ASTM D2414-23

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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 current version
of the standard as published by ASTM is to be considered the official document.
Designation: D2414 − 22 D2414 − 23
Standard Test Method for
Carbon Black—Oil Absorption Number (OAN)
This standard is issued under the fixed designation D2414; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method covers the determination of the oil absorption number of carbon black.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids
D1765 Classification System for Carbon Blacks Used in Rubber Products
D1799 Practice for Carbon Black—Sampling Packaged Shipments
D1900 Practice for Carbon Black—Sampling Bulk Shipments
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries
D4821 Guide for Carbon Black—Validation of Test Method Precision and Bias
D5554 Test Method for Determination of the Iodine Value of Fats and Oils
2.2 DIN Standards:
DIN 16945 Testing of resins, hardeners and accelerators, and catalyzed resins
DIN EN ISO 660 Animal and vegetable fats and oils - Determination of acid value and acidity
3. Summary of Test Method
3.1 In this test method, oil is added by means of a constant-rate buret to a sample of carbon black in the mixer chamber of an
absorptometer. As the sample absorbs the oil, the mixture changes from a free-flowing state to one of a semiplastic agglomeration,
This test method is under the jurisdiction of ASTM Committee D24 on Carbon Black and is the direct responsibility of Subcommittee D24.11 on Carbon Black Structure.
Current edition approved June 1, 2022March 1, 2023. Published July 2022April 2023. Originally approved in 1965. Last previous edition approved in 20212022 as
D2414 – 21.D2414 – 22. DOI: 10.1520/D2414-22.10.1520/D2414-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Deutsches Institut fur Normung e.V.(DIN), Burggrafenstrasse 6, 10787 Berlin, Germany, http://www.din.de.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2414 − 23
with an accompanying increase in viscosity. This increased viscosity is transmitted to the torque-sensing system of the
absorptometer. When the viscosity of the mixture reaches a predetermined torque level, the absorptometer and buret will shut off
simultaneously. The volume of oil added is read from the direct-reading buret. The volume of oil per unit mass of carbon black
is the oil absorption number.
3.2 Either DBP, paraffin or Epoxidized Fatty Acid Ester (EFA) oils are acceptable for use with most standard pelleted grades of
carbon black including N-series carbon blacks found in Classification D1765. OAN testing using paraffin or EFA oils on some
standard blacks and specialty blacks including powder products may result in unacceptable differences as compared to OAN testing
with DBP oil. Paraffin and EFA oils are considered non-hazardous; some paraffin oils are FDA approved. For any of the oils,
Sections 8 – 12 (Calibration, Procedure, Calculation, and Report) are to be consistent with the oil selected for use. Referee testing
between suppliers and users should use DBP oil until such time that precision data are available for alternate oils.
4. Significance and Use
4.1 The oil absorption number of a carbon black is related to the processing and vulcanizate properties of rubber compounds
containing the carbon black.
5. Apparatus
5.1 Balance, analytical, with an 0.01-g sensitivity.
5.2 Oven, gravity-convection type, capable of maintaining 125° 6 5°C.
5.3 Spatula, rubber, 100-mm.
5.4 Absorptometer, equipped with a constant-rate buret that delivers 4 6 0.024 cm /min.
5.5 Desiccator.
6. Reagent and Standards
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
6.2 n-Dibutyl Phthalate, having a density of 1.042 to 1.047 Mg/m at 25°C and a relative density of 1.045 to 1.050 at 25°C.
6.3 Paraffın Oil, having a kinematic viscosity of 10 to 34 mm /s (cSt) at 40°C.
NOTE 1—Three paraffin oils have been found suitable including Marcol 82 from Exxon, 80/90 White Oil from Conoco-Phillips, and LC1 oil from Lab
Chemicals, Germany. All three oils are pharmaceutical or food grade oil, or both, based on available data.
6.4 Epoxidized Fatty Acid Ester (EFA), meeting the specifications listed in Annex A4. It is recommended to store the product at
temperatures between 7 and 30°C. If stored in sealed original containers, the product is stable for at least 12 months. For handling
and safety, please refer to safety data sheet.
6.5 ASTM D24 Standard Reference Blacks, SRB.
All apparatus are to be operated and maintained in accordance with the manufacturers’ directions for optimum performance.
Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K. and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
The sole source of supply of ASTM Standard Reference Blacks known to the committee at this time is Laboratory Standards and Technologies, 227 Somerset, Borger,
TX 79007, http://carbonstandard.com/. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will
receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D2414 − 23
7. Sampling
7.1 Samples shall be taken in accordance with Practices D1799 and D1900.
8. Oil Absorptometers, Instrument Calibration, and End-Point Procedures
8.1 Absorptometer:
8.1.1 Model—Three different types of absorptometers are in use: (1) early models based on springs and mechanical indication of
torque (Type A and B), (2) second generation absorptometers equipped with load cells and digital torque display (Type E ), and
(3) current model absorptometers which are designed with a torque measuring system that includes a micro-computer and software
7 7
to continuously record torque and oil volume with time (Types H and C and modified Type E ). Types A, B, and E are designed
to stop mixing at a predetermined, fixed torque level, which is the recommended procedure for measuring hard or tread blacks
(calibration Procedure A). The computer controlled models (Types H and C and modified Type E ) absorptometers can provide
an end-point at a fixed or predetermined torque level such that these types of absorptometers are well-suited for measuring OAN
of all types of carbon blacks.
8.1.2 Mixing Bowl—Typically the absorptometer is delivered with either a surface-treated stainless steel or anodized aluminum
mixing bowl. These bowls are considered acceptable provided they give the correct reading for the appropriate SRB reference
standards. The surface finish of the mixer chamber is critical for maintaining proper calibration, and the bowl should not be
modified to achieve calibration.
NOTE 2—Stainless steel chambers have been found satisfactory for the test when they are manufactured to a roughness value (Ra) of 2.5 6 0.4 μm (100
6 15 μin.) based upon 8 measurements. No single measurement should be greater than 3.6 μm (140 μin.) or less than 1.5 μm (60 μin.). Stainless steel
bowls purchased with an absorptometer have been pre-polished for 16 h to minimize bowl surface changes affecting calibration during their initial use.
It is recommended that new replacement stainless steel bowls should also be pre-polished in the same manner (see Annex A3).
8.2 Instrument Calibration—Several components influence the calibration: the dynamometer torque spring or the load cell, the
torque limit switch or the indicator set point, the damper (oil damper or electronic damping), and the mixing head consisting of
two counter rotating blades and a mixing bowl. It is necessary that all of these components are in good condition and are properly
adjusted to achieve acceptable calibration.
8.2.1 Rotor Blades—The speed of the motor driving the rotor blades is either fixed (Type A and B) or has to be set (Type E, C,
and H) to 125 r/min. Due to a gear, one blade spins at 125 r/min, the other blade at 250 r/min.
8.2.2 Constant-Rate Buret—The delivery rate of the buret is to be 4 cm /min. See Annex A1 for detailed instructions on the
procedure for calibration check of the constant-rate buret.
8.2.3 Spring Tension (Type A and B)—It is recommended that the torque spring is adjusted so that the SRB F standard will develop
a maximum torque between 70 % and full-scale deflection. This is achieved by selecting the appropriate spring strength and
adjusting the spring tension in accordance with the instructions of the manufacturer.
NOTE 3—The absorptometers Type E, C, and H are calibrated by the manufacturer to give a direct reading of torque in mNm; this calibration should not
be modified in order to achieve a desired level of torque. If calibration is necessary, refer to the instrument manufacturer’s recommendations. The
instrument torque calibration should not be confused with the torque limit switch described in 8.3.1.
8.2.4 Damper—For the Type A absorptometer, it is recommended to keep the valve of the oil damper fully closed. The Type B
absorptometer shall provide a full-scale recovery of 3 6 0.5 s; the valve has to be adjusted accordingly. The Type E absorptometer
has an electronic damping option and Types C and H have appropriate software damping. Make sure that these damping options
are activated.
8.2.5 Stainless Mixing Bowls—When replacing an old mixing bowl with a new one, further pre-polish may be needed after
installation even if those mixing bowls are typically already pre-polished by the manufacturer. The surface finish of the mixer
chamber is critical for maintaining proper calibration, and the bowl shall not be modified to achieve calibration other than described
in Annex A3.
Type E absorptometers can be modified with additional hardware and micro-computer system.
D2414 − 23
8.3 End-Point Procedures:
8.3.1 Torque Limit Switch (TLS) or the Indicator Set Point—If the end-point of the test is determined by a fixed torque limit, the
setting of the TLS, also called indicator set-point, has to be selected using one of the following three procedures:
8.3.1.1 Procedure A: End-Point at Fixed Torque Level—This “classical” method is well suited for most hard or tread blacks but
may lead to problems when low-torque carcass blacks are to be tested; proceed to Procedure B for low-torque carbon blacks. For
Type A, B, and E absorptometers, adjust the TLS or the indicator set point in such way that the current SRB F standard gives the
correct target value within the limits as defined in Guide D4821. For Type E, C, and H absorptometers dedicated to testing tread
blacks only, there is no advantage to setting the TLS based on the SRB F standard; for these absorptometers, set the TLS to 3500
mNm for DBP oil, or 4000 mNm for paraffin oil.
8.3.1.2 Procedure B: End-Point at 70 % of the Maximum Torque—Certain carcass blacks and thermal blacks may fail to give an
end-point due to insufficient torque level. Therefore, the preferred method for testing soft blacks is to record the torque curve using
a chart-recorder or a data acquisition system and to read the end-point at 70 % of the maximum of the torque achieved. Set the
TLS or the indicator set point to full scale in order to disable the automatic shut-off of the absorptometer.
9. Normalization using Standard Reference Blacks (SRB)
9.1 Physically calibrate the test apparatus including TLS adjustment using the instructions in 8.3.
9.2 Test the six ASTM Standard Reference Blacks (SRBs) in duplicate to establish the average measured value. Additional values
are added periodically, typically on a weekly basis. An alternative to periodic normalizations are daily additions of SRB
normalization tests such that the normalization curve is continuously maintained. The rolling average of the measured values is
computed from the latest four values.
9.3 For a tread or carcass-type normalization curve, all three SRBs should be included.
9.4 For a tread or carcass-type normalization curve, because of the differing grades in SRB series and material ages, all three SRBs
should normally be from the same series (example: series-9). However, when the normalization range provided by a given SRB
set does not cover the normalization range needed, follow Guide D4821 Subsection 8.2 to choose the proper alternative SRB
material to be used in the normalization curve.
NOTE 4—When only tread- or carcass-type carbon blacks are to be tested, the normalization can be limited to either the three tread SRBs (example: 9A,
–5 3 3
9B, 9C for typical OAN levels or 9A, 9C, 9H for high OAN levels > 125 10 m /kg (cm /100 g)) or the three carcass-type SRBs (example: 9D, 9E,
9F).
9.5 Perform a regression analysis using the standard value of the standard (y value) and the rolling average measured value (x
value). Separate carcass and tread normalization curves should be maintained.
9.6 Normalize the values of all subsequent samples using the regression equation as follows:
Normalized value 5 measured value*slope 1intercept (1)
~ !
9.7 For normalized values of the SRBs that are consistently outside the x-chart limits listed in Guide D4821, the instrument
calibration and end-point procedures in Section 8 should be reviewed.
9.8 When any absorptometer or calibration changes occur, a new normalization curve must be initiated as described in Section
9.
9.9 In most instances, if normalized values of the SRB’s are not within x-chart limits provided in Guide D4821, and the
normalizations are current, it will be necessary to replace the mixer chamber with one of proper surface finish. Review Appendix
X1.
D2414 − 23
10. Procedure
10.1 Dry an adequate sample for 1 h in the specified oven set at 125°C. Prior to testing, cool the sample in a desiccator for a
minimum of 30 min.
NOTE 5—Very fluffy or low density material, for example, non-beaded, may require a pre-densification step prior to testing. Fill sufficient material for
OAN testing into a paper bag, close the bag properly and start carefully compressing the sample by hand. Let the air pass through the paper bag and then
compress more rigorously to densify the sample so that the desired sample mass fits into the mixing chamber. Failure to densify samples can lead to high
uncertainty in OAN results. If this densification step did not reduce sample volume sufficiently for the weights listed in 10.2, refer to Note 6.
10.2 Weigh the sample to the nearest 0.01 g. The recommended masses are as follows:
Carbon Black Mass, g
N630, N642, and N700 series, except N765 25
N800 and N900 series, SRB-9D 40
N800 and N900 series, SRB D-7, D-8 and D-9 40
All others 20
All others 20*
*See Note 6 for exceptions.
NOTE 6—Non-ASTM grades may differ significantly in their Oil Adsorption Number from the N-grades; therefore, the 20-g sample mass listed above
for “All Others” might result in under- or overfilling of the OAN mixing chamber. In these cases, alternative sample masses can be used for grades that
are NOT included in Classification D1765.
10.3 It is recommended that a testing temperature of 23 6 5°C be maintained, as measured by a thermocouple in the mixing bowl.
If a temperature controllable mixing bowl is not available, keep the bowl temperature below 30°C and comply with Note 57 and
Note 68 while running the samples.
NOTE 7—If the absorptometer has remained idle for more than 15 min and a temperature controllable bowl is not being used, a 10-min warm-up sample
must be run before beginning a test. It is important that the mixer chamber temperature be kept uniform. Preferably, allow 5 min between the end of one
test and the start of another.
NOTE 8—It is important that the temperature of the bowl be the same for machine calibration as for oil absorption testing. ASTM task group work has
shown that an increase in bowl temperature can cause higher values that increased variability in bowl temperatures cause increased test variability.
10.4 Transfer the sample to the absorptometer mixer chamber and replace the chamber cover. For Type H, close the safety door
surrounding the mixing chamber.
10.5 Position the buret delivery tube over the hole in the mixer chamber cover, and for Types A, B, or E set the buret digital counter
to zero (Types C and H have automatic reset). Insure the buret delivery tubes have no air bubbles.
A
TABLE 1 Precision Parameters for Test Method D2414, Method N/A (Type 1 Precision)
−5 3 3
Units 10 m /kg (cm /100 g)
Number of
Laborato-
ries
Mean
B
Material Period (M/H/L) Sr r (r) SR R (R)
Level
SRB-9A Mar 2013 77(0/1/1) 71.5 0.47 1.33 1.9 1.55 4.38 6.1
SRB-9B Mar 2016 87(0/2/0) 98.9 0.40 1.14 1.1 1.11 3.14 3.2
SRB-9D Mar 2018 75(2/2/1) 34.5 0.25 0.72 2.1 0.72 2.03 5.9
SRB-9E Aug 2016 81(1/3/0) 89.2 0.44 1.24 1.4 0.89 2.53 2.8
SRB-9F Mar 2015 74(1/0/0) 134.5 0.53 1.51 1.1 1.59 4.51 3.3
SRB-9G Aug 2017 74(0/2/1) 38.6 0.23 0.64 1.7 1.76 4.98 12.9
SRB-9C Aug 2019 79(1/2/0) 124.4 0.44 1.24 1.0 1.23 3.49 2.8
SRB-9A2 Aug 2018 76(0/2/0) 71.4 0.34 0.97 1.4 1.18 3.34 4.7
Mar/Apr
SRB-9H 74(1/1/0) 178.3 0.57 1.63 0.9 1.92 5.43 3.0
Average 94.0
Pooled Values 0.42 1.19 1.3 1.38 3.90 4.1
A
Preferred precision shown in bold text.
B
M = number of outliers for Mean; H = number of outliers for High variation; L = number of outliers for Low variation.
D2414 − 23
10.6 Activate the “start” button. On the Type E absorptometer, activate both “start” buttons simultaneously. The apparatus will
operate until one of the following conditions are met: 1) sufficient torque has developed to activate the torque-limit switch, which
will halt the absorptometer and buret; 2) the sample torque has reached a maximum and then dropped below maximum torque for
a preset period of time (using Procedure B).
NOTE 9—In the event that an endpoint is not obtained (maximum torque blacks using a coarse grinder such as a coffee mill. The carbon black should be milled for only a few seconds to allow sufficient grind time to change
the pellets to powder form. High-speed micronizing mills and air-jet mills are not acceptable, as they can reduce the carbon black structure.
10.7 For Type B and E oil absorptometers, record the volume of oil used as indicated by the buret digital counter. For Type C and
H oil absorptometers, the normalized OAN test results are obtained directly from
...

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Contact ASTM International (www.astm.org) for the latest information
Designation: D2414 − 23
Standard Test Method for
Carbon Black—Oil Absorption Number (OAN)
This standard is issued under the fixed designation D2414; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope Gravity of Liquids by Digital Density Meter
D4483 Practice for Evaluating Precision for Test Method
1.1 This test method covers the determination of the oil
Standards in the Rubber and Carbon Black Manufacturing
absorption number of carbon black.
Industries
1.2 The values stated in SI units are to be regarded as the
D4821 Guide for Carbon Black—Validation of Test Method
standard. The values given in parentheses are for information
Precision and Bias
only.
D5554 Test Method for Determination of the Iodine Value of
1.3 This standard does not purport to address all of the
Fats and Oils
safety concerns, if any, associated with its use. It is the
2.2 DIN Standards:
responsibility of the user of this standard to establish appro-
DIN 16945 Testing of resins, hardeners and accelerators, and
priate safety, health, and environmental practices and deter-
catalyzed resins
mine the applicability of regulatory limitations prior to use.
DIN EN ISO 660 Animal and vegetable fats and oils -
1.4 This international standard was developed in accor-
Determination of acid value and acidity
dance with internationally recognized principles on standard-
3. Summary of Test Method
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1 In this test method, oil is added by means of a
mendations issued by the World Trade Organization Technical
constant-rate buret to a sample of carbon black in the mixer
Barriers to Trade (TBT) Committee.
chamber of an absorptometer. As the sample absorbs the oil,
the mixture changes from a free-flowing state to one of a
2. Referenced Documents
semiplastic agglomeration, with an accompanying increase in
2.1 ASTM Standards:
viscosity. This increased viscosity is transmitted to the torque-
D445 Test Method for Kinematic Viscosity of Transparent
sensing system of the absorptometer. When the viscosity of the
and Opaque Liquids (and Calculation of Dynamic Viscos-
mixture reaches a predetermined torque level, the absorptom-
ity)
eter and buret will shut off simultaneously. The volume of oil
D1218 Test Method for Refractive Index and Refractive
added is read from the direct-reading buret. The volume of oil
Dispersion of Hydrocarbon Liquids
per unit mass of carbon black is the oil absorption number.
D1765 Classification System for Carbon Blacks Used in
3.2 Either DBP, paraffin or Epoxidized Fatty Acid Ester
Rubber Products
(EFA) oils are acceptable for use with most standard pelleted
D1799 Practice for Carbon Black—Sampling Packaged
grades of carbon black including N-series carbon blacks found
Shipments
in Classification D1765. OAN testing using paraffin or EFA
D1900 Practice for Carbon Black—Sampling Bulk Ship-
oils on some standard blacks and specialty blacks including
ments
powder products may result in unacceptable differences as
D4052 Test Method for Density, Relative Density, and API
compared to OAN testing with DBP oil. Paraffin and EFA oils
are considered non-hazardous; some paraffin oils are FDA
approved. For any of the oils, Sections 8 – 12 (Calibration,
This test method is under the jurisdiction of ASTM Committee D24 on Carbon
Procedure, Calculation, and Report) are to be consistent with
Black and is the direct responsibility of Subcommittee D24.11 on Carbon Black
Structure. the oil selected for use. Referee testing between suppliers and
Current edition approved March 1, 2023. Published April 2023. Originally
users should use DBP oil until such time that precision data are
approved in 1965. Last previous edition approved in 2022 as D2414 – 22. DOI:
available for alternate oils.
10.1520/D2414-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from Deutsches Institut fur Normung e.V.(DIN), Burggrafenstrasse 6,
the ASTM website. 10787 Berlin, Germany, http://www.din.de.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2414 − 23
4. Significance and Use 8. Oil Absorptometers, Instrument Calibration, and End-
Point Procedures
4.1 The oil absorption number of a carbon black is related to
the processing and vulcanizate properties of rubber compounds 8.1 Absorptometer:
containing the carbon black. 8.1.1 Model—Three different types of absorptometers are in
use: (1) early models based on springs and mechanical indica-
tion of torque (Type A and B), (2) second generation absorp-
5. Apparatus
tometers equipped with load cells and digital torque display
5.1 Balance, analytical, with an 0.01-g sensitivity.
(Type E ), and (3) current model absorptometers which are
5.2 Oven, gravity-convection type, capable of maintaining
designed with a torque measuring system that includes a
125° 6 5°C.
micro-computer and software to continuously record torque
and oil volume with time (Types H and C and modified Type
5.3 Spatula, rubber, 100-mm.
7 7
E ). Types A, B, and E are designed to stop mixing at a
5.4 Absorptometer, equipped with a constant-rate buret that
predetermined, fixed torque level, which is the recommended
delivers 4 6 0.024 cm /min.
procedure for measuring hard or tread blacks (calibration
5.5 Desiccator.
Procedure A). The computer controlled models (Types H and C
and modified Type E ) absorptometers can provide an end-
6. Reagent and Standards
point at a fixed or predetermined torque level such that these
types of absorptometers are well-suited for measuring OAN of
6.1 Purity of Reagents—Reagent grade chemicals shall be
all types of carbon blacks.
used in all tests. Unless otherwise indicated, it is intended that
8.1.2 Mixing Bowl—Typically the absorptometer is deliv-
all reagents shall conform to the specifications of the Commit-
ered with either a surface-treated stainless steel or anodized
tee on Analytical Reagents of the American Chemical Society,
aluminum mixing bowl. These bowls are considered accept-
where such specifications are available. Other grades may be
able provided they give the correct reading for the appropriate
used, provided it is first ascertained that the reagent is of
SRB reference standards. The surface finish of the mixer
sufficiently high purity to permit its use without lessening the
chamber is critical for maintaining proper calibration, and the
accuracy of the determination.
bowl should not be modified to achieve calibration.
6.2 n-Dibutyl Phthalate, having a density of 1.042 to 1.047
NOTE 2—Stainless steel chambers have been found satisfactory for the
Mg/m at 25°C and a relative density of 1.045 to 1.050 at 25°C.
test when they are manufactured to a roughness value (Ra) of 2.5 6
6.3 Paraffın Oil, having a kinematic viscosity of 10 to
0.4 µm (100 6 15 µin.) based upon 8 measurements. No single measure-
34 mm /s (cSt) at 40°C. ment should be greater than 3.6 µm (140 µin.) or less than 1.5 µm (60
µin.). Stainless steel bowls purchased with an absorptometer have been
NOTE 1—Three paraffin oils have been found suitable including Marcol
pre-polished for 16 h to minimize bowl surface changes affecting
82 from Exxon, 80/90 White Oil from Conoco-Phillips, and LC1 oil from
calibration during their initial use. It is recommended that new replace-
Lab Chemicals, Germany. All three oils are pharmaceutical or food grade
ment stainless steel bowls should also be pre-polished in the same manner
oil, or both, based on available data.
(see Annex A3).
6.4 Epoxidized Fatty Acid Ester (EFA), meeting the speci-
8.2 Instrument Calibration—Several components influence
fications listed in Annex A4. It is recommended to store the
the calibration: the dynamometer torque spring or the load cell,
product at temperatures between 7 and 30°C. If stored in sealed
the torque limit switch or the indicator set point, the damper
original containers, the product is stable for at least 12 months.
(oil damper or electronic damping), and the mixing head
For handling and safety, please refer to safety data sheet.
consisting of two counter rotating blades and a mixing bowl. It
is necessary that all of these components are in good condition
6.5 ASTM D24 Standard Reference Blacks, SRB.
and are properly adjusted to achieve acceptable calibration.
8.2.1 Rotor Blades—The speed of the motor driving the
7. Sampling
rotor blades is either fixed (Type A and B) or has to be set
7.1 Samples shall be taken in accordance with Practices
(Type E, C, and H) to 125 r/min. Due to a gear, one blade spins
D1799 and D1900.
at 125 r/min, the other blade at 250 r/min.
8.2.2 Constant-Rate Buret—The delivery rate of the buret is
to be 4 cm /min. See Annex A1 for detailed instructions on the
All apparatus are to be operated and maintained in accordance with the procedure for calibration check of the constant-rate buret.
manufacturers’ directions for optimum performance.
8.2.3 Spring Tension (Type A and B)—It is recommended
Reagent Chemicals, American Chemical Society Specifications , American
that the torque spring is adjusted so that the SRB F standard
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
will develop a maximum torque between 70 % and full-scale
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K. and the United States Pharmacopeia and
deflection. This is achieved by selecting the appropriate spring
National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
strength and adjusting the spring tension in accordance with the
6 instructions of the manufacturer.
The sole source of supply of ASTM Standard Reference Blacks known to the
committee at this time is Laboratory Standards and Technologies, 227 Somerset,
Borger, TX 79007, http://carbonstandard.com/. If you are aware of alternative
suppliers, please provide this information to ASTM International Headquarters.
Your comments will receive careful consideration at a meeting of the responsible Type E absorptometers can be modified with additional hardware and micro-
technical committee, which you may attend. computer system.
D2414 − 23
NOTE 3—The absorptometers Type E, C, and H are calibrated by the
9.4 For a tread or carcass-type normalization curve, because
manufacturer to give a direct reading of torque in mNm; this calibration
of the differing grades in SRB series and material ages, all
should not be modified in order to achieve a desired level of torque. If
three SRBs should normally be from the same series (example:
calibration is necessary, refer to the instrument manufacturer’s recommen-
series-9). However, when the normalization range provided by
dations. The instrument torque calibration should not be confused with the
torque limit switch described in 8.3.1. a given SRB set does not cover the normalization range
needed, follow Guide D4821 Subsection 8.2 to choose the
8.2.4 Damper—For the Type A absorptometer, it is recom-
proper alternative SRB material to be used in the normalization
mended to keep the valve of the oil damper fully closed. The
curve.
Type B absorptometer shall provide a full-scale recovery of 3
6 0.5 s; the valve has to be adjusted accordingly. The Type E
NOTE 4—When only tread- or carcass-type carbon blacks are to be
absorptometer has an electronic damping option and Types C
tested, the normalization can be limited to either the three tread SRBs
(example: 9A, 9B, 9C for typical OAN levels or 9A, 9C, 9H for high OAN
and H have appropriate software damping. Make sure that
–5 3 3
levels > 125 10 m /kg (cm /100 g)) or the three carcass-type SRBs
these damping options are activated.
(example: 9D, 9E, 9F).
8.2.5 Stainless Mixing Bowls—When replacing an old mix-
9.5 Perform a regression analysis using the standard value
ing bowl with a new one, further pre-polish may be needed
of the standard (y value) and the rolling average measured
after installation even if those mixing bowls are typically
value (x value). Separate carcass and tread normalization
already pre-polished by the manufacturer. The surface finish of
curves should be maintained.
the mixer chamber is critical for maintaining proper
calibration, and the bowl shall not be modified to achieve
9.6 Normalize the values of all subsequent samples using
calibration other than described in Annex A3.
the regression equation as follows:
8.3 End-Point Procedures:
Normalized value5 ~measured value*slope!1intercept (1)
8.3.1 Torque Limit Switch (TLS) or the Indicator Set
9.7 For normalized values of the SRBs that are consistently
Point—If the end-point of the test is determined by a fixed
outside the x-chart limits listed in Guide D4821, the instrument
torque limit, the setting of the TLS, also called indicator
calibration and end-point procedures in Section 8 should be
set-point, has to be selected using one of the following three
reviewed.
procedures:
8.3.1.1 Procedure A: End-Point at Fixed Torque Level—
9.8 When any absorptometer or calibration changes occur, a
This “classical” method is well suited for most hard or tread
new normalization curve must be initiated as described in
blacks but may lead to problems when low-torque carcass
Section 9.
blacks are to be tested; proceed to Procedure B for low-torque
9.9 In most instances, if normalized values of the SRB’s are
carbon blacks. For Type A, B, and E absorptometers, adjust the
not within x-chart limits provided in Guide D4821, and the
TLS or the indicator set point in such way that the current SRB
normalizations are current, it will be necessary to replace the
F standard gives the correct target value within the limits as
mixer chamber with one of proper surface finish. Review
defined in Guide D4821. For Type E, C, and H absorptometers
Appendix X1.
dedicated to testing tread blacks only, there is no advantage to
setting the TLS based on the SRB F standard; for these
10. Procedure
absorptometers, set the TLS to 3500 mNm for DBP oil, or 4000
mNm for paraffin oil. 10.1 Dry an adequate sample for 1 h in the specified oven
8.3.1.2 Procedure B: End-Point at 70 % of the Maximum
set at 125°C. Prior to testing, cool the sample in a desiccator for
Torque—Certain carcass blacks and thermal blacks may fail to a minimum of 30 min.
give an end-point due to insufficient torque level. Therefore,
NOTE 5—Very fluffy or low density material, for example, non-beaded,
the preferred method for testing soft blacks is to record the
may require a pre-densification step prior to testing. Fill sufficient material
torque curve using a chart-recorder or a data acquisition system
for OAN testing into a paper bag, close the bag properly and start carefully
and to read the end-point at 70 % of the maximum of the torque compressing the sample by hand. Let the air pass through the paper bag
and then compress more rigorously to densify the sample so that the
achieved. Set the TLS or the indicator set point to full scale in
desired sample mass fits into the mixing chamber. Failure to densify
order to disable the automatic shut-off of the absorptometer.
samples can lead to high uncertainty in OAN results. If this densification
step did not reduce sample volume sufficiently for the weights listed in
9. Normalization using Standard Reference Blacks (SRB)
10.2, refer to Note 6.
9.1 Physically calibrate the test apparatus including TLS
10.2 Weigh the sample to the nearest 0.01 g. The recom-
adjustment using the instructions in 8.3.
mended masses are as follows:
9.2 Test the six ASTM Standard Reference Blacks (SRBs)
Carbon Black Mass, g
in duplicate to establish the average measured value. Addi-
N630, N642, and N700 series, except N765 25
tional values are added periodically, typically on a weekly
N800 and N900 series, SRB D-7, D-8 and D-9 40
All others 20*
basis. An alternative to periodic normalizations are daily
*See Note 6 for exceptions.
additions of SRB normalization tests such that the normaliza-
tion curve is continuously maintained. The rolling average of NOTE 6—Non-ASTM grades may differ significantly in their Oil
Adsorption Number from the N-grades; therefore, the 20-g sample mass
the measured values is computed from the latest four values.
listed above for “All Others” might result in under- or overfilling of the
9.3 For a tread or carcass-type normalization curve, all three
OAN mixing chamber. In these cases, alternative sample masses can be
SRBs should be included. used for grades that are NOT included in Classification D1765.
D2414 − 23
10.3 It is recommended that a testing temperature of 23 6 results are obtained directly from the instrument software. A
5°C be maintained, as measured by a thermocouple in the summary of recommended end-point type is shown below for
mixing bowl. If a temperature controllable mixing bowl is not the two general types of carbon black:
available, keep the bowl temperature below 30°C and comply
Recommended End-Point Procedure and Results
End-Point
with Note 7 and Note 8 while running the samples.
CB Type Result*
Procedure
NOTE 7—If the absorptometer has remained idle for more than 15 min Hard/Tread A Normalized
Soft/Carcass B Normalized
and a temperature controllable bowl is not being used, a 10-min warm-up
*OAN test results should always be normalized to standard reference blacks
sample must be run before beginning a test. It is important that the mixer
(SRB) when reported.
chamber temperature be kept uniform. Preferably, allow 5 min between
the end of one test and the start of another.
10.8 Dismantle the mixer chamber and clean the mixing
NOTE 8—It is important that the temperature of the bowl be the same for
blades and chamber with a rubber spatula and reassemble.
machine calibration as for oil absorption testing. ASTM task group work
has shown that an increase in bowl temperature can cause higher values
10.9 Mixing chamber cleanup can be aided by the addition
that increased variability in bowl temperatures cause increased test
of dry carbon black to the mixing chamber prior to
variability.
disassembly, and the use of the preset cleanup cycle for Types
10.4 Transfer the sample to the absorptometer mixer cham-
E, C, and H (use of water to aid cleanup is not recommended).
ber and replace the chamber cover. For Type H, close the safety
NOTE 10—It is not necessary to clean and polish the mixing blades and
door surrounding the mixing chamber.
chamber with a solvent, but it is recommended to remove all visible
10.5 Position the buret delivery tube over the hole in the
residues by wiping the chamber and mixing blade surfaces.
mixer chamber cover, and for Types A, B, or E set the buret
digital counter to zero (Types C and H have automatic reset). 11. Calculation
Insure the buret delivery tubes have no air bubbles.
11.1 Calculate the oil absorption number of the sample, to
–5 3 3
10.6 Activate the “start” button. On the Type E
the nearest 0.1 10 m /kg (cm /100 g) as follows:
absorptometer, activate both “start” buttons simultaneously.
A
25 3
The apparatus will operate until one of the following condi- Oil absorption number, 10 m /kg5 × 100 × C 1D (2)
H J
B
tions are met: 1) sufficient torque has developed to activate the
where:
torque-limit switch, which will halt the absorptometer and
buret; 2) the sample torque has reached a maximum and then A = volume of oil used, cm ,
dropped below maximum torque for a preset period of time B = mass of tested sample, g,
C = slope of normalization curve (see Section 9), and
(using Procedure B).
D = y-intercept of normalization curve (see Section 9).
NOTE 9—In the event that an endpoint is not obtained (maximum torque
12. Report
carbon blacks using a coarse grinder such as a coffee mill. The carbon
black should be milled for only a few seconds to allow sufficient grind
12.1 Report the following information:
time to change the pellets to powder form. High-speed micronizing mills
12.1.1 Proper identification of the sample,
and ai
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