ASTM D3765-02
(Test Method)Standard Test Method for Carbon Black—CTAB (Cetyltrimethylammonium Bromide) Surface Area
Standard Test Method for Carbon Black—CTAB (Cetyltrimethylammonium Bromide) Surface Area
SCOPE
1.1 This test method covers the measurement of the specific surface area of carbon black exclusive of area contained in micropores too small to admit hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, commonly referred to as CTAB) molecules. This test method is suitable for characterizing rubber-grade carbon blacks of all types.
1.2 The values stated in SI units are to be regarded as the standard. The values given 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 responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D 3765 – 02
Standard Test Method for
Carbon Black—CTAB (Cetyltrimethylammonium Bromide)
1
Surface Area
This standard is issued under the fixed designation D 3765; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
4
1. Scope nate (Aerosol OT ) solution to a turbidity maximum end point
is used to determine the unadsorbed CTAB after removal of the
1.1 This test method covers the measurement of the specific
colloidally dispersed carbon black by ultrafiltration. All results
surface area of carbon black exclusive of area contained in
are scaled by using the Industry Tint Reference Black (ITRB)
micropores too small to admit hexadecyltrimethylammonium
as a primary standard and taking its accessible surface area to
bromide (cetyltrimethylammonium bromide, commonly re-
3 2
be exactly 83.0 3 10 m /kg.
ferred to as CTAB) molecules. This test method is suitable for
3.2 Titration of the unadsorbed CTAB with Aerosol OT
characterizing rubber-grade carbon blacks of all types.
solution is accomplished by the following:
1.2 The values stated in SI units are to be regarded as the
3.2.1 Part A—Automatic Titration.
standard. The values given in parentheses are for information
3.2.2 Part B—Manual Turbidity Titration.
only.
1.3 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 The CTAB molecule is relatively large; so it is not
responsibility of the user of this standard to establish appro-
adsorbed in micropores or on surface roughness. Thus, the
priate safety and health practices and determine the applica-
CTAB surface area reflects only the surface of the carbon black
bility of regulatory limitations prior to use.
that is available for interaction with rubber molecules.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
2 5.1 Analytical Balance, 0.1-mg sensitivity.
D 1193 Specification for Reagent Water
5
5.2 Ultrasonic Cleaning Bath, modified to incorporate
D 1799 Practice for Carbon Black—Sampling Packaged
3 integral magnetic stirring and vial holder to properly position
Shipments
two sample vials. (If desired, a separate ultrasonic cleaning
D 1900 Practice for Carbon Black—Sampling Bulk Ship-
6 7
3 bath and a separate magnetic stirrer may be used.)
ments
8
5.3 Magnetic Spinbars, chemically resistant covered (poly-
D 4483 Practice for Determining Precision for Test Method
3 chlorotrifluoroethylene or TFE-fluorocarbon), 6.4 or 4.8-mm
Standards in the Rubber and Carbon Black Industries
1 3
( ⁄4 or ⁄16-in.) diameter, and length nearly equal to the diameter
3
3. Summary of Test Method of 50 or 100-cm Berzelius beakers, glass vials, or other glass
vessels.
3.1 The isotherm for adsorption of an aqueous solution of
9
5.4 Microfiltration Membrane Filter Disks, 47-mm diam-
CTAB on carbon black has a long horizontal plateau corre-
eter.
sponding to a monolayer coverage of the substrate surface from
which the adsorbate is not sterically excluded. The CTAB
adsorption by carbon black is independent of residual tars and
4
Aerosol OT is a registered trademark of the American Cyanamid Co., Process
functional groups containing hydrogen and oxygen, etc. Rapid
Chemicals Dept., Wayne, NM 07470.
5
Available from L.A. King Manufacturing Corp., LAKO Division, P.O. Box
equilibration is achieved by using mechanical stirring and
2415, Tulsa, OK 74101.
ultrasonic vibration. Titration with dioctyl sodium sulfosucci-
6
Millipore Corp., Bedford, MA 01730, Catalog No. XX 66 00900 is satisfactory.
7
Sargent magnetic stirrer S-76490 is satisfactory.
8
Examples of suitable spinbars are Catalog No. 9235-U7, A. H. Thomas Co.,
1
This test method is under the jurisdiction of ASTM Committee D24 on Carbon Philadelphia, PA 19105, or Catalog No. S-76497-30, Sargent Welch Scientific Co.,
Black and is the direct responsibility of Subcommittee D24.21 on Adsorptive Skokie, IL 60076.
9
Properties of Carbon Black. This test is based on the use of three brands of microfiltration membrane: (1)
Current edition approved Nov. 10, 2002. Published December 2002. Originally Gelman HT-200, Gelman No. 66199, Baxter Scientific Cat. No. F2988-2, Baxter
approved in 1979. Last previous edition approved in 1999 as D 3765 – 99.
Scientific Products, 1430 Waukegan Rd., McGraw Park, IL 60085; (2) Microfiltra-
2
Annual Book of ASTM Standards, Vol 11.01.
tion Systems, Cat. No. A-010A047A, 6800 Sierra Court, Dublin, CA 94566; and (3)
3
Annual Book of ASTM Standards, Vol 09.01.
Millipore Cat. No. SAIJ076H7 Filters, Millipore Corp., Bedford, MA 01730.
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