ASTM F2136-2018 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: F2136 08 (Reapproved 2015)F2136 18Standard 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 designat

2、ion 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. Scope Scope*1.1 This test method is used to

3、 determine the susceptibility of high-density polyethylene (HDPE) resins or corrugated pipe toslow-crack-growth under a constant ligament-stress in an accelerating environment. This test method is intended to apply only toHDPE of a limited melt index (0.947 to 0.955 g/cm3 StandardSpecification M 294

4、. ). This test method may be applicable for other materials, but data are not available for other materials at thistime.1.2 This test method measures the failure time associated with a given test specimen at a constant, specified, ligament-stresslevel.1.3 The values stated in inch-pound units are to

5、 be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.1.4 Definitions are in accordance with Terminology F412AASHTO Standard Specification M 294, , and abbreviations are inaccordance wi

6、th Terminology D1600, unless otherwise specified.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and deter

7、mine theapplicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations i

8、ssuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1600 Terminology for Abbreviated Terms Relating to PlasticsD1822 Test Method for Tensile-Impact Energy to Break Plastics and Electrical Insulating MaterialsD4703 Practice for

9、Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or SheetsD5397 Test Method for Evaluation of Stress Crack Resistance of Polyolefin Geomembranes Using Notched Constant TensileLoad TestE4 Practices for Force Verification of Testing MachinesE691 Practice for Conducting an Inte

10、rlaboratory Study to Determine 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, notched test-specimen (Fig. 1) to a constant ligament-stres

11、s in the presenceof a surface-active agent at an elevated temperature. It differs from Test Method D5397 in that a constant ligament stress is usedinstead of a constant tensile load.1 This test method is under the jurisdiction of ASTM Committee F17 on Plastic Piping Systems and is the direct respons

12、ibility of Subcommittee F17.40 on Test Methods.Current edition approved Dec. 1, 2015Feb. 15, 2018. Published December 2015February 2018. Originally approved in 2001. Last previous edition approved in 20082015as F213608F213608(2015). DOI: 10.1520/F2136-08R15.10.1520/F2136-18.2 For referencedASTM stan

13、dards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an A

14、STM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as publishe

15、d by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 This test method does not purport to inter

16、pret the data generated.4.2 This test method is intended to compare slow-crack-growth (SCG) resistance for a limited set of HDPE resins.4.3 This test method may be used on virgin HDPE resin compression-molded into a plaque or on extruded HDPE corrugatedpipe that is chopped and compression-molded int

17、o a plaque (see 7.1.1 for details).5. Apparatus5.1 Blanking DieA die suitable for cutting test specimens. Acceptable dies are: the type L die per Test Method D1822, withholes drilled or punched in the tab areas after die cutting; a die with the dimensions and tolerances specified in Fig. 2.5.2 Stres

18、s-Crack Testing ApparatusA lever loading machine, with a lever arm ratio of 2:1 to 5:1 similar to that described inTest Method D5397. Alternatively, the tensile load may be applied directly using dead weights or any other method for producingT = thickness.W = specimen width.NOTE 1The test specimen i

19、s 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. (13 mm) long.NOTE 2It is preferable to modify the specimen die s

20、o 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 they be carefullyaligned so as to avoid adding a twisting compo

21、nent to the stress being placed on the specimen.FIG. 1 Notching PositionF2136 182a constant ligament stress. Determine the zero-load offset and lever-arm ratio for each test station, using a force standard thatcomplies with Practices E4.The load on the specimen shall be accurate to 0.5 % of the calc

22、ulated or applied load.The bath solutiontemperature shall be set at 122 6 2F (50 6 1C).5.3 Notching DeviceNotch depth is an important variable that must be controlled. Paragraph 7.2.1 describes the notchingprocedure and type of apparatus used. The approximate thickness of the blade should be 0.2 to

23、0.3 mm.NOTE 1A round robin was conducted to determine the effect of types of blades on the notch depth. In this study, several types of steel blades(single-edge, double-edge, and so forth) from various manufacturers were used by the round-robin participants. The round robin consisted of sevenlaborat

24、ories using two types of resins molded into plaques. The standard deviation 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 equivalent device capable of accurately measuring the n

25、otch depth.5.6 Compression-Molding Press and Suitable Chase for Compression-Molding the Specimens, in accordance with PracticeD4703.5.7 Metal Shot, for weight tubes.5.8 Electronic Scale, for measuring shot weight tubes capable of measuring to 60.1 g.5.9 Timing Device, capable of recording failure ti

26、me to the nearest 0.1 h.6. Reagents6.1 The stress-cracking reagent shall consist of 10 % nonylphenoxy poly (ethyleneoxy) ethanol by volume in 90 % deionizedwater. The solution level is to be checked daily and deionized water used to keep the bath at a constant level.7. Procedure7.1 Specimen Preparat

27、ion:7.1.1 Compression-mold pellet specimens (virgin resin) or chopped pipe into 0.075-in. (1.9-mm) sheet in accordance withProcedure C of Practice D4703, except that the pellets do not have to be roll-milled prior to being compression-molded. The rateof cooling shall be 27 +/- 3.6F (15 6 2C) per min

28、ute. If desired, the sheet may be trimmed by 0.6 in. (15 mm) on each side inorder to avoid any edge effects. Since pipes have extrusion-induced orientation that can significantly affect the test results, it isnecessary to remove the orientation effect by molding into a plaque. Chop and mold a pipe s

29、pecimen in accordance with thefollowing procedure. Cut 1-in. (25-mm) wide sections from the pipe along its longitudinal axis. To randomize the orientation, cutthese sections into smaller pieces until there is about 1 lb (0.5 kg) of material. These sections represent a complete cross-sectionalsample

30、from the inside to the outside of the pipe specimen. Compression mold a plaque as previously stated. If different materialsare used for the inner and outer wall of dual wall pipe, each wall must be tested separately.7.1.2 Die cut test specimens from the sheet, and make holes in the specimen as shown

31、 in Fig. 1.7.1.3 Specimen tolerances are as follows:NOTE 1Dimensions are in inches with tolerance of 60.005 in., except specimen width, which has a tolerance of 60.001 in.FIG. 2 Specimen GeometryTest Specimen DimensionsF2136 183Length = 2.36 0.01 in. (60.00 0.25 mm)Width = 0.125 0.001 in. (3.20 0.02

32、 mm)Thickness = 0.075 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 as shownin Figs. 1 and 2. Cut the notch perpendicular to the plane defined by specimen length and width, and align at a right a

33、ngle to thedirection of load application. Cut the notch at a maximum rate of 0.1 in./min (2.5 mm/min) to a depth ofa 50.203T (1)where:a = notch depth, andT = measured thickness of the specimen.Control notch depth to 60.001 in. (60.025 mm) by measuring the notch depth with a microscope.7.2.2 No singl

34、e razor blade shall be used for more than ten test 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 determine the width (W) with a micro

35、meter and determine the ligamentthickness directly with a microscope to the nearest 0.0001 in. In the latter case, substitute the ligament thickness in inches for theterm (T-a) in Eq 2.7.3.2 At each loading point, determine the weight that must be hung on the lever arm to produce the required ligame

36、nt-stressdirectly, by installing a calibrated load cell in the position of the future test specimen and preparing the necessary weight accuratelyenough that the ligament stress does not vary by more than 60.5 %. The appropriate load cell reading is as follows:Required load cell reading lbs grams!5T

37、2a! W S (2)andP = the necessary weight to be applied to the lever at the loading station to produce the required load cell reading as measureddirectly by the load cell.where:P is measured directly by adding weight, as necessary at each loading station while the load cell is in place,W = cross-sectio

38、nal width of the test specimen,a = the depth of the notch measured in accordance with 7.3.1,T = the thickness of the test specimen, andS = specified ligament stress, psi (MPa).Each test weight so determined is to be labeled (or otherwise correlated to each test position) and applied to the appropria

39、te leverarm on the test apparatus.NOTE 2S = the specified ligament-stress. It is the stress at the notch location within each test specimen during the test. It may be expressed as a percent(%) of the reference yield stress of 4000 psi (27.5 MPa). The specified ligament stress is selected at a level

40、that is high enough to provide a differentiationbetween materials that provide acceptable stress-crack resistance and those that do not, within a reasonable testing time period. The reference yield stressof 4000 psi has been selected for all resins meetingAASHTO M 294 density specifications of 0.945

41、 0.955 g/cc. This value is near the actual yield stresslevels of PE materials representing the upper end of this density range.7.4 NCLS Testing:7.4.1 Maintain temperature in the bath at 122 6 2F (50 6 1C).7.4.2 Test five specimens at a single ligament stress level.7.4.3 Determine the weight to be pl

42、aced 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 care that the notch is not activated by bending the specimen. Lower thespecimen into the bath, and condition the specimens in the bath for at

43、least 30 min.7.4.5 Reset the specimen timer to zero.7.4.6 Check that the weight is the correct weight for the particular specimen, and carefully connect the weight tube to theappropriate lever arm for the specimen.Apply the load gradually within a period of 5 to 10 s without any impact on the specim

44、en.7.4.7 Start the specimen timer immediately after loading.7.4.8 Record the time to failure of each specimen to the nearest 0.1 h.8. Report8.1 Report the following information:8.1.1 All details necessary for complete identification of the material tested (density, melt index, lot number, and so for

45、th).8.1.2 Reference to this ASTM Test Method (F2136).8.1.3 The load placed on each level in accordance with Equation and cross-sectional dimension of each specimen.F2136 1848.1.4 The ligament-stress (in MPa or psi) based on the cross-sectional area of the test specimen.8.1.5 Test temperature.8.1.6 I

46、f applicable, the extrusion or molding from which the test pieces has been taken.8.1.7 The failure time for each of the five specimens and the arithmetic average of each specimen set of five specimens. Thearithmetic average shall be reported as the NCLS value of the resin or pipe under test.9. Preci

47、sion and Bias39.1 PrecisionBased on Practice E691, a nine-laboratory round-robin conducted on four HDPE materials, the precision (onestandard deviation) of this test method is summarized as follows. This precision was determined using the Practice E691“Interlaboratory Data Analysis Software” compute

48、r program. The within-laboratory repeatability standard deviation (Sr) andbetween-laboratory reproducibility standard deviation (SR) are based on reporting the average of five specimens as one data set.HDPEMaterialRepeatability, (Sr),Within laboratory, %Reproducibility, (SR),Between laboratory, %A 2

49、0 50B 24 39C 11 45D 6 279.2 BiasData obtained using this test method are believed to be reliable since accepted techniques of analysis are used. Sinceno referee method is available, no bias statement can be made.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!5 S*T 2a!*WMA!*9.81!#310002 CFMA SI units! (X1.1)orLoad lb!5S*T 2a!*W 2CFMA! Inch2pound units! (X1.2)3 Supporting data have been