1、Designation: F 2136 05An 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 F 2136; the number immediately following the des
2、ignation 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is used to
3、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 AASHTO Standard Speci
4、fication 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 in inch-pound un
5、its are to be regardedas the standard. Values given in parentheses are for informationonly.1.4 Definitions are in accordance with Terminology F 412,and abbreviations are in accordance with Terminology D 1600,unless otherwise specified.1.5 This standard does not purport to address all of thesafety co
6、ncerns, 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:2D 1600 Terminology for Abbreviated Te
7、rms Relating toPlasticsD 1822 Test Method for Tensile-Impact Energy to BreakPlastics and Electrical Insulating MaterialsD 4703 Practice for Compression Molding ThermoplasticMaterials in Test Specimens, Plaques, or SheetsD 5397 Test Method for Evaluation of Stress Crack Resis-tance of Polyolefin Geom
8、embranes Using Notched Con-stant Tensile Load TestE4 Practices for Force Verification of Testing MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF 412 Terminology Relating to Plastic Piping SystemsF 1473 Test Method for Notch Tensile Test to
9、Measure theResistance to Slow Crack Growth of Polyethylene Pipesand Resins2.2 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 ag
10、ent at an elevated temperature.It differs from Test Method D 5397 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 (SC
11、G) 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 DieAdie suitable for cutting te
12、st specimens.Acceptable dies are: the type L die per Test Method D 1822,with holes drilled or punched in the tab areas after die cutting;a die with the dimensions and tolerances specified in Fig. 2.5.2 Stress-Crack Testing Apparatus4A lever loading ma-chine, with a lever arm ratio of 2:1 to 5:1 simi
13、lar to that1This test method is under the jurisdiction of ASTM Committee F17 on PlasticPiping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved June 1, 2005. Published June 2005. Originallyapproved in 2001. Last previous edition approved in 2001
14、as F213601e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of State Hi
15、ghway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001.4Testing apparatus is available from BT Technology, Inc., 320 N. Railroad St.,Rushville, IL 62681; Materials Performance, Inc., 2151 Harvey Mitchell Pkwy, S.,Suite 208, College Station, TX 77840; Sate
16、c Systems, 900 Liberty St., Grove City,PA 16127; or equivalent.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.T = thickness.W = specimen width.NOTE 1The test specimen is intended to have the same geometry used for Test Method D 5397
17、 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. (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
18、 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 they be carefullyaligned so as to avoid adding a twisting component to the stress being placed on the specimen.FIG. 1 Notching
19、 PositionF2136052described in Test Method D 5397. Alternatively, the tensileload may 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 P
20、ractices E4. The load onthe specimen shall be accurate to 0.5 % of the calculated orapplied load. The bath solution temperature shall be set at 1226 2F (50 6 1C).5.3 Notching Device5Notch depth is an important vari-able that must be controlled. Paragraph 7.2.1 describes thenotching procedure and typ
21、e of apparatus used. The approxi-mate thickness of 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 wereuse
22、d by the round-robin participants. The round robin 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 wit
23、h micrometer or an equivalentdevice capable of accurately measuring the notch depth.5.6 Compression-Molding Press and Suitable Chase forCompression-Molding the Specimens, in accordance with Prac-tice D 4703.5.7 Metal Shot, for weight tubes.5.8 Electronic Scale, for measuring shot weight tubes ca-pab
24、le 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 (Igepal CO-630 fromRhone-Poulenc or equivalent) by volume in 90 % deionizedwater. The solution
25、level is to be checked daily and deionizedwater 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 D 4703 or 8.4 of Test Method F
26、1473,except that the pellets do not have to be roll-milled prior tobeing compression-molded. If desired, the sheet may betrimmed by 0.6 in. (15 mm) on each side in order to avoid anyedge effects. Since pipes have extrusion-induced orientationthat can significantly affect the test results, it is nece
27、ssary toremove the orientation effect by molding into a plaque. Chopand mold a pipe specimen in accordance with the followingprocedure. Cut 1-in. (25-mm) wide sections from the pipealong its longitudinal axis. To randomize the orientation, cutthese sections into smaller pieces until there is about 1
28、 lb (0.5kg) of material. These sections represent a complete cross-sectional sample from the inside to the outside of the pipespecimen. Compression mold a plaque as previously stated. Ifdifferent materials are used for the inner and outer wall of dualwall pipe, each wall must be tested separately.7.
29、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 6 0.01 in. (60.00 6 0.25 mm)Width = 0.125 6 0.001 in. (3.20 6 0.02 mm)Thickness = 0.075 6 0.003 in. (1.90 6 0.08 mm)7.2 Notching:7.2.1 Notch specimens ac
30、ross 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 notch ata maximum rate of 0.1 in./m
31、in (2.5 mm/min) to a depth ofa 5 0.20 3 T (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 tentest specimens.7.3 Calculation of Tes
32、t 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 directly with a microscope to the nearest
33、0.0001 in. In the latter case, substitute the ligament thickness ininches for the term (T-a)inEq2.5Notching apparatus is available from BT Technology, Inc., 320 N. RailroadStreet, Rushville, IL 62681; Satec Systems, 900 Liberty St., Grove City, PA 16127;or equivalent.NOTE 1Dimensions are in inches w
34、ith tolerance of 60.005 in., exceptspecimen width, which has a tolerance of 60.001 in.FIG. 2 Specimen GeometryTest Specimen DimensionsF21360537.3.2 At each loading point, determine the weight that mustbe hung on the lever arm to produce the required ligament-stress directly, by installing a calibrat
35、ed 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!5Ta! WS (2)andP = the necessary weight to be appl
36、ied 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 ateach loading station while the load cell is in place,W = cross-sectional width of the test specimen,a = the depth of the
37、 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 apparatus.NOTE 2S = the speci
38、fied ligament-stress. It is the stress at the notchlocation within each test specimen during 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
39、 materials that provide acceptable stress-crack resistance and those that do not, within a 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
40、levels of PE materialsrepresenting the upper end of this density range.7.4 NCLS Testing:7.4.1 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
41、. Do not attach the shot tubeto the lever arm.7.4.4 Attach the specimens to the loading frame. 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 Ch
42、eck that the weight is the correct weight for theparticular specimen, and carefully connect 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.
43、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 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 (F 2136).8.1.3 The
44、load placed on each level in accordance withEquation2 and cross-sectional dimension of each specimen.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
45、 taken.8.1.7 The failure time for each of the five specimens and thearithmetic average of each specimen set of five specimens. Thearithmetic average shall be reported as the NCLS value of theresin or pipe under test.9. Precision and Bias9.1 PrecisionBased on Practice E 691, a nine-laboratoryround-ro
46、bin conducted on four HDPE materials, the precision(one standard deviation) of this test method is summarized asfollows. This precision was determined using the PracticeE 691 “Interlaboratory Data Analysis Software” computerprogram. The within-laboratory repeatability standard devia-tion (Sr) and be
47、tween-laboratory reproducibility standard de-viation (SR) are based on reporting the average of fivespecimens as one data set.6HDPE MaterialRepeatability, (Sr),Within laboratory, %Reproducibility, (SR),Between laboratory, %A20 50B24 39C11 4D6 279.2 BiasData obtained using this test method are believ
48、edto be reliable since accepted techniques of analysis are used.Since no referee method is available, no bias statement can bemade.10. Keywords10.1 constant ligament-stress; corrugated HDPE pipe; slow-crack-growth resistance6See ASTM Research Report F17-1046 for details. Available from ASTMHeadquart
49、ers.F2136054APPENDIX(Nonmandatory Information)X1. Example of Load CalculationX1.1 Calculate load as follows:Load grams!5S*Ta!*WMA!*9.81!#3 1 000 CFMASI units!(X1.1)orLoad lb!5S*Ta!*W CFMA!Inch2pound 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.ASTM International takes no position respecting the validity of any patent rights asserted in conne
