1、Designation: F3260 17Standard Test Method forDetermining the Flexural Stiffness of Medical Textiles1This standard is issued under the fixed designation F3260; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. 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 covers the measurement of flexuralstiffness properties of medical textiles (for example, surgicalmesh, films, and
3、 membranes). Bending length is measured andflexural rigidity is calculated.1.2 This test method may be used for absorbable or non-absorbable medical textiles.1.3 This test method measures the flexural stiffness at roomtemperature in air and, if used directly, may not provide anaccurate measure of in
4、-vivo behavior for implantable medicaltextiles.1.4 This test method is not suitable for testing tubularsamples.1.5 The values stated in SI units are to be regarded asstandard. Values in parentheses are for information only.1.6 This standard does not purport to address all of thesafety concerns, if a
5、ny, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internatio
6、nally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D747 Test
7、Method for Apparent Bending Modulus of Plas-tics by Means of a Cantilever BeamD1388 Test Method for Stiffness of FabricsF1635 Test Method for in vitro Degradation Testing ofHydrolytically Degradable Polymer Resins and FabricatedForms for Surgical Implants3. Terminology3.1 Definitions:3.1.1 flexural
8、stiffness, nresistance to bending, measuredas bending length and flexural rigidity.3.1.2 medical textile, na fabric, film, or membrane usedfor medical purposes that may be woven, knit, braided, felted,or nonwoven.3.2 Definitions of Terms Specific to This Standard:3.2.1 back, nwith regard to textile
9、orientation, (1) thedownward facing surface of the textile during manufacture; (2)the inward or downward facing surface of the textile duringnormal use.3.2.2 bending length, ngeneralthe length of textile thatwill bend under its own weight to a definite extent; specificthe measured length of overhang
10、 divided by two (per 11.2)atwhich the edge of the specimen touches the bend angleindicator per the test method (per 10.6).3.2.3 cross-machine direction, CD, nthe direction in theplane of the textile perpendicular to the direction ofmanufacture, analogous to the weft direction for knit andwoven texti
11、les.3.2.4 face, nwith regard to textile orientation, (1) theupward facing surface of the textile during manufacture; (2) theoutward or upward facing surface of the textile during normaluse.3.2.5 flexural rigidity, nthe couple on either end of atextile strip of unit width bent into unit curvature.3.2
12、.6 machine direction, MD, nthe direction in the planeof the textile parallel to the direction of manufacture, analo-gous to the warp direction for knit and woven textiles.3.2.7 weight, nwith regard to textiles, mass per unit area.4. Summary of Test Method4.1 A specimen is slid at a specified rate in
13、 a directionparallel to its long dimension, until its leading edge projectsfrom the edge of a horizontal surface. The length of theoverhang is measured when the tip of the specimen is de-pressed under its own mass to the point where the line joiningthe top to the edge of the platform makes a 0.724 r
14、ad (41.5)1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Aug. 1, 2017. Published September 2017. DOI:10.1520/F3260-17.2For reference
15、d 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
16、hohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Or
17、ganization Technical Barriers to Trade (TBT) Committee.1angle with the horizontal. From this measured length and thespecimens weight, the bending length and flexural rigidity arecalculated.5. Significance and Use5.1 Consideration of the flexural stiffness of medical textilesis important, as these de
18、vices often need to possess propertiesthat allow them to conform readily to the anatomic structuresthey are designed to support or protect. This test methodoutlines the materials and methods for the determination offlexural properties along the different textile directions (that is,machine and cross
19、-machine) and for the effects of textilesurface orientation (that is, face and back orientations).5.2 This test method can be used for quality control pur-poses.5.3 This test method can be used for non-absorbable,absorbable, and partially absorbable medical textiles includingfilms and membranes. Tes
20、ting should be performed on both dryand appropriately conditioned specimens. If the specimen isfabricated from a hydrolytically degradable absorbable mate-rial or contains an absorbable component, testing after hydro-lytic conditioning at appropriate time intervals should beundertaken using Test Met
21、hod F1635. For partially absorbabletextiles, testing should be performed through at least two timeintervals that exceed the point where the absorbable componentno longer contributes to the specimens measurable mechanicalproperties.5.4 If flexural rigidity values are found to show effectsrelated to p
22、lanar and surface orientation, results from this testmethod could potentially help in determining if devices shouldbe implanted or used only at specific textile directions andsurface orientations. Considerations for determining deviceplanar and surface orientations for use would include, but arenot
23、limited to, primary direction of bending once implanted orduring use, anatomic structures that will interact with thedevice, and physiologic loads (normal, pathological, andworst-case) the device would experience during use.5.5 No evidence has been found showing that bendinglength is dependent on th
24、e width. However, the tendency forspecimens to curl or twist can affect the result through therigidity provided at the edge. Consequently, use of test speci-mens with greater width can help to reduce this edge effect.5.6 This test method differs from Test Method D1388 in thatit requires tracking of
25、sample surface orientation and includesabsorbable and partially absorbable medical textiles. Medicaltextiles with stiffness higher than is measureable using thiscantilever bending method should consider evaluation usingthe cantilever beam method described in Test Method D747.6. Apparatus6.1 Cantilev
26、er Bending Tester3(Fig. 1):6.1.1 Horizontal Platform, with a minimum area of 38 by200 mm and having a smooth, low-friction, flat surface such aspolished metal or plastic. A linear scale (1-mm divisions)should be included on the front of the platform to allow formeasurement of overhang lengths. A lev
27、eling bubble shall beincorporated in the platform or movable specimen slide.6.1.2 Movable Specimen Slide and Weight, consisting of ametal bar not less than 25 by 200 mm by approximately 3 mmthick and having a mass of 270 6 5g.6.1.3 Bend Angle Indicator, inclined at an angle of 0.724 60.01 rad (41.5
28、6 0.5) below the plane of the horizontalplatform surface.6.1.4 Leveling Legs, independently adjustable to ensure thatthe horizontal platform is level during testing.6.1.5 Cutting Die, 25 6 1mmby2006 1 mm (optional;not shown).6.1.6 Analytical Balance, capable of weighing each speci-men to within 60.1
29、 % of mass.7. Sampling and Test Specimens7.1 Specimens shall be taken from fully processed, finishedproducts. Specimens should be free of folds, creases, orwrinkles.NOTE 1Avoid getting oil, water, grease, etc. on the specimens whenhandling because they can affect the measured flexural rigidity.3Appa
30、ratus is available commercially.FIG. 1 Example of Cantilever Test ApparatusF3260 1727.1.1 For devices that are too small to provide sufficientlysized specimens or devices that have substantial folds, creases,or wrinkles, specimens may be taken from the uncut textilesheet or roll used in the manufact
31、ure of the device. Thesespecimens should be subjected to the same processing(cleaning, sterilization, etc.) experienced by the finished prod-uct. Note in the testing report if specimens are taken fromuncut textile sheets or rolls.7.2 Include in the report the number of samples and ratio-nale used fo
32、r determining the number of samples.7.3 Direction of TestThe long dimension of the testspecimen is the direction of test.7.4 Surface OrientationThe surface orientation of speci-mens shall be tracked during testing.NOTE 2For implantable devices, it is suggested that definition 1 forface (see 3.2.4) a
33、nd back (see 3.2.1) is most appropriate. For non-implantable devices, definition 2 is most appropriate.7.4.1 If the surface orientation is not known based on theprovided definitions, the user shall define and maintain consis-tent surface orientation during testing. For this case, theorientations sha
34、ll be referred to as top and bottom instead offace and back.NOTE 3For example, warp-knit textiles may have one surface that istactilely rough compared to the other. The user may define the relativelyrough surface as the top orientation and the relatively smooth surface asthe bottom orientation.7.5 C
35、utting Test SpecimensCut the specimens to be usedfor the measurement of machine direction with the longerdimension parallel to the machine direction. Cut the specimensto be used for the measurement of the cross-machine directionwith the longer dimension parallel to the cross-machine direc-tion. Labe
36、l to maintain specimen identity.7.5.1 Cut test specimens 25 by 200 6 1 mm.7.5.1.1 Deviation from these dimensions is allowed, pro-vided the specimens do not twist or curl substantially at asmaller width and the specimen length is sufficient to allow thespecimen to reach the prescribed bend angle for
37、 both surfaceorientations.7.5.1.2 In no situation shall the test specimen width exceedthe working width of the horizontal platform.8. Preparation of Test Apparatus8.1 Set the tester on a table or bench and adjust the platformto horizontal as indicated by the leveling bubble.8.2 Verify that the bend
38、angle indicator is at the 0.724 rad(41.5) angle marked on the scale.9. Conditioning9.1 For testing of non-absorbable textiles, if minor folds,creases, or wrinkles are present, specimens should be pre-conditioned by placing them flat in a standard letter envelope.The envelope should be placed on a fl
39、at surface and leftundisturbed for a sufficient time (for example, 7 days) to allowthe specimens to flatten. If specimens do not flatten, newspecimens may be taken from uncut textile sheets or rolls. Notein the test report if specimens were subjected to this pre-conditioning and for what duration.9.
40、2 For testing of hydrolytically degradable absorbabletextiles, degradation testing should be performed using TestMethod F1635. Initial “un-degraded” specimens shall be pre-conditioned in phosphate buffered saline at 37 6 0.2 C asspecified in Test Method F1635 for at least 1 h before testing.The pre-
41、conditioning time to reach moisture equilibration ofthe specimen may be as long as 24 h (or more), depending onboth the fiber cross-section and the hydrophobic nature of thepolymer. Include in the test report the length of the pre-conditioning time period before testing and a rationale for thechosen
42、 time period. For partially and fully absorbable textiles,testing should be done on un-degraded specimens and onspecimens at intermediate levels of degradation. Note alldegradation time points in the test report. Partially absorbabletextiles should be tested through at least two time intervals thate
43、xceed the point where the absorbable component no longercontributes to the specimens measurable mechanical proper-ties. The same sample forms (that is, raw material, processingmethods, as-cut dimensions, etc.) should be used for both thedry and appropriately conditioned test specimens.10. Procedure1
44、0.1 Record the room temperature and relative humidity.10.2 Weigh each specimen to within 60.1 % of its initialmass using a balance with suitable repeatability.NOTE 4Using a consistent drying method throughout testing, removeany excess conditioning solution prior to weighing.10.3 Remove the movable s
45、lide. Place the specimen on thehorizontal platform, face-side up, with the length of thespecimen parallel to the platform edge. Align the leading edgeof the specimen with the right-hand edge of the platform (thatis, the horizontal platform edge closest to the bend angleindicator) (see Fig. 1).10.4 P
46、lace the movable slide on the specimen, being carefulnot to change its initial position.10.5 For automatic testers, turn the tester switch on andwatch the leading edge of the specimen closely. Turn theswitch off the instant the edge of the specimen touches the bendangle indicator.10.6 For manual tes
47、ters, move the specimen slide by hand ina smooth manner at approximately 120 6 5 % mm min untilthe edge of the specimen touches the bend angle indicator.10.7 Read and record the overhang length from the linearscale to the nearest 1 mm.NOTE 5If the specimen has a tendency to twist, take the reference
48、point at the center of the leading edge.10.8 Repeat 10.2 10.6 to test the face and back of bothends of each specimen for a minimum of four readings perspecimen. Test the face and back of one specimen end beforeproceeding to test the face and back of the other end of thespecimen.NOTE 6As degradation
49、progresses, the sliding weight could alter theflexural properties of the specimen for partially degraded samples. Takethis into account when selecting degradation time points.F3260 17310.9 Replace specimens that will be tested at additional timepoints back into soaking solution immediately after testing toavoid affecting the ongoing degradation.11. Calculations11.1 For each specimen, calculate the mass per unit areausing Eq 1.M 5ml 3w3106(1)where:M = specimen mass per unit area, g/m2,m = specimen mass, g,l = specimen length, mm,w = specimen width, m
