1、Designation: F 1634 95 (Reapproved 2008)Standard Practice forIn-Vitro Environmental Conditioning of Polymer MatrixComposite Materials and Implant Devices1This standard is issued under the fixed designation F 1634; the number immediately following the designation indicates the year oforiginal adoptio
2、n 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 practice covers two procedures for conditioningnon-absorbable polymer
3、matrix composite (PMC) materialsand implant devices in a liquid environment to obtain a state ofsaturation.1.2 The purpose of this practice is to standardize methodsand reporting procedures for conditioning PMC materials andimplant devices (PMC specimens) in a user selected liquidenvironment prior t
4、o conducting subsequent tests. It is not thepurpose of this practice to determine the diffusion coefficientsor actual saturation levels of a given liquid into the materialsand devices. For these determinations, other procedures, suchas Test Method D 5229, may be followed.1.3 Diffusion of liquid into
5、 a solid material is a slowprocess. While the time necessary to achieve saturation at 37Cmay be sufficiently short for thin specimens, such as fracturefixation plates, it may be prohibitively long in thick sections,such as femoral components for hip arthroplasty. However, thediffusion process may be
6、 accelerated at an elevated tempera-ture. Consequently, two separate procedures (ProceduresAandB) are presented in this practice. Procedure A covers exposingthe specimen to the desired conditioning environment at 37C.Procedure B prescribes a method to accelerate the diffusionprocess by conditioning
7、the specimen at a selected elevatedtemperature.1.4 This practice does not specify the test environment to beused for conditioning. However, the pH value of immersionliquid shall be maintained at 7.4 6 0.2 to simulate the in vivoenvironment.1.5 The values stated in SI units are to be regarded asstand
8、ard. No other units of measurement are included in thisstandard.1.6 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 determine the appli
9、ca-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 756 Practice for Determination of Weight and ShapeChanges of Plastics Under Accelerated Service Condi-tions3D 3878 Terminology for Composite MaterialsD 52
10、29/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma-trix Composite Materials3. Terminology3.1 Definitions:3.1.1 cumulative moisture content, Mt(%), nthe amountof absorbed moisture in a material at a given time t, expressedas a percentage of the weight
11、of absorbed moisture divided bythe initial specimen weight, as follows:Mt,%5Wi2 WbWb3 100 (1)where:Wt= current specimen weight, g, andWb= initial (baseline) specimen weight at t = 0 and stan-dard laboratory atmosphere, g.3.1.2 liquid, nwater, saline solution, calf serum, or anyother liquid solution
12、that is used to condition PMC specimens.3.1.3 nominal saturated moisture content, Ms(%)an ap-proximation of the amount of moisture absorbed by a specimenat saturation, expressed as a percentage of the weight ofabsorbed moisture at approximate saturation divided by theinitial specimen weight, as foll
13、ows:Ms,%5Ws2 WbWb3 100 (2)1This practice is under the jurisdiction ofASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Aug. 1, 2008. Published August 2008. Originallyapproved in 199
14、5. Last previous edition approved in 2000 as F 1634 95 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website
15、.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where:Ws= specimen weight at approximate saturation, g, andWb= initial (baseline) specimen weight at t = 0 and stan-dard laboratory atmosphere, g.3.1.4 standard laboratory a
16、tmosphere, n a laboratoryatmosphere having a temperature of 23 6 2C and a relativehumidity of 50 6 10 %.4. Summary of Test Method4.1 In Procedure A, a specimen is immersed in a liquid bathat 37 6 1C with a pH value of 7.4 6 0.2.4.2 In Procedure B, conditioning occurs in a liquid bath at aselected el
17、evated temperature.4.3 Weight change is monitored over time until specimensreach the nominal moisture saturation content.4.4 Keep specimens in the conditioning bath for storageprior to subsequent tests.5. Significance and Use5.1 The conditioning procedures covered in this practiceprovide methods for
18、 saturating PMC specimens in a liquidenvironment prior to conducting other tests for propertyevaluation.5.2 The conditioning may affect geometric and dimensionalchanges in specimens. In some severe cases, chemical changesmay occur in the fiber, polymer and fiber-polymer interphaseand interface.5.3 C
19、aution must be taken if Procedure B (10.2, ProcedureBAccelerated Moisture Saturation at Elevated Temperature)is followed to condition PMC specimens at an elevatedtemperature. Physical and chemical reactions in materials arenormally temperature dependent. An increase in experimentaltemperature may ac
20、celerate a desirable moisture diffusionprocess. However, elevated temperatures above 37C may alsocause undesirable reactions that do not represent appropriateresponses of materials at 37C. Consequently, a pilot study isrecommended in Procedure B to determine if a selectedelevated temperature can be
21、used for accelerated conditioning.If the properties of materials are determined to be irreversiblyaffected by this pilot study at the selected elevated temperature,then either an appropriate lower elevated temperature shouldbe determined by repeating the pilot study, or Procedure Bshould not be used
22、.6. Apparatus6.1 BalanceAn analytical balance capable of measuringweight of specimens to within a resolution of at least 0.005 %of the total specimen weight.6.2 Conditioning BathA temperature-controlled liquidbath shall be capable of maintaining the required temperatureto within 61C. The bath shall
23、be monitored either on anautomated continuous basis or on a manual basis at regularintervals.6.3 Specimen Bag A sealable, flexible, moisture-proofbag made of material suitable for exposure to specimens thathave been removed from the conditioning bath for coolingprior to weighing. Bags that meet the
24、requirement of MIL-B-131 have been found to be satisfactory for use in suchapplications.6.4 Absorbent Cloth Clean, non-linting absorbent clothfor use in wiping excess liquid from surface of specimens.6.5 GlovesClean, non-linting gloves for use when han-dling specimens.6.6 pH Measurement SystemAn ana
25、lytical system capableof measuring pH to within 60.1.6.7 Differential Scanning CalorimeterAn analytical sys-tem capable of heating a specimen at a controlled rate whilemeasuring heat input and temperature.7. Sampling and Test Specimens7.1 Preparation Precaution shall be taken to avoid theentrapment
26、of moisture in uneven surfaces, or delaminationdue to inappropriate machining and manufacturing processes.7.2 LabelingLabel the specimen so as to be distinct fromeach other in a manner that will both be unaffected by the testand not influence the test and, furthermore, will not be removedduring cond
27、itioning.8. Measurements of Test Specimens8.1 The following measurements shall be made on speci-mens prior to immersion, after conditioning at the end of a testprocedure, and at any intermediate stage as prescribed in thetest procedures:8.1.1 WeightThe weight within 0.005 % of specimenweight.8.1.2 C
28、haracteristic dimensions of specimens may be mea-sured as a function of immersion time to determine the amountof swelling induced by moisture absorption.9. Visual Examination9.1 Noticeable qualitative changes in surfaces, outline, andgeneral appearance of the test specimen shall be recorded aftereac
29、h stage of the testing procedure. These changes includecolor, surface irregularities, odor, surface voids, delaminationand cracking. The immersion liquid should also be observedfor evidence of material that has leached from specimens orholders, and evidence of bacterial or fungal contamination. Ifba
30、cterial or fungal contamination is found, specimens shouldbe removed from the solution, washed with detergent andwater, rinsed, and placed in fresh solution. If contamination isa recurring problem, antibacterial or antifungal agents must beadded to the solution; minimal amounts should be used as the
31、ymay affect specimen properties.10. Procedures10.1 Procedure AMoisture Saturation Determination at37C:10.1.1 Specimen PreconditioningBring the test specimensto a uniform 23 6 2C after manufacturing process.10.1.2 Moisture Absorption:10.1.2.1 Record the initial (baseline) weight, Wb.10.1.2.2 Place th
32、e specimen in the conditioning bath, whichhas previously reached the specified temperature 37 6 1C.The pH value of immersion liquid used shall be maintained at7.4 6 0.2 throughout the conditioning process and monitoredat least once a week. If the solution pH falls outside thedesignated range, the so
33、lution should be changed. The pHshould not be maintained by repeatedly adding buffer to theF 1634 95 (2008)2same solution. This will change solution composition and mayaffect specimen properties. Evaporation losses should be madeup with sterile deionized water if saline, serum, plasma, orother hydro
34、us medium is used as the conditioning environ-ment.10.1.2.3 Monitor the weight gain of specimens over time. Asuggested schedule is to weigh each specimen every 24 h forthe first 120 h, then every 96 h.10.1.2.4 At the end of each time interval, remove thespecimens from the conditioning bath and place
35、 them in thespecimen bag. Seal the bag and allow the specimens to come tolaboratory standard temperature. Remove the specimens fromthe bag and wipe the specimens free of surface moisture withan absorbent lint-free cloth. Wait for 10 min and measure theweight of specimens to the required precision, a
36、nd Wt, alongwith the corresponding total elapsed time and the time intervalsince the previous measurement.10.1.2.5 Return the specimens to the conditioning bath. Thespecimens shall not be out of the conditioning bath for morethan 30 min and shall not be out of the specimen bag for morethan 15 min.10
37、.1.2.6 Calculate cumulative moisture content, Mt(%),using Eq 1 at each time interval and plot versus time.10.1.2.7 The minimum time, tmin, required to reach nominalsaturated moisture content, Ms, is the time at which the changein cumulative moisture content from the prior measurement isless than 0.0
38、10 % of specimen weight for three consecutiveweighings with no less than 96 h of elapsed time between eachconsecutive weighing.10.1.2.8 Following moisture saturation within the specifiedtolerance range, the specimen should be stored in a bath of thesame fluid which is to be used for post-conditionin
39、g testinguntil the time the post-conditioning testing is conducted.10.2 Procedure BAccelerated Moisture Saturation at El-evated Temperature:10.2.1 Determination of Accelerated Temperature (Ta)Level:10.2.1.1 Specimens should be first saturated in the condi-tioning environment at 37C and then evaluate
40、d by differentialscanning calorimeter (DSC) evaluation over a temperaturerange of 37 to 120C. The purpose of this is to determine if amaterial transition temperature (that is, glass transition ormelting temperature), or a degradation temperature (such as anoxidation or thermal decomposition temperat
41、ure), occurswithin this temperature range. If the material is stable withinthis range, then accelerated conditioning may be conducted atTa= 95C in a conditioning environment containing water. If atransition or degradation temperature is found between 37 and120C, then the maximum acceleration tempera
42、ture to be usedshould be at least 25C below the lowest transition or decom-position temperature. If nonhydrous solutions are used as theconditioning environment (that is, pure lipid), then a similarprocedure can be followed except the temperature would nowbe governed by the boiling or decomposition
43、temperature ofthe given environment and specimen combination.10.2.2 Effect of Accelerated Temperature Conditioning:10.2.2.1 Once Tais determined from 10.2.1.1, at least fivesamples representative of the specimen being evaluated shouldbe conditioning at both Taand 37C and then tested to checkfor cond
44、itioning temperature induced differences. Becauseconditioning may influence different material properties ofPMC specimens in different ways, the test implemented tocheck for differences between Taand 37C should closelymatch the intended post-conditioning test that the PMC speci-men will be condition
45、ed for. If Tainfluences the properties inquestion, then a lower conditioning temperature must beidentified by repeating this procedure at selected lower tem-peratures in which the property is not influenced by condition-ing. If the property is determined to be not influenced by Ta,then Tacan be used
46、 to accelerate the conditioning process forsubsequent specimens.10.2.3 Accelerated Conditioning:10.2.3.1 Follow the procedures outlined in 10.1.2 with theexception that the conditioning bath will be maintained at Ta61.0C. The same time-measurement sequence as described in10.1.2 should be used to det
47、ermine the minimum time, tmin,when saturation is reached. The bath should be adequatelysealed to minimize evaporation loss and periodically monitoredto ensure adequate bath depth is maintained for completeimmersion of samples. If the bath is physically sealed, a safemechanism of pressure relief (tha
48、t is, pressure relief valve orreleasable lid seal) must be provided to prevent pressurebuild-up if the oven is accidentally overheated. Evaporationlosses should be made up with sterile deionized water if saline,serum, plasma, or other hydrous medium is used as theconditioning environment.10.2.3.2 Fo
49、llowing moisture saturation within the specifiedtolerance range, the specimen should be stored in a bath of thesame fluid which is to be used for post-conditioning testinguntil the time the post-conditioning testing is conducted.11. Selection of Conditioning Procedure11.1 The choice between procedures should preferably bebased on the one that gives the most reproducible results.12. Report12.1 Report the following information:12.1.1 Description of the specimen or device being consid-ered (that is, material name, dimensions, part number, modelnumber
