1、Designation: D7854 15D7854 16Standard 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7、 and BiasD6086 Test Method for Carbon BlackVoid Volume (VV) (Withdrawn 2015)33.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 June 1, 2015Jan. 1, 2016. Published September 2015February 2016. Originally approved in 2013. Last previous edition approved in 20132015as D7854 13.D7854 15. DOI: 10.1520/D7854
13、-15.10.1520/D7854-16.2 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 ASTM standard an
14、d 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 all cases only
15、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 volume (carbon black), na measure of the intra-aggregate void space or occlud
16、ed 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 function of specified uniaxial compression pressure, andnormalized to 100
17、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 aggregate branches. Compressed void volume is also affectedby reacting forces
18、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 density. Sincecompressed void volumes as a function of applied pressure
19、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 between the sample and cylinder wall interface. There is presently no known te
20、chnique 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 useful technique for comparing compressed void volumesis based on a nume
21、rical 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 andtransmitted force or pressure. Such a design allows the computation o
22、f 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 weighed dry test sample is obtained in a void volume instrumentas a funct
23、ion 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 compressed void volumeis obtained by subtracting the theoretical volume from t
24、he 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, VVGM, is a carbon black structureproperty. Structure is a generic term that
25、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 compressed volume and void volume. Also, the more that a carbon black resist
26、s 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 tires, mechanical rubber goods, and other manufactured rubber products. Struc
27、ture 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, Oven, capable of maintaining 125 6 5C.6.3 Weighing Dish, Camel Hair or S
28、imilar 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 volume is calculated at specified intervals of geometric mean pressure (that
29、 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 have a rigid framework that contains a cylindrical sample chamber. Hyste
30、resis 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 sufficient power for the compression forces as required for testing, the piston
31、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 piston to the end of thecylinder; this is designated as a “height” in th
32、e 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 applied and transmittedpressures.D7854 1626.4.5 The instrument design shall
33、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 fluid to operate a linear actuator attached to a piston.6.4.7 The instrument
34、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 pressure for subsequent analysis.7. Sampling7.1 Samples of candidate carbon bl
35、acks shall be taken in accordance with Practice D1799 or D1900.8. Calibration8.1 CalibrationThe manufacturer 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 typ
36、ically calibrated or verifiedusing a reference load cell. Traceability is recommended for all calibration devices. 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 gra
37、vity-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 manufacturer, typically 1.000, 2.000 g, or 4.000 g to the near
38、est 0.1mg.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 the lowest detection pressureto at least 100 MPa geometric mean press
39、ure.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 been removed from the cylinder and piston tips.10. Void Volume Calculat
40、ions10.1 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 carbon black sample, cm3, from a single uniaxial compression.h = the “hei
41、ght” 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 black sample, cm3,dCB = accepted true (skeletal) density of the carbon bla
42、ck = 1.90 g/cm3, andm = mass of the carbon black sample, g.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
43、.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 1.25 2.39A Precision is based on absolute void volume measurements (non-normalized data) from an inte
44、r-laboratory precision program conducted in 2014.D7854 16310.3 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 = the apparent compressed volume of the carbon black sample, cm3, from
45、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 density of rubber carbon blackis 1.90 g/cm3.11. Report11.1 Report the follow
46、ing information:11.1.1 Sample Identification.11.1.2 Void volume expressed to the nearest 0.1 105m3/kg (0.1 cm3/100g) 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 the nearest 0.001 mm.12. Precision and
47、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
48、 in the particular interlaboratory program described below. The precision parameters should not be used foracceptance or rejection testing of any group of materials without documentation that they are applicable to those particularmaterials and the specific testing protocols of the test method.12.3
49、A type 2 inter-laboratory precision program was conducted in 2014 as detailed in Tables 1-3. Both repeatability andreproducibility represent short term (daily) testing conditions. The testing was performed using two operators in each laboratoryperforming the test once on each of two days (total of four tests). Acceptable difference values were not measured. The betweenoperator component of variation is included in the calculated values for r, (r), R, and (R).12.4 The results of the precision calculations for this test method are given in Tables 1-3.
