1、Designation: F1634 95 (Reapproved 2016)Standard Practice forIn-Vitro Environmental Conditioning of Polymer MatrixComposite Materials and Implant Devices1This standard is issued under the fixed designation F1634; the number immediately following the designation indicates the year oforiginal adoption
2、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 ma
3、trix 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 to
4、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 D5229/D5229M, may be followed.1.3 Diffusion of liquid
5、into 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 ma
6、y be 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 condition
7、ing 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 ass
8、tandard. 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 a
9、pplica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD756 Practice for Determination of Weight and ShapeChanges of Plastics UnderAccelerated Service Conditions(Withdrawn 1998)3D3878 Terminology for Composit
10、e MaterialsD5229/D5229M Test Method for MoistureAbsorption Prop-erties and Equilibrium Conditioning of Polymer MatrixComposite 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
11、 the weight of absorbed moisture divided bythe initial specimen weight, as follows:Mt,%5Wi2 WbWb3100 (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 liqui
12、d solution 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 weig
13、ht, as follows: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 June 1, 2016. Published June 2016. Originallyapproved in 1995. Last previ
14、ous edition approved in 2008 as F1634 95 (2008).DOI: 10.1520/F1634-95R16.2For 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 A
15、STM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesNOTICE: This standard has either been superseded and replaced by a new version or withdrawn
16、.Contact ASTM International (www.astm.org) for the latest information1Ms,%5Ws2 WbWb3100 (2)where:Ws= specimen weight at approximate saturation, g, andWb= initial (baseline) specimen weight at t = 0 and standardlaboratory atmosphere, g.3.1.4 standard laboratory atmosphere, n a laboratoryatmosphere ha
17、ving 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 elevated temperature.4.3 Weight change i
18、s 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 saturating PMC specimens in a liquide
19、nvironment 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 Caution must be taken if Procedure B (1
20、0.2, 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 accelerate a desirable moisture diffusio
21、nprocess. 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 used for accelerated conditioning.If t
22、he 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.6. Apparatus6.1 BalanceAn analytical
23、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 be monitored either on anautomated con
24、tinuous basis or on a manual basis at regularintervals.6.3 Specimen BagA sealable, flexible, moisture-proof bagmade of material suitable for exposure to specimens that havebeen removed from the conditioning bath for cooling prior toweighing. Bags that meet the requirement of MIL-B-131 havebeen found
25、 to be satisfactory for use in such applications.6.4 Absorbent ClothClean, non-linting absorbent cloth foruse 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 analytical system capableof measuring pH to
26、 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 PreparationPrecaution shall be taken to avoid theentrapment of moisture in uneven surfaces, or delami
27、nationdue 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 conditioning.8. Measurements of Test Specimen
28、s8.1 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 Characteristic dimensions of specimens may
29、 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 aftereach stage of the testing procedure. These c
30、hanges 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. Ifbacterial or fungal contamination is found,
31、 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 theymay affect specimen properties.10. Proce
32、dures10.1 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:F1634 95 (2016)210.1.2.1 Record the initial (baseline) weight, Wb.10.1.2.2 Place the specimen in the conditi
33、oning 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 solution should be changed.
34、 The pHshould not be maintained by repeatedly adding buffer to thesame solution. This will change solution composition and mayaffect specimen properties. Evaporation losses should be madeup with sterile deionized water if saline, serum, plasma, orother hydrous medium is used as the conditioning envi
35、ron-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 them in thespecimen bag. Seal the bag and
36、 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, and Wt, alongwith the corresponding total e
37、lapsed 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.10.1.2.6 Calculate cumulative moisture conte
38、nt, 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 0.010 % of specimen weight for three consecut
39、iveweighings 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-conditioning testinguntil the time the post-condition
40、ing 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 evaluated by differentialscanning calorimeter (DSC
41、) 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 temperature), occurswithin this temperature range.
42、 If the material is stable withinthis range, then accelerated conditioning may be conducted atTa= 95C in a conditioning environment containing water. Ifa transition or degradation temperature is found between 37and 120C, then the maximum acceleration temperature to beused should be at least 25C belo
43、w the lowest transition ordecomposition temperature. If nonhydrous solutions are usedas the conditioning environment (that is, pure lipid), then asimilar procedure can be followed except the temperaturewould now be governed by the boiling or decompositiontemperature of the given environment and spec
44、imen combina-tion.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 conditioning temperature induced differences. B
45、ecauseconditioning 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 conditioned for. If Tainfluences the properties inqu
46、estion, 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 to accelerate the conditioning process for
47、subsequent 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 determine the minimum time, tmin,when saturati
48、on 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 (that is, pressure relief valve orreleasable li
49、d 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 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-conditioning testinguntil the time the post-conditioning testing is conducted.11. Selection of Conditioning Procedure11.1 The choice be
