1、Designation: F2381 10Standard Test Method forEvaluating Trans-Vinylene Yield in Irradiated Ultra-HighMolecular Weight Polyethylene Fabricated Forms Intendedfor Surgical Implants by Infrared Spectroscopy1This standard is issued under the fixed designation F2381; the number immediately following the d
2、esignation indicates the year oforiginal 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 test method describes
3、the measurement of thenumber of trans-vinylene groups in ultra-high molecularweight polyethylene (UHMWPE) intended for use in medicalimplants. The material is analyzed by infrared spectroscopy.1.2 This test method is based on Guide F2102.1.3 The applicability of the infrared method has beendemonstra
4、ted in other literature reports. This particularmethod, using the intensity (area) of the C-H absorptioncentered at 1370 cm-1to normalize for the samples thickness,will be validated by an Interlaboratory Study (ILS) conductedaccording to Practice E691.1.4 The values stated in SI units are to be rega
5、rded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determi
6、ne the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared (FT-MIR) Sp
7、ectrom-eters: Level Zero and Level One TestsF2102 Guide for Evaluating the Extent of Oxidation inUltra-High-Molecular-Weight Polyethylene FabricatedForms Intended for Surgical Implants3. Terminology3.1 Definitions:3.1.1 trans-vinylene index (TVI)a trans-vinylene index isdefined as the ratio of the a
8、rea of the absorption peak centerednear 965 cm-1to the area of the absorption peak centered near1370 cm-1.3.1.2 depth locator (DL)a measurement of the distancefrom the articular surface, or surface of interest, that a spectrumwas collected and a corresponding TVI calculated.3.1.3 trans-vinylene inde
9、x profilea trans-vinylene indexprofile is defined as the graphical representation of variation ofthe samples trans-vinylene index with distance from itsarticular surface or the surface of interest. This is a plot of TVIversus DL. Typically, the graph will show the profile throughthe entire thickness
10、 of the sample.4. Significance and Use4.1 Published literature shows that the yield of radiolyticreactions that occur during radiation treatment increases withradiation dose level. Measurement of the products of thesereactions can be used as an internal dosimeter.4.2 Trans-vinylene unsaturations are
11、 formed during ioniza-tion treatment by abstraction of a hydrogen molecule, and to alesser extent by the recombination of two adjacent alkyl freeradicals that reside on the same chain.4.3 Previous work generated calibration curves of trans-vinylene absorption area as a function of absorbed radiation
12、dose, yielding a linear relationship for both gamma- andelectron beam-irradiated polyethylene.4.4 This data can be used to determine received dose as afunction of position, assuming a calibration curve (TVI versusradiation dose level) is known for the particular material andradiation conditions used
13、, and can be used to determineuniformity of dose level in irradiated polyethylene.1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Jun
14、e 1, 2010. Published July 2010. Originally approved2004. Last previous edition approved in 2004 as F238104. DOI: 10.1520/F2381-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informat
15、ion, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Apparatus5.1 Infrared Spectrometer:5.1.1 A calibrated infrared spectrometer capable of record-ing a transmission
16、absorption spectrum over a minimum rangeof 900 to about 2000 cm-1using about 200 m-thick films at aresolution of 4 cm-1and an aperture of approximately 200 by200 m for a rectangular aperture, or 200 m diameter for acircular aperture.5.1.1.1 Other modes of collection (that is, reflection, attenu-ated
17、 total reflection (ATR), and so forth) and aperture andsampling step sizes may be used to generate the samplesabsorption spectrum provided they can be demonstrated toproduce equivalent results. Too large an aperture can result ina loss of profile accuracy.5.1.1.2 When a Fourier Transform Infrared (F
18、TIR) spec-trometer is used, a minimum of 32 scans shall be collected perspectrum.5.1.1.3 The FTIR instrument and sample compartmentshould be purged with a moisture- and carbon-dioxide-freeinert gas (for example, nitrogen, helium, or argon) to minimizespectral interference from these components.5.2 S
19、pecimen HolderEquipment, such as an x-y table,capable of accurately positioning the sample under the FTIRaperture with a minimum resolution at the scale of the aperturedimensions.5.3 MicrotomeEquipment capable of producing films ofthickness 200 m or less of a sample perpendicular to thearticular sur
20、face or the surface of interest.6. Sampling, Test Specimens, and Test Units6.1 Using a microtome, or other appropriate device, preparea thin slice of the sample about 200 m thick. If the detectedsignal from the FTIR is too weak with this thickness, a thickersample may be used.6.2 The slice shall typ
21、ically be taken near the center of thesamples articular surface or the surface of interest.6.3 The orientation of the slice shall typically be perpen-dicular to the articular surface or the surface of interest.6.4 Waviness in the infrared spectrum caused by Fourierrippling on the lower wavelengths c
22、an interfere with thetrans-vinylene absorbance at 965 cm-1. This rippling is causedby internal reflection of the infrared beam, and can be avoidedby lightly rubbing the sample film against 400 grit sandpaperuntil the film becomes translucent. This roughening procedureshould be done slowly to avoid h
23、eating the film, and should beperformed until the area under a single peak due to Fourierrippling is less than 10 % of the area under the trans-vinylenepeak.7. Preparation of Apparatus7.1 Prepare the infrared spectrometer for collection of atransmission absorption spectrum from a thin film of theUHM
24、WPE sample according to the manufacturers recommen-dations, Practice E1421, and the conditions described in 5.1.8. Procedure8.1 The test film (slice) shall be first configured in thespectrometer (after an appropriate background spectrum hasbeen collected) such that the aperture is positioned over th
25、efirst 200 m of the film starting at the surface of interest.8.2 Subsequent spectra shall be collected sequentially atincrements matching the aperture size (that is, about 200 m)from the articular surface, or surface of interest, across thewidth of the film to the opposite surface.8.3 Larger increme
26、nts may be used; however, too large anincrement size may result in a loss of profile accuracy.9. Calculation of Results9.1 Trans-vinylene Peak Area:9.1.1 For each absorbance spectrum, calculate the total areaof the absorption peak centered near 965 cm-1(see Fig. 1).9.1.2 This area is the area below
27、the samples absorbancecurve and above the straight baseline drawn between the samestarting and ending points used in 3.1.1.9.2 Normalization of Peak Area:9.2.1 For each absorbance spectrum, calculate the total areaof the absorption peak centered near 1370 cm-1(see Fig. 2).9.2.2 This area is the area
28、 below the samples absorbancecurve and above the straight baseline drawn between the samestarting and ending points used in 3.1.1.9.3 Trans-vinylene Index (TVI)For each absorbance spec-trum, calculate its TVI by dividing the area of its trans-vinylenepeak (see 9.1) by the area of its normalization p
29、eak (see 9.2).9.4 Depth Locator (DL)Calculate the distance from thearticular surface, or surface of interest, termed the depth locator(DL), for each spectrum and its corresponding TVI from thefollowing equation:DL 5 0.5A! 1 nS! (1)where:A = the size of the aperture in micrometers in the stepdirectio
30、n,n = the number of steps (increments) the aperture had beenmoved from its initial location at the articular surfaceor surface of interest, andS = the step (increment) size in micrometers.10. Report10.1 The report shall contain at least the following experi-mental details and results:10.1.1 Material
31、 Information:10.1.1.1 Resin type and resin lot number,10.1.1.2 Consolidation method and manufacturer and manu-facturer lot number, and10.1.1.3 Any special post-consolidation treatments, for ex-ample, HIPing, annealing, sterilization, crosslinking, stabiliza-tion, accelerated aging, and storage condi
32、tions.10.1.2 Sample Information:10.1.2.1 Indicate whether the sample is an orthopedic im-plant or laboratory test specimen,10.1.2.2 Articular surface or non-articular surface,10.1.2.3 Test samples original dimensions,10.1.2.4 Any special post-treatments of the original testsample, for example, annea
33、ling, sterilization, crosslinking,stabilization, accelerated aging, and storage conditions,10.1.2.5 Test film thickness and total width, andF2381 102NOTEFourier rippling disappears with increased surface roughening. The original absorption peaks are unaffected by the surface roughening.FIG. 1 FTIR S
34、pectra of Thin UHMWPE Film Showing the Effects of Roughening on Fourier RipplingFIG. 2 Typical FTIR Spectrum of Radiation-Crosslinked UHMWPE, Showing the Definition of an Area-Based Trans-VinyleneIndex Based on the Normalization Peak at 1370 cm-1F2381 10310.1.2.6 Any special post-treatments of the t
35、est films, forexample, annealing, sterilization, crosslinking, stabilization,accelerated aging, and storage conditions.10.1.3 Spectrometer Information:10.1.3.1 Manufacturer and model number,10.1.3.2 Analog or Fourier transform spectrometer, and10.1.3.3 Aperture dimensions, profile step size, spectra
36、lresolution, and number of scans per spectrum.10.1.4 Data Analysis Information:10.1.4.1 Manual or by spectrometers software algorithms.11. Precision and Bias11.1 Precision and bias data will be forthcoming followinga round-robin test.12. Keywords12.1 crosslinking; FTIR (Fourier Transform Infrared);
37、im-plant; trans-vinylene index; TVI; UHMWPE (ultra-high mo-lecular weight polyethylene)APPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 The extent of crosslinking present in orthopedicimplant components made of UHMWPE has been shown toaffect both mechanical properties and wear behavior. It isther
38、efore important to have standard methods for assessing thedegree of crosslinking of such materials.X1.2 The method described herein is an adaptation ofmethods described in the literature, and of other ASTMstandards.X1.3 The intensity (area) of the trans-vinylene absorptions(-C=C-) centered near 965
39、cm-1is related to the amount ofcrosslinking experienced by the material when exposed toionizing radiation. The correlation between TVI and actualreceived radiation dose depends on the nature of the irradiationconditions, for example, radiation source (gamma or electronbeam), temperature, dose rate,
40、and oxygen level. To determineradiation doses from TVI measurements, a calibration curvemust be prepared for the specific radiation conditions used,using validated dosimeters (such as photochromic dyes) as anindicator of the delivered radiation dose.X1.4 This test method is useful for assessing the
41、uniformityof crosslinking in an irradiated component or pre-form.X1.5 This test method does not specify desired levels ofTVI to achieve optimal functional characteristics.REFERENCES(1) Muratoglu, O. K., OConnor, D. O., Bragdon, C. R., Delaney, J., Jasty,M., Harris, W. H., Merrill, E., and Venugopala
42、n, P., “GradientCrosslinking of UHMWPE Using Irradiation in Molten State for TotalJoint Arthroplasty,” Biomaterials, 23, 2002, pp. 717-724.(2) Muratoglu, O. K., Harris, W. H., “Identification and Quantification ofIrradiation in UHMWPE Through Trans-vinylene Yield,” J. Biomed.Mat. Res., 56, 2001, PP.
43、 584-592.(3) Lyons, B. J., Johnson, W. C., “Radiolytic Formation and Decay ofTrans-vinylene Unsaturation in Polyethylene,” Irradiation of Poly-meric Materials: Processes, Mechanisms, and Applications, Reichma-nis et al., ed., American Chemical Society, Washington, D.C., Vol 527,1993, pp. 62-73.(4) J
44、ohnson, W. C., Lyons, B. J., “Radiolytic Formation and Decay ofTrans-vinylene Unsaturation in Polyethylene: Fournier TransformInfra-Red Measurements,” Rad. Phys. Chem., 46, 1995, pp. 829-832.(5) Lyons, B. J., “Role of Intramolecular Crosslinking in the Radiolysis ofBulk Crystallized High Density Pol
45、yethylene,” Rad. Phys. Chem., 28,1986, pp. 149-155.(6) McLaughlin, W. L., Silverman, J., Al-Sheikhly, M., Chappas, W. J.,Zhan-Jun, L., Miller, A., and Batsberg-Pedersen, W., “High DensityPolyethylene Dosimetry by Trans-vinylene FTIR Analysis,” Rad.Phys. Chem., 56, 1999, pp. 503-508.F2381 104ASTM Int
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