ASTM F1839-08(2012)
(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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Standards Content (Sample)
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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.
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
Plastics
1.3 The foam described herein possesses mechanical prop-
E4 Practices for Force Verification of Testing Machines
erties which are on the order of those reported for human
F543 Specification and Test Methods for Metallic Medical
cancellous bone. See Appendix X1, Rationale, for further
Bone Screws
information regarding the appropriateness of using the speci-
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
instruments.
1.5 This specification provides qualification criteria for
3.1.1.1 Discussion—This is the condition of the foam prod-
vendor or end-user processes and acceptance criteria for
uct of which all physical and mechanical tests required by this
individual material lots.
specification are performed.
1.6 Thisspecificationprovidesmechanicalpropertiesoffive
3.1.1.1 solid—the foam is in a uniform solid form, such as
different grades of foam in the solid final form. A foam that
a slab, plate, or block.
does not meet the specified mechanical properties shall be
identified as an ungraded foam. 3.1.2 foam rise direction—the nominal direction that the
foam rises during the polymerization (“foaming”) process,
1.7 The values stated in SI units are to be regarded as
either at the supplier’s production facilities for the solid
standard. No other units of measurement are included in this
supplied foam, or at the end-user’s facilities for foam produced
standard.
from the liquid supplied form. The foam rise direction shall be
1.8 The following precautionary statement pertains to the
marked on the foam block or indicated in the shipping
test method portion only, Section 8, of this specification: This
documentation for foam that is supplied in the solid form.
standard does not purport to address all of the safety concerns,
3.1.3 grades—The grade designation refers to the nominal
if any, associated with its use. It is the responsibility of the user
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:
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
ε2
approved in 1997. Last previous edition approved in 2008 as F1839 – 08 . DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F1839-08R12. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1839−08 (2012)
3 TABLE 1 Requirements for Voids, Cracks, and Nonuniform Areas
Grade 5: 80.1 kg/m
Grade 10: 160.2 kg/m
Defects Requirements
Grade 12: 192.2 kg/m
Voids
Grade 15: 240.3 kg/m
Grade 20: 320.4 kg/m
Void depth (measured perpendicular Void depth shall be less than 50 % of
Grade 25: 400.5 kg/m
to slab’s transverse plane) the slab thickness, and less than
Grade 30: 480.5 kg/m
6.35 mm
Grade 35: 560.6 kg/m
Grade 40: 640.7 kg/m
Void diameter (measured parallel to
Grade 50: 800.9 kg/m
slab’s transverse plane)
Foam that does not fit into one of these ten grades be-
Larger than 6.35 mm None allowed in any grade
cause it does not meet one or more of the physical require-
Between 3.18 mm No more than 10 allowed per 230
ments of Section 4 is termed ungraded.
and 6.35 mm cm surface area for Grades 5 and
3.1.3.1 Discussion—Grade 5 designates the nominal value
10. No more than 1 allowed for
of 5 lbm/ft .
Grades 12, 15, 20, 25, 30, and 35.
None allowed for Grades 40 and 50.
3.1.4 supplied form—the condition of the foam product
when received from the supplier by the end user. Between 1.57 mm No more than 20 allowed per 230
and 3.18 mm cm surface area for Grades 5 and
3.1.4.1 Discussion—The supplied form may be a solid or a
10. No more than 6 allowed for
liquid.Thefoammaybeinauniformsolidformsuchasaslab,
Grades 12, 15, 20, 25, 30, and 35.
No more than 3 allowed for Grades
plate, or block or a liquid in which two liquid components
40 and 50.
(base and activator) can be mixed by the end user to produce
a rigid, unicellular foam slab.
Cracks None allowed
Non-uniform areas Concentrated areas of poor
4. Physical and Mechanical Requirements
construction, irregular cells, and hard
and soft spots shall not exceed 10 %
4.1 Composition—The material shall be supplied either in
of the visible surface area
solid or liquid form. The solid or combined liquid parts shall
produce a foam consisting of polyether polyurethane.
TABLE 2 Grade Designation and Density
4.2 Appearance:
Minimum Density, Maximum Density,
4.2.1 Solid Supplied Form—The solid supplied form shall
Grade
3 3
kg/m kg/m
befreeofobviousextraneousmatter,andappeartotheunaided
5 72.10 88.10
eye to be uniform throughout the slab in color and porosity.
10 144.0 176.0
4.2.2 Liquid Supplied Form—The two liquid components 12 173.0 211.5
15 216.0 264.5
shall appear to the unaided eye throughout their volumes to be
20 288.5 352.5
uniform and free from obvious extraneous matter or particulate
25 360.5 440.5
debris. 30 432.5 528.5
35 504.5 617.0
4.2.3 SolidFinalForm—Thesolidfinalformshallbefreeof
40 576.5 705.0
obvious extraneous matter, and appear to the unaided eye to be
50 721.0 881.0
uniform throughout the slab in color and porosity.
4.3 Void Content—The material in the solid final form shall
TABLE 3 Requirements for Compressive Strength
meet the requirements of Table 1 for voids, cracks and
Minimum Maximum
nonuniform areas, when examined using the procedures de-
Compressive Compressive
Grade
scribed in 8.1. All specimens shall meet this requirement.
Strength, Strength,
MPa MPa
4.4 Density—The material in the solid final form shall have
5 0.4495 0.7800
a density within the ranges specified in Table 2, according to
10 1.745 2.820
12 2.485 3.970
the foam’s grade specification.The density shall be determined
15 3.820 6.050
using the method described in 8.2. All specimens shall meet
20 6.630 10.45
this requirement.
25 10.15 16.00
30 14.30 22.70
4.5 Dimensional Stability—The material in the solid final
35 19.15 30.55
form shall have an average percentage thickness change less 40 24.60 39.55
50 37.35 61.05
than 5.0 %, when tested according to the method described in
8.3.
4.6 Compressive Strength—The material in the solid final
formshallmeetthecompressivestrengthrequirementsgivenin
Table 3, when tested according to the method described in 8.4.
in Table 4, when tested according to the method described in
All specimens shall meet this requirement.
8.4. All specimens shall meet this requirement.
4.7 Compressive Modulus—The material in the solid final 4.8 Shear Strength—The material in the solid final form
form shall meet the compressive modulus requirements given shall meet the shear strength requirements given in Table 5,
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.
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 A4.4 of
8.2.3 Calculate the average apparent density of the three Specification F543,Annex 4), while Grades 30, 35, 40, and 50
foam specimens. shall utilize screws or threaded tools with the thread form of
HA 4.5 screws (see Table A4.2 of Specification F543, Annex
8.3 Determination of Dimensional Stability:
4).
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 The lot number, specified grade (if applicable),
8.4.1 Prep
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