1、Designation: D1709 15Standard Test Methods forImpact Resistance of Plastic Film by the Free-Falling DartMethod1This standard is issued under the fixed designation D1709; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast 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 U.S. Department of Defense.1. Scope*1.1 These test methods cover the det
3、ermination 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 de
4、scribed: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.
5、1.2.2 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
6、 the 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 techniq
7、ue 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 failur
8、eweight 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 ha
9、s been 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
10、 Subcommittee D20.19 throughASTM International Headquarters.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 r
11、egulatorylimitations prior to use.NOTE 2Film has been arbitrarily defined as sheeting having nominalthickness not greater than 0.25 mm (0.010 in.).NOTE 3This test method is technically equivalent to ISO 7765-1:1988, with the exception of a larger tolerance on the drop height in TestMethod B, smaller
12、 tolerances on the dart diameters for Test Methods Aand B, and the requirement for a vented dart well in 5.1.1. Also, the ISOmethod does not allow the alternative testing technique described inSection 11 of this test method.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Pl
13、astics for TestingD883 Terminology Relating to PlasticsD1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD3420 Test Method for Pendulum Impact Resistance ofPlastic FilmD4272 Test Method for Total Energy Impact of Plastic FilmsBy Dart DropD6988 Guide for Determination
14、 of Thickness of Plastic FilmTest SpecimensE177 Practice for Use of the Terms Precision and Bias inASTM Test Methods1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.19 on Film, Sheeting,and Molded Products.Current e
15、dition approved Jan. 1, 2015. Published January 2015. Originallyapproved in 1959. Last previous edition approved in 2009 as D1709 09. DOI:10.1520/D1709-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
16、Standards 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 States1E691 Practice for Conductin
17、g an Interlaboratory Study toDetermine the Precision of a Test Method2.2 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 plastics, see Ter-minology D8
18、83.3.2 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 % of the specimens would fa
19、il 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 under the conditionsspecified
20、. 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 specimendiameter, and thickness. The values obtained by these testvariables are highly
21、 dependent on the method of film fabrica-tion.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 quality,uniformity of film gage,
22、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 thickness, has no simple corre
23、lation 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 % from the nominal or averag
24、e 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 (polypropyl-ene and linear low-density polyeth
25、ylene), with two film thick-nesses for each resin, were impacted using Test MethodsD1709 (Method A), D3420 (Procedures A and B), and D4272.The test results are shown in the Appendix. Differences inresults between Test Methods D1709 and D4272 may beexpected since Test Methods D1709 represents failure
26、 initiatedenergy, while Test Method D4272 is initiation plus completionenergy. Some films may show consistency when the initiationenergy is the same as the total energy. This statement and thetest data also appear in the significance sections and appen-dixes of Test Methods D3420 and D4272.5. Appara
27、tus5.1 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 of 625 mm2(1 in.2) to provide adeq
28、uateventing.NOTE 4Some 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 elongation during testing, resulti
29、ngin atypically high impact values.NOTE 5The 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 specimenclamp having an inside diamete
30、r 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 bedesigned to maintain positive and plane
31、 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.5.1.2.3 Rubber-like gaskets may be affixe
32、d 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 diameter and 150 6 3.0 mm (6.0 + 0.02, 0.
33、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 tape so that the abrasive surface is i
34、n 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 inside wall of the specimen clamps and
35、 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 dart3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, Ne
36、w York, NY 10036, http:/www.ansi.org.D1709 152assembly. It shall be equipped with a centering device, such asa removable plumb bob, to ensure a reproducible drop. Eitheran electromagnetic- or pneumatic-operated release mechanismmay be used.5.1.4 Positioning DeviceThe apparatus shall be able todrop t
37、he 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. The dart shall be positionedvertically
38、 above the center of the test specimen.5.1.5 Micrometer, or other suitable thickness gauge, formeasuring specimen thickness in accordance with GuideD6988.5.1.6 Cushioning and Shielding Devices, to protect person-nel and to avoid damaging the impinging surface of the dart.These devices shall not inte
39、rfere 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 Methods A and B shall have hemispheri-cal heads, each fitted with a 6.5 6 1-mm (0.25 + 0.04,
40、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 other irregularities. The shaft shall beattached to the center of the flat surface of the
41、head with itsNOTE 1Values for tolerances in SI units are to be regarded 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
42、are notexpected to have a significant effect on the results but the 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
43、in.) OD and at least 115 mm (4.5 in.) long:14 20 thd. (N.C.) 12.5 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: MethodA38.10 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
44、.E. Collar and screw.FIG. 1 Apparatus for Free-Falling Dart Impact Test for Plastic FilmD1709 153longitudinal 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 12.5 6 0.2 mm(0.50 + 0.00, 0.02 in.) long
45、at the end held by the electromag-net.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.5.2.2 For Test Method B, the dart head shall be50.80 6 0.1
46、3mm (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 report using the following designations:Material Construction DesignationStainless Steel AA
47、luminum BPhenolic CComposite DOther ENOTE 6Data have shown a sensitivity of impact results related to thematerial of construction and finish of the dart head used. The differenceshave been especially significant when testing films exhibiting high impact,or high elongation characteristics, or both.Th
48、is 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 shallhave a center hole 6.6 + 1.0, 0.00 mm (0.26 + 0.03, 0.00 in.)in diameter. The thickness of
49、 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 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
