ASTM F2136-2008(2015) Standard Test Method for Notched Constant Ligament-Stress (NCLS) Test to Determine Slow-Crack-Growth Resistance of HDPE Resins or HDPE Corrugated Pipe《测定HDPE树.pdf

1、Designation: F2136 08 (Reapproved 2015) An American National StandardStandard Test Method forNotched, Constant Ligament-Stress (NCLS) Test toDetermine Slow-Crack-Growth Resistance of HDPE Resinsor HDPE Corrugated Pipe1This standard is issued under the fixed designation F2136; the number immediately

2、following the designation indicates the year oforiginal 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 me

3、thod is used to determine the susceptibilityof high-density polyethylene (HDPE) resins or corrugated pipeto slow-crack-growth under a constant ligament-stress in anaccelerating environment. This test method is intended to applyonly to HDPE of a limited melt index and density range asdefined in AASHT

4、O Standard Specification M 294. This testmethod may be applicable for other materials, but data are notavailable for other materials at this time.1.2 This test method measures the failure time associatedwith a given test specimen at a constant, specified, ligament-stress level.1.3 The values stated

5、in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 Definitions are in accordance with TerminologyAASHTO Standard Specification M 294, and abbreviations ar

6、ein accordance with Terminology D1600, unless otherwisespecified.1.5 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 appl

7、ica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1600 Terminology forAbbreviated Terms Relating to Plas-ticsD1822 Test Method for Tensile-Impact Energy to BreakPlastics and Electrical Insulating MaterialsD4703 Practice for Compression Molding Thermoplasti

8、cMaterials into Test Specimens, Plaques, or SheetsD5397 Test Method for Evaluation of Stress Crack Resis-tance of Polyolefin Geomembranes Using Notched Con-stant Tensile Load TestE4 Practices for Force Verification of Testing MachinesE691 Practice for Conducting an Interlaboratory Study toDetermine

9、the Precision of a Test MethodF412 Terminology Relating to Plastic Piping Systems2.2 Other Document:AASHTO Standard Specification M 29433. Summary of Test Method3.1 This test method subjects a dumbbell-shaped, notchedtest-specimen (Fig. 1) to a constant ligament-stress in thepresence of a surface-ac

10、tive agent at an elevated temperature.It differs from Test Method D5397 in that a constant ligamentstress is used instead of a constant tensile load.4. Significance and Use4.1 This test method does not purport to interpret the datagenerated.4.2 This test method is intended to compare slow-crack-grow

11、th (SCG) resistance for a limited set of HDPE resins.4.3 This test method may be used on virgin HDPE resincompression-molded into a plaque or on extruded HDPEcorrugated pipe that is chopped and compression-molded intoa plaque (see 7.1.1 for details).5. Apparatus5.1 Blanking DieA die suitable for cut

12、ting test specimens.Acceptable dies are: the type L die per Test Method D1822,with holes drilled or punched in the tab areas after die cutting;a die with the dimensions and tolerances specified in Fig. 2.1This test method is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and i

13、s the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Dec. 1, 2015. Published December 2015. Originallyapproved in 2001. Last previous edition approved in 2008 as F213608 DOI:10.1520/F2136-08R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org

14、, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Wa

15、shington, DC 20001,http:/www.transportation.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Stress-Crack Testing ApparatusA lever loadingmachine, with a lever arm ratio of 2:1 to 5:1 similar to thatdescribed in Test Method D53

16、97.Alternatively, the tensile loadmay be applied directly using dead weights or any othermethod for producing a constant ligament stress. Determine thezero-load offset and lever-arm ratio for each test station, usinga force standard that complies with Practices E4. The load onthe specimen shall be a

17、ccurate to 0.5 % of the calculated orapplied load. The bath solution temperature shall be set at 1226 2F (50 6 1C).5.3 Notching DeviceNotch depth is an important variablethat must be controlled. Paragraph 7.2.1 describes the notchingprocedure and type of apparatus used. The approximate thick-ness of

18、 the blade should be 0.2 to 0.3 mm.NOTE 1A round robin was conducted to determine the effect of typesof blades on the notch depth. In this study, several types of steel blades(single-edge, double-edge, and so forth) from various manufacturers wereused by the round-robin participants. The round robin

19、 consisted of sevenlaboratories using two types of resins molded into plaques. The standarddeviation of the test results within laboratories is less than 610 %.5.4 Micrometer, capable of measuring to 60.001 in.(60.025 mm).5.5 Microscope, equipped with micrometer or an equivalentdevice capable of acc

20、urately measuring the notch depth.T = thickness.W = specimen width.NOTE 1The test specimen is intended to have the same geometry used for Test Method D5397 specimens. The length of the specimen can be changedto suit the design of the test apparatus. However, there should be a constant neck section w

21、ith length at least 0.5 in. (13 mm) long.NOTE 2It is preferable to modify the specimen die so that the attachment holes are punched out at the same time as the specimen rather than punchingor machining them into the specimen at a later time. If the attachment holes are introduced at a later time, it

22、 is extremely important that they be carefullyaligned so as to avoid adding a twisting component to the stress being placed on the specimen.FIG. 1 Notching PositionF2136 08 (2015)25.6 Compression-Molding Press and Suitable Chase forCompression-Molding the Specimens, in accordance with Prac-tice D470

23、3.5.7 Metal Shot, for weight tubes.5.8 Electronic Scale, for measuring shot weight tubes ca-pable of measuring to 60.1 g.5.9 Timing Device, capable of recording failure time to thenearest 0.1 h.6. Reagents6.1 The stress-cracking reagent shall consist of 10 % non-ylphenoxy poly (ethyleneoxy) ethanol

24、by volume in 90 %deionized water. The solution level is to be checked daily anddeionized water used to keep the bath at a constant level.7. Procedure7.1 Specimen Preparation:7.1.1 Compression-mold pellet specimens (virgin resin) orchopped pipe into 0.075-in. (1.9-mm) sheet in accordance withProcedur

25、e C of Practice D4703, except that the pellets do nothave to be roll-milled prior to being compression-molded. Therate of cooling shall be 27 +/- 3.6F (15 6 2C) per minute. Ifdesired, the sheet may be trimmed by 0.6 in. (15 mm) on eachside in order to avoid any edge effects. Since pipes haveextrusio

26、n-induced orientation that can significantly affect thetest results, it is necessary to remove the orientation effect bymolding into a plaque. Chop and mold a pipe specimen inaccordance with the following procedure. Cut 1-in. (25-mm)wide sections from the pipe along its longitudinal axis. Torandomiz

27、e the orientation, cut these sections into smallerpieces until there is about 1 lb (0.5 kg) of material. Thesesections represent a complete cross-sectional sample from theinside to the outside of the pipe specimen. Compression molda plaque as previously stated. If different materials are used forthe

28、 inner and outer wall of dual wall pipe, each wall must betested separately.7.1.2 Die cut test specimens from the sheet, and make holesin the specimen as shown in Fig. 1.7.1.3 Specimen tolerances are as follows:Length = 2.36 0.01 in. (60.00 0.25 mm)Width = 0.125 0.001 in. (3.20 0.02 mm)Thickness = 0

29、.075 0.003 in. (1.90 0.08 mm)7.2 Notching:7.2.1 Notch specimens across the center of the 0.125-in.(3.20-mm) wide, 0.500-in. (12.7-mm) long reduced section asshown in Figs. 1 and 2. Cut the notch perpendicular to theplane defined by specimen length and width, and align at aright angle to the directio

30、n of load application. Cut the notch ata maximum rate of 0.1 in./min (2.5 mm/min) to a depth ofa 5 0.20 3T (1)where:a = notch depth, andT = measured thickness of the specimen.Control notch depth to 60.001 in. (60.025 mm) by mea-suring the notch depth with a microscope.7.2.2 No single razor blade sha

31、ll be used for more than tentest specimens.7.3 Calculation of Test Load:7.3.1 For each specimen, measure the reduced section width(W), thickness (T), and notch depth (a) to the nearest 0.001 in.(0.025 mm) using a micrometer and a microscope, or deter-mine the width (W) with a micrometer and determin

32、e theligament thickness directly with a microscope to the nearest0.0001 in. In the latter case, substitute the ligament thickness ininches for the term (T-a)inEq 2.7.3.2 At each loading point, determine the weight that mustbe hung on the lever arm to produce the required ligament-stress directly, by

33、 installing a calibrated load cell in the positionof the future test specimen and preparing the necessary weightaccurately enough that the ligament stress does not vary bymore than 60.5 %. The appropriate load cell reading is asfollows:Required load cell reading lbs grams! 5 T 2 a! WS (2)andP = the

34、necessary weight to be applied to the lever at theloading station to produce the required load cell reading asmeasured directly by the load cell.where:P is measured directly by adding weight, as necessary at eachloading station while the load cell is in place,W = cross-sectional width of the test sp

35、ecimen,a = the depth of the notch measured in accordance with7.3.1,T = the thickness of the test specimen, andS = specified ligament stress, psi (MPa).Each test weight so determined is to be labeled (or otherwisecorrelated to each test position) and applied to the appropriatelever arm on the test ap

36、paratus.NOTE 1Dimensions are in inches with tolerance of 60.005 in., exceptspecimen width, which has a tolerance of 60.001 in.FIG. 2 Specimen GeometryTest Specimen DimensionsF2136 08 (2015)3NOTE 2S = the specified ligament-stress. It is the stress at the notchlocation within each test specimen durin

37、g the test. It may be expressed asa percent (%) of the reference yield stress of 4000 psi (27.5 MPa). Thespecified ligament stress is selected at a level that is high enough toprovide a differentiation between materials that provide acceptable stress-crack resistance and those that do not, within a

38、reasonable testing timeperiod. The reference yield stress of 4000 psi has been selected for allresins meeting AASHTO M 294 density specifications of 0.945 0.955g/cc. This value is near the actual yield stress levels of PE materialsrepresenting the upper end of this density range.7.4 NCLS Testing:7.4

39、.1 Maintain temperature in the bath at 122 6 2F (50 61C).7.4.2 Test five specimens at a single ligament stress level.7.4.3 Determine the weight to be placed on each specimen,and load the weight tubes with shot. Do not attach the shot tubeto the lever arm.7.4.4 Attach the specimens to the loading fra

40、me. Take carethat the notch is not activated by bending the specimen. Lowerthe specimen into the bath, and condition the specimens in thebath for at least 30 min.7.4.5 Reset the specimen timer to zero.7.4.6 Check that the weight is the correct weight for theparticular specimen, and carefully connect

41、 the weight tube tothe appropriate lever arm for the specimen. Apply the loadgradually within a period of 5 to 10 s without any impact on thespecimen.7.4.7 Start the specimen timer immediately after loading.7.4.8 Record the time to failure of each specimen to thenearest 0.1 h.8. Report8.1 Report the

42、 following information:8.1.1 All details necessary for complete identification of thematerial tested (density, melt index, lot number, and so forth).8.1.2 Reference to this ASTM Test Method (F2136).8.1.3 The load placed on each level in accordance withEquation and cross-sectional dimension of each s

43、pecimen.8.1.4 The ligament-stress (in MPa or psi) based on thecross-sectional area of the test specimen.8.1.5 Test temperature.8.1.6 If applicable, the extrusion or molding from which thetest pieces has been taken.8.1.7 The failure time for each of the five specimens and thearithmetic average of eac

44、h specimen set of five specimens. Thearithmetic average shall be reported as the NCLS value of theresin or pipe under test.9. Precision and Bias49.1 PrecisionBased on Practice E691, a nine-laboratoryround-robin conducted on four HDPE materials, the precision(one standard deviation) of this test meth

45、od is summarized asfollows. This precision was determined using the PracticeE691 “Interlaboratory Data Analysis Software” computer pro-gram. The within-laboratory repeatability standard deviation(Sr) and between-laboratory reproducibility standard deviation(SR) are based on reporting the average of

46、five specimens asone data set.HDPEMaterialRepeatability, (Sr),Within laboratory, %Reproducibility, (SR),Between laboratory, %A20 50B24 39C11 4D6 279.2 BiasData obtained using this test method are believedto be reliable since accepted techniques of analysis are used.Since no referee method is availab

47、le, no bias statement can bemade.10. Keywords10.1 constant ligament-stress; corrugated HDPE pipe; slow-crack-growth resistanceAPPENDIX(Nonmandatory Information)X1. Example of Load CalculationX1.1 Calculate load as follows:Load grams! 5S*T 2 a!*WMA!*9.81!#31 000 2CFMASI units!(X1.1)orLoad lb! 5S*T 2

48、a!*W 2 CFMA!Inch 2 pound units! (X1.2)where:a = notch depth, in. (mm),MA = mechanical advantage of the apparatus (equipmentdependent),W = specimen width, in. (mm),T = specimen thickness, in. (mm),S = constant ligament-stress, psi (MPa), andCF = correction factor for the arm weight.4Supporting data h

49、ave been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:F17-1046.F2136 08 (2015)4ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical co