ASTM F2136-2008 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树脂或HDPE.pdf

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1、Designation: F 2136 08An 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is used to d

3、etermine 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 Specif

4、ication 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 uni

5、ts 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 Terminology F 412,and abbreviations are in accordance with Terminology D 1600,unless

6、otherwise specified.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 limitations prior to

7、 use.2. Referenced Documents2.1 ASTM Standards:2D 1600 Terminology for Abbreviated Terms Relating toPlasticsD 1822 Test Method for Tensile-Impact Energy to BreakPlastics and Electrical Insulating MaterialsD 4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens, Plaques, or

8、 SheetsD 5397 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 MachinesE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF 412 Termi

9、nology 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 temperature.It

10、 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 (SCG) resistance for a limited set o

11、f 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 test specimens.Acceptable dies are:

12、 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 ApparatusA lever loading ma-chine, with a lever arm ratio of 2:1 to 5:1 similar to thatdescribed in Test Metho

13、d 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, using1This test method is under the jurisdiction of ASTM Committee F17 on PlasticP

14、iping Systems and is the direct responsibility of Subcommittee F17.40 on TestMethods.Current edition approved Nov. 1, 2008. Published November 2008. Originallyapproved in 2001. Last previous edition approved in 2005 as F2136052For referenced ASTM standards, visit the ASTM website, www.astm.org, orco

15、ntact 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, Washingt

16、on, DC 20001,http:/www.transportation.org.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 specimens. The lengt

17、h 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 the specimen rather

18、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 PositionF2136082a fo

19、rce standard that complies with Practices 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 DeviceNotch depth is an important variablethat must be controlled. Paragraph 7.2.1 describes

20、 the notchingprocedure and type of apparatus used. The approximate thick-ness 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

21、 various manufacturers wereused 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

22、).5.5 Microscope, equipped with 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 meas

23、uring 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 water. The solution level is to be che

24、cked 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 D 4703, except that the pellets do nothave to be

25、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 significantly affect thetest resu

26、lts, 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 sections into smallerpieces until t

27、here 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 wall pipe, each wall must betested

28、 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 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 Notc

29、h 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 notch ata maximum rat

30、e of 0.1 in./min (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 Calc

31、ulation 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 directly with a microscope

32、to the nearest0.0001 in. In the latter case, substitute the ligament thickness ininches for the term (T-a)inEq2.7.3.2 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 cell in the positionof

33、 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)andNOTE 1Dimensions are in inches with tolerance of 60.005 in., exce

34、ptspecimen width, which has a tolerance of 60.001 in.FIG. 2 Specimen GeometryTest Specimen DimensionsF2136083P = the 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

35、 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 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 i

36、s to be labeled (or otherwisecorrelated to each test position) and applied to the appropriatelever arm on the test apparatus.NOTE 2S = the specified 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

37、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. The reference yield stress of 4000

38、 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 bath at 122 6 2F (50 61C).7.4.2 Te

39、st 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 not activated by bending the speci

40、men. 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 appropriate lever arm for the specimen. Ap

41、ply 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 All details necessary for complete i

42、dentification 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 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 thec

43、ross-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 specimens. Thearithmetic average shall b

44、e reported as the NCLS value of theresin or pipe under test.9. Precision and Bias49.1 PrecisionBased on Practice E 691, a nine-laboratoryround-robin conducted on four HDPE materials, the precision(one standard deviation) of this test method is summarized asfollows. This precision was determined usin

45、g the PracticeE 691 “Interlaboratory Data Analysis Software” computerprogram. The within-laboratory repeatability standard devia-tion (Sr) and between-laboratory reproducibility standard de-viation (SR) are based on reporting the average of fivespecimens as one data set.HDPE MaterialRepeatability, (

46、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 bemade.10. Keywords10.1 constant

47、 ligament-stress; corrugated HDPE pipe; slow-crack-growth resistance4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: F17-1046.F2136084APPENDIX(Nonmandatory Information)X1. Example of Load CalculationX1.1 Calculate load as follow

48、s: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 (M

49、Pa), andCF = correction factor for the arm weight.ASTM 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 every five years andif not revised, either reapproved or