1、Designation: D1693 15Standard Test Method forEnvironmental Stress-Cracking of Ethylene Plastics1This standard is issued under the fixed designation D1693; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This test method covers the determination of th
3、e sus-ceptibility of ethylene plastics, as defined in TerminologyD883, to environmental stress-cracking when subjected to theconditions herein specified. Under certain conditions of stressand in the presence of environments such as soaps, wettingagents, oils, or detergents, ethylene plastics may exh
4、ibitmechanical failure by cracking.1.2 The values stated in SI units are to be regarded asstandard.1.3 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 healt
5、h practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1204 Test Method for Linear
6、Dimensional Changes ofNonrigid Thermoplastic Sheeting or Film at ElevatedTemperatureD1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD3350 Specification for Polyethylene Plastics Pipe and Fit-tings MaterialsD4703 Practice for Compression Molding ThermoplasticMateria
7、ls into Test Specimens, Plaques, or SheetsD4976 Specification for Polyethylene Plastics Molding andExtrusion MaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ASTM Adjuncts:Apparatus Drawings and Blueprints33. Terminology3.1 Definitions:3.1.
8、1 stress-crack, nan external or internal rupture in aplastic caused by tensile stresses less than its short-timemechanical strength.3.1.1.1 DiscussionThe development of such cracks isfrequently accelerated by the environment to which the plasticis exposed. The stresses which cause cracking may be pr
9、esentinternally or externally, or may be a combination of thesestresses. The appearance of a network of fine cracks is calledcrazing.3.1.2 stress-crack failure, nfor purposes of this testmethod, any crack visible to an observer with normal eyesightshall be interpreted as a failure of the entire spec
10、imen (1).4Extension of the controlled imperfection shall not be construedas a failure. The appearance of more than one crack in a singlespecimen shall be construed as a single failure.3.1.2.1 DiscussionCracks generally develop at the con-trolled imperfection and run to the outer edge of the specimen
11、approximately at right angles to it (2). The cracks need notextend completely through the specimen to constitute failure.Cracks sometimes develop under the polymer surface, mani-festing themselves as depressions on the surface. The timewhen this occurs should be noted, and if the depression laterdev
12、elops into a crack, the time of dimpling should be consid-ered as the failure time.4. Summary of Test Method4.1 Bent specimens of the plastic, each having a controlledimperfection on one surface, are exposed to the action of asurface-active agent. The proportion of the total number ofspecimens that
13、crack in a given time is observed.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-als.Current edition approved May 1, 2015. Published June 2015. Originallyapproved in 1959. Last previous edit
14、ion approved in 2013 as D1693 - 13. DOI:10.1520/D1693-15.2For 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.3Det
15、ail drawings of the apparatus are available from ASTM Headquarters.Request ADJD169301,ADJD169302,ADJD169303, and ADJD169304.4The boldface numbers in parentheses refer to the list of references at the end ofthis test method.*A Summary of Changes section appears at the end of this standardCopyright AS
16、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 This test method may be used for routine inspectionpurposes by subjecting a required number of specimens to thetest conditions for a specified time and noting the number t
17、hatfail. The cracking obtained with the test reagent is indicative ofwhat may be expected from a wide variety of surface-activeagents, soaps, and organic substances that are not absorbedappreciably by the polymer.5.2 Environmental stress-cracking is a property that ishighly dependent upon the nature
18、 and level of the stressesapplied and on the thermal history of the specimen (1). Underthe conditions of the test method, high local multiaxial stressesare developed through the introduction of a controlled imper-fection (2, 3). Environmental stress-cracking has been found tooccur most readily under
19、 such conditions.NOTE 2Different types of polyethylene plastics as defined in Speci-fication D1248 are generally tested under different levels of strain andstress. When it is expressly desired to compare the types at equal levels ofstrain, the specimens for all types should be tested under Condition
20、 B,Table 1 (4).5.3 Information from this test method is not intended to beused for direct application to engineering problems.NOTE 3Caution should be used in comparing and ranking variousethylene plastics into distinct and separate groups by this test method (seeSection 13 and Note 12).As thermal hi
21、story is recognized as an important variable, test results bythis test method employing laboratory molded samples cannot necessarilybe expected to show agreement with test results from samples obtained byother means. The true performance potential of a given ethylene plasticmay, however, best be det
22、ermined with specimens obtained from com-mercially prepared items (5).6. Apparatus6.1 Blanking DieArectangular die or other means suitablefor cutting specimens 38 6 2.5 mm by 13 6 0.8 mm(1.5 6 0.1 in. by 0.50 6 0.03 in.). These specimens must becut with square edges. Beveled ends in particular are t
23、o beavoided.6.2 JigA jig for making a controlled imperfection inspecimens of the dimensions shown in Table 1, parallel to thelong edges of the specimen and centered on one of the broadfaces. A jig as shown in Fig. 1 and capable of notching thespecimens in accordance with 10.2 shall be used.NOTE 4It
24、is recommended that the jig be permanently mounted toensure notching consistency.6.3 Specimen HoldersLengths of hard or half-hard brassor stainless steel channel having the dimensions shown in (B)of Fig. 2 shall be used. The sides of the channel shall beparallel and the inside corners sharp and squa
25、re. Any burrspresent on the inside of the channel shall be removed. Theinside width is critical (see Dimension F in Fig. 2).6.4 Test Tubes and ClosuresHard glass tubes nominally200 mm long with a preferred minimum inside diameter of31.5 mm and a cork or rubber stopper.Alternatively, tubes withthread
26、ed ends and plastic caps are permissible.NOTE 5Some older test tubes have inside diameters of less than 31.5mm. These are acceptable as long as there is adequate clearance to allowthe filled specimen holder to be inserted into the tube without anyinterference.NOTE 6Hard glass (borosilicate) tubes an
27、d No. 15 corks have beenfound satisfactory.6.5 Aluminum FoilApproximately 0.08 to 0.13 mm (0.003to 0.005 in.) thick, for wrapping.6.6 Constant-Temperature BathA constant-temperatureliquid bath maintained at 50.0 6 0.5C for Conditions A and Bof Table 1 and 100.0 6 0.5C for Condition C of Table 1.6.7
28、Test Tube RackA rack to hold test tubes immersed toreagent level.6.8 Bending ClampAs shown in Fig. 3.6.9 Transfer ToolAs shown in Fig. 4.TABLE 1 Standard Test ConditionsConditionSpecimenThicknessNotch DepthBath Temperature,CmmAin. mmAin.ABmin 3.00 0.120 0.50 0.020 50max 3.30 0.130 0.65 0.025BBmin 1.
29、84 0.0725 0.30 0.012 50max 1.97 0.0775 0.40 0.015CCmin 1.84 0.0725 0.30 0.012 100Cmax 1.97 0.0775 0.40 0.015ADimensional values are not exactly equivalent. However, for referee purposes themetric units shall apply.BFor referee purposes, concentration of Igepal will be consistent with the appro-priat
30、e material standard. If no concentration is given, then 10 % volume solutionshall be used.CAt a temperature of 100C, a full-strength reagent, rather than an aqueoussolution of a reagent, is generally used because solutions tend to change theircompositions by water evaporation losses during the perio
31、d of test.mm in.A318B 18.919.2 0.7450.755C (radius) 1.5 max116 maxFIG. 1 Nicking JigD1693 1527. Reagent7.1 The preferred reagent is a nonylphenoxy poly(ethylene-oxy)ethanol.5NOTE 7There are environmental concerns regarding the disposal ofNonylphenoxy poly(ethyleneoxy) ethanol (CAS 68412-54-4), forex
32、ample, Igepal CO-630. Users are advised to consult their supplier orlocal environmental office and follow the guidelines provided for theproper disposal of this chemical.NOTE 8The reagent should be stored in closed metal or glasscontainers because it is somewhat hygroscopic.NOTE 9The manufacturer ha
33、s stated that this aggressive agentundergoes no known degradation when used as follows: A10 % volumesolution in water at 50C for 1000 h of testing.NOTE 10The appearance of carbonyl bands in an Igepal Fouriertransform infrared (FT-IR) scan is an indication of degradation.7.2 Other surface-active agen
34、ts, soaps, or any liquid organicsubstance that is not absorbed appreciably by the polymer canalso be used.8. Test Specimen8.1 Unless otherwise specified, the test specimens shall bemolded in accordance with Procedure C of Annex A1 ofPractice D4703.NOTE 11Use no liquid release agents, waxes, polishes
35、, and so forth,when molding. However, inert materials such as polyester film, unplasti-cized cellophane, polytetrafluoroethylene, and aluminum foil have beenfound satisfactory.5For referee purposes Igepal CO-630 should be obtained from Rhone-Poulenc,Prospect Plains, Cranbury, NJ 08512.Dimensionsmm i
36、n.A 382.5 1.50.1B 130.8 0.50.03C see Table 1D see Table 1E 165 612F(outside) 1658(inside) 11.75 0.05 0.463 0.002G138H153764I 2 0.081(12B polyethylene; stress-crackingANNEX(Mandatory Information)A1. GRAPHICAL METHOD OF DETERMINING FAILURE POINTSA1.1 Under some circumstances a 50 % failure point (F50)
37、is of interest and relevant, as other failure points may be. Anexample of calculation using a graphical method for the 50 %(or almost any other %) failure point is as follows:A1.1.1 The value reported by this graphical method isobtained without reference to 0 % failure time. Plot the data onlogarith
38、mic probability graph paper, Fig. A1.1 or Fig. A1.2,with appropriate time scales chosen and probability expressedas percentage. (The user is encouraged to copy these figures.)Elapsed time belongs on the logarithmic scale. Number offailures (breaks or cracks), divided by one more than thenumber of or
39、iginal specimens, belongs on the probability scale.Adding one to the number of specimens provides a divisor that(a) produces a symmetrical treatment of the data, (b) enablesplotting all the data points, (c) is easy to remember without atable, (d) permits using any otherwise appropriate number ofspec
40、imens, and (e) is widely accepted.NOTE A1.1This plotting convention does not necessarily provide amathematically optimum unbiased estimate of the standard deviation, butusing the convention appears nearly optimal with ten specimens. Consid-erable mathematical bias is usually introduced anyway by the
41、 economicnecessity of periodic inspection, that is, not continuously watching forbreaks during 48 h. The recorded failure times are generally later than theactual failure times. This limitation seems to engulf the slight biasintroduced for convenience by the plotting convention (6), (7). For further
42、information see Refs (6-9) and the references contained therein.A1.2 If one or more specimens broke since the previousobservation, plot a point for each of the failed specimens.Therefore, one point will appear for each specimen that fails.Apoint does not necessarily appear for each observation time.
43、Draw the best-fitting straight line for the plot. The timeindicated at the intersection of the data line and the 50 %probability line shall be the 50 % failure point (F50). Similarly,F10, F20, F90,orFxinformation is obtained from the intersec-tion of the data line and the 10 %, 20 %, 90 %, or X %pro
44、bability lines. The F0and F100points cannot be obtained, asthey do not formally exist.A1.3 A specimen that breaks on bending is called failed at1 min, or less, an arbitrary convenient short time that is lessthan the first inspection time. The plotting directions are thenstill valid. Convenient suita
45、ble inspection times have beenfound to be 0.1, 0.25, 0.5, 1.0, 1.5, 2, 3, 4, 5, 8, 16, 24, 32, 40,and 48 h. Extended tests are inspected every 24 h thereafter.Certain work schedules would eliminate the 16 and 32-hinspections, and possibly shorten the 8, 24, and 48-h periods afew minutes to enable in
46、spection during an 8-h working day.Laboratories on round-the-clock operations would not beaffected by this problem.A1.4 Specific examples of calculations using the graphicalmethod, in conjunction with Fig.A1.3, are given in TableA1.1.A1.5 Avoid overextrapolation when using this graphicalmethod. In c
47、ase of unreasonably extended life of somespecimens, the test may be terminated before all specimenshave failed. The available data may then be plotted. Reducedprecision may result.A1.6 Generally ten specimens are used so that ten pointsappear on the graph. Occasionally a specimen may be irretriev-ab
48、ly lost. The plotting positions on the probability scalechange, but the instructions remain the same.NOTE A1.2Some possible hints on fitting lines by eye are given inRefs (6) and (7).A1.7 After experience with the test method and graphicalprocedures, an occasional outlier specimen may be noted thatv
49、iolates credibility. The plotting procedure should be reason-able in such cases. A conceivable situation exists, however, inwhich the apparent outlier is the only point of interest.D1693 156FIG.A1.1Probability2LogCyclesD1693 157FIG.A1.2Probability3LogCyclesD1693 158TABLE A1.1 Examples of CalculationsNOTE 1Integers in the upper part of the body of the table show the number of specimens failed at the indicated elapsed time.Elapsed Time, h0.10.250.511.5234681624324048Example 1 (three specimens do not fail in time) 000000000005667Exa
