1、Designation:D384913D384914 Standard Test Method for Carbon BlackMorphological Characterization of Carbon Black Using Electron Microscopy 1 This standard is issued under the xed designation D3849; the number immediately following the designation indicates the year of original adoption or, in the case
2、 of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This test method covers (1) the morphological (for example, size and shape) characterization
3、 of carbon black from transmission electron microscope images which are used to derive the mean particle and aggregate size of carbon black in the dry (as manufactured) state, from CAB chip dispersion or removed from a rubber compound and (2) the certication of mean particle size using a correlation
4、 based on statistical thickness surface area measurements. 1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the re
5、sponsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 D6556Test Method for Carbon BlackTotal and External Surface Area by Nitrogen Adsorption
6、 3. Terminology 3.1 Denitions: 3.1.1 General: 3.1.1.1 carbonblackparticleasmallspheroidallyshaped,paracrystalline,non-discretecomponentofanaggregate;itcanonly be separated from the aggregate by fracturing; carbon black particle size is a distributional property; therefore, the term particle size imp
7、lies the mean value from multiple measurements. 3.1.1.2 carbon black aggregatea discrete, rigid colloidal entity that is the smallest dispersible unit; it is composed of extensively coalesced particles; carbon black aggregate size is a distributional property; therefore, the term aggregate size impl
8、ies the mean value from multiple measurements. 3.1.1.3 statistical thickness surface area (STSA)the external specic surface area of carbon black that is calculated from nitrogen adsorption data using the de Boer theory and a carbon black-specic model. 3.1.1.4 glow dischargea plasma of ionized gas th
9、at is formed in a high-voltage eld at pressures of about 3 to 20 Pa (25 to 150 10 -3 torr); an alternating current (a-c) glow discharge using air is effective in cleaning and oxidizing the surface of carbon substrates to improve the wetting characteristics of polar vehicles containing pigment disper
10、sions. 3.1.1.5 substratea thin lm that is used to support electron microscope specimens; evaporated carbon lms are commonly used because of relatively good mechanical strength, stability, and conductivity. 3.1.2 Aggregate Dimensional Properties from Image Analysis: 3.1.2.1 area (A)the two-dimensiona
11、l projected area of the carbon black aggregate image. 3.1.2.2 perimeter (P)the total boundary length of an aggregate. 3.1.2.3 volume (V)an estimate of the volume of the carbon black aggregate using stereological principles. 1 This test method is under the jurisdiction of ASTM Committee D24 on Carbon
12、 Black and is the direct responsibility of Subcommittee D24.81 on Carbon Black Microscopy and Morphology. Current edition approved Oct. 1, 2013Jan. 1, 2014. Published October 2013January 2014. Originally approved in 1980. Last previous edition approved in 20112013 as D384907 (2011).D384913. DOI: 10.
13、1520/D3849-13.10.1520/D3849-14. 2 ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatserviceastm.org.ForAnnualBookofASTMStandards volume information, refer to the standards Document Summary page on the ASTM website. This document is not anASTM standard and is i
14、ntended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the cu
15、rrent version of 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 States 13.1.3 Image Analysis: 3.1.3.1 dilationthe converse of erosion; this process is accomplished
16、 by changing any OFF pixel to ON if it has greater than a preset minimum of ON neighbors, causing image features to grow in size, which lls in small breaks in features, internal voids, or small indentations along the feature surface. 3.1.3.2 erosionthe process by which image features are reduced in
17、size by selectively removing pixels from their periphery; it consists of examining each binary pixel and changing it from ON to OFF if it has greater than a preset minimum of neighbors thatareOFF;itservesanumberofusefulfunctions,suchassmoothingfeatureoutlinesandseparatingfeaturestouchingeachother. 3
18、.1.3.3 featureareaswithinasinglecontinuousboundarythathavegray-levelrangesthatallowthemtobedistinguishedfrom the background area outside the feature via thresholding. 3.1.3.4 thresholdingselecting a range of brightness such that discrimination is possible between the feature and the background; the
19、gray levels within carbon black images become lower with decreasing particle size. 4. Signicance and Use 4.1 Carbonblackmorphologysignicantlyaffectsthetransientandend-usepropertiesofcarbonblackloadedpolymersystems. A carbon blacks particle size distribution is its single most important property, and
20、 it relates to degree of blackness, rubber reinforcement, and ability to impart UV protection. For a given loading of carbon black, blackness, reinforcement, and UV protection increase with smaller particle size. Aggregate size and shape (structure) also affect a carbon blacks end-use performance, a
21、s higher carbon black structure increases viscosity and improves dispersion. The stiffness (modulus) of elastomer systemsbecomessignicantlyhigherwithincreasingstructure.Thepreferredmethodformeasuringcarbonblackmorphology(for example, size and shape) is transmission electron microscopy (TEM), but due
22、 to the semi-quantitative nature of TEM, it is not suited for mean particle size (MPS) certication. 4.2 Carbon black aggregate dimensional and shape properties are dependent upon the nature of the system in which the sample is dispersed, as well as the mixing procedure. Test MethodA Morphological Ev
23、aluation (Semi-Quantitative) Via Transmission Electron Microscopy 5. Summary of Test Method 5.1 Transmission electron microscopy (TEM) is utilized to measure the morphological properties of carbon black.Avariety of dispersion methods are offered depending upon the sample type. Both dry black and CAB
24、 chip dispersions are used for measuring themorphologyofbulkcarbonblack.Apyrolysistechniqueisincludedthatfacilitatestheremovalofcarbonblackfromvulcanized rubber. This aforementioned technique can be employed to identify the carbon black type from an end use product. It should be noted that the accur
25、acy and precision of MethodAis insufficient for generating quantitative data as required in the case of MPS certication. Please refer to Method B for MPS certication. 6. Apparatus 6.1 Electron Microscope, transmission-type, with a point-to-point resolution of 1.0 nm or better. Operating voltages sho
26、uld be high enough to provide the desired resolution and low enough to produce images of sufficient contrast. Recommended voltages can be in the 60 to 120 kV range. The microscope column should contain a liquid nitrogen-cooled anti-contamination device or a cold nger to reduce sample contamination a
27、nd to maintain column cleanliness. For image acquisition, the microscope should include a charge-coupled device (CCD) camera mounted either above or below the instruments viewing chamber. 6.2 ImageAnalysisSystem,consistingatminimumofaTEM-interfacedcameracapableof640480pixelorbetterresolution, a comp
28、uter equipped with frame grabbing hardware to capture TEM images digitally, and software to perform morphological operations and measurements on image features and store resulting data. Operations must include background/noise elimination, thresholding, and edge smoothing. Area and perimeter are the
29、n measured on features in the processed images. 6.3 Two-Roll Mill. 6.4 Vacuum Evaporator, standard-type, for preparing carbon lms to be used as substrates for electron microscopy. The evaporator should be capable of reducing the absolute pressure to 1.3 mPa (1 10 -5 torr) and should also contain the
30、 necessary apparatus for a-c glow discharge. 6.5 Ultrasonic Generator, variable power tank-type or probe that provides sufficient energy to give acceptable dispersion. 6.6 Dry Box, capable of maintaining a relative humidity level of no greater than 30%. 6.7 Analytical Balance, with an accuracy of ab
31、out 0.5 mg. 6.8 Electrically Heated Tube Furnace, capable of being heated to 800 to 900C under an inert environment, with the ability to introduce and remove the sample boat to the heated zone without allowing oxygen intrusion. 6.9 Pyroprobe, capable of being heated from 150 to 1000C in an inert env
32、ironment. 6.10 Carbon Rods, approximately 3.1 mm in diameter. D384914 26.11 Carbon Rod Sharpener. 6.12 Glass Microscope Slides, 25 by 75-mm. 6.13 Test Tubes, 75 by 10-mm, 4-cm 3 capacity, 0.5-mm wall thickness, with corks. 6.14 Transfer Pipets, disposable Pasteur-type, 225 mm long, 1-mm inside diame
33、ter at tip. 6.15 Rubber Bulbs, for pipets. 6.16 Glass Vials, 40-cm 3 capacity, with solvent-resistant tops. 6.17 Bchner Funnel, No. 3, 111-mm inside diameter. 6.18 Filter Paper, general purpose. 6.19 Carbon Coated Electron Microscope Specimen Grids, 3-mm diameter, 200 to 300 mesh. Commercially avail
34、able or can be prepared as described in Annex A1. 6.20 Wire Screening, with openings approximately 1 mm 2 . 6.21 Tweezers, ne-tipped. 6.22 Spatulas, micro-type with V-shaped spoon that is approximately 2 mm wide at top and 12.5 mm long. 6.23 Fluorocarbon Duster. 6.24 Lens Tissue, lint-free. 6.25 Por
35、celain Boats, for pyrolysis, 98 mm long, 15 mm wide at top. 6.26 Centrifuge, high speed (15000 to 20000 r/min) with head for 75 by 10 mm test tubes. 6.27 Beakers, 2000-cm 3 capacity. 7. Reagents and Materials 7.1 Chloroform, reagent grade. 7.2 Tetrahydrofuran (THF), reagent grade. 7.3 1,2-Dichloroet
36、hane, 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. Sample PreparationDispersion Procedures 8.1 Dry Carbon Black (Sonic Bath): 8.1.1 Weigh 8 to 10 mg of
37、carbon black into a test tube containing 1 cm 3 of solvent (typically chloroform or THF). NOTE1Withexperience,itmaynotbenecessarytoweigheachcarbonblacksample,asanestimatedamountfromthemicrospatulamaybesufficient. There is considerable latitude in the amount of carbon black used. The ner N100 and N20
38、0 blacks may require somewhat less carbon black than the coarser semi-reinforcing types. 8.1.2 Adjust the power of the ultrasonic bath for maximum agitation; this may require that the water level be adjusted.As the ultrasonic energy heats the water in the bath, ice should be added to control the tem
39、perature in order to maintain maximum dispersive capability. 8.1.3 Place the stoppered test tube containing the carbon black and solvent mixture into the most intense part of the ultrasonic eld and allow the mixture to agitate for 3 to 5 min. The test tube should be held with tongs or mounted in a s
40、imple wire holder. 8.1.4 Transfer a small portion of the concentrated carbon black-solvent mixture into another test tube containing 1 cm 3 of fresh solvent. The amount of concentrate required increases with particle size. Blend the mixture by repeatedly transferring the sample between the transfer
41、pipet and the test tube, then cork the test tube and repeat the ultrasonic dispersion procedure. 8.1.5 Checktheconcentrationofthediluteddispersionbyextractingasmallamountintothetipofthepipetandviewingagainst a white background. For tread grade carbon blacks, the dispersions should be relatively tran
42、sparent, becoming somewhat darker with increasing particle size. The diluted dispersions for very coarse carbon blacks such as N700 to N900 series will be on the thresholdofcompleteopacity.Ifnecessary,adjusttheconcentrationbyaddingmoreconcentrateorsolventasrequired,thenrepeat the ultrasonic agitatio
43、n. The volume of the carbon black-solvent mixture should be maintained at approximately 1 cm 3 . If considerable dilution is required, the excess volume above 1 cm 3 should be discarded. NOTE2Areasonabledegreeoflatitudeexistsforachievingtheproperconcentrationlevelsinthenaldispersionsfordifferentgrad
44、esofcarbonblack. Concentration and overall dispersion quality are best determined by screening the actual specimens in the electron microscope and then making the necessary adjustments. D384914 38.1.6 Place a specimen grid with carbon substrate (lm side up) on a piece of lter paper. Remove a small a
45、mount of the nal diluted dispersion using a fresh pipet and place one drop on the grid as close to the center as possible, from a height of about 12 mm.Allowthespecimentodryforabout1minonapieceoflterpaper.Thisspecimenpreparationprocedureshouldbeperformed in a dry box if the relative humidity in the
46、room exceeds 30%. 8.1.7 ForTEMgridsthatcontainformvarorresidualCAB(CABchipdispersions),placetheTEMgridinanappropriatesample holder, place in the pyrolysis chamber and allow adequate time for the chamber to be purged by an inert gas to prevent oxidation of the sample. Pyrolize the specimen grid at a
47、sufficient temperature (typically greater than 550C) to remove the poly (vinyl formal) lm or CAB, or both. 8.1.8 Acceptable dispersions of a carbon black in the dry state and removed from a rubber compound (SBR) are illustrated for N-220 and N-774 carbon blacks in Figs. 1 and 2. 8.2 Dry Carbon Black
48、 (Ultrasonic Probe): 8.2.1 Weigh 5 to 10 mg of carbon black into a 30-cm 3 glass vial and add approximately 20 cm 3 of solvent (typically chloroform). NOTE3Withexperience,itmaynotbenecessarytoweigheachcarbonblacksample,asanestimatedamountfromthemicrospatulamaybesufficient. There is considerable lati
49、tude in the amount of carbon black used. The ner N100 and N200 blacks may require somewhat less carbon black than the coarser semi-reinforcing types. 8.2.2 Place the vial containing the carbon black and solvent into an ice-water bath. 8.2.3 Insert the probe to a depth of approximately 2.5 cm into the vial and ultrasonicate at 40 to 50 watts for 10 min. NOTE 4The ultrasonic probe and ice-water bath containing the sample vial should be housed in an acoustic enclosure to reduce cavitation noise. 8.2.4 Transferasmallportion(ap
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