ASTM D1709-2008 Standard Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method.pdf

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1、Designation: D 1709 08Standard Test Methods forImpact Resistance of Plastic Film by the Free-Falling DartMethod1This standard is issued under the fixed designation D 1709; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of

2、 last revision. A 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 Department of Defense.1. Scope*1.1 These test methods cover the determ

3、ination of theenergy that causes plastic film to fail under specified conditionsof impact of a free-falling dart. This energy is expressed interms of the weight (mass) of the missile falling from aspecified height which would result in 50 % failure of speci-mens tested.1.2 Two test methods are descr

4、ibed:1.2.1 Test Method A employs a dart with a38.10 6 0.13-mm (1.500 6 0.005-in.) diameter hemisphericalhead dropped from a height of 0.66 6 0.01 m (26.0 6 0.4 in.).This test method may be used for films whose impact resis-tances require masses of about 50 g or less to about 2 kg tofracture them.1.2

5、.2 Test Method B employs a dart with a50.80 6 0.13-mm (2.000 6 0.005-in.) diameter hemisphericalhead dropped from a height of 1.50 6 0.03 m (60.0 + 0.25,1.70 in.). Its range of applicability is from about 0.3 kg toabout 2 kg.1.3 Two testing techniques are described:1.3.1 The standard technique is th

6、e staircase method. Bythis technique, a uniform missile weight increment is employedduring test and the missile weight is decreased or increased bythe uniform increment after test of each specimen, dependingupon the result (fail or not fail) observed for the specimen.1.3.2 The alternative technique

7、provides for testing speci-mens in successive groups of ten. One missile weight isemployed for each group and missile weight is varied inuniform increments from group to group.1.3.3 The staircase technique and the alternative techniquegive equivalent results both as to the values of impact failurewe

8、ight which are obtained and as to the precisions with whichthey are determined.1.4 The values stated in SI units are to be regarded asstandard. The values stated in parentheses are for informationonly.NOTE 1Tests on materials that do not break, for any reason, are notconsidered to be valid. It has b

9、een noted that certain materials may stretchso far as to bottom out at the base of certain test instruments withoutactually rupturing. Subcommittee D20.19 is currently considering meth-ods for testing these materials.Anyone interested in participating in a TaskGroup should contact the Chairman of Su

10、bcommittee D20.19 throughASTM International Headquarters.NOTE 2This test method is technically equivalent to ISO 7765-1:1988, with the exception of a larger tolerance on the drop height in TestMethod B. Also, the ISO method does not allow the alternative testingtechnique described in Section 11 of t

11、his test method.1.5 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referen

12、ced Documents2.1 ASTM Standards:2D 374 Test Methods for Thickness of Solid Electrical Insu-lationD 618 Practice for Conditioning Plastics for TestingD 883 Terminology Relating to PlasticsD 1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD 3420 Test Method for Pendul

13、um Impact Resistance ofPlastic FilmD 4272 Test Method for Total Energy Impact of PlasticFilms By Dart DropE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method1These test methods are

14、 under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.19 on Film andSheeting.Current edition approved Nov. 1, 2008. Published November 2008. Originallyapproved in 1959. Last previous edition approved in 2004 as D 1709 04.2For referenced ASTM s

15、tandards, 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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM I

16、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 ISO Standard:ISO 7765:1988 Plastic Film and SheetingDeterminationof Impact Resistance by the Free Falling Dart MethodPart 1: Staircase Method33. Terminology3.1 DefinitionsFor definitions related to

17、plastics, seeTerminology D 883.3.2 Definitions of Terms Specific to This Standard:3.2.1 failureany break through the film that can be ob-served readily by feeling or by viewing the specimen underbacklighted condition.3.2.2 impact failure weightthat missile weight, estimatedstatistically, at which 50

18、 % of the specimens would fail in thespecified test.3.2.3 missile weightthe weight (mass) of the dart plus thetotal value of incremental weights attached plus the lockingcollar.4. Significance and Use4.1 Test MethodsAand B are used to establish the weight ofthe dart when 50 % of the specimens fail u

19、nder the conditionsspecified. Data obtained by one test method cannot be com-pared directly with the other test method nor with thoseobtained from tests employing different conditions of missilevelocity, impinging surface diameter, effective specimen diam-eter, and thickness. The values obtained by

20、these test variablesare highly dependent on the method of film fabrication.4.2 The results obtained by Test Methods A and B aregreatly influenced by the quality of film under test. Theconfidence limits of data obtained by this procedure can,therefore, vary significantly, depending on the sample qual

21、ity,uniformity of film gage, die marks, contaminants, etc. (seeSection 15).4.3 Test Methods A and B have been found useful forspecification purposes. Correlation between test results andfield performance can usually be established.4.4 The impact resistance of plastic film, while partlydependent on t

22、hickness, has no simple correlation with samplethickness. Hence, impact values cannot be normalized over arange of thickness without producing misleading data as to theactual impact resistance of the material. Data from these testmethods are comparable only for specimens that vary by nomore than 625

23、 % from the nominal or average thickness of thespecimens tested.4.5 Several impact test methods are used for film. It issometimes desirable to know the relationships among testresults derived by different test methods. A study was con-ducted in which four films made from two resins (polypropy-lene a

24、nd linear low-density polyethylene), with two filmthicknesses for each resin, were impacted using Test MethodsD 1709 (Method A), D 3420 (Procedures A and B), andD 4272. The test results are shown in the Appendix. Differ-ences in results betweenTest Methods D 1709 and D 4272 maybe expected since Test

25、 Methods D 1709 represents failureinitiated energy, while Test Method D 4272 is initiation pluscompletion energy. Some films may show consistency whenthe initiation energy is the same as the total energy. Thisstatement and the test data also appear in the significancesections and appendixes of Test

26、Methods D 3420 and D 4272.5. Apparatus5.1 The apparatus shall be constructed essentially as shownin Fig. 1, using the following components common to both testmethods:5.1.1 Dart WellIf the dart impact machine utilizes anenclosed dart well, it must contain a single unobstructed ventwith a minimum area

27、 of 625 mm2(1 in.2) to provide adequateventing.NOTE 3Some dart impact machine designs utilize enclosed dart wellsthat do not permit adequate venting to the atmosphere during impact. Datahave shown that this has a significant effect on the observed impact value,especially with films that exhibit high

28、 elongation during testing, resultingin atypically high impact values.NOTE 4The use of smaller, multiple vents is permitted if it can bedemonstrated that the venting efficiency is comparable and has nostatistically significant effect on the values obtained.5.1.2 Specimen ClampA two-piece annular spe

29、cimenclamp having an inside diameter of 125 6 2.0 mm (5.0 + 0.0,0.15 in.) and conforming to the following requirements:5.1.2.1 The lower or stationary half of the clamp shall bemounted rigidly so that the plane of the specimen is horizontal.5.1.2.2 The upper or movable part of the clamp shall bedesi

30、gned to maintain positive and plane contact with the lowerpart of the clamp when in position. The clamps shall beprovided with suitable means of maintaining sufficient contactto hold the film sample firmly in place during the test.Pneumatically operated clamps have been successfully em-ployed.5.1.2.

31、3 Rubber-like gaskets may be affixed to the specimencontact surfaces of both clamps to provide a cushion whichminimizes thickness variation effects. Rubber gasketing3.0 6 1 mm (0.125 + 0.025, 0.04 in.) thick, of 50 to 60 ShoreA durometer hardness, 125 6 2.0 mm (5.00 + 0.00, 0.15 in.)in inside diamet

32、er and 150 6 3.0 mm (6.0 + 0.02, 0.2 in.) inoutside diameter has been found satisfactory for this purpose.5.1.2.4 Slippage of films greater than 0.10 mm (0.004 in.) inthickness may be minimized or eliminated by securing crocuscloth or 50D garnet abrasive paper to the gaskets with doublesensitive tap

33、e so that the abrasive surface is in direct contactwith the film. There should be sufficient clamping force toeliminate detectable slippage. Other means of reducing slip-page such as additional clamping devices or positive clampingsurfaces may be used provided that the film is not weakened atthe ins

34、ide wall of the specimen clamps and that the effectivediameter of 125 6 2.0 mm (5.00 + 0.00, 0.15 in.) of the filmis not changed.5.1.3 Dart Release Mechanism, capable of supporting a2-kg weight shall be used for supporting and releasing the dartassembly. It shall be equipped with a centering device,

35、 such asa removable plumb bob, to ensure a reproducible drop. Eitheran electromagnetic- or pneumatic-operated release mechanismmay be used.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.D 1709 0825.1.4 Positioning Device

36、The apparatus shall be able todrop the dart from heights of 0.66 6 0.01 m (26.0 6 0.4 in.)for Test Method A and 1.50 6 0.03 m (60.0 + 0.25, 1.70 in.)forTest Method B.The distance between the impinging surfaceof the dart head and the surface of the test specimen isconsidered to be the drop height. Th

37、e dart shall be positionedvertically above the center of the test specimen.5.1.5 Micrometer, accurate to 60.0025 mm (60.0001 in.)in the range from 0.0025 mm (0.0001 in.) to 1 mm (0.4 in.) formeasuring specimen thickness (see Test Methods D 374).5.1.6 Cushioning and Shielding Devices, to protect pers

38、on-nel and to avoid damaging the impinging surface of the dart.These devices shall not interfere with the dart or the specimenprior to penetrating the specimen.5.1.7 Collar with inside diameter of approximately 7 mm(0.28 in.) and with set screw for securing collar to dart shaft.5.2 Darts for Test Me

39、thods A and B shall have hemispheri-cal heads, each fitted with a 6.5 6 1-mm (0.25 + 0.04, 0.03-in.) diameter shaft at least 115 mm (4.5 in.) long to accommo-date removable incremental weights. Each dart weight shall beknown to 60.5 % relative. Dart head surfaces shall be free ofnicks, scratches, or

40、 other irregularities. The shaft shall beattached to the center of the flat surface of the head with itslongitudinal axis perpendicular to the surface. If an electro-magnet is used, the shaft shall be made of material that is notmagnetic and shall have a steel tip 125 6 0.2 mm (0.50 + 0.00,0.02 in.)

41、 long at the end held by the electromagnet.5.2.1 For Test Method A, the dart head shall be38.10 6 0.13mm (1.500 6 0.005in.) in diameter. It may beconstructed of smooth, polished aluminum, phenolic, or otherlow-density material of similar hardness.NOTE 1Values for tolerances in SI units are to be reg

42、arded as standard. The numbers in parentheses reflect the allowable tolerance range of olderequipment and are only provided for information and, in many cases, do not correspond directly to the tolerances in SI units. The differences are notexpected to have a significant effect on the results but th

43、e dimensions in SI units shall be used in cases of dispute.NOTE 2Legend Dart Assembly:A. Steel shaft tip 6.5 6 1 mm (0.25 + 0.04, 0.03 in.) OD by 12.5 6 0.2 mm (0.50 + 0.00, 0.02 in.) long.B. Dart shaft: 6.5 6 1 mm (0.25 + 0.04, 0.03 in.) OD and at least 115 mm (4.5 in.) long:14 20 thd. (N.C.) 12.5

44、6 0.2 mm (0.50 + 0.00, 0.02 in.)long on bottom: No. 540 thd. (N.F.) for steel tip.C. Hemispherical head: Method A38.10 6 0.13mm (1.500 6 0.005in.) in diameter. Method B50.80 6 0.13mm (2.000 6 0.005 in.) in diameter.D. Removable weights.E. Collar and screw.FIG. 1 Apparatus for Free-Falling Dart Impac

45、t Test for Plastic FilmD 1709 0835.2.2 For Test Method B, the dart head shall be50.80 6 0.13mm (2.000 6 0.005 in.) in diameter. It may beconstructed of smooth, polished stainless steel or other materialof similar durability.5.3 The material of construction of the dart head shall bereferenced in the

46、report using the following designations:Material Construction DesignationStainless Steel AAluminum BPhenolic CComposite DOther ENOTE 5Data have shown a sensitivity of impact results related to thematerial of construction and finish of the dart head used. The differenceshave been especially significa

47、nt when testing films exhibiting high impact,or high elongation characteristics, or both.This issue, together with relatedconcerns, is currently under study in Subcommittee D20.19.5.4 Incremental Weights for Test Methods A and B shall beof stainless steel or brass and cylindrical in shape. Each shal

48、lhave a center hole 6.6 + 1.0, 0.00 mm (0.26 + 0.03, 0.00 in.)in diameter. The thickness of each shall be adjusted to obtainthe specified weight within 60.5 %. The diameter of theweights shall not exceed the diameter of the dart head.Suggested combination of weights for the specified diametersare as

49、 follows:5.4.1 For Test MethodA, 31.5 6 1-mm (1.25 + 0.03, 0.05-in.) diameter weights.Number Weight, g2 or more 581830865.4.2 For Test Method B, 45.0 6 1-mm (1.75 + 0.06, 0.02-in.) diameter weights.Number Weight, g2 or more 15848905.4.3 Optionally, additional weights, each 120 g 6 0.5 %for Test Method A or 180 g 6 0.5 % for Test Method B, maybe constructed for use if it is necessary to extend the missileweight beyond that attainable when using all weights in thestandard set.6. Test Specimen6.1 Test specimens shall be large enough to ex