ASTM F1839-08(2012)e1
(Specification)Standard Specification for Rigid Polyurethane Foam for Use as a Standard Material for Testing Orthopaedic Devices and Instruments
Standard Specification for Rigid Polyurethane Foam for Use as a Standard Material for Testing Orthopaedic Devices and Instruments
ABSTRACT
This specification covers rigid polyurethane foam blocks or sheets recommended for use as a standard material for mechanical testing using orthopedic devices and instruments. Although the physical properties of the foam are in the order of those reported for human cancellous bones, these materials are not intended for implantation into the human body. All materials should conform to the specified quality of appearance, dimensional stability, and composition, and values of void content, compressive strength, compressive modulus, shear strength, shear modulus, and screw pullout.
SIGNIFICANCE AND USE
5.1 This specification describes the compositional requirements, physical requirements, mechanical requirements, and test methods for rigid unicellular polyurethane foam for use in testing orthopaedic devices or instruments.
5.2 This foam described in this specification is not intended to replicate the mechanical properties of human or animal bone. The requirements of this specification are intended to provide a consistent and uniform material with properties on the order of human cancellous bone to use as a test medium when testing various orthopaedic devices, such as bone screws.
SCOPE
1.1 This specification covers rigid unicellular polyurethane foam for use as a standard material for performing mechanical tests utilizing orthopaedic devices or instruments. The specification is applicable to sheets or blocks of foam, or foam that is made by the user using a two-part liquid mixture.
1.2 This specification covers polyurethane foam material that is used in the laboratory for mechanical testing, as described in 1.1. These materials are not intended for implantation into the human body.
1.3 The foam described herein possesses mechanical properties which are on the order of those reported for human cancellous bone. See Appendix X1, Rationale, for further information regarding the appropriateness of using the specified foam as a model for human cancellous bone.
1.4 This specification covers compositional requirements, physical requirements, mechanical requirements, and test methods for rigid polyurethane foam in the solid final form.
1.5 This specification provides qualification criteria for vendor or end-user processes and acceptance criteria for individual material lots.
1.6 This specification provides mechanical properties of five different grades of foam in the solid final form. A foam that does not meet the specified mechanical properties shall be identified as an ungraded foam.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 The following precautionary statement pertains to the test method portion only, Section 8, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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´1
Designation:F1839 −08(Reapproved 2012)
Standard Specification for
Rigid Polyurethane Foam for Use as a Standard Material for
Testing Orthopaedic Devices and Instruments
This standard is issued under the fixed designation F1839; 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.
ε NOTE—Section 8.6.2 was corrected editorially in May 2016.
1. Scope of this standard to establish appropriate safety and health
practices and determine the applicability of regulatory limita-
1.1 This specification covers rigid unicellular polyurethane
tions prior to use.
foam for use as a standard material for performing mechanical
tests utilizing orthopaedic devices or instruments. The specifi-
2. Referenced Documents
cation is applicable to sheets or blocks of foam, or foam that is
2.1 ASTM Standards:
made by the user using a two-part liquid mixture.
C273 Test Method for Shear Properties of Sandwich Core
1.2 This specification covers polyurethane foam material
Materials
that is used in the laboratory for mechanical testing, as
D1621 Test Method for Compressive Properties of Rigid
described in 1.1. These materials are not intended for implan-
Cellular Plastics
tation into the human body.
D1622 Test Method for Apparent Density of Rigid Cellular
1.3 The foam described herein possesses mechanical prop-
Plastics
erties which are on the order of those reported for human
E4 Practices for Force Verification of Testing Machines
cancellous bone. See Appendix X1, Rationale, for further
F543 Specification and Test Methods for Metallic Medical
information regarding the appropriateness of using the speci-
Bone Screws
fied foam as a model for human cancellous bone.
3. Terminology
1.4 This specification covers compositional requirements,
3.1 Definitions:
physical requirements, mechanical requirements, and test
3.1.1 final form—the condition of the foam product when
methods for rigid polyurethane foam in the solid final form.
used by the end user to perform tests of orthopaedic devices or
1.5 This specification provides qualification criteria for
instruments.
vendor or end-user processes and acceptance criteria for
3.1.1.1 Discussion—This is the condition of the foam prod-
individual material lots.
uct of which all physical and mechanical tests required by this
1.6 Thisspecificationprovidesmechanicalpropertiesoffive
specification are performed.
different grades of foam in the solid final form. A foam that
3.1.1.1 solid—the foam is in a uniform solid form, such as
does not meet the specified mechanical properties shall be
a slab, plate, or block.
identified as an ungraded foam.
3.1.2 foam rise direction—the nominal direction that the
1.7 The values stated in SI units are to be regarded as
foam rises during the polymerization (“foaming”) process,
standard. No other units of measurement are included in this
either at the supplier’s production facilities for the solid
standard.
supplied foam, or at the end-user’s facilities for foam produced
1.8 The following precautionary statement pertains to the
from the liquid supplied form. The foam rise direction shall be
test method portion only, Section 8, of this specification: This
marked on the foam block or indicated in the shipping
standard does not purport to address all of the safety concerns,
documentation for foam that is supplied in the solid form.
if any, associated with its use. It is the responsibility of the user
3.1.3 grades—The grade designation refers to the nominal
density of the foam, in its solid final form, expressed in units
This specification is under the jurisdiction of ASTM Committee F04 on
Medical and Surgical Materials and Devices and is the direct responsibility of
Subcommittee F04.21 on Osteosynthesis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2012. Published October 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1997. Last previous edition approved in 2012 as F1839 – 08(2012). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/F1839-08R12E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
F1839−08 (2012)
TABLE 1 Requirements for Voids, Cracks, and Nonuniform Areas
of kg/m . Ten grades of foam have been defined in this
specification. Their nominal densities are: Defects Requirements
3 Voids
Grade 5: 80.1 kg/m
Grade 10: 160.2 kg/m
3 Void depth (measured perpendicular Void depth shall be less than 50 % of
Grade 12: 192.2 kg/m
to slab’s transverse plane) the slab thickness, and less than
Grade 15: 240.3 kg/m
3 6.35 mm
Grade 20: 320.4 kg/m
Grade 25: 400.5 kg/m
Void diameter (measured parallel to
Grade 30: 480.5 kg/m
slab’s transverse plane)
Grade 35: 560.6 kg/m
Grade 40: 640.7 kg/m
3 Larger than 6.35 mm None allowed in any grade
Grade 50: 800.9 kg/m
Between 3.18 mm No more than 10 allowed per 230
Foam that does not fit into one of these ten grades be-
and 6.35 mm cm surface area for Grades 5 and
cause it does not meet one or more of the physical require-
10. No more than 1 allowed for
ments of Section 4 is termed ungraded.
Grades 12, 15, 20, 25, 30, and 35.
None allowed for Grades 40 and 50.
3.1.3.1 Discussion—Grade 5 designates the nominal value
of 5 lbm/ft .
Between 1.57 mm No more than 20 allowed per 230
and 3.18 mm cm surface area for Grades 5 and
3.1.4 supplied form—the condition of the foam product
10. No more than 6 allowed for
when received from the supplier by the end user.
Grades 12, 15, 20, 25, 30, and 35.
No more than 3 allowed for Grades
3.1.4.1 Discussion—The supplied form may be a solid or a
40 and 50.
liquid.Thefoammaybeinauniformsolidformsuchasaslab,
plate, or block or a liquid in which two liquid components Cracks None allowed
(base and activator) can be mixed by the end user to produce
Non-uniform areas Concentrated areas of poor
a rigid, unicellular foam slab.
construction, irregular cells, and hard
and soft spots shall not exceed 10 %
of the visible surface area
4. Physical and Mechanical Requirements
4.1 Composition—The material shall be supplied either in
TABLE 2 Grade Designation and Density
solid or liquid form. The solid or combined liquid parts shall
produce a foam consisting of polyether polyurethane.
Minimum Density, Maximum Density,
Grade
3 3
kg/m kg/m
4.2 Appearance:
5 72.10 88.10
4.2.1 Solid Supplied Form—The solid supplied form shall
10 144.0 176.0
12 173.0 211.5
befreeofobviousextraneousmatter,andappeartotheunaided
15 216.0 264.5
eye to be uniform throughout the slab in color and porosity.
20 288.5 352.5
25 360.5 440.5
4.2.2 Liquid Supplied Form—The two liquid components
30 432.5 528.5
shall appear to the unaided eye throughout their volumes to be
35 504.5 617.0
uniformandfreefromobviousextraneousmatterorparticulate
40 576.5 705.0
50 721.0 881.0
debris.
4.2.3 SolidFinalForm—Thesolidfinalformshallbefreeof
obvious extraneous matter, and appear to the unaided eye to be
TABLE 3 Requirements for Compressive Strength
uniform throughout the slab in color and porosity.
Minimum Maximum
4.3 Void Content—The material in the solid final form shall
Compressive Compressive
Grade
Strength, Strength,
meet the requirements of Table 1 for voids, cracks and
MPa MPa
nonuniform areas, when examined using the procedures de-
5 0.4495 0.7800
scribed in 8.1. All specimens shall meet this requirement.
10 1.745 2.820
12 2.485 3.970
4.4 Density—The material in the solid final form shall have
15 3.820 6.050
a density within the ranges specified in Table 2, according to
20 6.630 10.45
25 10.15 16.00
thefoam’sgradespecification.Thedensityshallbedetermined
30 14.30 22.70
using the method described in 8.2. All specimens shall meet
35 19.15 30.55
this requirement.
40 24.60 39.55
50 37.35 61.05
4.5 Dimensional Stability—The material in the solid final
form shall have an average percentage thickness change less
than 5.0 %, when tested according to the method described in
4.7 Compressive Modulus—The material in the solid final
8.3.
form shall meet the compressive modulus requirements given
in Table 4, when tested according to the method described in
4.6 Compressive Strength—The material in the solid final
8.4. All specimens shall meet this requirement.
formshallmeetthecompressivestrengthrequirementsgivenin
Table 3, when tested according to the method described in 8.4. 4.8 Shear Strength—The material in the solid final form
All specimens shall meet this requirement. shall meet the shear strength requirements given in Table 5,
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F1839−08 (2012)
TABLE 4 Requirements for Compressive Modulus TABLE 7 Requirements for Screw Pullout
Minimum Maximum Minimum Maximum
Compressive Compressive Grade Pullout, Pullout,
Grade
Modulus, Modulus, N N
MPa MPa
5 56.00 176.0
5 12.30 20.35 10 220.0 453.0
10 45.75 71.70 12 309.5 592.5
12 64.50 100.5 15 464.5 831.0
15 98.00 151.0
20 770.0 1310
20 167.5 257.5 25 1125 1890
25 253.5 390.0 30 1520 2570
30 355.5 548.5 35 1950 3355
35 472.0 732.0 40 2400 4245
40 603.0 941.0 50 3380 6350
50 907.5 1435
5.2 This foam described in this specification is not intended
TABLE 5 Requirements for Shear Strength
to replicate the mechanical properties of human or animal
Minimum Maximum
bone. The requirements of this specification are intended to
Grade Shear Strength, Shear Strength,
provide a consistent and uniform material with properties on
MPa MPa
the order of human cancellous bone to use as a test medium
5 0.420 0.805
10 1.225 2.010
whentestingvariousorthopaedicdevices,suchasbonescrews.
12 1.610 2.580
15 2.235 3.510
6. Apparatus
20 3.395 5.275
25 4.665 7.275
6.1 Analytical Balance or Scale—capable of weighing foam
30 6.025 9.495
specimens to the nearest mg.
35 7.460 11.95
40 8.960 14.55
6.2 Micrometer Dial Gage or Caliper—capable of measur-
50 12.10 20.40
ing dimensions of the foam specimens to 60.1 %.
6.3 Conditioning Oven—Forced-air circulating oven ca-
pable of maintaining 121 6 2.8°C for 24 h.
when tested according to the method described in 8.5. All
6.4 Desiccator—containing desiccant with high affinity for
specimens shall meet this requirement.
water vapor (anhydrous calcium chloride or equivalent).
4.9 Shear Modulus—The material in the solid final form
6.5 Vacuum Apparatus—capable of applying a vacuum
shall meet the shear modulus requirements given in Table 6,
pressure of 508 mm (20 in.) of mercury to foam specimen for
when tested according to the method described in 8.5. All
dimensional stability test.
specimens shall meet this requirement.
6.6 Testing Machine and Load Cell—conforming to Prac-
4.10 Screw Pullout—The material in the solid final form
tices E4 and capable of applying tensile and compressive loads
shall meet the screw pullout requirements given in Table 7,
at a constant displacement rate.
when tested according to the method described in 8.6. All
specimens shall meet this requirement.
7. Sampling and Test Specimens
5. Significance and Use 7.1 The number of test specimens and the specimen sizes
required for physical characterization and mechanical testing
5.1 This specification describes the compositional
are described in 8.1 – 8.6.Test specimens are required for each
requirements,physicalrequirements,mechanicalrequirements,
grade and formulation.
and test methods for rigid unicellular polyurethane foam for
use in testing orthopaedic devices or instruments. 7.2 Test specimens shall be solid foam blocks. The short-
transverse direction of the specimens shall coincide with the
foam rise direction of the original foam bun.
TABLE 6 Requirements for Shear Modulus
8. Procedure
Minimum Maximum
Grade Shear Modulus, Shear Modulus,
8.1 Determination of Void Content:
MPa† MPa†
8.1.1 Use the foam block specimens described and specified
5 5.460 9.000
10 15.15 22.75
in 8.2 – 8.6.
12 19.70 29.20
8.1.2 Examine all of the surfaces and edges of test speci-
15 27.10 39.70
mens for voids and nonuniform areas with the unaided eye.
20 40.75 59.25
25 55.70 81.15 Measure the dimensions of the void or nonuniform areas using
30 71.70 105.0
an instrument capable of measuring 60.025 mm.
35 88.65 131.0
40 106.5 159.0
8.2 Determination of Foam Density:
50 144.0 220.0
8.2.1 Prepare three specimens, 25.4 by 25.4 by 25.4 mm
†Editorially corrected.
from solid foam.
´1
F1839−08 (2012)
8.2.2 Determine the apparent density of the three foam Grades 5, 10, 12, 15, 20, and 25 shall use screws or threaded
specimens, in kg/m , in accordance with Test Method D1622. tools with the thread form of HB 6.5 screws (seeTable A5.4 of
8.2.3 Calculate the average apparent density of the three Specification F543, Annex A5), while Grades 30, 35, 40, and
foam specimens. 50shallutilizescrewsorthreadedtoolswiththethreadformof
HA 4.5 screws (see Table A5.2 of Specification F543, Annex
8.3 Determination of Dimensional Stability:
A5).
8.3.1 Prepare three specimens, 25.4 by 25.4 by 12.7 mm
8.6.3 Drill a 3.2-mm hole in the center of each foam
from solid foam.
specimen, parallel to the thickness direction. The hole shall be
8.3.2 Condition the specimen for 24 h at 21 6 2.8°C and
positioned a minimum of 10 mm from any void or nonuniform
50 6 10 % relative humidity. Measure the specimen thickness
area. Tap the hole to a minimum depth of 25.4 mm using a tap
near the center of the length to 60.025 mm and mark the
that corresponds to HB 6.5 or HA 4.5, as appropriate.
location of the measurement.
8.6.4 Insert the screw or threaded tool into each foam
8.3.3 Place the specimen on a 6.35-mm thick aluminum
specimen to a depth of 20 mm.
plate and apply a minimum vacuum pressure of 508 mm of
8.6.5 Test in accordance with Specification F543, Annex
mercury under a vacuum bag or diaphragm. Place this assem-
A3.
bly in a circulating forced-air oven for not less than2hat121
8.6.6 Determine the maximum force, in Newtons, required
6 2.8°C. Remove the assembly and allow to cool to 49°C or
to remove the screw or threaded tool from the foam specimen.
less while maintaining the vacuum.
8.6.7 Calculate the average pullout force for the five speci-
8.3.4 Recondition and remeasure the thickness at the
mens.
marked location in accordance with 8.3.2. Calculate the per-
cent thickness change.
9. Report
8.3.5 Calculate the average percent thickness change of the
9.1 Include the following information in the test report of
three specimens.
the mechanical properties of the foam:
8.4 Determination of Compressive Strength and Modulus:
9.1.1
...
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.
´1
Designation: F1839 − 08 (Reapproved 2012) F1839 − 08 (Reapproved 2012)
Standard Specification for
Rigid Polyurethane Foam for Use as a Standard Material for
Testing Orthopaedic Devices and Instruments
This standard is issued under the fixed designation F1839; 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.
ε NOTE—Section 8.6.2 was corrected editorially in May 2016.
1. Scope
1.1 This specification covers rigid unicellular polyurethane foam for use as a standard material for performing mechanical tests
utilizing orthopaedic devices or instruments. The specification is applicable to sheets or blocks of foam, or foam that is made by
the user using a two-part liquid mixture.
1.2 This specification covers polyurethane foam material that is used in the laboratory for mechanical testing, as described in
1.1. These materials are not intended for implantation into the human body.
1.3 The foam described herein possesses mechanical properties which are on the order of those reported for human cancellous
bone. See Appendix X1, Rationale, for further information regarding the appropriateness of using the specified foam as a model
for human cancellous bone.
1.4 This specification covers compositional requirements, physical requirements, mechanical requirements, and test methods for
rigid polyurethane foam in the solid final form.
1.5 This specification provides qualification criteria for vendor or end-user processes and acceptance criteria for individual
material lots.
1.6 This specification provides mechanical properties of five different grades of foam in the solid final form. A foam that does
not meet the specified mechanical properties shall be identified as an ungraded foam.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 The following precautionary statement pertains to the test method portion only, Section 8, of this specification: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.
2. Referenced Documents
2.1 ASTM Standards:
C273 Test Method for Shear Properties of Sandwich Core Materials
D1621 Test Method for Compressive Properties of Rigid Cellular Plastics
D1622 Test Method for Apparent Density of Rigid Cellular Plastics
E4 Practices for Force Verification of Testing Machines
F543 Specification and Test Methods for Metallic Medical Bone Screws
3. Terminology
3.1 Definitions:
3.1.1 final form—the condition of the foam product when used by the end user to perform tests of orthopaedic devices or
instruments.
This specification is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.21 on Osteosynthesis.
ε2
Current edition approved Oct. 1, 2012. Published October 2012. Originally approved in 1997. Last previous edition approved in 20082012 as F1839 – 08 .(2012). DOI:
10.1520/F1839-08R12.10.1520/F1839-08R12E01.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
F1839 − 08 (2012)
3.1.1.1 Discussion—
This is the condition of the foam product of which all physical and mechanical tests required by this specification are performed.
3.1.1.1 solid—the foam is in a uniform solid form, such as a slab, plate, or block.
3.1.2 foam rise direction—the nominal direction that the foam rises during the polymerization (“foaming”) process, either at the
supplier’s production facilities for the solid supplied foam, or at the end-user’s facilities for foam produced from the liquid supplied
form. The foam rise direction shall be marked on the foam block or indicated in the shipping documentation for foam that is
supplied in the solid form.
3.1.3 grades—The grade designation refers to the nominal density of the foam, in its solid final form, expressed in units of
kg/m . Ten grades of foam have been defined in this specification. Their nominal densities are:
Grade 5: 80.1 kg/m
Grade 10: 160.2 kg/m
Grade 12: 192.2 kg/m
Grade 15: 240.3 kg/m
Grade 20: 320.4 kg/m
Grade 25: 400.5 kg/m
Grade 30: 480.5 kg/m
Grade 35: 560.6 kg/m
Grade 40: 640.7 kg/m
Grade 50: 800.9 kg/m
Foam that does not fit into one of these ten grades because it does not meet one or more of the physical requirements of
Section 4 is termed ungraded.
3.1.3.1 Discussion—
Grade 5 designates the nominal value of 5 lbm/ft .
3.1.4 supplied form—the condition of the foam product when received from the supplier by the end user.
3.1.4.1 Discussion—
The supplied form may be a solid or a liquid. The foam may be in a uniform solid form such as a slab, plate, or block or a liquid
in which two liquid components (base and activator) can be mixed by the end user to produce a rigid, unicellular foam slab.
4. Physical and Mechanical Requirements
4.1 Composition—The material shall be supplied either in solid or liquid form. The solid or combined liquid parts shall produce
a foam consisting of polyether polyurethane.
4.2 Appearance:
4.2.1 Solid Supplied Form—The solid supplied form shall be free of obvious extraneous matter, and appear to the unaided eye
to be uniform throughout the slab in color and porosity.
4.2.2 Liquid Supplied Form—The two liquid components shall appear to the unaided eye throughout their volumes to be
uniform and free from obvious extraneous matter or particulate debris.
4.2.3 Solid Final Form—The solid final form shall be free of obvious extraneous matter, and appear to the unaided eye to be
uniform throughout the slab in color and porosity.
4.3 Void Content—The material in the solid final form shall meet the requirements of Table 1 for voids, cracks and nonuniform
areas, when examined using the procedures described in 8.1. All specimens shall meet this requirement.
4.4 Density—The material in the solid final form shall have a density within the ranges specified in Table 2, according to the
foam’s grade specification. The density shall be determined using the method described in 8.2. All specimens shall meet this
requirement.
4.5 Dimensional Stability—The material in the solid final form shall have an average percentage thickness change less than
5.0 %, when tested according to the method described in 8.3.
4.6 Compressive Strength—The material in the solid final form shall meet the compressive strength requirements given in Table
3, when tested according to the method described in 8.4. All specimens shall meet this requirement.
4.7 Compressive Modulus—The material in the solid final form shall meet the compressive modulus requirements given in Table
4, when tested according to the method described in 8.4. All specimens shall meet this requirement.
4.8 Shear Strength—The material in the solid final form shall meet the shear strength requirements given in Table 5, when tested
according to the method described in 8.5. All specimens shall meet this requirement.
´1
F1839 − 08 (2012)
TABLE 1 Requirements for Voids, Cracks, and Nonuniform Areas
Defects Requirements
Voids
Void depth (measured perpendicular Void depth shall be less than 50 % of
to slab’s transverse plane) the slab thickness, and less than
6.35 mm
Void diameter (measured parallel to
slab’s transverse plane)
Larger than 6.35 mm None allowed in any grade
Between 3.18 mm No more than 10 allowed per 230
and 6.35 mm cm surface area for Grades 5 and
10. No more than 1 allowed for
Grades 12, 15, 20, 25, 30, and 35.
None allowed for Grades 40 and 50.
Between 1.57 mm No more than 20 allowed per 230
and 3.18 mm cm surface area for Grades 5 and
10. No more than 6 allowed for
Grades 12, 15, 20, 25, 30, and 35.
No more than 3 allowed for Grades
40 and 50.
Cracks None allowed
Non-uniform areas Concentrated areas of poor
construction, irregular cells, and hard
and soft spots shall not exceed 10 %
of the visible surface area
TABLE 2 Grade Designation and Density
Minimum Density, Maximum Density,
Grade
3 3
kg/m kg/m
5 72.10 88.10
10 144.0 176.0
12 173.0 211.5
15 216.0 264.5
20 288.5 352.5
25 360.5 440.5
30 432.5 528.5
35 504.5 617.0
40 576.5 705.0
50 721.0 881.0
TABLE 3 Requirements for Compressive Strength
Minimum Maximum
Compressive Compressive
Grade
Strength, Strength,
MPa MPa
5 0.4495 0.7800
10 1.745 2.820
12 2.485 3.970
15 3.820 6.050
20 6.630 10.45
25 10.15 16.00
30 14.30 22.70
35 19.15 30.55
40 24.60 39.55
50 37.35 61.05
4.9 Shear Modulus—The material in the solid final form shall meet the shear modulus requirements given in Table 6, when
tested according to the method described in 8.5. All specimens shall meet this requirement.
4.10 Screw Pullout—The material in the solid final form shall meet the screw pullout requirements given in Table 7, when tested
according to the method described in 8.6. All specimens shall meet this requirement.
´1
F1839 − 08 (2012)
TABLE 4 Requirements for Compressive Modulus
Minimum Maximum
Compressive Compressive
Grade
Modulus, Modulus,
MPa MPa
5 12.30 20.35
10 45.75 71.70
12 64.50 100.5
15 98.00 151.0
20 167.5 257.5
25 253.5 390.0
30 355.5 548.5
35 472.0 732.0
40 603.0 941.0
50 907.5 1435
TABLE 5 Requirements for Shear Strength
Minimum Maximum
Grade Shear Strength, Shear Strength,
MPa MPa
5 0.420 0.805
10 1.225 2.010
12 1.610 2.580
15 2.235 3.510
20 3.395 5.275
25 4.665 7.275
30 6.025 9.495
35 7.460 11.95
40 8.960 14.55
50 12.10 20.40
TABLE 6 Requirements for Shear Modulus
Minimum Maximum
Grade Shear Modulus, Shear Modulus,
MPa† MPa†
5 5.460 9.000
10 15.15 22.75
12 19.70 29.20
15 27.10 39.70
20 40.75 59.25
25 55.70 81.15
30 71.70 105.0
35 88.65 131.0
40 106.5 159.0
50 144.0 220.0
†Editorially corrected.
TABLE 7 Requirements for Screw Pullout
Minimum Maximum
Grade Pullout, Pullout,
N N
5 56.00 176.0
10 220.0 453.0
12 309.5 592.5
15 464.5 831.0
20 770.0 1310
25 1125 1890
30 1520 2570
35 1950 3355
40 2400 4245
50 3380 6350
5. Significance and Use
5.1 This specification describes the compositional requirements, physical requirements, mechanical requirements, and test
methods for rigid unicellular polyurethane foam for use in testing orthopaedic devices or instruments.
´1
F1839 − 08 (2012)
5.2 This foam described in this specification is not intended to replicate the mechanical properties of human or animal bone.
The requirements of this specification are intended to provide a consistent and uniform material with properties on the order of
human cancellous bone to use as a test medium when testing various orthopaedic devices, such as bone screws.
6. Apparatus
6.1 Analytical Balance or Scale—capable of weighing foam specimens to the nearest mg.
6.2 Micrometer Dial Gage or Caliper—capable of measuring dimensions of the foam specimens to 60.1 %.
6.3 Conditioning Oven—Forced-air circulating oven capable of maintaining 121 6 2.8°C for 24 h.
6.4 Desiccator—containing desiccant with high affinity for water vapor (anhydrous calcium chloride or equivalent).
6.5 Vacuum Apparatus—capable of applying a vacuum pressure of 508 mm (20 in.) of mercury to foam specimen for
dimensional stability test.
6.6 Testing Machine and Load Cell—conforming to Practices E4 and capable of applying tensile and compressive loads at a
constant displacement rate.
7. Sampling and Test Specimens
7.1 The number of test specimens and the specimen sizes required for physical characterization and mechanical testing are
described in 8.1 – 8.6. Test specimens are required for each grade and formulation.
7.2 Test specimens shall be solid foam blocks. The short-transverse direction of the specimens shall coincide with the foam rise
direction of the original foam bun.
8. Procedure
8.1 Determination of Void Content:
8.1.1 Use the foam block specimens described and specified in 8.2 – 8.6.
8.1.2 Examine all of the surfaces and edges of test specimens for voids and nonuniform areas with the unaided eye. Measure
the dimensions of the void or nonuniform areas using an instrument capable of measuring 60.025 mm.
8.2 Determination of Foam Density:
8.2.1 Prepare three specimens, 25.4 by 25.4 by 25.4 mm from solid foam.
8.2.2 Determine the apparent density of the three foam specimens, in kg/m , in accordance with Test Method D1622.
8.2.3 Calculate the average apparent density of the three foam specimens.
8.3 Determination of Dimensional Stability:
8.3.1 Prepare three specimens, 25.4 by 25.4 by 12.7 mm from solid foam.
8.3.2 Condition the specimen for 24 h at 21 6 2.8°C and 50 6 10 % relative humidity. Measure the specimen thickness near
the center of the length to 60.025 mm and mark the location of the measurement.
8.3.3 Place the specimen on a 6.35-mm thick aluminum plate and apply a minimum vacuum pressure of 508 mm of mercury
under a vacuum bag or diaphragm. Place this assembly in a circulating forced-air oven for not less than 2 h at 121 6 2.8°C.
Remove the assembly and allow to cool to 49°C or less while maintaining the vacuum.
8.3.4 Recondition and remeasure the thickness at the marked location in accordance with 8.3.2. Calculate the percent thickness
change.
8.3.5 Calculate the average percent thickness change of the three specimens.
8.4 Determination of Compressive Strength and Modulus:
8.4.1 Prepare five specimens, 50.8 by 50.8 by 25.4 mm, from solid foam, with the thickness of the specimen parallel to the foam
rise direction. Measure the dimensions within 60.025 mm. The specimens shall be conditioned at 24 6 2.8°C for 3 h prior to
testing.
8.4.2 Test in accordance with Test Method D1621 at 24 6 2.8°C. The specimens shall be oriented such that the axis of the
compressive load is applied parallel to the foam rise direction.
8.4.3 Determine the compressive strength using Procedure A of Test Method D1621 and the maximum compressive modu
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