ASTM D6086-2008 809 Standard Test Method for Carbon Black&x2014 Void Volume (VV).pdf

1、Designation: D 6086 08Standard Test Method forCarbon BlackVoid Volume (VV)1This standard is issued under the fixed designation D 6086; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthes

2、es 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. Compressedvoid volumes are obtained by measuring the

3、 compressedvolume of a weighed sample as a function of applied pressurein a cylindrical chamber by a movable piston with a displace-ment transducer on the piston mechanism. A profile of voidvolume as a function of applied pressure provides a means toassess carbon black structure at varying levels of

4、 density andaggregate reduction.1.2 Void volume is an important carbon black structureproperty that relates to the compounded physical properties forcarbon black-filled elastomers including viscosity, modulus,and die swell.1.3 The values stated in SI units are to be regarded asstandard. No other uni

5、ts of measurement are included in thisstandard.1.4 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-priate safety and health practices and determine the applica-bility of regu

6、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1799 Practice for Carbon BlackSampling PackagedShipmentsD 1900 Practice for Carbon BlackSampling Bulk Ship-mentsD 2414 Test Method for Carbon BlackOil AbsorptionNumber (OAN)D 3493 Test Method for Carbon BlackOil AbsorptionN

7、umber of Compressed Sample (COAN)D 4821 Guide for Carbon BlackValidation of TestMethod Precision and Bias3. Terminology3.1 Definitions of Terms Specific to This StandardRefer toSections 4 and 9 for a more complete understanding of the useof these terms in this test method.3.1.1 compressed volume (ca

8、rbon black), nthe measuredapparent volume that a specified mass of carbon black occupieswhen it is contained in a specified cylindrical chamber andsubjected to a specified applied pressure by means of amovable piston.3.1.2 theoretical volume (carbon black), nthe volume thata specific mass of carbon

9、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.3.1.3 void volume (carbon black), na measure of theoccluded pore volume within the primary structure of ca

10、rbonblack, characterized by the irregularity and non-sphericity ofcarbon black aggregate particles, and expressed as the differ-ence (compressed volume minus theoretical volume) as afunction of applied pressure, and normalized to 100 g mass.3.1.3.1 DiscussionCarbon blacks resist packing, com-pressio

11、n, and fracture due to aggregate irregularities andentanglements, size distribution, and aggregate strength orparticle-to-particle necks within aggregate branches. Carbonblack compressed void volume is also affected by reactingforces to the cylinder wall and the piston tip, which in turndepend on fa

12、ctors including sample shape (that is, the ratio ofsample height to cylinder diameter) or interfacial area, whichcan influence the uniformity of the compaction density. Sincethe compressed void volumes are specific to the cylindergeometry and possibly to the cylinder wall surface (that is,friction e

13、ffects), a measured compressed volume is not a truecompressed volume unless these factors are corrected orsufficiently minimized.4. Summary of Test Method4.1 The measured compressed volume (apparent volume) ofa weighed dry test sample as a function of applied pressure isobtained in a void volume ins

14、trument appropriately calibratedby the manufacturer or user. From the measured compressed1This test method is under the jurisdiction of Committee D24 on Carbon Blackand are the direct responsibility of Subcommittee D24.11 on Carbon BlackStructure.Current edition approved July 1, 2008. Published Augu

15、st 2008. Originallyapproved in 1997. Last previous edition approved in 2005 as D 6086 05.2For 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 standards Document Summ

16、ary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.volume, the measured void volume is obtained by subtractingthe theoretical volume from the apparent volume then express-ing the result normalized to 100 g ma

17、ss. A true void volume isobtained by correcting the measured void volume for instru-ment geometry, sample mass, and possible friction effects.5. Significance and Use5.1 The void volume of a carbon black expressed as afunction of applied pressure, VV, is a carbon black structureproperty. Structure is

18、 a generic term that is a function of theshape irregularity and deviation from sphericity of carbonblack aggregates. The greater a carbon black resists compres-sion by having substantial aggregate irregularity and non-sphericity, the greater the compressed volume and void vol-ume. Also, the more tha

19、t a carbon black resists compression,the greater the energy required to compress the sample per unitvoid volume.5.2 Structure, traditionally measured by OAN (Test MethodD 2414) and COAN (Test Method D 3493), is a property thatstrongly influences the physical properties developed in carbonblack-elast

20、omer compounds for use in tires, mechanical rubbergoods, and other manufactured rubber products. Several stud-ies within D24 have demonstrated that void volume data can beused to estimate OAN and COAN numbers of carbon blacksusing mathematical models derived from void volume-pressuredata and oil abs

21、orption data. The models may vary dependingon whether dynamic or static void volume measurements areused and the number and types of carbon blacks includedwithin a modeling data set. If necessary, OAN and COANestimates from void volume models can also be normalizedusing current SRBs (as practiced in

22、 Guide D 4821). Anyestimates of OAN or COAN derived from prediction modelsusing void volume-pressure data should be labeled appropri-ately (that is, Test Method D 6086) to avoid confusion withOAN or COAN data obtained directly from oil absorptionmethods.6. Apparatus6.1 Analytical Balance, or equival

23、ent, capable 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 the samples.6.4 Void Volume Instrument, to be used to measure thecompressed volume (apparent volume) of carbon

24、blacks as afunction of applied pressure from which the void volume iscalculated. The void volume instrument or device shall con-form to the following generic specifications and be capable ofoperating as outlined in 6.4.1-6.4.3.6.4.1 The instrument shall have a rigid framework thatcontains a cylindri

25、cal sample chamber (see an example in Fig.X1.1). Hysteresis in the framework under the range of appliedforces should be accounted for in the displacement measure-ment.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

26、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;

27、 this is designated as a “height”in the procedure discussed in Section 9. The sample height andcylinder diameter are used to calculate an apparent samplevolume.6.4.4 A load cell or other suitable force or pressure mea-surement device is used to measure the pressure applied to thesample.6.4.5 Two typ

28、es of void volume instruments are commer-cially available:6.4.5.1 A static or equilibrium measurement instrumentwhich is designed to target one or more target pressures; anoption to step from one target pressure to another is availableallowing the collection of several data points. This typeinstrume

29、nt uses an air-powered control cylinder to move thepiston and does not control the rate of piston movement. Thepressure applied to the sample is not directly measured, butcalculated based on air pressure applied to the control cylinder.See Appendix X1 for a brief description of a commercial voidvolu

30、me instrument that meets these specifications.6.4.5.2 A dynamic void volume instrument is also availablewhich is designed to dynamically scan a pressure range at acontrolled rate thereby allowing continuous measurements ofapparent volume and pressure at specified data intervals. Thedynamic instrumen

31、t uses an electric motor to operate a linearactuator attached to the piston. The instrument incorporates aload cell to directly measure force or pressure applied to thesample.7. Sampling7.1 Samples of candidate carbon blacks shall be taken inaccordance with Practice D 1799 or D 1900.8. Calibration a

32、nd Normalization8.1 CalibrationFollow the manufacturers instructions toset up the instrument and to calibrate the 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

33、 load cell withtraceability is recommended to calibrate or verify the forcetransducer.8.2 Normalization (non-mandatory; user should follow rec-ommendations from manufacturer):8.2.1 Test the 6 current ASTM Standard Reference Blacks(SRBs) four times each to establish the average measured valuefor each

34、 SRB over the range of compression pressures ofinterest. Additional values are added periodically.8.2.2 Perform a regression analysis using target SRB values(y value) and the rolling average of the last 4 measured values(x value) across the range of applied pressures specified by themanufacturer. If

35、 target SRB curves represent measured voidvolumes, then the curves are instrument specific and should beobtained from the manufacturer.NOTE 1Use only one normalization curvedo not separate thecarcass and tread blacks as practiced in Test Method D 2414. TheD6086082regression model is a straight-line

36、equation or first-order linear modelwithout a fixed or zero intercept from which both a slope and intercept arecalculated.8.2.3 Normalize all test samples as follows:Normalized value 5 measured value 3 slope! 1 y2intercept (1)8.2.4 For normalized VV values on the SRBs that areconsistently outside th

37、e expected measurement range, the testapparatus should be recalibrated in accordance with 8.1.NOTE 2The expected measurement range for void volumes at specificapplied pressures for an SRB is typically established through round robintesting. In the absence of industry precision data, this information

38、 can beestablished within a laboratory and apparatus through periodic monitoringof the SRBs to determine 3-sigma limits.8.2.5 When any changes are made to the apparatus such ascalibration of the measurement systems or replacement ofcylinder or piston tip, a new normalization curve must begenerated a

39、s described in 8.2.1 and 8.2.2.9. Procedure9.1 Method ADynamic Void Volume Measurement:9.1.1 Sample PreparationDry 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

40、mm. Cool to roomtemperature in a desiccator before use.9.1.2 Weigh a mass of sample specified by the instrumentmanufacturer.9.1.3 Define the analysis conditions including a scan rate,ending pressure, and data collection interval.9.1.4 Initiate the test, and at the appropriate time, transferthe weigh

41、ed sample to the instrument. Brush the sample panand funnel to ensure the entire sample is introduced into thecylinder. Proceed with the test.9.2 Method BEquilibrium Void Volume Measurement:9.2.1 Sample PreparationSee 9.1.1.9.2.2 Weigh a mass of sample specified by the instrumentmanufacturer.9.2.3 D

42、efine the analysis conditions including target pres-sure and, if applicable, any subsequent target pressure(s).Define the initial hold time and, if applicable, any subsequenttime intervals.9.2.4 Transfer the weighed sample to the instrument using afunnel. Brush the sample pan and funnel to insure th

43、e entiresample is introduced into the cylinder.9.2.5 At the end of the test insure residual carbon black hasbeen removed from piston tip.10. Void Volume Calculations10.1 The measured void volume (VVM) is calculated fromthe measured apparent compressed volume as follows. Theapparent compressed volume

44、 of the sample is evaluated by Eq2.VA5 h 3 3.1416 D2/4000 (2)where:VA= the apparent compressed volume of the carbon blacksample, cm3,h = the “height” of the compressed carbon black in thecylinder, mm, andD = the diameter of the cylinder, mm.10.2 The theoretical volume of the carbon black is evaluate

45、dby Eq 3.VT5 m/dCB(3)where:VT= the theoretical volume of the carbon black sample,cm3,dCB= accepted true (skeletal) density of the carbonblack = 1.90 g/cm3, andm = mass of the carbon black sample, g.10.3 The measured void volume of the candidate carbonblack per unit mass (100 g) is given by Eq 4.VVM5

46、VA2 VTm100! (4)where:VVM= measured void volume of carbon black sample,105m3/kg (cm3/100 g),VA= the apparent compressed volume of the carbonblack sample, cm3, (Eq 2), andVT= the theoretical volume of the carbon black sample,cm3, (Eq 3).NOTE 3Some carbon blacks have reported skeletal densities of 1.8

47、to2.0 g/cm3. The accepted skeletal density of rubber carbon black is 1.90g/cm3.10.4 The corrected or true void volume (VVT) at an appliedpressure is a value that is independent of the sample shape (thatis, the sample to height ratio). It can be determined from themeasured void volume with a given cy

48、linder at various samplemasses, and subsequent extrapolation of a linear line to aninfinitely small mass, VVTis then only a function of theapplied pressure. A method of determining a corrected or truevoid volume from extrapolation is shown as follows:VVMD,p! 5 aD,p! * m 1 VVTp! (5)where:VVT= correct

49、ed or true void volume (cm3/100g), atan applied pressure (the intercept of a linearor straight-line fit through VVMat variousmasses (m),VVT(p) = the true void volume at an applied pressure,p (the intercept of the linear line with slopeat zero mass),VVM(D,p) = the measured void volume in a cylinder ofdiameter D, at an applied pressure p anddetermined for variable mass m, anda(D,p) = The slope of the linear line describing VVMand mass.11. Report11.1 Report the following information:11.1.1 Sample identification.D608608311.1.2 Sample mass to nearest digit s