1、Designation: F1839 08 (Reapproved 2012)Standard Specification forRigid Polyurethane Foam for Use as a Standard Material forTesting Orthopaedic Devices and Instruments1This standard is issued under the fixed designation F1839; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers rigid unicellular polyurethanefoam fo
3、r use as a standard material for performing mechanicaltests utilizing orthopaedic devices or instruments. The specifi-cation is applicable to sheets or blocks of foam, or foam that ismade by the user using a two-part liquid mixture.1.2 This specification covers polyurethane foam materialthat is used
4、 in the laboratory for mechanical testing, asdescribed in 1.1. These materials are not intended for implan-tation into the human body.1.3 The foam described herein possesses mechanical prop-erties which are on the order of those reported for humancancellous bone. See Appendix X1, Rationale, for furt
5、herinformation regarding the appropriateness of using the speci-fied foam as a model for human cancellous bone.1.4 This specification covers compositional requirements,physical requirements, mechanical requirements, and testmethods for rigid polyurethane foam in the solid final form.1.5 This specifi
6、cation provides qualification criteria forvendor or end-user processes and acceptance criteria forindividual material lots.1.6 This specification provides mechanical properties of fivedifferent grades of foam in the solid final form. A foam thatdoes not meet the specified mechanical properties shall
7、 beidentified as an ungraded foam.1.7 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.8 The following precautionary statement pertains to thetest method portion only, Section 8, of this specification: Thisstandard does not pur
8、port to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenced Documents2.1 ASTM Standards:2C273
9、 Test Method for Shear Properties of Sandwich CoreMaterialsD1621 Test Method for Compressive Properties of RigidCellular PlasticsD1622 Test Method for Apparent Density of Rigid CellularPlasticsE4 Practices for Force Verification of Testing MachinesF543 Specification and Test Methods for Metallic Med
10、icalBone Screws3. Terminology3.1 Definitions:3.1.1 final formthe condition of the foam product whenused by the end user to perform tests of orthopaedic devices orinstruments.3.1.1.1 DiscussionThis is the condition of the foam prod-uct of which all physical and mechanical tests required by thisspecif
11、ication are performed.3.1.1.1 solidthe foam is in a uniform solid form, such asa slab, plate, or block.3.1.2 foam rise directionthe nominal direction that thefoam rises during the polymerization (“foaming”) process,either at the suppliers production facilities for the solidsupplied foam, or at the e
12、nd-users facilities for foam producedfrom the liquid supplied form. The foam rise direction shall bemarked on the foam block or indicated in the shippingdocumentation for foam that is supplied in the solid form.3.1.3 gradesThe grade designation refers to the nominaldensity of the foam, in its solid
13、final form, expressed in unitsof kg/m3. Ten grades of foam have been defined in thisspecification. Their nominal densities are:1This specification is under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and is the direct responsibility ofSubcommittee F04.21 on Os
14、teosynthesis.Current edition approved Oct. 1, 2012. Published October 2012. Originallyapproved in 1997. Last previous edition approved in 2008 as F1839 082. DOI:10.1520/F1839-08R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.or
15、g. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Grade 5: 80.1 kg/m3Grade 10: 160.2 kg/m3Grade 12: 192.2 kg/m3Grade
16、 15: 240.3 kg/m3Grade 20: 320.4 kg/m3Grade 25: 400.5 kg/m3Grade 30: 480.5 kg/m3Grade 35: 560.6 kg/m3Grade 40: 640.7 kg/m3Grade 50: 800.9 kg/m3Foam that does not fit into one of these ten grades be-cause it does not meet one or more of the physical require-ments of Section 4 is termed ungraded.3.1.3.
17、1 DiscussionGrade 5 designates the nominal valueof 5 lbm/ft3.3.1.4 supplied formthe condition of the foam productwhen received from the supplier by the end user.3.1.4.1 DiscussionThe supplied form may be a solid or aliquid. The foam may be in a uniform solid form such as a slab,plate, or block or a
18、liquid in which two liquid components(base and activator) can be mixed by the end user to producea rigid, unicellular foam slab.4. Physical and Mechanical Requirements4.1 CompositionThe material shall be supplied either insolid or liquid form. The solid or combined liquid parts shallproduce a foam c
19、onsisting of polyether polyurethane.4.2 Appearance:4.2.1 Solid Supplied FormThe solid supplied form shallbe free of obvious extraneous matter, and appear to the unaidedeye to be uniform throughout the slab in color and porosity.4.2.2 Liquid Supplied FormThe two liquid componentsshall appear to the u
20、naided eye throughout their volumes to beuniform and free from obvious extraneous matter or particulatedebris.4.2.3 Solid Final FormThe solid final form shall be free ofobvious extraneous matter, and appear to the unaided eye to beuniform throughout the slab in color and porosity.4.3 Void ContentThe
21、 material in the solid final form shallmeet the requirements of Table 1 for voids, cracks andnonuniform areas, when examined using the procedures de-scribed in 8.1. All specimens shall meet this requirement.4.4 DensityThe material in the solid final form shall havea density within the ranges specifi
22、ed in Table 2, according tothe foams grade specification. The density shall be determinedusing the method described in 8.2. All specimens shall meetthis requirement.4.5 Dimensional StabilityThe material in the solid finalform shall have an average percentage thickness change lessthan 5.0 %, when tes
23、ted according to the method described in8.3.4.6 Compressive StrengthThe material in the solid finalform shall meet the compressive strength requirements given inTable 3, when tested according to the method described in 8.4.All specimens shall meet this requirement.4.7 Compressive ModulusThe material
24、 in the solid finalform shall meet the compressive modulus requirements givenin Table 4, when tested according to the method described in8.4. All specimens shall meet this requirement.4.8 Shear StrengthThe material in the solid final formshall meet the shear strength requirements given in Table 5,TA
25、BLE 1 Requirements for Voids, Cracks, and Nonuniform AreasDefects RequirementsVoidsVoid depth (measured perpendicularto slabs transverse plane)Void depth shall be less than 50 % ofthe slab thickness, and less than6.35 mmVoid diameter (measured parallel toslabs transverse plane)Larger than 6.35 mm No
26、ne allowed in any gradeBetween 3.18 mmand 6.35 mmNo more than 10 allowed per 230cm2surface area for Grades 5 and10. No more than 1 allowed forGrades 12, 15, 20, 25, 30, and 35.None allowed for Grades 40 and 50.Between 1.57 mmand 3.18 mmNo more than 20 allowed per 230cm2surface area for Grades 5 and1
27、0. No more than 6 allowed forGrades 12, 15, 20, 25, 30, and 35.No more than 3 allowed for Grades40 and 50.Cracks None allowedNon-uniform areas Concentrated areas of poorconstruction, irregular cells, and hardand soft spots shall not exceed 10 %of the visible surface areaTABLE 2 Grade Designation and
28、 DensityGradeMinimum Density,kg/m3Maximum Density,kg/m35 72.10 88.1010 144.0 176.012 173.0 211.515 216.0 264.520 288.5 352.525 360.5 440.530 432.5 528.535 504.5 617.040 576.5 705.050 721.0 881.0TABLE 3 Requirements for Compressive StrengthGradeMinimumCompressiveStrength,MPaMaximumCompressiveStrength
29、,MPa5 0.4495 0.780010 1.745 2.82012 2.485 3.97015 3.820 6.05020 6.630 10.4525 10.15 16.0030 14.30 22.7035 19.15 30.5540 24.60 39.5550 37.35 61.05F1839 08 (2012)2when tested according to the method described in 8.5. Allspecimens shall meet this requirement.4.9 Shear ModulusThe material in the solid f
30、inal formshall meet the shear modulus requirements given in Table 6,when tested according to the method described in 8.5. Allspecimens shall meet this requirement.4.10 Screw PulloutThe material in the solid final formshall meet the screw pullout requirements given in Table 7,when tested according to
31、 the method described in 8.6. Allspecimens shall meet this requirement.5. Significance and Use5.1 This specification describes the compositionalrequirements, physical requirements, mechanical requirements,and test methods for rigid unicellular polyurethane foam foruse in testing orthopaedic devices
32、or instruments.5.2 This foam described in this specification is not intendedto replicate the mechanical properties of human or animalbone. The requirements of this specification are intended toprovide a consistent and uniform material with properties onthe order of human cancellous bone to use as a
33、test mediumwhen testing various orthopaedic devices, such as bone screws.6. Apparatus6.1 Analytical Balance or Scalecapable of weighing foamspecimens to the nearest mg.6.2 Micrometer Dial Gage or Calipercapable of measur-ing dimensions of the foam specimens to 60.1 %.6.3 Conditioning OvenForced-air
34、circulating oven ca-pable of maintaining 121 6 2.8C for 24 h.6.4 Desiccatorcontaining desiccant with high affinity forwater vapor (anhydrous calcium chloride or equivalent).6.5 Vacuum Apparatuscapable of applying a vacuumpressure of 508 mm (20 in.) of mercury to foam specimen fordimensional stabilit
35、y test.6.6 Testing Machine and Load Cellconforming to Prac-tices E4 and capable of applying tensile and compressive loadsat a constant displacement rate.7. Sampling and Test Specimens7.1 The number of test specimens and the specimen sizesrequired for physical characterization and mechanical testinga
36、re described in 8.1-8.6. Test specimens are required for eachgrade and formulation.7.2 Test specimens shall be solid foam blocks. The short-transverse direction of the specimens shall coincide with thefoam rise direction of the original foam bun.8. Procedure8.1 Determination of Void Content:8.1.1 Us
37、e the foam block specimens described and specifiedin 8.2-8.6.8.1.2 Examine all of the surfaces and edges of test speci-mens for voids and nonuniform areas with the unaided eye.Measure the dimensions of the void or nonuniform areas usingan instrument capable of measuring 60.025 mm.8.2 Determination o
38、f Foam Density:8.2.1 Prepare three specimens, 25.4 by 25.4 by 25.4 mmfrom solid foam.TABLE 4 Requirements for Compressive ModulusGradeMinimumCompressiveModulus,MPaMaximumCompressiveModulus,MPa5 12.30 20.3510 45.75 71.7012 64.50 100.515 98.00 151.020 167.5 257.525 253.5 390.030 355.5 548.535 472.0 73
39、2.040 603.0 941.050 907.5 1435TABLE 5 Requirements for Shear StrengthGradeMinimumShear Strength,MPaMaximumShear Strength,MPa5 0.420 0.80510 1.225 2.01012 1.610 2.58015 2.235 3.51020 3.395 5.27525 4.665 7.27530 6.025 9.49535 7.460 11.9540 8.960 14.5550 12.10 20.40TABLE 6 Requirements for Shear Modulu
40、sGradeMinimumShear Modulus,MPaMaximumShear Modulus,MPa5 5.460 9.00010 15.15 22.7512 19.70 29.2015 27.10 39.7020 40.75 59.2525 55.70 81.1530 71.70 105.035 88.65 131.040 106.5 159.050 144.0 220.0Editorially corrected.TABLE 7 Requirements for Screw PulloutGradeMinimumPullout,NMaximumPullout,N5 56.00 17
41、6.010 220.0 453.012 309.5 592.515 464.5 831.020 770.0 131025 1125 189030 1520 257035 1950 335540 2400 424550 3380 6350F1839 08 (2012)38.2.2 Determine the apparent density of the three foamspecimens, in kg/m3, in accordance with Test Method D1622.8.2.3 Calculate the average apparent density of the th
42、reefoam specimens.8.3 Determination of Dimensional Stability:8.3.1 Prepare three specimens, 25.4 by 25.4 by 12.7 mmfrom solid foam.8.3.2 Condition the specimen for 24 h at 21 6 2.8C and50 6 10 % relative humidity. Measure the specimen thicknessnear the center of the length to 60.025 mm and mark thel
43、ocation of the measurement.8.3.3 Place the specimen on a 6.35-mm thick aluminumplate and apply a minimum vacuum pressure of 508 mm ofmercury under a vacuum bag or diaphragm. Place this assem-bly in a circulating forced-air oven for not less than2hat1216 2.8C. Remove the assembly and allow to cool to
44、 49C orless while maintaining the vacuum.8.3.4 Recondition and remeasure the thickness at themarked location in accordance with 8.3.2. Calculate the per-cent thickness change.8.3.5 Calculate the average percent thickness change of thethree specimens.8.4 Determination of Compressive Strength and Modu
45、lus: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 tothe foam rise direction. Measure the dimensions within60.025 mm. The specimens shall be conditioned at 24 62.8C for 3 h prior to testing.8.4.2 Test in accordance with Test Method
46、D1621 at 24 62.8C. The specimens shall be oriented such that the axis of thecompressive load is applied parallel to the foam rise direction.8.4.3 Determine the compressive strength using ProcedureA of Test Method D1621 and the maximum compressivemodulus for each specimen.8.4.4 Calculate the average
47、compressive strength and modu-lus of the five specimens.8.5 Determination of Shear Strength and Modulus:8.5.1 Prepare five specimens, 76.2 by 25.4 by 6.35 mm,from solid foam, with the thickness of the specimen parallel tothe foam rise direction. Measure the dimensions within60.025 mm. The specimens
48、shall be conditioned at 24 62.8C for 3 h before testing.8.5.2 Bond the edges of the foam specimen directly to theshear plates with an appropriate adhesive, such as an epoxy, sothat the foam rise direction is perpendicular to the plane ofmaximum shear stress.8.5.3 Test in accordance with Test Method
49、C273.8.5.4 Determine the shear strength and shear modulus foreach specimen.8.5.5 Calculate the average shear strength and modulus ofthe five specimens.8.6 Determination of Screw Pullout Strength8.6.1 Prepare five specimens, 50.8 by 50.8 by 25.4 mm,from solid foam, with the thickness of the specimen parallel tothe foam rise direction.8.6.2 Obtain five steel screws or threaded tools that meet thethread requirements given in Specification F543, Annex 4.Grades 5, 10, 12, 15, 20, and 25 shall use screws or threadedtools with the thread form of
