1、Designation: D5397 07 (Reapproved 2012)Standard Test Method forEvaluation of Stress Crack Resistance of PolyolefinGeomembranes Using Notched Constant Tensile Load Test1This standard is issued under the fixed designation D5397; the number immediately following the designation indicates the year ofori
2、ginal adoption 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 test method is used to develop test data from whichthe su
3、sceptibility of polyolefin geomembrane sheet material tostress cracking under a constant tensile load condition and anaccelerated environmental condition can be evaluated.1.2 This test method measures the failure time associatedwith a given test specimen at a specified tensile load level.Results fro
4、m a series of such tests utilizing a range of loadlevels can be used to construct a stress-time plot on a log-logaxis.1.3 The values stated in SI units are to be regarded as thestandard. The inch-pound units given in parentheses areprovided for information only.1.4 This standard does not purport to
5、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 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D638 Test
6、Method for Tensile Properties of PlasticsD883 Terminology Relating to PlasticsD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs) for TestingD4833 Test Method for Index Puncture Resistance ofGeomembranes and Related Products3. Terminology3.1 Definitions:3.1.1 geome
7、mbrane, nvery low permeability syntheticmembrane liners or barriers used with any geotechnical engi-neering related material so as to control fluid migration in aman-made project, structure, or system (see Test MethodD4833).3.1.2 stress crack, nan external or internal crack in aplastic caused by ten
8、sile stresses less than its short-timemechanical strength (see Definitions D883).3.1.2.1 DiscussionThe development of such cracks isfrequently accelerated by the environment to which the plasticis exposed. The stresses that cause cracking may be presentinternally or externally or may be combinations
9、 of thesestresses.4. Summary of Test Method4.1 This test method consists of subjecting a dumbbellshaped notched test specimen from a polyolefin sheet to aconstant tensile load in the presence of a surface-active agentand at an elevated temperature. The time to failure of the testspecimen is recorded
10、. The results of a series of such testsconducted at different stress levels are presented by plottingstress level against failure time for each stress level on alog-log axis.5. Significance and Use5.1 This test method does not purport to interpret theresulting response curve. Such interpretation is
11、left to theparties involved in the commissioning and reporting of the testresults.5.2 This test method is intended as an index test and may beused for grading polyolefin geomembrane sheets in regard totheir stress cracking sensitivity.5.2.1 Conditions that can affect stress cracking include:level of
12、 loading, test temperature and environment,microstructure, polymer additive package, processing history,and thermal history.6. Apparatus6.1 Blanking DieA die suitable for cutting test specimensto the dimensions and tolerances shown in Fig. 1.NOTE 1The length of the specimen can be changed to suit th
13、e designof the test apparatus. However, there should be a constant neck sectionwith length at least 13 mm (0.5 in.) long. The width should be 3.20 mm(0.125 in.).1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.02 o
14、n Endur-ance Properties.Current edition approved July 1, 2012. Published July 2012. Originally approvedin 1993. Last previous edition approved in 2007 as D5397 07. DOI: 10.1520/D5397-07R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
15、eastm.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 Conshohocken, PA 19428-2959. United States16.2 Notching DeviceAdevice or machine that can producea co
16、nsistent notch depth.3NOTE 2An evaluation of the notching technique can be performed byquenching a notched specimen in liquid nitrogen and then fracturing it.The notch depth can readily be measured by examining the fracturesurface under a reflected light microscope. Other methods of verifyingnotch d
17、epth include viewing the cut specimen on its side in a microscopewith the aid of a eyepiece micrometer or a calibrated reticle.6.3 BladeA single-edged razor made of carbon steel. Thetip profile is that of an arrow rather than that of a chisel point.The sharpness of the point is critical to the clean
18、liness of thecut which effects the results of the test significantly.6.4 Stress Cracking ApparatusEquipment suitable forsubjecting test specimens to a tensile stress of up to 13.8 MPa(2000 lb/in.2). The specimens shall be maintained at a constanttemperature of 50 6 1C (122 6 2F) while being totallyi
19、mmersed in a surface-active agent. The solution should beconstantly agitated to provide a uniform concentration through-out the bath.NOTE 3The apparatus4shown in Fig. 2 is one type that has been usedand is capable of testing up to 20 specimens at a time. This equipment usesa lever system with a mech
20、anical advantage (MA) of three to impose thedesired loading on each specimen. The surface-active agent in which thespecimens are immersed is contained in an open stainless steel tank. Asubmersion heater and controller are used to maintain the test temperature.Apump keeps the liquid in a constant sta
21、te of agitation.Atiming clock foreach test specimen is also provided to record automatically the failure timeof the test specimens to the nearest 0.1 h.NOTE 4If “on/off” switches are used to control the timing clock, theswitch must be sensitive enough to be turned off under 200 g of the force.7. Rea
22、gent7.1 The reagent should consist of 10 % surface-active agentwith 90 % water. The surface-active agent is Igepal CO-6305that is nonylphenoxy poly(ethyleneoxy)ethanol. The reagentshould be stored in a closed container. The reagent in the bathshould be replaced every two weeks to maintain a constant
23、concentration.NOTE 5In case of dispute, the water should be distilled or deionizedat the discretion of the parties involved.NOTE 6Other incubation solutions may also be used in the test,provided that the parties involved mutually agree to the changes and statethe specific details in the final report
24、.8. Sampling8.1 Lot SampleDivide the product into lots and take thelot sample as directed in Practice D4354.8.2 Laboratory SampleAs a laboratory sample for accep-tance testing, take a full-width swatch approximately1m(40in.) long in the machine direction from each roll in the lotsample. The sample m
25、ay be taken from the end portion of a rollprovided there is no evidence it is distorted or different fromother portions of the roll.8.3 Test SpecimensAt least thirty test specimens are cutfrom each swatch in the laboratory sample. For each set oftests, all specimens must be taken from one direction.
26、NOTE 7Quite often the test is required to challenge the weakestdirection of the sheet material. If this is the cross machine direction, thetest specimens should be cut in this direction. Hence the notch is placedin the machine direction so that the specimens are stressed in the desiredcross machine
27、direction.NOTE 8It has been found that inserting a grommet or eyelet in the twoholes at the end tabs of the test specimen helps to reduce the number of“grip failures” or failures occurring outside of the neck section of thespecimen.9. Procedure9.1 Measure the thickness of each individual test specim
28、enat its minimum cross section to the nearest 0.013 mm (0.001in.). The variation in thickness should not be greater than 60.026 mm (6 0.002 in.) of the nominal thickness of thegeomembrane.9.2 Cut into each specimen a control imperfection (notch)on one surface as shown in Fig. 3. The depth of the not
29、ch3Notching equipment is available through REMCO Industrial Machine Co.,Manville, NJ 08850.4This equipment is available through Custom Scientific Instruments Co., CedarKnolls, NJ 07927, and BT Technology Inc., 613 W. Clinton St., Rushville, IL62681.5Igepal CO-630 may be obtained from Rhone-Poulenc,
30、CN 7500, ProspectPlains Road, Cranbury, NJ 08512-7500.NOTE 1Dimensioned in millimetres to an accuracy of 0.02 mm.FIG. 1 Dimensions of Test Method D1822 Type“ L” Test Speci-mensNOTE 1The number of positions in the test frame is optional.FIG. 2 Constant Stress Loading Apparatus Consisting of TwentySpe
31、cimen Test PositionsD5397 07 (2012)2should produce a ligament thickness of 80 % of the nominalthickness of the specimen.NOTE 9Using this procedure the actual notch depth will vary inaccordance with the actual thickness of the test specimen. For example, asheet of nominal thickness of 2 mm (80 mil) m
32、ight have thicknessesranging from 1.98 to 2.08 mm (78 to 82 mil). To obtain a constant hingethickness of 1.6 mm (64 mil), the notch depth would vary from 0.36 to0.46 mm (14 to 18 mil), depending upon the actual thickness of theindividual test specimens.9.3 Inspect the edge of the blade for scratches
33、 and burrsunder normal vision prior to the cut. No single blade shall beused for notching more than 20 test specimens.9.4 Test specimens are loaded at various percentages oftheir room temperature yield stress. The applied stress levelsshould range from approximately 20 to 65 % at maximumincrements o
34、f 5 %. Three specimens are tested at each stresslevel to produce statistically significant results.NOTE 10To develop the entire curve in a single direction at therecommended values listed above will require ten increments at threespecimens each, or 30 individual tests. If both directions are to bech
35、allenged, the entire test will require twice as many test specimens.9.5 For each set of test, the yield stress of the materialshould be measured according to Test Method D638 (Type IV).Five specimens should be tested and the average value is usedto calculate the applied force. The test specimens sho
36、uld be cutfrom the same sample and same direction as stated in 8.3.9.6 Calculate the tensile force to be applied to each indi-vidual specimen from the equation given below:applied force 5 A!y!w!tL!1/MA! (1)where:applied force = force to be applied to achieve a specificpercentage of the yield stress,
37、A = percentage of yield stress to be achieved,y= the yield stress of the material at roomtemperature,w = width of the neck of the test specimen,tL= the ligament thickness of the test specimen,that is, recommended to be 80 % of thenominal thickness, andMA = mechanical advantage of the test apparatus,
38、that is 3.0 for the apparatus shown in Fig. 2.9.7 Fill the test bath with reagent, and adjust the temperatureto 50 6 1C (122 6 2F).NOTE 11Other temperatures may be used when conducting this test.However, it must be mutually agreed upon by parties involved and the testtemperature must be stated in th
39、e final report.9.8 Attach the test specimens to the hooks of the testapparatus.FIG. 3 Front and Side Views of the Notched Test Specimen of NCTL TestD5397 07 (2012)39.9 Adjust the distance between the lever arm and theswitch to a dimension equal to 20 mm (0.80 in.).9.10 Immerse the test specimens and
40、 allow temperatureequilibrium to be reached. The minimum time is 30 min.9.11 Prepare the appropriated weight of lead shot (or othertypes) required for each individual test specimen according tothe calculation in 9.6.9.12 Load each individual specimen with its respectiveweight and record the elapsed
41、time to failure to the nearest 0.1h.NOTE 12Other test duration time can be used besides failure time.However, it must be mutually agreed upon by parties involved and theduration of the test must be stated in the final report.NOTE 13Expanded polystyrene or other types of insulation can beplaced on to
42、p of the liquid to minimize the evaporation of water andoxidation of liquid.NOTE 14The liquid level in the bath can be maintained by using anautomatic water feeder.9.13 For each of the applied stress levels, calculate thearithmetic mean of the three failure time values and report it asthe“ average f
43、ailure time” for that particular applied stresslevel.9.14 Calculate the coefficient of variation as follows andreport it to two significant figures:coefficient of variation V! 5 standard deviation/mean! 3100%(2)The value (V) must be less than 15 % for those with averagefailure time greater than 10 h
44、. If not, three new specimensshould be tested at that specific applied stress level again.10. Interpretation of Results10.1 Present the test data in graphic form by plotting thelogarithm of percentage yield stress versus the logarithm of theaverage failure time for each stress level. Three possible
45、typesof curves can result, see Fig. 4.11. Report11.1 Report the following:11.1.1 Complete identification of the material tested,11.1.2 Yield stress used in the test,11.1.3 Method of conditioning used if different from thatspecified herein,11.1.4 Report the average failure time and coefficient ofvari
46、ation values for each of the applied stress levels, and11.1.5 A plot of the percent yield stress against averagefailure time on log-log axes.12. Precision and Bias12.1 PrecisionThe precision of the procedure in this testmethod is being established.12.2 BiasThe procedure in this test method for measu
47、ringthe failure time at different applied stress has no bias becausethe value of the failure time can be defined only in terms of atest method.13. Keywords13.1 failure time; geomembrane; notch; polyolefin; yieldstressFIG. 4 Possible Response of Curves Resulting from a CompleteNotched Constant Tensil
48、e Load (NCLT) TestD5397 07 (2012)4APPENDIX(Nonmandatory Information)X1. PROCEDURE TO PERFORM A SINGLE POINT NOTCHED CONSTANT TENSILE LOAD (SP-NCTL) TESTX1.1 Sampling:X1.1.1 Test SpecimensFive test specimens are cut from arepresentative sample of the geomembrane sheet under inves-tigation. All specim
49、ens must be cut in the same direction.NOTE X1.1Notes 7 and 8 of this test method should also apply.NOTE X1.2The procedure is recommended for sheets with thick-nesses ranging from 1.0 to 2.5 mm (0.040 to 0.10 in.).NOTE X1.3This procedure is not appropriate for testing geomem-branes with textured or irregular rough surfaces. The irregular surfacemakes the determination of the ligament thickness, and subsequentapplied stress unreliable.X1.2 Recommended Procedure:X1.2.1 The specimen notching procedure should be inaccordance with 9.1-9.3.X
