ASTM D3576-98
(Test Method)Standard Test Method for Cell Size of Rigid Cellular Plastics
Standard Test Method for Cell Size of Rigid Cellular Plastics
SCOPE
1.1 This test method covers the determination of the apparent cell size of rigid cellular plastics by counting the number of cell-wall intersections in a specified distance.
1.2 Procedure A requires the preparation of a thin slice, not more than one half the average cell diameter in thickness, that is mechanically stable. For most rigid cellular plastics this limits the test method to materials with an average cell size of at least 0.2 mm.
1.3 Procedure B is intended for use with materials whose friable nature makes it difficult to obtain a thin slice for viewing.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 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. Note 1-The annex to ISO 2896 is technically equivalent to this test method.
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Designation: D 3576 – 98
Standard Test Method for
Cell Size of Rigid Cellular Plastics
This standard is issued under the fixed designation D 3576; 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 * 3. Terminology
1.1 This test method covers the determination of the appar- 3.1 Definitions:
ent cell size of rigid cellular plastics by counting the number of 3.1.1 Definitions of terms applicable to this test method are
cell-wall intersections in a specified distance. given in Terminology D 883.
1.2 Procedure A requires the preparation of a thin slice, not
4. Summary of Test Method
more than one half the average cell diameter in thickness, that
4.1 Procedure A— The cellular plastic specimen is cut to
is mechanically stable. For most rigid cellular plastics this
limits the test method to materials with an average cell size of not more than one half the average cell diameter in thickness
on a slicer and the shadowgraph is projected on a screen by the
at least 0.2 mm.
use of a cell-size scale slide assembly and a projector. The
1.3 Procedure B is intended for use with materials whose
friable nature makes it difficult to obtain a thin slice for average chord length is obtained by counting the cells on
cell-wall intersections and converting this value to average cell
viewing.
1.4 The values stated in SI units are to be regarded as the size by mathematical derivation.
4.2 Procedure B— The cellular plastic specimen is sliced to
standard. The values given in parentheses are for information
only. provide a smooth surface. The cell walls are accented by the
use of a marking pen. The average chord length is obtained by
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the counting the cell wall intersections and converting this value to
average cell size by mathematical derivation.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use.
5.1 Several physical properties of rigid cellular plastics are
NOTE 1—The annex to ISO 2896 is technically equivalent to this test
dependent on cell size and cell orientation. Measuring water
method.
absorption and open-cell content in accordance with Test
2. Referenced Documents Method D 2842 and Test Method D 2856 requires knowledge
of surface cell volume, which uses cell size values in the
2.1 ASTM Standards:
calculations.
D 883 Terminology Relating to Plastics
5.2 This test method provides an apparent cell size because
D 2842 Test Method for Water Absorption of Rigid Cellular
it assumes that there is no measurable edge to edge or top to
Plastics
bottom variation in average cell size and that the cell size
D 2856 Test Method for Open-Cell Content of Rigid Cel-
3 distribution about the average cell size is normal. If the analyst
lular Plastics by the Air Pycnometer
is concerned there may be significant variation in either the
E 691 Practice for Conducting an Interlaboratory Study to
4 average cell size or the cell size distribution more detailed
Determine the Precision of a Test Method
analysis may be required.
2.2 ISO Standard:
5.3 Before proceeding with this test method, reference
ISO 2896 Cellular Plastics, Rigid—Determination of Water
5 should be made to the specification of the material being tested.
Absorption
Any test specimen preparation, conditioning, dimensions, or
testing parameters, or a combination thereof, covered in the
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics materials specification shall take precedence over those men-
and is the direct responsibility of Subcommittee D20.22 on Cellular Plastics.
tioned in this test method. If there are no material specifica-
Current edition approved Nov. 10, 1998. Published January 1999. Originally
tions, then the default conditions apply
published as D 3576 – 77. Last previous edition D 3576 – 94.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 08.02.
Annual Book of ASTM Standards, Vol 14.02.
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 3576
FIG. 1 Razor Blade Cell Size Specimen Slicer
FIG. 2 Cell Size Scale Slide Assembly
D 3576
6. Apparatus 8.1.5 Count the number of cell walls that intersect the
reference line.
6.1 The apparatus required to perform the test as defined by
8.1.6 Determine the average cell chord length, t. Divide the
Procedure A is listed as follows:
length of the reference line by the number of cells counted to
6.1.1 Cell Size Specimen Slicer —Cutting blade apparatus
obtain the average chord length, t. The length of the reference
capable of slicing thin specimens (0.02 mm) for cell size
line is expressed in millimetres.
viewing. Fig. 1 shows an acceptable alternative slicing appa-
8.2 Procedure B:
ratus.
8.2.1 Cut a 25-mm (1-in.) section across the width of the
6.1.2 Cell Size Projector—Conventional 35-mm slide pro-
sample.
jector that accepts standard 50 by 50-mm (2 by 2-in.) slides.
8.2.2 Identify the length (L) and width (W) direction in the
6.1.3 Cell Size Scale Slide Assembly, consisting of two
middle of the strip.
pieces of slide glass hinged by tape along one edge, between
8.2.3 Cut a 25-mm (1-in.) section with the L and W marking
which a calibrated scale (30 mm in length) printed on a thin
from the center of the strip giving a specimen of 25 by 25 mm
plastic sheet is placed (see Fig. 2).
by thickness (1 by 1 in. by thickness).
6.2 The apparatus required to perform the test as defined by
8.2.4 Shave adjacent planes of the sample giving exposed
Procedure B is listed as follows:
6 cut cells in the L, W, and thickness (T) directions (see Note 2).
6.2.1 Cell Size Specimen Slicer —Cutting blade apparatus
8.2.5 Coat the shaved planes with the marker with a uniform
capable of providing a smooth surface.
coating in such a manner that additional cell walls are not
6.2.2 Optical Magnification System, capable of 5 to 253
broken.
magnification with a calibrated scale of the appropriate length.
8.2.6 Place the sample in a manner to observe cells in the T
6.2.3 Highlighting Market, that does not contain a solvent
direction. The sample holder should be of sufficient size and
which will attack the polymer system. The ink used should
integrity so as to hold the sample steady during measurement
contrast with the color of the foam.
(see Note 3).
7. Sampling
NOTE 3—For samples with an apparent cell size of 0.3 mm or smaller
7.1 Generally one specimen is sufficient to determine the
the cell size may be measured by the use of a B&L Model STZ-201
apparent cell size of a sample. Monocular Zoomscope with a 10-mm calibrated reference line. For
samples with an apparent cell size of 1.0 mm or greater a handheld
7.2 The number of samples may be dictated by the end-use
eyepiece with a calibrated scale of 30-mm length can be used.
data needed.
8.2.7 Count the number of cell walls which intersect the
8. Procedures
reference line.
8.1 Procedure A:
8.2.8 The cells counted must be a random selection, how-
8.1.1 Cut a specimen 50 by 50 mm by thickness (2 by 2 in.
ever, the specific placement of the line should be adjusted to
by thickness) from the sample in the area to be tested.
start the count to include a full cell at the beginning of the line.
8.1.2 Prepare the cell size viewing specimen by cutting a
8.2.9 Determine the average cell chord length, t. Divide the
thin slice (less than monocellular) from one of the cut surfaces
length of the reference line by the number of cells counted to
of the specimen (slice thickness should be as thin as practi-
obtain the average chord length, t. The length of the reference
cable; so that a shadowgraph will not be occluded by overlap-
line is expressed in millimetres.
ping cell walls. Optimum slice thickness will vary with the
9. Calculation
average cell size of the foam, with smaller cell foams requiring
thinner slices.)
9.1 Calculate the cell size for each direction measured as
follows:
NOTE 2—One cell size measurement will provide a representative
apparent cell size for cellular plastics having symmet
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