1、Designation: D7723 11Standard Test Method forRubber PropertyMacro-Dispersion of Fillers inCompounds1This standard is issued under the fixed designation D7723; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. 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 a procedure to measure themacro-dispersion of fillers in a rubber matrix by quantifyingthe surface roughne
3、ss of a freshly cut specimen using anoptical microscope in reflection mode.1.2 The method provides a procedure to measure the qualityof mixing of reinforcing fillers such as silica and carbon black,as well as inert fillers such as chalk, clay and other solids.1.3 The method includes a sample prepara
4、tion procedure forfilled uncured rubber compounds as well as filled cured rubbercompounds.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, assoc
5、iated 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 regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2663 Test Methods for Carbon BlackDispersion inRubberD305
6、3 Terminology Relating to Carbon Black3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 agglomerates, nany number of filler aggregates heldtogether by van der Waals Forces (carbon black) or hydrogenbonding (silica).3.1.2 macro dispersion, ndegree of distribution of fillerinto a
7、compound, generally on a scale of less than 100 m butgreater than 2 m; represents micron range agglomeration.3.1.3 nodges, nbumps in a cut surface caused by filleragglomerates in a rubber matrix.3.1.4 surface roughness, nthe bumps (nodges), or hillsand valleys that are on the visible side of a sampl
8、e.3.1.5 white area, nthe portion of the scan area whichcontains nodges, or other surface defects; it is described here aswhite, because the reflected light from these surface defects iswhite.4. Summary of Test Method4.1 This standard uses mathematical algorithms to quantifythe surface roughness of f
9、reshly cut rubber specimens asmeasured by a reflected light optical method in two dimen-sions.4.2 The reflected light optical method, generally used todetermine a comparative dispersion rating, is expanded to givequantitative data as to the size and number of nodges. Nodgesdo not show the actual siz
10、e of filler agglomerates. It is assumedthat as the sample is cut, large agglomerates are pushed to oneside or the other leaving a contoured surface. The diameter andfrequency of the surface contours are measured using imageprocessing. These contours are referred to as “nodges” todifferentiate them f
11、rom actual agglomerates. This data ispresented in histogram form of count versus nodge diameter,and allows calculating a measure of dispersion.5. Significance and Use5.1 The incorporation of fillers into the rubber matrix ischaracterized by their macrodispersion as an indicator of thequality of mixi
12、ng. This test method provides a measure of themacro-dispersion of reinforcing fillers, like silica and carbonblack, as well as of inert fillers. Based on their polymer nature,different types of rubbers can show a different degree ofacceptance for the incorporation of fillers, as indicated by theirma
13、cro-dispersion.5.2 Macro-dispersion of carbon black and silica in rubbercompounds may be measured by different methods. Carbonblack provides a direct physical reinforcement; silica requiresa silane coupling agent in order to initiate reinforcement, andtherefore, a different technology of mixing. Sil
14、ica is also a1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.12 on Processability Tests.Current edition approved May 1, 2011. Published July 2011. DOI: 10.1520/D7723-11.2For referenced ASTM standards, visit the ASTM webs
15、ite, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United Stat
16、es.non-conductor, making electrical methods of dispersion mea-surement impracticable. This test method is specifically appro-priate for the characterization of the microdispersion in silicatechnology.5.3 This test method also can measure the mixing quality ofcolored rubbers. It uses variable exposur
17、e in order to be able toimage a wide range of colors.5.4 This test method is intended for use in research anddevelopment as well as in quality control of filler processabilityin rubber and may be used for both the evaluation of produc-tion processes or referee purposes.6. Apparatus6.1 Razor Blade (r
18、ecommended) or Sharp KnifeThespecimen may be prepared using a static cut as shown in Fig.1 or cut while being bi-directionally elongated as shown in Fig.2.6.2 Reflected Light Microscope, with the following specifi-cations:6.2.1 Imaging power to resolve to 1 m, 3 m, or 10 mdepending on the instrument
19、 used.6.2.2 Dark field illumination as shown in Fig. 3.6.3 The light microscope is to be equipped with an imagesensor. The sensor used to capture the image is a common CCD(Charged Coupled Device) or CMOS (Complementary MetalOxide Semiconductor) sensor. In the dark field mode, anaperture is lit at a
20、30 angle for analysis. The sensor picks upthe reflection of bumps on the surface, nodges representingundispersed filler. Flat areas of the sample surface are dark.6.4 A scan is made by taking a digital gray-level image inthe dark field mode of the microscope with 1 m, 3 m, or 10m resolution.6.5 The
21、image captured by the sensor shall be digitized andanalyzed by the image processing software. The area of nodgesis represented as “White Area.” The percent White Area,URF%, is the percentage of the white area representing thenodges to the total area of the image. Based on this area ratio,percent dis
22、persion can be calculated.7. Calculation7.1 As the specimen is cut, the underlying agglomerates arepushed to one side or another resulting in hills and valleys onthe cut surface. They represent agglomerates under the surfaceof the cut. The nodge diameter that is calculated from theseimages is larger
23、 than the underlying agglomerate. For simpli-fication, nodge size is reported as Agglomerate Size andrepresented by a histogram (Fig. 4).7.2 In order to stay within the 2-100 m range of macro-dispersion defined in Terminology D3053, it is necessary todisregard small nodges that are covering the smal
24、ler agglom-erates by introducing a threshold of 5 m for the nodge size.The frequency of occurrence of nodges decreases with a higherlevel of dispersion. Dispersion, therefore, is calculated fromthe white area, which is determined from the radius andfrequency of all nodges greater than the nodge thre
25、shold.7.3 Calculate the White Area, URF%, as ratio to the totalscan area.7.4 Calculate the percent dispersion of fillers as follows:Dispersion % 5 100 100 URF%/L (1)where:URF% = % of total scan from of undispersed filler mea-sured in reflectionL = the filler volume fraction in the compound7.4.1 For
26、maximum accuracy, the filler volume fraction canbe calculated from the following expression, which alsoappears in Test Methods D2663:L 5compound density 3 filler massfiller density 3 compound mass(2)7.5 If the volume percentage of filler in the rubber com-pound L is either not given or unknown, calc
27、ulate the weightedpercent dispersion or Z Value as follows:Z value 5 100 100 URF% / 0.35 (3)The Z Value assumes a maximum of 35 % white area.8. Test Specimen8.1 The test specimen is prepared from a vulcanized orunvulcanized sample of a filled rubber compound. A razorblade cut shall be made, so that
28、two similar surfaces areexposed. The surfaces shall be bigger than 5 by 5 mm.8.1.1 When preparing the test specimen, it is recommendedthat a new razor blade be used for each cut. The abrasivenessof the rubber as well as contaminates from the rubber left onthe blade may affect successive cuts.8.1.2 T
29、he thickness of the uncut specimen shall be 5 to 10mm. Thicker specimens cause excessive drag between therazor blade and rubber and may affect the quality of the cut.8.1.3 The specimen shall be cut in one continuous motion.8.2 For unvulcanized samples, porosity which is generatedduring the slab prep
30、aration process should be eliminated. Thisis accomplished by pressing a hot sample while cooling. Thecut is made by placing the unvulcanized sample in a samplepreparation system, where it is pulled bi-directionally, while arazor cuts. This is not required, but also recommended forcured specimens. Th
31、e procedures specified in 7.1 shall befollowed for bi-directionally cut specimens.9. Procedure9.1 Aspecimen cut according to 8.1 or 8.2 shall be placed infront of the testing window within two minutes after cutting.9.2 A minimum of three scans of different locations of thefreshly cut surface shall b
32、e taken. Five scans of differentlocations are recommended. The user does not need to make afresh cut for the five scans.9.3 Apply the calculations expressed in Section 7.FIG. 1 Static CutD7723 11210. Report10.1 Percent Dispersion ValuesReport measured disper-sion ratings to the nearest 0.1 %.10.2 If
33、 the calculation of percent dispersion in 7.4 is used,report the L value used in the calculation. If the calculation ofthe Z value in 7.5 is used, report the use of the 0.35 Z factor inthe calculation.10.3 Agglomerate SizeReport the agglomerate size ashistogram in classes of a width of 3 m.10.4 Repo
34、rt the average agglomerate size. In instanceswhere a bimodal agglomerate distribution exists, two catego-ries may be listed.10.5 White AreaReport the ratio of area of the undis-persed filler to the total area.10.6 Compound IdentificationWhen possible, list perti-nent information regarding the follow
35、ing:10.6.1 Filler, type and loading,10.6.2 Other fillers, type and loading,10.6.3 Polymer type, and10.6.4 Extender oil, type and loading.11. Precision and Bias11.1 A precision and bias study for this test method iscurrently being planned.12. Keywords12.1 filler; incorporation; macro-dispersion; micr
36、o-roughness; reflected light microscopeFIG. 2 Bi-Directional CutFIG. 3 Darkfield IlluminationD7723 113ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that de
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39、hat your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprint
40、s (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. 4 Example HistogramD7723 114
