1、Designation: 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 designation indicates the year ofo
2、riginal 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*1.1 This test method is used to determine the susceptibilityof
3、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 (0.947 to 0.955 g/cm3). This test method maybe applicable for other materials, but
4、data are not available forother 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 regardedas standard. The values given in parentheses are math
5、ematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 Definitions are in accordance with Terminology F412,and abbreviations are in accordance with Terminology D1600,unless otherwise specified.1.5 This standard does not purport to address all of the
6、safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-
7、dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM
8、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, Plaques, or SheetsD5397 Test Method for Evaluation
9、 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 MethodF412 Terminology Relating to Plastic Piping Systems3
10、. 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 differs from Test Method D5397 in that a constant ligamentstress is used instead of a constant t
11、ensile 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 of HDPE resins.4.3 This test method may be used on virgin HDPE resincompression-molded into a plaqu
12、e or on extruded HDPEcorrugated pipe that is chopped and compression-molded intoa plaque (see 7.1.1 for details).1This 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
13、Feb. 15, 2018. Published February 2018. Originallyapproved in 2001. Last previous edition approved in 2015 as F213608(2015). DOI:10.1520/F2136-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards
14、 volume information, refer to the standards Document Summary page onthe ASTM website.*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 StatesThis international standard was devel
15、oped in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Apparatus5.1 Bla
16、nking DieA die suitable for cutting 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. 2.5.2 Stress-Crack Testing ApparatusA lever loadingmachine, with a
17、lever arm ratio of 2:1 to 5:1 similar to thatdescribed in Test Method D5397.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 sta
18、ndard 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 the no
19、tchingprocedure 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 variou
20、s 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 %.T = thickness.W = specimen width.NOTE 1The test specimen is intende
21、d 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 so that th
22、e 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 component to t
23、he stress being placed on the specimen.FIG. 1 Notching PositionF2136 1825.4 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 depth.5.6 Compression-Molding Press and Suitable Chase forCo
24、mpression-Molding the Specimens, in accordance with Prac-tice D4703.5.7 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 reage
25、nt shall consist of 10 % non-ylphenoxy poly (ethyleneoxy) ethanol 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) orcho
26、pped pipe into 0.075-in. (1.9-mm) sheet in accordance withProcedure 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 eac
27、hside in order to avoid any edge effects. Since pipes haveextrusion-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)w
28、ide sections from the pipe along its longitudinal axis. Torandomize 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 p
29、laque as previously stated. If different materials are used forthe 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.
30、(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)7.2 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 sp
31、ecimen length and width, and align at aright angle to the direction 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
32、 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 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 micr
33、oscope, or deter-mine the width (W) with a micrometer and determine 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
34、the lever arm to produce the required ligament-stress directly, by 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 asfollow
35、s:Required load cell reading lbs grams! 5 T 2 a! WS (2)andP = 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 weight, as necessary at eachloading station while
36、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).NOTE 1Dimensions are in inches with tolerance of 60.005 in., exceptspecimen width,
37、which has a tolerance of 60.001 in.FIG. 2 Specimen GeometryTest Specimen DimensionsF2136 183Each 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 specified ligament-stress. It is the
38、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 materials that provide acceptab
39、le 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 density specifications of 0.945 0.955 g/cc. This value isnear the actual yield stress levels of materials representing the upper en
40、dof 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. Do not attach the shot tubeto the lever arm.7.
41、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 Check that the weight is the correct weight for th
42、eparticular 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.7.4.8 Record the time to failure of each specimen
43、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 (F2136).8.1.3 The load placed on each level in accordance withEquat
44、ion 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 taken.8.1.7 The failure time for each of the five
45、 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 Bias39.1 PrecisionBased on Practice E691, a nine-laboratoryround-robin conducted on four HDPE materials, the precisio
46、n(one standard deviation) of this test method 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
47、(SR) are based on reporting the average of five specimens asone data set.MaterialRepeatability, (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
48、used.Since no referee method is available, 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
49、 2CFMASI units!(X1.1)orLoad lb! 5S*T 2 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.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:F17-1046.F2136 184SUMMARY OF CHANGESCommittee F17 has identified the location of selected changes to t
