ASTM D3576-20

Standard Test Method for Cell Size of Rigid Cellular Plastics

SIGNIFICANCE AND USE
5.1 Several physical properties of rigid cellular plastics are dependent on cell size and cell orientation. Measuring water absorption and open-cell content in accordance with Test Method D2842 and Test Method D6226 requires knowledge of surface cell volume, which uses cell size values in the calculations.  
5.2 This test method provides an apparent cell size because it assumes that there is no measurable edge to edge or top to bottom variation in average cell size and that the cell size distribution about the average cell size is normal. If the analyst is concerned there may be significant variation in either the average cell size or the cell size distribution more detailed analysis may be required.  
5.3 Before proceeding with this test method, reference should be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.
FIG. 1 Razor Blade Cell Size Specimen Slicer
FIG. 2 Cell Size Scale Slide Assembly
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 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, health, and environmental 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.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Nov-2020
• ICS: 83.100 - Cellular materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.22 - Cellular Materials - Plastics and Elastomers

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D2842-19 - Standard Test Method for Water Absorption of Rigid Cellular Plastics
• Effective Date: 01-May-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017
• Refers: ASTM E456-13a - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013
• Refers: ASTM E456-13ae2 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013

Overview

ASTM D3576-20: Standard Test Method for Cell Size of Rigid Cellular Plastics establishes a reliable method for determining the apparent cell size in rigid cellular plastics by counting the number of cell-wall intersections within a defined distance. Developed by ASTM International, this test method plays a critical role in the plastics industry and materials science by providing essential data for evaluating several key physical properties of rigid foams and cellular plastics. Understanding cell size is crucial for quality control, product development, and compliance with performance specifications in various applications, including insulation, packaging, construction materials, and more.

Key Topics

• Purpose and Scope: ASTM D3576-20 specifies the procedures to assess the average cell size in rigid cellular plastics, which directly influences material properties such as water absorption and open-cell content.
• Test Procedures
  • Procedure A: Utilized for materials where thin slicing is feasible (typically for foams with cell sizes ≥0.2 mm), requiring a mechanically stable, thin sample slice.
  • Procedure B: Designed for friable materials challenging to slice thin; it involves highlighting the cell walls for easier visualization and measurement.
• Measurement Principles: The method counts cell-wall intersections along a reference line to calculate average cell chord length, then determines apparent cell size using standardized mathematical relationships.
• Significance: Cell size measurements are crucial for downstream tests, such as water absorption (ASTM D2842) and open-cell content (ASTM D6226), both of which rely on accurate cell volume data for their calculations.
• Assumptions and Limitations: Results assume no significant variation in cell size across the sample. For materials with non-uniform cell size distribution, additional analysis may be necessary.

Applications

The determination of cell size in rigid cellular plastics according to ASTM D3576-20 has broad practical significance:

• Quality Control: Manufacturers use this test method to ensure product consistency and that material properties align with technical specifications and end-use requirements.
• Research and Development: The method provides critical data for optimizing formulation, processing, and performance parameters in new product development for foams and cellular polymers.
• Material Characterization: Cell size is a key parameter influencing properties like insulation capability, mechanical strength, and absorption rates, making testing essential for applications in construction, automotive, appliance insulation, and packaging.
• Performance Validation: Understanding cell structure helps predict behavior under environmental exposure, such as moisture ingress, which is vital for thermal insulation and structural applications.

Related Standards

• ASTM D2842: Test Method for Water Absorption of Rigid Cellular Plastics - Requires cell size data for surface cell volume calculations.
• ASTM D6226: Test Method for Open Cell Content of Rigid Cellular Plastics - Relies on accurate cell size assessment for calculating open-cell percentages.
• ASTM D883: Terminology Relating to Plastics - Provides definitions relevant to this and related methods.
• ASTM E456: Terminology Relating to Quality and Statistics - Offers terms for precision, repeatability, and reproducibility in test methods.
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.
• ISO 2896: Rigid Cellular Plastics - Determination of Water Absorption (annex is technically equivalent to ASTM D3576-20).

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Keywords: ASTM D3576-20, rigid cellular plastics, cell size, foam cell measurement, quality control, water absorption, open-cell content, thermal insulation, plastics testing standards, materials characterization.

Standards Content (Sample)

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.
Designation: D3576 − 20
Standard Test Method for
Cell Size of Rigid Cellular Plastics
This standard is issued under the fixed designation D3576; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* D2842Test Method for Water Absorption of Rigid Cellular
Plastics
1.1 This test method covers the determination of the appar-
D6226TestMethodforOpenCellContentofRigidCellular
entcellsizeofrigidcellularplasticsbycountingthenumberof
Plastics
cell-wall intersections in a specified distance.
E456Terminology Relating to Quality and Statistics
1.2 ProcedureArequires the preparation of a thin slice, not
E691Practice for Conducting an Interlaboratory Study to
more than one half the average cell diameter in thickness, that
Determine the Precision of a Test Method
is mechanically stable. For most rigid cellular plastics this
2.2 ISO Standard:
limits the test method to materials with an average cell size of
ISO 2896Cellular Plastics, Rigid—Determination of Water
at least 0.2 mm.
Absorption
1.3 Procedure B is intended for use with materials whose
friable nature makes it difficult to obtain a thin slice for
3. Terminology
viewing.
3.1 Terms used in this standard are defined in accordance
1.4 The values stated in SI units are to be regarded as
with Terminology D883, unless otherwise specified. For terms
standard. The values given in parentheses are for information
relating to precision and bias and associated issues, the terms
only.
used in this standard are defined in accordance with Terminol-
ogy E456.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.1 Procedure A—Thecellularplasticspecimeniscuttonot
mine the applicability of regulatory limitations prior to use.
more than one half the average cell diameter in thickness on a
slicer and the shadowgraph is projected on a screen by the use
NOTE 1—The annex to ISO 2896 is technically equivalent to this test
of a cell-size scale slide assembly and a projector.The average
method.
chord length is obtained by counting the cells on cell-wall
1.6 This international standard was developed in accor-
intersections and converting this value to average cell size by
dance with internationally recognized principles on standard-
mathematical derivation.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.2 Procedure B—The cellular plastic specimen is sliced to
mendations issued by the World Trade Organization Technical
provide a smooth surface. The cell walls are accented by the
Barriers to Trade (TBT) Committee.
useofamarkingpenormarkingink.Theaveragechordlength
is obtained by counting the cell wall intersections and convert-
2. Referenced Documents
ing this value to average cell size by mathematical derivation.
2.1 ASTM Standards:
5. Significance and Use
D883Terminology Relating to Plastics
5.1 Several physical properties of rigid cellular plastics are
dependent on cell size and cell orientation. Measuring water
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
absorption and open-cell content in accordance with Test
and is the direct responsibility of Subcommittee D20.22 on Cellular Materials -
MethodD2842andTestMethodD6226requiresknowledgeof
Plastics and Elastomers.
surface cell volume, which uses cell size values in the
Current edition approved Dec. 1, 2020. Published December 2020. Originally
approved in 1977. Last previous edition approved in 2015 as D3576-15. DOI:
calculations.
10.1520/D3576-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
*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
D3576 − 20
FIG. 1 Razor Blade Cell Size Specimen Slicer
5.2 This test method provides an apparent cell size because 6.2.1 Cell Size Specimen Slicer—Cutting blade apparatus
it assumes that there is no measurable edge to edge or top to capable of providing a smooth surface.
bottom variation in average cell size and that the cell size 6.2.2 Optical Magnification System, capable of 5 to 25×
distributionabouttheaveragecellsizeisnormal.Iftheanalyst magnification with a calibrated scale of the appropriate length.
is concerned there may be significant variation in either the 6.2.3 Highlighting Marker/Ink, that does not contain a
average cell size or the cell size distribution more detailed solvent which will attack the polymer system. The ink used
analysis may be required. should contrast with the color of the foam.
5.3 Before proceeding with this test method, reference
7. Sampling
shouldbemadetothespecificationofthematerialbeingtested.
7.1 Generally one specimen is sufficient to determine the
Any test specimen preparation, conditioning, dimensions, or
apparent cell size of a sample.
testing parameters, or a combination thereof, covered in the
materials specification shall take precedence over those men- 7.2 The number of samples may be dictated by the end-use
tioned in this test method. If there are no material data needed.
specifications, then the default conditions apply.
8. Procedures
6. Apparatus
8.1 Procedure A:
8.1.1 Cut a specimen 50 by 50 mm by thickness (2 by 2 in.
6.1 The apparatus required to perform the test as defined by
by thickness) from the sample in the area to be tested.
Procedure A is listed as follows:
8.1.2 Prepare the cell size viewing specimen by cutting a
6.1.1 Cell Size Specimen Slicer—Cutting blade apparatus
thin slice (less than monocellular) from one of the cut surfaces
capable of slicing thin specimens (0.02 mm) for cell size
of the specimen. (Slice thickness should be as thin as practi-
viewing. Fig. 1 shows an acceptable alternative slicing appa-
cable; so that a shadowgraph will not be occluded by overlap-
ratus.
ping cell walls. Optimum slice thickness will vary with the
6.1.2 Cell Size Projector—Conventional 35-mm slide pro-
averagecellsizeofthefoam,withsmallercellfoamsrequiring
jector that accepts standard 50 by 50-mm (2 by 2-in.) slides.
thinner slices.)
6.1.3 Cell Size Scale Slide Assembly, consisting of two
pieces of slide glass hinged by tape along one edge, between
NOTE 2—One cell size measurement will provide a representative
which a calibrated scale (30 mm in length) printed on a thin apparent cell size for cellular plastics having symmetric cells of relatively
uniform size. However, if the cell size in the three normal directions is
plastic sheet is placed (see Fig. 2).
suspected of varying by a value greater than the precision of this test
6.2 The apparatus required to perform the test as defined by
method, all three directions should be measured and reported for maxi-
Procedure B is listed as follows: mum accuracy.An acceptable procedure, in this case, is to determine the
D3576 − 20
FIG. 2 Cell Size Scale Slide Assembly
cell size in two planes perpendicular to each other.The size of the cells in
8.2.6 Place the sample in a manner to observe cells in the T
the three normal directions can then be compared and reported separately
direction. The sample holder should be of sufficient size and
if desired.
integrity so as to hold the sample steady during measurement
8.1.3 Insert the thin-sliced foam specimen into the cell size
(see Note 3).
slide assembly. Position the zero on the grid line at the top of
the area to be measured. Reassemble the slide. NOTE 3—For samples with an apparent cell size of 0.3 mm or smaller
the cell size may be measured by the use of a scope with a 10-mm
8.1.4 Insert the slide assembly into the projector. Focus the
calibratedreferenceline.Forsampleswithanapparentcellsizeof1.0mm
projector on the wall or screen so that a sharp image shadow-
orgreaterahandheldeyepiecewithacalibratedscaleof30-mmlengthc
...

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: D3576 − 15 D3576 − 20
Standard Test Method for
Cell Size of Rigid Cellular Plastics
This standard is issued under the fixed designation D3576; 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.
1. 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 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 safety, health, and healthenvironmental 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.
NOTE 1—The annex to ISO 2896 is technically equivalent to this test method.
1.6 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:
D883 Terminology Relating to Plastics
D2842 Test Method for Water Absorption of Rigid Cellular Plastics
D6226 Test Method for Open Cell Content of Rigid Cellular Plastics
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.22 on Cellular Materials - Plastics
and Elastomers.
Current edition approved Oct. 1, 2015Dec. 1, 2020. Published October 2015December 2020. Originally approved in 1977. Last previous edition approved in 20102015
as D3576 - 04D3576 - 15.(2010). DOI: 10.1520/D3576-15.10.1520/D3576-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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
D3576 − 20
2.2 ISO Standard:
ISO 2896 Cellular Plastics, Rigid—Determination of Water Absorption
3. Terminology
3.1 Definitions of terms applicable to this test method are given in Terms used in this standard are defined in accordance with
Terminology D883, unless otherwise specified. For terms relating to precision and bias and associated issues, the terms used in
this standard are defined in accordance with Terminology E456.
4. Summary of Test Method
4.1 Procedure A—The cellular plastic specimen is cut to not more than one half the average cell diameter in thickness on a slicer
and the shadowgraph is projected on a screen by the use of a cell-size scale slide assembly and a projector. The average chord
length is obtained by counting the cells on cell-wall intersections and converting this value to average cell size by mathematical
derivation.
4.2 Procedure B—The cellular plastic specimen is sliced to provide a smooth surface. The cell walls are accented by the use of
a marking pen or marking ink. The average chord length is obtained by counting the cell wall intersections and converting this
value to average cell size by mathematical derivation.
5. Significance and Use
5.1 Several physical properties of rigid cellular plastics are dependent on cell size and cell orientation. Measuring water absorption
and open-cell content in accordance with Test Method D2842 and Test Method D6226 requires knowledge of surface cell volume,
which uses cell size values in the calculations.
5.2 This test method provides an apparent cell size because it assumes that there is no measurable edge to edge or top to bottom
variation in average cell size and that the cell size distribution about the average cell size is normal. If the analyst is concerned
there may be significant variation in either the average cell size or the cell size distribution more detailed analysis may be required.
5.3 Before proceeding with this test method, reference should be made to the specification of the material being tested. Any test
specimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materials
specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default
conditions apply.
6. Apparatus
6.1 The apparatus required to perform the test as defined by Procedure A is listed as follows:
6.1.1 Cell Size Specimen Slicer—Cutting blade apparatus capable of slicing thin specimens (0.02 mm) for cell size viewing. Fig.
1 shows an acceptable alternative slicing apparatus.
6.1.2 Cell Size Projector—Conventional 35-mm slide projector that accepts standard 50 by 50-mm (2 by 2-in.) slides.
6.1.3 Cell Size Scale Slide Assembly, consisting of two pieces of slide glass hinged by tape along one edge, between which a
calibrated scale (30 mm in length) printed on a thin plastic sheet is placed (see Fig. 2).
6.2 The apparatus required to perform the test as defined by Procedure B is listed as follows:
6.2.1 Cell Size Specimen Slicer—Cutting blade apparatus capable of providing a smooth surface.
6.2.2 Optical Magnification System, capable of 5 to 25× magnification with a calibrated scale of the appropriate length.
6.2.3 Highlighting Marker/Ink, that does not contain a solvent which will attack the polymer system. The ink used should contrast
with the color of the foam.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D3576 − 20
FIG. 1 Razor Blade Cell Size Specimen Slicer
FIG. 2 Cell Size Scale Slide Assembly
7. Sampling
7.1 Generally one specimen is sufficient to determine the apparent cell size of a sample.
D3576 − 20
7.2 The number of samples may be dictated by the end-use data needed.
8. Procedures
8.1 Procedure A:
8.1.1 Cut a specimen 50 by 50 mm by thickness (2 by 2 in. by thickness) from the sample in the area to be tested.
8.1.2 Prepare the cell size viewing specimen by cutting a thin slice (less than monocellular) from one of the cut surfaces of the
specimen. (Slice thickness should be as thin as practicable; so that a shadowgraph will not be occluded by overlapping cell walls.
Optimum slice thickness will vary with the average cell size of the foam, with smaller cell foams requiring thinner slices.)
NOTE 2—One cell size measurement will provide a representative apparent cell size for cellular plastics having symmetric cells of relatively uniform size.
However, if the cell size in the three normal directions is suspected of varying by a value greater than the precision of this test method, all three directions
should be measured and reported for maximum accuracy. An acceptable procedure, in this case, is to determine the cell size in two planes perpendicular
to each other. The size of the cells in the three normal directions can then be compared and reported separately if desired.
8.1.3 Insert the thin-sliced foam specimen into the cell size slide assembly. Position the zero on the grid line at the top of the area
to be measured. Reassemble the slide.
8.1.4 Insert the slide assembly into the projector. Focus the projector on the wall or screen so that a sharp image shadowgraph
results.
8.1.5 Count the number of cell walls that intersect the reference line.
8.1.6 Determine the average cell chord length, t. Divide the length of the reference line by the number of cells counted to obtain
the average chord length, t. The length of the reference line is expressed in millimetres.
8.2 Procedure B:
8.2.1 Cut a 25-mm (1-in.) section across the width of the sample.
8.2.2 Identify the length (L) and width (W) direction in the middle of the strip.
8.2.3 Cut a 25-mm (1-in.) section with the L and W marking from the center of the strip giving a specimen of 25 by 25 mm by
thickness (1 by 1 in. by thickness).
8.2.4 Shave adjacent planes of the sample giving exposed cut cells in the L, W, and thickness (T) directions (see Note 2).
8.2.5 Coat the shaved planes with the marker/ink with a uniform coating in such a manner that additional cell walls are not broken.
8.2.6 Place the sample in a manner to observe cells in the T direction. The sample holder sh
...