1、Designation: F3260 17F3260 18Standard 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
2、 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 covers the measurement of flexural stiffness properties of medical textiles (for example, surgical mesh,f
3、ilms, and membranes). Bending length is measured and flexural 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 room temperature in air and, if used directly, may not provide an accurateme
4、asure of in-vivo behavior for implantable medical textiles.1.4 This test method is not suitable for testing tubular samples.1.5 The values stated in SI units are to be regarded as standard. Values in parentheses are for information only.1.6 This standard does not purport to address all of the safety
5、 concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.7 This international standard was developed in accordance with
6、 internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D
7、747 Test Method for Apparent Bending Modulus of Plastics by Means of a Cantilever BeamD1388 Test Method for Stiffness of FabricsE141 Practice for Acceptance of Evidence Based on the Results of Probability SamplingF1635 Test Method for in vitro Degradation Testing of Hydrolytically Degradable Polymer
8、 Resins and Fabricated Forms forSurgical Implants3. Terminology3.1 Definitions:3.1.1 flexural stiffness, nresistance to bending, measured as bending length and flexural rigidity.3.1.2 medical textile, na fabric, film, or membrane used for medical purposes that may be woven, knit, braided, felted, or
9、nonwoven.3.2 Definitions of Terms Specific to This Standard:3.2.1 back, nwith regard to textile orientation,(1) the downward facing surface of the textile during manufacture; (2) theinward or downward facing surface of the textile during normal use.3.2.2 bending length, ngeneralthe length of textile
10、 that will bend under its own weight to a definite extent; specificthemeasured length of overhang divided by two (per 11.2) at which the edge of the specimen touches the bend angle indicator perthe test method (per 10.6).1 This test method is under the jurisdiction of ASTM Committee F04 on Medical a
11、nd Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Aug. 1, 2017March 1, 2018. Published September 2017April 2018. Originally approved in 2017. Last previous edition approved in 2017 asF326017. DOI: 10.1520/F3260-
12、17.10.1520/F3260-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and
13、 is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only t
14、he current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 cross-machine direction, CD, nthe direction in the plane of the textile perpendicul
15、ar to the direction of manufacture,analogous to the weft direction for knit and woven textiles.3.2.4 face, nwith regard to textile orientation,(1) the upward facing surface of the textile during manufacture; (2) the outwardor upward facing surface of the textile during normal use.3.2.5 flexural rigi
16、dity, nthe couple on either end of a textile strip of unit width bent into unit curvature.3.2.6 machine direction, MD, nthe direction in the plane of the textile parallel to the direction of manufacture, analogous tothe warp direction for knit and woven textiles.3.2.7 weight, nwith regard to textile
17、s, mass per unit area.4. Summary of Test Method4.1 A specimen is slid at a specified rate in a direction parallel to its long dimension, until its leading edge projects from theedge of a horizontal surface. The length of the overhang is measured when the tip of the specimen is depressed under its ow
18、n massto the point where the line joining the top to the edge of the platform makes a 0.724 rad (41.5) angle with the horizontal. Fromthis measured length and the specimens weight, the bending length and flexural rigidity are calculated.5. Significance and Use5.1 Consideration of the flexural stiffn
19、ess of medical textiles is important, as these devices often need to possess properties thatallow them to conform readily to the anatomic structures they are designed to support or protect. This test method outlines thematerials and methods for the determination of flexural properties along the diff
20、erent textile directions (that is, machine andcross-machine) and for the effects of textile surface orientation (that is, face and back orientations).5.2 This test method can be used for quality control purposes.5.3 This test method can be used for non-absorbable, absorbable, and partially absorbabl
21、e medical textiles including films andmembranes. Testing should be performed on both dry and appropriately conditioned specimens. If the specimen is fabricated froma hydrolytically degradable absorbable material or contains an absorbable component, testing after hydrolytic conditioning atappropriate
22、 time intervals should be undertaken using Test Method F1635. For partially absorbable textiles, testing should beperformed through at least two time intervals that exceed the point where the absorbable component no longer contributes to thespecimens measurable mechanical properties.5.4 If flexural
23、rigidity values are found to show effects related to planar and surface orientation, results from this test methodcould potentially help in determining if devices should be implanted or used only at specific textile directions and surfaceorientations. Considerations for determining device planar and
24、 surface orientations for use would include, but are not limited to,primary direction of bending once implanted or during use, anatomic structures that will interact with the device, and physiologicloads (normal, pathological, and worst-case) the device would experience during use.5.5 No evidence ha
25、s been found showing that bending length is dependent on the width. However, the tendency for specimensto curl or twist can affect the result through the rigidity provided at the edge. Consequently, use of test specimens with greater widthcan help to reduce this edge effect.5.6 This test method diff
26、ers from Test Method D1388 in that it requires tracking of sample surface orientation and includesabsorbable and partially absorbable medical textiles. Medical textiles with stiffness higher than is measureable using this cantileverbending method should consider evaluation using the cantilever beam
27、method described in Test Method D747.6. Apparatus6.1 Cantilever Bending Tester3 (Fig. 1):6.1.1 Horizontal Platform, with a minimum area of 38 by 200 mm and having a smooth, low-friction, flat surface such aspolished metal or plastic.Alinear scale (1-mm divisions) should be included on the front of t
28、he platform to allow for measurementof overhang lengths. A leveling bubble shall be incorporated in the platform or movable specimen slide.6.1.2 Movable Specimen Slide and Weight, consisting of a metal bar not less than 25 by 200 mm by approximately 3 mm thickand having a mass of 270 6 5 g.6.1.3 Ben
29、d Angle Indicator, inclined at an angle of 0.724 6 0.01 rad (41.5 6 0.5) below the plane of the horizontal platformsurface.6.1.4 Leveling Legs, independently adjustable to ensure that the horizontal platform is level during testing.6.1.5 Cutting Die, 25 6 1 mm by 200 6 1 mm (optional; not shown).6.1
30、.6 Analytical Balance, capable of weighing each specimen to within 60.1 % of mass.3 Apparatus is available commercially.F3260 1827. Sampling and Test Specimens7.1 Specimens shall be taken from fully processed, finished products. Specimens should be free of folds, creases, or wrinkles.NOTE 1Avoid get
31、ting oil, water, grease, etc. on the specimens when handling because they can affect the measured flexural rigidity.7.1.1 For devices that are too small to provide sufficiently sized specimens or devices that have substantial folds, creases, orwrinkles, specimens may be taken from the uncut textile
32、sheet or roll used in the manufacture of the device. These specimensshould be subjected to the same processing (cleaning, sterilization, etc.) experienced by the finished product. Note in the testingreport if specimens are taken from uncut textile sheets or rolls.7.2 Include in the report the number
33、 of samples and rationale used for determining the number of samples.NOTE 2Practice E141 may be helpful in determining an appropriate sample size.7.3 Direction of TestThe long dimension of the test specimen is the direction of test.7.4 Surface OrientationThe surface orientation of specimens shall be
34、 tracked during testing.NOTE 3For implantable devices, it is suggested that definition 1 for face(see 3.2.4) and back(see 3.2.1) is most appropriate. For non-implantabledevices, definition 2 is most appropriate.7.4.1 If the surface orientation is not known based on the provided definitions, the user
35、 shall define and maintain consistentsurface orientation during testing. For this case, the orientations shall be referred to as top and bottom instead of face and back.NOTE 4For example, warp-knit textiles may have one surface that is tactilely rough compared to the other. The user may define the r
36、elatively roughsurface as the top orientation and the relatively smooth surface as the bottom orientation.7.5 Cutting Test SpecimensCut the specimens to be used for the measurement of machine direction with the longer dimensionparallel to the machine direction. Cut the specimens to be used for the m
37、easurement of the cross-machine direction with the longerdimension parallel to the cross-machine direction. Label 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, provided the specimens do not twist or curl substantially at a
38、 smaller widthand the specimen length is sufficient to allow the specimen to reach the prescribed bend angle for both surface orientations.7.5.1.2 In no situation shall the test specimen width exceed the working width of the horizontal platform.8. Preparation of Test Apparatus8.1 Set the tester on a
39、 table or bench and adjust the platform to horizontal as indicated by the leveling bubble.8.2 Verify that the bend 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, specime
40、ns should be pre-conditionedby placing them flat in a standard letter envelope. The envelope should be placed on a flat surface and left undisturbed for asufficient time (for example, 7 days) to allow the specimens to flatten. If specimens do not flatten, new specimens may be takenfrom uncut textile
41、 sheets or rolls. Note in the test report if specimens were subjected to this pre-conditioning and for what duration.9.2 For testing of hydrolytically degradable absorbable textiles, degradation testing should be performed using Test MethodF1635. Initial “un-degraded” specimens shall be pre-conditio
42、ned in phosphate buffered saline at 37 6 0.2 C as specified in TestMethod F1635 for at least 1 h before testing. The pre-conditioning time to reach moisture equilibration of the specimen may beFIG. 1 Example of Cantilever Test ApparatusF3260 183as long as 24 h (or more), depending on both the fiber
43、cross-section and the hydrophobic nature of the polymer. Include in the testreport the length of the pre-conditioning time period before testing and a rationale for the chosen time period. For partially andfully absorbable textiles, testing should be done on un-degraded specimens and on specimens at
44、 intermediate levels of degradation.Note all degradation time points in the test report. Partially absorbable textiles should be tested through at least two time intervalsthat exceed the point where the absorbable component no longer contributes to the specimens measurable mechanical properties.The
45、same sample forms (that is, raw material, processing methods, as-cut dimensions, etc.) should be used for both the dry andappropriately conditioned test specimens.10. Procedure10.1 Record the room temperature and relative humidity.10.2 Weigh each specimen to within 60.1 % of its initial mass using a
46、 balance with suitable repeatability.NOTE 5Using a consistent drying method throughout testing, remove any excess conditioning solution prior to weighing.10.3 Remove the movable slide. Place the specimen on the horizontal platform, face-side up, with the length of the specimenparallel to the platfor
47、m edge.Align the leading edge of the specimen with the right-hand edge of the platform (that is, the horizontalplatform edge closest to the bend angle indicator) (see Fig. 1).10.4 Place the movable slide on the specimen, being careful not to change its initial position.10.5 For automatic testers, tu
48、rn the tester switch on and watch the leading edge of the specimen closely. Turn the switch off theinstant the edge of the specimen touches the bend angle indicator.10.6 For manual testers, move the specimen slide by hand in a smooth manner at approximately 120 6 5 % mmmin until theedge of the speci
49、men touches the bend angle indicator.10.7 Read and record the overhang length from the linear scale to the nearest 1 mm.NOTE 6If the specimen has a tendency to twist, take the reference point at the center of the leading edge.10.8 Repeat 10.2 10.6 to test the face and back of both ends of each specimen for a minimum of four readings per specimen.Test the face and back of one specimen end before proceeding to test the face and back of the other end of the specimen.NOTE 7As degradation progresses, the sliding weight could alter the flexural proper
