1、Designation: F2136 08 (Reapproved 2015)Standard 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 following the designation indi
2、cates 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 method is used to determine the
3、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 AASHTO Standard Specification M 294
4、. 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 in inch-pound units are to be
5、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 arein accordance with Terminolog
6、y 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 applica-bility of regulatory limit
7、ations 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 ThermoplasticMaterials into Test Specimens
8、, 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 the Precision of a Test Method
9、F412 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-active agent at an elevated temp
10、erature.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-growth (SCG) resistance for a limi
11、ted 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 cutting test specimens.Acceptable
12、 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 is the direct responsibility of
13、 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, orcontact ASTM Customer Serv
14、ice 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, Washington, DC 20001,http:/www.t
15、ransportation.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 D5397.Alternatively, the tensile
16、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 accurate to 0.5 % of the calcul
17、ated 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 the blade should be 0.2 to 0.
18、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 consisted of sevenlaboratorie
19、s 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 accurately measuring the notch de
20、pth.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 with length at least 0.5 in. (1
21、3 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 is extremely important that t
22、hey 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 D4703.5.7 Metal Shot, for weight t
23、ubes.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 by volume in 90 %deionized wat
24、er. 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 withProcedure C of Practice D4703, except
25、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 haveextrusion-induced orientation that can
26、 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. Torandomize the orientation, cut these s
27、ections 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 inner and outer wall of dual
28、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 = 0.075 0.003 in. (1.90 0.08 mm)7
29、.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 direction of load application. Cut the
30、 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 shall be used for more than tente
31、st 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 determine theligament thickness direct
32、ly 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 installing a calibrated load
33、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 necessary weight to be applied
34、 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 specimen,a = the depth of the no
35、tch 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 apparatus.NOTE 1Dimensions are i
36、n 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 during the test. It may be expresse
37、d 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 reasonable testing timeperiod.
38、 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:7.4.1 Maintain temperature in the
39、 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 frame. Take carethat the notch is
40、 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 the weight tube tothe appropr
41、iate 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 following information:8.1.1 A
42、ll 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 specimen.8.1.4 The ligament-str
43、ess (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 each specimen set of five specime
44、ns. 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 method is summarized asfollows. Th
45、is 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 five specimens asone data set.
46、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 available, no bias statement can bema
47、de.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 a!*W 2 CFMA!Inch 2 pound units
48、! (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 have been filed at ASTM Interna
49、tional 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 committee and must be reviewed e
