1、Designation: D3849 13Standard Test Method forCarbon BlackMorphological Characterization of CarbonBlack Using Electron Microscopy1This standard is issued under the fixed designation D3849; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of last revision. A 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 (1) the morphological (forexample, size and shape) characterization of carbon
3、 black fromtransmission electron microscope images which are used toderive the mean particle and aggregate size of carbon black inthe dry (as manufactured) state, from CAB chip dispersion orremoved from a rubber compound and (2) the certification ofmean particle size using a correlation based on sta
4、tisticalthickness surface area measurements.1.2 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the
5、 user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D6556 Test Method for Carbon BlackTotal and ExternalSurface Area by Nitrogen Adsorption3. Terminology3.1 Def
6、initions:3.1.1 General:3.1.1.1 carbon black particlea small spheroidally shaped,paracrystalline, non-discrete component of an aggregate; it canonly be separated from the aggregate by fracturing; carbonblack particle size is a distributional property; therefore, theterm particle size implies the mean
7、 value from multiplemeasurements.3.1.1.2 carbon black aggregatea discrete, rigid colloidalentity that is the smallest dispersible unit; it is composed ofextensively coalesced particles; carbon black aggregate size isa distributional property; therefore, the term aggregate sizeimplies the mean value
8、from multiple measurements.3.1.1.3 statistical thickness surface area (STSA)the exter-nal specific surface area of carbon black that is calculated fromnitrogen adsorption data using the de Boer theory and a carbonblack-specific model.3.1.1.4 glow dischargea plasma of ionized gas that isformed in a h
9、igh-voltage field at pressures of about 3 to 20 Pa(25 to 150 10-3torr); an alternating current (a-c) glowdischarge using air is effective in cleaning and oxidizing thesurface of carbon substrates to improve the wetting character-istics of polar vehicles containing pigment dispersions.3.1.1.5 substra
10、tea thin film that is used to support electronmicroscope specimens; evaporated carbon films are commonlyused because of relatively good mechanical strength, stability,and conductivity.3.1.2 Aggregate Dimensional Properties from Image Analy-sis:3.1.2.1 area (A)the two-dimensional projected area of th
11、ecarbon black aggregate image.3.1.2.2 perimeter (P)the total boundary length of anaggregate.3.1.2.3 volume (V)an estimate of the volume of the carbonblack aggregate using stereological principles.3.1.3 Image Analysis:3.1.3.1 dilationthe converse of erosion; this process isaccomplished by changing an
12、y OFF pixel to ON if it hasgreater than a preset minimum of ON neighbors, causing imagefeatures to grow in size, which fills in small breaks in features,internal voids, or small indentations along the feature surface.3.1.3.2 erosionthe process by which image features arereduced in size by selectivel
13、y removing pixels from theirperiphery; it consists of examining each binary pixel andchanging it from ON to OFF if it has greater than a presetminimum of neighbors that are OFF; it serves a number ofuseful functions, such as smoothing feature outlines andseparating features touching each other.1This
14、 test method is under the jurisdiction of ASTM Committee D24 on CarbonBlack and is the direct responsibility of Subcommittee D24.81 on Carbon BlackMicroscopy and Morphology.Current edition approved Oct. 1, 2013. Published October 2013. Originallyapproved in 1980. Last previous edition approved in 20
15、11 as D3849 07 (2011).DOI: 10.1520/D3849-13.2For 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 Summary page onthe ASTM website.Copyright ASTM In
16、ternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.3.3 featureareas within a single continuous boundarythat have gray-level ranges that allow them to be distinguishedfrom the background area outside the feature via thresholding.3.1.3.4 thresholdingse
17、lecting a range of brightness suchthat discrimination is possible between the feature and thebackground; the gray levels within carbon black imagesbecome lower with decreasing particle size.4. Significance and Use4.1 Carbon black morphology significantly affects the tran-sient and end-use properties
18、 of carbon black loaded polymersystems. A carbon blacks particle size distribution is its singlemost important property, and it relates to degree of blackness,rubber reinforcement, and ability to impart UV protection. Fora given loading of carbon black, blackness, reinforcement, andUV protection inc
19、rease with smaller particle size. Aggregatesize and shape (structure) also affect a carbon blacks end-useperformance, as higher carbon black structure increases vis-cosity and improves dispersion. The stiffness (modulus) ofelastomer systems becomes significantly higher with increas-ing structure. Th
20、e preferred method for measuring carbonblack morphology (for example, size and shape) is transmis-sion electron microscopy (TEM), but due to the semi-quantitative nature of TEM, it is not suited for mean particlesize (MPS) certification.4.2 Carbon black aggregate dimensional and shape proper-ties ar
21、e dependent upon the nature of the system in which thesample is dispersed, as well as the mixing procedure.Test Method A Morphological Evaluation (Semi-Quantitative) Via Transmission Electron Microscopy5. Summary of Test Method5.1 Transmission electron microscopy (TEM) is utilized tomeasure the morp
22、hological properties of carbon black. Avariety of dispersion methods are offered depending upon thesample type. Both dry black and CAB chip dispersions areused for measuring the morphology of bulk carbon black. Apyrolysis technique is included that facilitates the removal ofcarbon black from vulcani
23、zed rubber. This aforementionedtechnique can be employed to identify the carbon black typefrom an end use product. It should be noted that the accuracyand precision of Method A is insufficient for generatingquantitative data as required in the case of MPS certification.Please refer to Method B for M
24、PS certification.6. Apparatus6.1 Electron Microscope, transmission-type, with a point-to-point resolution of 1.0 nm or better. Operating voltagesshould be high enough to provide the desired resolution andlow enough to produce images of sufficient contrast. Recom-mended voltages can be in the 60 to 1
25、20 kV range. Themicroscope column should contain a liquid nitrogen-cooledanti-contamination device or a “cold finger” to reduce samplecontamination and to maintain column cleanliness. For imageacquisition, the microscope should include a charge-coupleddevice (CCD) camera mounted either above or belo
26、w theinstruments viewing chamber.6.2 Image Analysis System, consisting at minimum of aTEM-interfaced camera capable of 640 480 pixel or betterresolution, a computer equipped with frame grabbing hardwareto capture TEM images digitally, and software to performmorphological operations and measurements
27、on image featuresand store resulting data. Operations must include background/noise elimination, thresholding, and edge smoothing. Area andperimeter are then measured on features in the processedimages.6.3 Two-Roll Mill.6.4 Vacuum Evaporator, standard-type, for preparing carbonfilms to be used as su
28、bstrates for electron microscopy. Theevaporator should be capable of reducing the absolute pressureto 1.3 mPa (1 10-5torr) and should also contain the necessaryapparatus for a-c glow discharge.6.5 Ultrasonic Generator, variable power tank-type orprobe that provides sufficient energy to give acceptab
29、le disper-sion.6.6 Dry Box, capable of maintaining a relative humiditylevel of no greater than 30 %.6.7 Analytical Balance, with an accuracy of about 0.5 mg.6.8 Electrically Heated Tube Furnace, capable of beingheated to 800 to 900C under an inert environment, with theability to introduce and remove
30、 the sample boat to the heatedzone without allowing oxygen intrusion.6.9 Pyroprobe, capable of being heated from 150 to 1000Cin an inert environment.6.10 Carbon Rods, approximately 3.1 mm in diameter.6.11 Carbon Rod Sharpener.6.12 Glass Microscope Slides, 25 by 75-mm.6.13 Test Tubes, 75 by 10-mm, 4-
31、cm3capacity, 0.5-mm wallthickness, with corks.6.14 Transfer Pipets, disposable Pasteur-type, 225 mm long,1-mm inside diameter at tip.6.15 Rubber Bulbs, for pipets.6.16 Glass Vials, 40-cm3capacity, with solvent-resistanttops.6.17 Bchner Funnel, No. 3, 111-mm inside diameter.6.18 Filter Paper, general
32、 purpose.6.19 Carbon Coated Electron Microscope Specimen Grids,3-mm diameter, 200 to 300 mesh. Commercially available orcan be prepared as described in Annex A1.6.20 Wire Screening, with openings approximately 1 mm2.6.21 Tweezers, fine-tipped.6.22 Spatulas, micro-type with V-shaped spoon that isappr
33、oximately 2 mm wide at top and 12.5 mm long.6.23 Fluorocarbon Duster.6.24 Lens Tissue, lint-free.6.25 Porcelain Boats, for pyrolysis, 98 mm long, 15 mmwide at top.D3849 1326.26 Centrifuge, high speed (15 000 to 20 000 r/min) withhead for 75 by 10 mm test tubes.6.27 Beakers, 2000-cm3capacity.7. Reage
34、nts and Materials7.1 Chloroform, reagent grade.7.2 Tetrahydrofuran (THF), reagent grade.7.3 1,2-Dichloroethane, reagent grade.7.4 Ethyl Acetate, reagent grade.7.5 Poly (Vinyl Formal) Resin, Grade 15/95.7.6 Cellulose Acetate Butyrate Resin (CAB).7.7 Phthalate-Type Plasticizer (such as santicizer).8.
35、Sample PreparationDispersion Procedures8.1 Dry Carbon Black (Sonic Bath):8.1.1 Weigh 8 to 10 mg of carbon black into a test tubecontaining 1 cm3of solvent (typically chloroform or THF).NOTE 1With experience, it may not be necessary to weigh eachcarbon black sample, as an estimated amount from the mi
36、crospatula maybe sufficient. There is considerable latitude in the amount of carbon blackused. The finer N100 and N200 blacks may require somewhat less carbonblack than the coarser semi-reinforcing types.8.1.2 Adjust the power of the ultrasonic bath for maximumagitation; this may require that the wa
37、ter level be adjusted. Asthe ultrasonic energy heats the water in the bath, ice should beadded to control the temperature in order to maintain maximumdispersive capability.8.1.3 Place the stoppered test tube containing the carbonblack and solvent mixture into the most intense part of theultrasonic f
38、ield and allow the mixture to agitate for 3 to 5 min.The test tube should be held with tongs or mounted in a simplewire holder.8.1.4 Transfer a small portion of the concentrated carbonblack-solvent mixture into another test tube containing 1 cm3of fresh solvent. The amount of concentrate required in
39、creaseswith particle size. Blend the mixture by repeatedly transferringthe sample between the transfer pipet and the test tube, thencork the test tube and repeat the ultrasonic dispersion proce-dure.8.1.5 Check the concentration of the diluted dispersion byextracting a small amount into the tip of t
40、he pipet and viewingagainst a white background. For tread grade carbon blacks, thedispersions should be relatively transparent, becoming some-what darker with increasing particle size. The diluted disper-sions for very coarse carbon blacks such as N700 to N900series will be on the threshold of compl
41、ete opacity. Ifnecessary, adjust the concentration by adding more concentrateor solvent as required, then repeat the ultrasonic agitation. Thevolume of the carbon black-solvent mixture should be main-tained at approximately 1 cm3. If considerable dilution isrequired, the excess volume above 1 cm3sho
42、uld be discarded.NOTE 2Areasonable degree of latitude exists for achieving the properconcentration levels in the final dispersions for different grades of carbonblack. Concentration and overall dispersion quality are best determined byscreening the actual specimens in the electron microscope and the
43、nmaking the necessary adjustments.8.1.6 Place a specimen grid with carbon substrate (film sideup) on a piece of filter paper. Remove a small amount of thefinal diluted dispersion using a fresh pipet and place one dropon the grid as close to the center as possible, from a height ofabout 12 mm. Allow
44、the specimen to dry for about 1 min on apiece of filter paper. This specimen preparation procedureshould be performed in a dry box if the relative humidity in theroom exceeds 30 %.8.1.7 For TEM grids that contain formvar or residual CAB(CAB chip dispersions), place the TEM grid in an appropriatesamp
45、le holder, place in the pyrolysis chamber and allowadequate time for the chamber to be purged by an inert gas toprevent oxidation of the sample. Pyrolize the specimen grid ata sufficient temperature (typically greater than 550C) toremove the poly (vinyl formal) film or CAB, or both.8.1.8 Acceptable
46、dispersions of a carbon black in the drystate and removed from a rubber compound (SBR) are illus-trated for N-220 and N-774 carbon blacks in Figs. 1 and 2.8.2 Dry Carbon Black (Ultrasonic Probe):8.2.1 Weigh 5 to 10 mg of carbon black into a 30-cm3glassvial and add approximately 20 cm3of solvent (typ
47、icallychloroform).NOTE 3With experience, it may not be necessary to weigh eachcarbon black sample, as an estimated amount from the microspatula maybe sufficient. There is considerable latitude in the amount of carbon blackused. The finer N100 and N200 blacks may require somewhat less carbonblack tha
48、n the coarser semi-reinforcing types.8.2.2 Place the vial containing the carbon black and solventinto an ice-water bath.8.2.3 Insert the probe to a depth of approximately 2.5 cminto the vial and ultrasonicate at 40 to 50 watts for 10 min.NOTE 4The ultrasonic probe and ice-water bath containing the s
49、amplevial should be housed in an acoustic enclosure to reduce cavitation noise.8.2.4 Transfer a small portion (approximately 2 to 4 cm3)ofthe concentrated carbon black/solvent mixture into another vialand add 20 cm3of fresh solvent. An additional three-minutesonication is recommended.8.2.5 Check the concentration of the diluted dispersion byextracting a small amount into a pipet and then placing 1 dropon a white filter paper. For tread grade carbon blacks, thedispersions should be relatively transparent, becoming some-what darker with increasing par
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