1、Designation: F2255 05 (Reapproved 2010)Standard Test Method forStrength Properties of Tissue Adhesives in Lap-Shear byTension Loading1This standard is issued under the fixed designation F2255; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 is intended to provide a means forcomparison of the adhesive strengths of tissu
3、e adhesivesintended for use as surgical adhesives or sealants, or both, onsoft tissue. With the appropriate choice of substrate, it may alsobe used for purposes of quality control in the manufacture oftissue adhesive based medical devices.1.2 The values stated in SI units are to be regarded asstanda
4、rd. No other units of measurement are included in thisstandard.1.3 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 applic
5、a-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D907 Terminology of AdhesivesE4 Practices for Force Verification of Testing Machines2.2 American Association of Tissue Banks Standards:3Standards for Tissue Banking3. Terminology3.1 DefinitionsMany terms in th
6、is test method are definedin Terminology D907.3.2 Definitions:3.2.1 tissue adhesivefor the purposes of this test method,tissue adhesive is defined as a compound or system intendedfor use in closing wounds (surgical or traumatic) or for sealingagainst leakage of body fluids.3.2.2 tissue sealanta surf
7、ace coating with adequate adhe-sive strength to prevent leakage of body fluids.4. Significance and Use4.1 Materials and devices that function at least in part byadhering to living tissues are finding increasing use in surgicalprocedures either as adjuncts to sutures and staples, or as frankreplaceme
8、nts for those devices in a wide variety of medicalprocedures. While the nature and magnitude of the forcesinvolved varies greatly with indication and with patient specificcircumstances, all uses involve to some extent the ability of thematerial to resist imposed mechanical forces. Therefore, themech
9、anical properties of the materials, and in particular theadhesive properties, are important parameters in evaluatingtheir fitness for use. In addition, the mechanical properties of agiven adhesive composition can provide a useful means ofdetermining product consistency for quality control, or as ame
10、ans for determining the effects of various surface treatmentson the substrate prior to use of the device.4.2 The complexity and variety of individual applicationsfor tissue adhesive devices, even within a single indicated use(surgical procedure) is such that the results of a single-lap-shear test ar
11、e not suitable for determining allowable designstresses without thorough analysis and understanding of theapplication and adhesive behaviors.4.3 This test method may be used for comparing adhesivesor bonding processes for susceptibility to fatigue and environ-mental changes, but such comparisons mus
12、t be made with greatcaution since different adhesives may respond differently tovarying conditions.5. Apparatus5.1 Testing Machine, of the constant-rate-of-crosshead-movement type and comprising essentially the following:5.1.1 Fixed Member, a fixed or essentially stationary mem-ber carrying one grip
13、.5.1.2 Movable Member, a movable member carrying asecond grip.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 June 1, 2010. Publishe
14、d September 2010. Originallyapproved in 2003. Last previous edition approved in 2005 as F2255 05. DOI:10.1520/F2255-05R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, ref
15、er to the standards Document Summary page onthe ASTM website.3Available from the American Association of Tissue Banks (AATB), 1350Beverly Rd., Suite 220-A, McLean, VA 22101.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.3 Grips,
16、 for holding the test specimen between the fixedmember and the movable member of the testing machine canbe either the fixed or self-aligning type.5.1.3.1 Fixed Grips are rigidly attached to the fixed andmovable members of the testing machine. When this type ofgrip is used extreme care should be take
17、n to ensure that the testspecimen is inserted and clamped so that the long axis of thetest specimen coincides with the direction of pull through thecenterline of the grip assembly.5.1.3.2 Self-aligning Grips are attached to the fixed andmovable members of the testing machine in such a manner thatthe
18、y will move freely into alignment as soon as any load isapplied so that the long axis of the test specimen will coincidewith the direction of the applied pull through the center line ofthe grip assembly. The specimens should be aligned as per-fectly as possible with the direction of pull so that no
19、rotarymotion that may induce slippage or damage to the sample willoccur in the grips; there is a limit to the amount of misalign-ment self-aligning grips will accommodate.5.1.4 Drive Mechanism, for imparting to the movable mem-ber a uniform, controlled velocity with respect to the stationarymember,
20、with this velocity to be regulated as specified in 9.3.5.1.5 Load Indicator, a suitable load-indicating mechanismcapable of showing the total tensile load carried by the testspecimen when held by the grips. This mechanism shall beessentially free of inertia lag at the specified rate of testing andsh
21、all indicate the load with an accuracy of 61 % of theindicated value, or better. The accuracy of the testing machineshall be verified in accordance with Practices E4.5.2 Temperature-controlling Equipment, capable of main-taining the test temperature to 62C. If ambient laboratoryconditions are employ
22、ed the same degree of control is required.Awater bath or environmental chamber capable of maintaining37C is required for testing on tissue substrates.6. Test Substrate6.1 For comparative testing, either fresh or frozen splitthickness porcine skin graft may be used.6.1.1 Frozen split thickness porcin
23、e skin that has beenaseptically prepared is available commercially and is preferreddue to ease of use and the potential for more consistentproperties. It should be thawed according to the manufacturersinstructions prior to use. Unused graft may be kept at 2 to 8Cfor up to two weeks after thawing.6.1
24、.2 If fresh skin is chosen, it should be prepared accordingto the method in Appendix X1.6.2 Application Specific Testing:6.2.1 The strength of any adhesive is highly dependent onthe test substrate, or adherend. For a specific application, thepreferred substrate is freshly harvested tissue from the t
25、argetorgan of a domestic food animal. Tissue from bovine, porcine,or ovine origin is preferred due to wide availability and the factthat relatively large samples of tissue can be harvested from asingle source. Ideally, the tissue should be used within 24 h ofharvest, and should be kept between 5 and
26、 10C prior to testingif it cannot be used immediately after harvesting. Storage andhandling of tissue samples should be carried out according tothe guidelines set forth in Standards for Tissue Banking by theAmerican Association of Tissue Banks. The specimens shouldbe brought to the test temperature
27、or other prescribed tempera-ture (such as body temperature) prior to application of theadhesive.6.2.2 Fixed tissue should not be used since it has beendemonstrated that fixatives cause large alterations in themechanical properties of the tissue and it is probable that theadhesive strength would be a
28、ffected as well.6.2.3 If the target organ is of a size or geometry, or both, thatdoes not allow fabrication of test samples as shown in Fig. 1,a tissue of similar origin but larger size should be used. Forexample, if the intended indication is for anastomosis of smallblood vessels, a larger vessel s
29、hould be substituted.6.2.4 The thickness of the tissue sample should be mini-mized and should not exceed 5 mm. Thicker samples will leadto distortion of the substrate and mixed loading (shear andtension). It is also important that the thickness be as uniform aspossible.6.3 Substrates for Quality Con
30、trol Testing:6.3.1 For testing that is undertaken as part of a qualitycontrol process in the manufacturing of a tissue adhesivedevice, the use of freshly harvested tissue is highly inconve-nient and may also lead to unacceptable variation in the testresults, especially if the failure occurs in the a
31、dherend (sub-strate failure). Since the purpose of quality control testing is todemonstrate consistency in the device, substitution of a modelsubstrate is preferred so long as it is demonstrated that theadhesive does bond to the adherand. For devices that requirecontact with tissues to cure, Mediski
32、n XenoGraft should beused for quality control testing as well as comparative testing.7. Test Specimen7.1 Specimens with Soft-tissue Substrates shall conform tothe form shown in Fig. 1. The length of the tissue substrate (L)attached to each specimen holder should be at least 1.5 timesthe length of th
33、e overlap area in order to ensure that the failureoccurs at the overlap bond and doesnt pull the tissue substrateoff of the specimen holder. For very strong adhesives, L mayneed to be 2 to 3 times the overlap length. The tissue can bebonded to the specimen holder with any suitable adhesive.Gel-type
34、cyanoacrylate adhesives have been found to beconvenient for this purpose since they adhere well to moisttissues and cure quickly.7.2 Specimens with Polymer or Metal Substrates shallconform to the form and dimensions shown in Fig. 2.7.3 Number of Test SpecimensTest at least 10 specimensof each type.
35、Discard results if failure occurs between the testfixture and the tissue sample and test additional samples toobtain a total of 10 valid tests. Tissue substrates tend to givehigher variances and may require more samples to attain areasonable estimate of the mean strength.8. Sample Preparation8.1 Tis
36、sue Preparation:8.1.1 Tissue substrate materials should be kept moist at alltimes with phosphate buffered saline (PBS).8.1.2 The substrate will be cut to the dimensions shown inFig. 1 using a template and a fresh scalpel blade or a cutterfabricated to the required dimensions. Alternatively, a slight
37、lyF2255 05 (2010)2oversized piece of tissue can be glued to the test fixture, andtrimmed to size using the fixture as a template.8.1.3 The back-side of the tissue sample will be glued to thetest fixture using a suitable adhesive. Gel-type cyanoacrylateadhesives have been found to be useful for this
38、purpose sincethey set quickly and adhere to most materials. Care must betaken to ensure that the substrate is aligned square with thesides of the test fixtures and does not extend past the end of thefixture.8.1.4 Wrap the tissue with gauze soaked in PBS, place thefixtures in a plastic bag, and place
39、 them in a water bath orenvironmental chamber at 37C.8.2 Preparation of the Adhesive Bond:8.2.1 Prepare the test adhesive according to the manufac-turers directions or by other prescribed procedure.8.2.2 Remove the test fixtures from the plastic bag and patthe surface of the tissue dry with fresh ga
40、uze.8.2.3 Apply sufficient adhesive to uniformly coat the over-lap area without significant overflow. Excess adhesive couldrun over the edge of the substrate, causing artificially high testvalues. The amount required will have to be determinedexperimentally. For adhesives that are delivered with a s
41、praydevice, controlling the amount and distribution of the materialwill be difficult. It may be necessary to use a template toprevent overspray. Alternatively, petroleum jelly may appliedto the portion of the tissue outside of the overlap area toprevent bonding.8.2.4 Bond the two sides of the test f
42、ixture together, takingcare to keep the fixtures aligned and to maintain the prescribedoverlap.FIG. 1 Soft Tissue FixtureFIG. 2 Metal/Polymer Substrate SpecimenF2255 05 (2010)38.2.5 Apply a force of approximately 1 to2Ntothebondarea until the adhesive sets. For slow-curing adhesives it maybe necessa
43、ry to use a clamping device that can be left in placewhile the fixture is returned to the environmental chamber orwater bath.8.3 Measure and record the width and length of the adhesivebond to within 0.05 cm.8.4 Re-cover the tissue with gauze soaked in PBS, replacethe sample in a plastic bag, and ret
44、urn it to the constanttemperature environment.9. Test Procedure9.1 Condition the test specimens for definite periods of timeunder specified, controlled conditions before testing if desired.For comparative testing, the conditioning time should be 1 h 615 min. Recommended conditions for Tissue adhesiv
45、es in-tended for internal applications are 37 6 1C in phosphatebuffered saline. For adhesives intended for external topical use,recommended conditions are 30 6 1C and 50 6 5 % relativehumidity. For quality control testing, the recommended condi-tions are 23 6 2C and 50 6 5 % relative humidity.9.2 Af
46、ter conditioning, it is recommended that all speci-mens be stabilized at the test temperature for 15 min beforetesting if the test temperature is different from the conditioningtemperature. Tissue samples must be kept moist throughout theprocess to prevent shrinkage due to drying. For comparativetes
47、ting the test conditions should be 23 6 2C and 50 6 5%relative humidity (see Annex A1).9.3 Place the test specimens in the grips of the testingmachine so that the applied load coincides with the long axis ofthe specimen. Load the specimen to failure at a constantcross-head speed of 5 mm/min.9.4 Reco
48、rd the load at failure (maximum load sustained)and the type of failure (percentage cohesive, adhesive, orsubstrate failure based on observation of the bond area).10. Calculations10.1 Calculate the bond area to the nearest 0.05 cm2.Calculate the apparent shear strength as the maximum loaddivided by t
49、he bond area in mega-Pascals (MPa).10.2 Calculate the average and standard deviation for eachgroup of samples.11. Report11.1 Report the following:11.1.1 Complete identification of the adhesive tested, in-cluding type, source, date manufactured, manufacturers codenumber, and lot number.11.1.2 Complete identification of the substrate used, itsthickness, and any method used to clean or prepare the surfaceprior to bonding. Also report the method used to adhere tissueto the specimen holder.11.1.3 Estimated amount of adhesive applied.11.1.4 Method of adhesive applicatio
