ASTM F1839-08(2021)
(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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 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
Relations
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:F1839 −08 (Reapproved 2021)
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.
1. Scope environmental practices and determine the applicability of
regulatory limitations prior to use.
1.1 This specification covers rigid unicellular polyurethane
1.9 This international standard was developed in accor-
foam for use as a standard material for performing mechanical
dance with internationally recognized principles on standard-
tests utilizing orthopaedic devices or instruments. The specifi-
ization established in the Decision on Principles for the
cation is applicable to sheets or blocks of foam, or foam that is
Development of International Standards, Guides and Recom-
made by the user using a two-part liquid mixture.
mendations issued by the World Trade Organization Technical
1.2 This specification covers polyurethane foam material
Barriers to Trade (TBT) Committee.
that is used in the laboratory for mechanical testing, as
described in 1.1. These materials are not intended for implan-
2. Referenced Documents
tation into the human body.
2.1 ASTM Standards:
1.3 The foam described herein possesses mechanical prop-
C273 Test Method for Shear Properties of Sandwich Core
erties which are on the order of those reported for human
Materials
cancellous bone. See Appendix X1, Rationale, for further
D1621 Test Method for Compressive Properties of Rigid
information regarding the appropriateness of using the speci-
Cellular Plastics
fied foam as a model for human cancellous bone.
D1622 Test Method for Apparent Density of Rigid Cellular
Plastics
1.4 This specification covers compositional requirements,
E4 Practices for Force Verification of Testing Machines
physical requirements, mechanical requirements, and test
F543 Specification and Test Methods for Metallic Medical
methods for rigid polyurethane foam in the solid final form.
Bone Screws
1.5 This specification provides qualification criteria for
vendor or end user processes and acceptance criteria for
3. Terminology
individual material lots.
3.1 Definitions:
1.6 Thisspecificationprovidesmechanicalpropertiesoffive
3.1.1 final form—the condition of the foam product when
different grades of foam in the solid final form. A foam that
used by the end user to perform tests of orthopaedic devices or
does not meet the specified mechanical properties shall be
instruments.
identified as an ungraded foam.
3.1.1.1 Discussion—This is the condition of the foam prod-
1.7 The values stated in SI units are to be regarded as uct of which all physical and mechanical tests required by this
standard. No other units of measurement are included in this specification are performed. In the final form the foam is in a
standard. uniform solid such as a slab, plate, or block.
1.8 The following precautionary statement pertains to the 3.1.2 foam rise direction—the nominal direction that the
test method portion only, Section 8, of this specification: This foam rises during the polymerization (“foaming”) process,
standard does not purport to address all of the safety concerns, either at the supplier’s production facilities for the solid
if any, associated with its use. It is the responsibility of the user supplied foam, or at the end user’s facilities for foam produced
of this standard to establish appropriate safety, health, and 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.
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 Feb. 1, 2021. Published February 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1997. Last previous edition approved in 2016 as F1839 – 08 (2016). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/F1839-08R21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1839−08 (2021)
TABLE 1 Requirements for Voids, Cracks, and Nonuniform Areas
3.1.3 grades—the grade designation refers to the nominal
density of the foam, in its solid final form, expressed in units Defects Requirements
of kg/m . Ten grades of foam have been defined in this Voids
specification. Their nominal densities are:
Void depth (measured perpendicular Void depth shall be less than 50 % of
Grade 5: 80.1 kg/m
to slab’s transverse plane) the slab thickness, and less than
Grade 10: 160.2 kg/m 6.35 mm
Grade 12: 192.2 kg/m
Grade 15: 240.3 kg/m
Void diameter (measured parallel to
Grade 20: 320.4 kg/m
slab’s transverse plane)
Grade 25: 400.5 kg/m
Grade 30: 480.5 kg/m Larger than 6.35 mm None allowed in any grade
Grade 35: 560.6 kg/m
Grade 40: 640.7 kg/m Between 3.18 mm No more than 10 allowed per 230
3 2
Grade 50: 800.9 kg/m
and 6.35 mm cm surface area for Grades 5 and
10. No more than 1 allowed for
Foam that does not fit into one of these ten grades be-
Grades 12, 15, 20, 25, 30, and 35.
cause it does not meet one or more of the physical require-
None allowed for Grades 40 and 50.
ments of Section 4 is termed ungraded.
Between 1.57 mm No more than 20 allowed per 230
3.1.3.1 Discussion—Grade 5 designates the nominal value
and 3.18 mm cm surface area for Grades 5 and
of 5 lbm/ft .
10. No more than 6 allowed for
Grades 12, 15, 20, 25, 30, and 35.
3.1.4 supplied form—the condition of the foam product
No more than 3 allowed for Grades
when received from the supplier by the end user.
40 and 50.
3.1.4.1 Discussion—The supplied form may be a solid or a
Cracks None allowed
liquid.Thefoammaybeinauniformsolidformsuchasaslab,
plate, or block or a liquid in which two liquid components
Nonuniform areas Concentrated areas of poor
construction, irregular cells, and hard
(base and activator) can be mixed by the end user to produce
and soft spots shall not exceed 10 %
a rigid, unicellular foam slab.
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
Minimum Density, Maximum Density,
Grade
3 3
produce a foam consisting of polyether polyurethane.
kg/m kg/m
5 72.10 88.10
4.2 Appearance:
10 144.0 176.0
4.2.1 Solid Supplied Form—The solid supplied form shall
12 173.0 211.5
befreeofobviousextraneousmatter,andappeartotheunaided 15 216.0 264.5
20 288.5 352.5
eye to be uniform throughout the slab in color and porosity.
25 360.5 440.5
4.2.2 Liquid Supplied Form—The two liquid components
30 432.5 528.5
35 504.5 617.0
shall appear to the unaided eye throughout their volumes to be
40 576.5 705.0
uniform and free from obvious extraneous matter or particulate
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
Compressive Compressive
4.3 Void Content—The material in the solid final form shall
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
20 6.630 10.45
a density within the ranges specified in Table 2, according to
25 10.15 16.00
the foam’s grade specification.The density shall be determined
30 14.30 22.70
using the method described in 8.2. All specimens shall meet
35 19.15 30.55
40 24.60 39.55
this requirement.
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,
F1839−08 (2021)
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
30 6.025 9.495
foam 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
7.1 The number of test specimens and the specimen sizes
5. Significance and Use
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
7.2 Test specimens shall be solid foam blocks. The short-
use in testing orthopaedic devices or instruments.
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
8.1 Determination of Void Content:
Grade Shear Modulus, Shear Modulus,
MPa MPa
8.1.1 Use the foam block specimens described and specified
5 5.460 9.000
in 8.2 – 8.6.
10 15.15 22.75
8.1.2 Examine all of the surfaces and edges of test speci-
12 19.70 29.20
mens for voids and nonuniform areas with the unaided eye.
15 27.10 39.70
20 40.75 59.25
Measure the dimensions of the void or nonuniform areas using
25 55.70 81.15
an instrument capable of measuring 60.025 mm.
30 71.70 105.0
35 88.65 131.0
8.2 Determination of Foam Density:
40 106.5 159.0
8.2.1 Prepare three specimens, 25.4 by 25.4 by 25.4 mm
50 144.0 220.0
from solid foam.
F1839−08 (2021)
8.2.2 Determine the apparent density of the three foam 8.6.2 Obtainfivesteelscrewsorthreadedtoolsthatmeetthe
specimens, in kg/m , in accordance with Test Method D1622. thread requirements given in Specification F543, Annex A5.
Grades 5, 10, 12, 15, 20, and 25 shall use screws or threaded
8.2.3 Calculate the average apparent density of the three
tools with the thread form of HB 6.5 screws (seeTable A5.4 of
foam specimens.
Specification F543, Annex A5), while Grades 30, 35, 40, and
8.3 Determination of Dimensional Stability:
50shallutilizescrewsorthreadedtoolswiththethreadformof
8.3.1 Prepare three specimens, 25.4 by 25.4 by 12.7 mm
HA 4.5 screws (see Table A5.2 of Specification F543, Annex
from solid foam.
A5).
8.3.2 Condition the specimen for 24 h at 21 6 2.8 °C and
8.6.3 Drill a 3.2-mm hole in the center of each foam
50 6 10 % relative humidity. Measure the specimen thickness
specimen, parallel to the thickness direction. The hole shall be
near the center of the length to 60.025 mm and mark the
positioned a minimum of 10 mm from any void or nonuniform
location of the measurement.
area. Tap the hole to a minimum depth of 25.4 mm using a tap
8.3.3 Place the specimen on a 6.35-mm thick aluminum
that corresponds to HB 6.5 or HA 4.5, as appropriate.
plate and apply a minimum vacuum pressure of 508 mm of
8.6.4 Insert the screw or threaded tool into each foam
mercury under a vacuum bag or diaphragm. Place this assem-
specimen to a depth of 20 mm.
bly in a circulating forced-air oven for not less than2hat121
8.6.5 Test in accordance with Specification F543, Annex
6 2.8 °C. Remove the assembly and allow to cool to 49 °C or
A3.
less while maintaining the vacuum.
8.6.6 Determine the maximum force, in Ne
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