1、Designation: D 1693 08Standard Test Method forEnvironmental Stress-Cracking of Ethylene Plastics1This standard is issued under the fixed designation D 1693; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the determination of the
3、sus-ceptibility of ethylene plastics, as defined in TerminologyD 883, 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 exhi
4、bitmechanical 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 health
5、 practices and determine the applica-bility of regulatory limitations prior to use.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:2D 618 Practice for Conditioning Plastics for TestingD 883 Terminology Relating to PlasticsD 1204 Test Method for Linear D
6、imensional Changes ofNonrigid Thermoplastic Sheeting or Film at ElevatedTemperatureD 1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD 3350 Specification for Polyethylene Plastics Pipe andFittings MaterialsD 4703 Practice for Compression Molding ThermoplasticMateria
7、ls into Test Specimens, Plaques, or SheetsD 4976 Specification for Polyethylene Plastics Molding andExtrusion MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ASTM Adjuncts:Apparatus Drawings and Blueprints33. Terminology3.1 Definitions:3.
8、1.1 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
9、presentinternally 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 sp
10、ecimen (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 specim
11、enapproximately 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 laterd
12、evelops 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 tha
13、t crack in a given time is observed.5. Significance and Use5.1 This test method may be used for routine inspectionpurposes by subjecting a required number of specimens to the1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee
14、D20.15 on Thermoplastic Materi-als.Current edition approved March 1, 2008. Published March 2008. Originallyapproved in 1959. Last previous edition approved in 2007 as D 1693 - 07a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org
15、. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Detail drawings of the apparatus are available from ASTM Headquarters.Request ADJD169301, ADJD169302, ADJD169303, and ADJD169304.4The boldface numbers in parentheses refer to the l
16、ist of references at the end ofthis test method.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.test conditions for a specified time and noting the number thatfail. Th
17、e 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 and level
18、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 such condit
19、ions.NOTE 2Different types of polyethylene plastics as defined in Speci-fication D 1248 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 B,Table 1
20、(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 history is re
21、cognized 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 determined wit
22、h specimens obtained from com-mercially prepared items (5).6. Apparatus6.1 Blanking DieA rectangular die or other means suit-able for cutting specimens 38 6 2.5 mm by 13 6 0.8 mm1.5 6 0.1 in. by 0.50 6 0.03 in. These specimens must becut with square edges. Beveled ends in particular are to beavoided
23、.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. The jig shown in Fig. 15shall be used.NOTE 4It is recommended that the jig be permanently mounted toensure notching cons
24、istency.6.3 Specimen HoldersLengths of hard or half-hard brasschannel having the dimensions shown in (B)ofFig. 2 shall beused. The sides of the channel shall be parallel and the insidecorners sharp and square.Any burrs present on the inside of thechannel shall be removed. The inside width is critica
25、l (seeDimension 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 withthreaded ends and plastic caps are permissible.NOTE 5Some older test tubes have inside diameters of l
26、ess 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 and No. 15 corks have beenfound satisfactory.6.5 Aluminum FoilApproximately 0.08 to 0.13 mm0.003
27、to 0.005 in. thick, for wrapping.5The sole source of supply of the apparatus known to the committee at this timeis Standard Scientific Supply Co., Bethlehem, PA. If you are aware of alternativesuppliers, please provide this information to ASTM International Headquarters.Your comments will receive ca
28、reful consideration at a meeting of the responsibletechnical committee,1which you may attend.TABLE 1 Standard Test ConditionsConditionSpecimen Thickness Notch DepthBath Temperature, CmmAin. mmAin.ABmin 3.00 0.120 0.50 0.020 50max 3.30 0.130 0.65 0.025BBmin 1.84 0.0725 0.30 0.012 50max 1.97 0.0775 0.
29、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 purposesthe metric units shall apply.BFor referee purposes, concentration of Igepal will be consistent with theappropriate material standard. If no concentration is
30、 given, then 10 % volumesolution shall 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 period of test.mm in.A318B 18.919.2 0.7450.755C
31、(radius) 1.5 max116 maxFIG. 1 Nicking JigD 1693 0826.6 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 Test Tube RackA rack to hold test tubes immersed toreagent level.6.8 Bending Cl
32、ampAs shown in Fig. 3.6.9 Transfer ToolAs shown in Fig. 4.7. Reagent7.1 The preferred reagent is a nonylphenoxy poly(ethyl-eneoxy)ethanol.6NOTE 7The reagent should be stored in closed metal or glasscontainers because it is somewhat hygroscopic.NOTE 8The manufacturer has stated that this aggressive a
33、gent under-goes no known degradation when used as follows: A 10 % volumesolution in water at 50C for 1000 h of testing.NOTE 9The appearance of carbonyl bands in an Igepal Fouriertransform infrared (FT-IR) scan is an indication of degradation.7.2 Other surface-active agents, soaps, or any liquid orga
34、nicsubstance 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 D 4703.NOTE 10Use no liquid release agents, waxes, polishes, and so forth,6For referee
35、purposes Igepal CO-630 should be obtained from Rhone-Poulenc,Prospect Plains, Cranbury, NJ 08512.Dimensionsmm in.A386 2.5 1.5 6 0.1B136 0.8 0.5 6 0.03C see Table 1D see Table 1E 165 612F(outside) 1658(inside) 11.75 6 0.05 0.463 6 0.002G1038H153764I 2 0.081(12B polyethylene;stress-crackingANNEX(Manda
36、tory Information)A1. GRAPHICAL METHOD OF DETERMINING FAILURE POINTSA1.1 Under some circumstances a 50 % failure point (F50)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
37、.1.1 The value reported by this graphical method isobtained without reference to 0 % failure time. Plot the data onlogarithmic 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.)El
38、apsed time belongs on the logarithmic scale. Number offailures (breaks or cracks), divided by one more than thenumber of original 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) enablesplot
39、ting all the data points, (c) is easy to remember without atable, (d) permits using any otherwise appropriate number ofspecimens, and (e) is widely accepted.NOTE A1.1This plotting convention does not necessarily provide amathematically optimum unbiased estimate of the standard deviation, butusing th
40、e convention appears nearly optimal with ten specimens. Consid-erable mathematical bias is usually introduced anyway by the economicnecessity of periodic inspection, that is, not continuously watching forbreaks during 48 h. The recorded failure times are generally later than theactual failure times.
41、 This limitation seems to engulf the slight biasintroduced for convenience by the plotting convention (6), (7). For furtherinformation 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.
42、Therefore, one point will appear for each specimen that fails.Apoint does not necessarily appear for each observation time.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). Simi
43、larly,F10, F20, F90,orFxinformation is obtained from the intersec-tion of the data line and the 10 %, 20 %, 90 %, or X %probability 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 conv
44、enient short time that is lessthan the first inspection time. The plotting directions are thenstill valid. Convenient suitable 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 sched
45、ules would eliminate the 16 and 32-hinspections, and possibly shorten the 8, 24, and 48-h periods afew minutes to enable inspection 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 graphicalmeth
46、od, in conjunction with Fig.A1.3, are given in TableA1.1.A1.5 Avoid overextrapolation when using this graphicalmethod. In case of unreasonably extended life of some speci-mens, the test may be terminated before all specimens havefailed. The available data may then be plotted. Reducedprecision may re
47、sult.A1.6 Generally ten specimens are used so that ten pointsappear on the graph. Occasionally a specimen may be irretriev-ably 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)
48、and (7).A1.7 After experience with the test method and graphicalprocedures, an occasional outlier specimen may be noted thatviolates 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 int
49、erest.D 1693 086FIG.A1.1Probability32LogCyclesD 1693 087FIG.A1.2Probability33LogCyclesD 1693 088TABLE 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, h0.1 0.25 0.5 1 1.5 234681624324048Example 1 (three specimens do not fail in time) 0000000000 05667Example 2 (ten specimens) 00223 7 9 10AExample 3 (nine specimens; one lost) 012459AExample 4 (15 specimens; special ESCR) 2 5 14 15Apercentage plotting positions for Example
