 50.0, 75.0, and 100.0 m
41、easurement at 50.0 MPageometric mean pressure with a compression rate of 1 to 2 MPa/s. In practice this is accomplished by defining a scan from thelowest detection pressure to at least 10050 MPa geometric mean pressure.9.4 Transfer the weighed sample to the instrument. Brush the sample pan and funne
42、l 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 been removed from the cylinder and piston tips.10. Void Volume Calculations10.1 The void volume (VV) is calculated from the apparent compressed volume as fo
43、llows. 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 carbon 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 c
44、ylinder, 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 black 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
45、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 0.34 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
46、.25 2.39A Precision is based on absolute void volume measurements (non-normalized data) from an inter-laboratory precision program conducted in 2014.D7854 183dCB = 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 c
47、arbon 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 = the apparent compressed volume of the carbon black sample, cm3, from a single uniaxial compression (Eq 2), andVT = the theoretical volume of the carbon bl
48、ack sample, cm3, (Eq 3).NOTE 1Some carbon blacks have reported skeletal densities of approximately 1.8 to 2.0 g/cm3. The accepted skeletal density 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 near
49、est 0.1 105m3/kg (0.1 cm3/100g) measured at 50.0, 75.0, and 100.0 50.0 MPaGeometric mean pressures.pressure.11.1.3 Sample mass in grams weighed to nearest 0.1 mg.11.1.4 Cylinder diameter to the nearest 0.001 mm.12. Precision and Bias312.1 These precision statements have been prepared in accordance with Practice D4483-99. Refer to this practice forterminology and other statistical details.12.2 The precision results in this precision and bias section give an estimate of the precision of this test method with thematerials used in the particular interlab
