ASTM D3849-95a(2000)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3849 – 95a (Reapproved 2000)
Standard Test Method for
Carbon Black — Primary Aggregate Dimensions from
Electron Microscope Image Analysis
This standard is issued under the fixed designation D 3849; 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.
1. Scope aggregate in a given direction. The mean chord (p A/P)isthe
average width of an aggregate in all directions.
1.1 This test method covers the morphological characteriza-
3.1.1.3 Feret’s diameter—the maximum spacing between
tion of carbon black primary aggregates from transmission
parallel tangents to an aggregate in a given direction. The
electron microscope images. The measurements are applicable
average Feret (L) is derived from an average of multiple
to carbon blacks in the dry (as manufactured) state, extracted
measurements at specific angular increments.
from unvulcanized rubber compounds and in a cellulose
3.1.1.4 length (L )—the longest Feret’s diameter of an
acetate butyrate paint chip dispersion. 1
aggregate.
1.2 The values stated in SI units are to be regarded as the
3.1.1.5 perimeter (P)—the total boundary length of an
standard. The values in parentheses are for information only.
aggregate.
1.3 This standard does not purport to address all of the
3.1.1.6 projected length (L )—the total length of an aggre-
safety concerns, if any, associated with its use. It is the 2
gate in a given direction, including the contribution of multiple
responsibility of the user of this standard to establish appro-
entrants. The projected length is equal to the number of scan
priate safety and health practices and determine the applica-
lines multiplied by a calibration factor that is equal to the scan
bility of regulatory limitations prior to use.
line spacing in the proper dimensional units (usually nanome-
2. Referenced Documents
tres for carbon blacks).
3.1.1.7 volume—the volume of carbon black aggregates
2.1 ASTM Standards:
may be measured directly by well-calibrated scanning mi-
D 297 Test Methods for Rubber Products—Chemical
crodensitometry (V) or geometrically (V ) as follows:
Analysis
D 1416 Test Methods for Rubber from Synthetic Sources—
V 5 8A /3P (1)
Chemical Analysis
3.1.1.8 width—the width of a carbon black aggregate may
D 3182 Practice for Rubber—Materials, Equipment, and
be described in terms of either the mean chord or Feret’s
Procedures for Mixing Standard Compounds and Prepar-
diameter. The average width (W) is defined as the mean chord
ing Standard Vulcanized Sheets
measured in a direction that is perpendicular to the longest
D 3191 Test Methods for Carbon Black in SBR (Styrene-
projection. W is equal to the projected area divided by the
Butadiene Rubber)—Recipe and Evaluation Procedures
longest projection. The average nondirectional width (W )is
D 3192 Test Methods for Carbon Black Evaluation in NR
equal to the mean chord (p A/P). The shortest width (W )is
(Natural Rubber)
equal to the shortest chord length and is derived from chord
sizing. The longest width (W ) is the shortest Feret’s diameter
3. Terminology
from multiple measurements in different directions.
3.1 Definitions:
3.1.2 Aggregate Nondimensional Shape Parameters
3.1.1 Aggregate Dimensional Properties from Image Analy-
3.1.2.1 circularity factor (C.F.)—the amount of deviation of
sis:
the two-dimensional projected aggregate area from a circle
3.1.1.1 area (A)—the two-dimensional projected area of the
expressed as follows:
carbon black aggregate image.
3.1.1.2 chord—the length of a scanning intercept across an C.F. 5 P /4pA (2)
3.1.2.2 form factor—the length/width ratio of the aggregate.
Some of the more commonly used ratios are as follows:
This test method is under the jurisdiction of ASTM Committee D24 on Carbon
Black and is the direct responsibility of Subcommittee D24.81 on Carbon Black F 5 L /W (3)
1 1 1
Microscopy.
Current edition approved Oct. 10, 1995. Published December 1995. Originally
F 5 L/W (4)
published as D 3849 – 80. Last previous edition D 3849 – 95. 2 1
Annual Book of ASTM Standards, Vol 09.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3849
F 5 L /W (5)
3.1.12.1 feature specific—image analysis data output that
3 1 3
provides individual measurements on each separate feature. A
multiparameter feature specific system enables the linking of
3.1.2.3 sphericity factor (S.F.)—The amount of deviation of
different type measurements for each separate feature, thus
the projected aggregate image from a sphere expressed as
enabling direct calculation of multivariate functions such as F,
follows:
P /A, etc.
3 2
S.F. 5 P /6p V (6)
3.1.12.2 field specific—an image analysis data output that
3.1.3 carbon black aggregate—a discrete, rigid colloidal
provides only field totals for each measured parameter. Num-
entity that is the smallest dispersible unit; it is composed of
ber average measurements are obtained by dividing the total
extensively coalesced particles.
measured parameter by the feature count.
3.1.4 carbon black particle—a small spheroidally shaped,
3.1.12.3 off-line—this type of image analysis system is
paracrystalline, non-discrete component of an aggregate; it is
based on scanning of negatives, transparencies, or photo-
separable from the aggregate only by fracturing.
graphic prints of the features utilizing an epidiascope or similar
3.1.5 chord sizing—an operation in which a specified length
optical device.
increment (DL) is cut off each detected chord in an image. All
3.1.12.4 on-line—a type of image analysis system in which
chords shorter than DL are completely eliminated from the
the scanner is a part of the microscope or directly coupled to
image and all chords larger than DL are shortened by DL. The
the microscope.
operation is repeated over a range that eventually eliminates all
3.1.13 microdensitometer—an image analysis device for
of the chords in the image and thereby provides a chord size
resolving gray-level differences within or between features and
distribution.
for integrating the optical density across scanned images of
3.1.6 detected image—an electronic monitor display of the
irregularly shaped objects. The latter provides three-
chords across the features in a given field. The detected image
dimensional size measurements (volume) of the particles or
should match the actual image as closely as possible.
aggregates of noncrystalline materials such as silicas, or poorly
3.1.7 epidiascope—a device for projecting images of pho-
crystallized materials such as carbon black.
tographic prints, negatives, or transparencies on the scanner
3.1.14 shading—variation in the electrical output from the
tube.
scanner from areas of identical gray level in different parts of
3.1.8 feature—areas within a single continuous boundary
the image. Shading can be due to optical effects, scanner
(for example, an aggregate image) that have an optical-density
deficiencies, or to artefacts in the specimen. A shading com-
value (gray-level range) that is distinct from the background
pensator is employed to correct any instrumental deficiencies.
area outside the feature.
3.1.15 specimen anticontamination device—a cold trap
3.1.8.1 feature cropping—the splitting of features at the
(cooled by liquid nitrogen) that is located in the vicinity of the
boundaries of the measuring frame that, if uncorrected, results
specimen in an electron microscope in order to prevent the
in erroneously small size values for these features.
deposition of contaminants, such as diffusion pump oil vapor
3.1.9 fiber optics coupling—bundles of small-diameter
from the vacuum system, on the specimen.
light-channeling fibers that transmit the optical image from the
3.1.16 specimen grid—a specimen mount in the form of a
fluorescent viewing screen within an electron microscope to
thin circular mesh about 3 mm in diameter that fits the standard
the scanner of the image analysis system with a minimal loss
specimen holders of transmission electron microscopes. Grids
of brightness.
are used to support the thin substrates required for electron
3.1.10 glow discharge—a plasma of ionized gas that is
microscopy and are made most commonly of copper. Tungsten
formed in a high-voltage field at pressures of about 3 to 20 Pa
grids are used when the specimen must be heated at elevated
−3
(25 to 150 3 10 torr). An alternating current (a-c) glow
temperatures.
discharge using air is effective in cleaning and oxidizing the
3.1.17 substrate—a thin cast or vacuum-evaporated film
surface of carbon substrates to improve the wetting character-
that is used to support electron microscope specimens. Evapo-
istics of polar vehicles containing pigment dispersions.
rated carbon films are a commonly used substrate because of
3.1.11 gray level—variations in the intensity of images in
relatively good mechanical strength, stability, and conductivity.
terms of the electrical output of the scanner. The brightest
region in an image gives the highest electrical output and is
4. Significance and Use
defined as“ white,” while the complete absence of light in a
4.1 Carbon black primary aggregate morphology signifi-
field is“ black.” The tone of detected features usually ranges
between these extremes and the electrical output signal is cantly affects the transient and end-use properties of black
loaded polymer systems. Vulcanizate hysteresis and strength
known as the gray level.
3.1.11.1 gray-level discrimination—the ability to distin- properties (tear, tensile, and abrasion resistance) increase with
diminishing aggregate size. Extrusion die swell diminishes and
guish between different gray levels within features or between
different features in a field. The gray levels within carbon black vulcanizate modulus increases with increasing aggregate ir-
regularity (for example, the amount of deviation from a
images in the electron microscope become lower with dimin-
ishing aggregate size. spherical shape).
3.1.12 image analysis—measurement of the size, shape, and 4.2 Carbon black aggregate dimensional and shape proper-
distributional parameters of feature images by electronic scan- ties are dependent upon the nature of the system in which the
ning methods. sample is dispersed, as well as the mixing procedure.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3849
5. Apparatus 1-mm inside diameter at tip.
5.13 Rubber Bulbs, for pipets.
5.1 Electron Microscope, transmission-type, with a point-
5.14 Glass Vials, 40-cm capacity, with solvent-resistant
to-point resolving power of 1.0 nm or better. Operating
tops.
voltages (electron beam) should include settings of 40 and 60
5.15 Glass Tubes, straight wall, flat bottom, 90 mm in
kV. The specimen chamber should contain an anticontamina-
height, 26 to 27-mm inside diameter.
tion device.
5.16 Glass Jars, 30-cm capacity, wide-mouth with solvent-
5.2 Image Analysis System, television scanner-type. The
resistant caps, height and outside diameter approximately 43
system shall also include a television monitor for viewing the
mm.
specimens, a well-defined measuring frame that is visible on
5.17 Glass Dishes, two 185 mm in diameter, 100 mm in
the monitor and has the capability of correcting for the effects
height.
of feature cropping at the borders, a compensator for eliminat-
5.18 Büchner Funnel, No. 3, 111-mm inside diameter.
ing shading effects, a detector for discerning the boundaries of
5.19 Vinyl Tubing, approximately 50 mm long, 12.5-mm
the carbon black aggregates at different gray levels, and one or
inside diameter.
more computer modules for converting the output of the
5.20 Clamp, hose cock, open-jaw type.
detector into dimensional information. Minimum requirements
5.21 Filter Paper, 125-mm diameter, fast.
for dimensional output are area, perimeter, average Feret’s
5.22 Electron Microscope Specimen Grids, 3-mm diameter,
diameter, and feature count. Desirable additional outputs are
300-mesh copper.
volume by microdensitometry and Feret’s diameters in differ-
5.23 Electron Microscope Specimen Grids, 3-mm diameter,
ent directions. The system shall contain one or more devices
200-mesh tungsten.
for automated data recording, processing, averaging, and
5.24 Specimen Grid Holders.
printing of results. Acceptable recorder-processing systems
5.25 Test Tube Holders, for 48 tubes up to 16 mm in outside
include an on-line computer, desk-top calculator, or a magnetic
diameter.
tape recorder-computer combination. The image analysis sys-
5.26 Wire Screening, with openings approximately 1 mm .
tem may be field or feature specific, the latter being preferred.
5.27 Forceps, fine-tipped, locking-type.
The system may be off-line or on-line. For the latter, a fiber
5.28 Tweezers, fine-tipped.
optics coupling between the scanner and electron microscope is
5.29 Spatulas, micro-type with V-shaped spoon that is
recommended.
approximately 2 mm wide at top and 12.5 mm long.
5.3 Vacuum Evaporator, standard-type, for preparing car-
5.30 Solvent Dispenser, portable high-speed type.
bon films to be used as substrates for electron microscopy. The
5.31 Fluorocarbon Duster.
evaporator should be capable of reducing the absolute pressure
−5
5.32 Lens Tissue, lint-free.
to 1.3 mPa (1 3 10 torr) and should also contain the
5.33 Porcelain Boats, for pyrolysis, 98 mm long, 15 mm
necessary apparatus for a-c glow discharge.
wide at top.
5.4 Ultrasonic Generator:
5.34 Centrifuge, 2094 rad/s (20 000 r/min) with head for 75
5.4.1 Dispersion Procedures A and C—Variable power
by 10 mm test tubes.
tank-type ultrasonic cleaning unit, 80 kHz, 100 W.
5.35 Test Tubes, polypropylene, 75 by 10 mm, 5 cm
5.4.2 Dispersion Procedure B—Probe-type ultrasonic gen-
capacity, 0.5 mm wall thickness with caps.
erator, 20 kHz, 150 W.
5.36 Beakers, 2000 cm capacity.
5.5 Dry Box, capable of maintaining a relative humidity
level of no greater than 30 %.
6. Reagents and Materials
5.6 Analytical Balance, with an accuracy of about 0.5 mg.
6.1 Castor Oil, laboratory grade.
5.7 Combustion Furnace and Tube—meeting the require-
6.2 Chloroform, reagent grade.
ments described in Methods D 1416 or D 297.
6.3 Collodion, typical commercial grade, U.S.P.
5.8 Carbon Rods, approximately
...