1、Designation: D1709 16Standard 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 can be used for films whose impact resis-tances require masses of about 50 g or less to about 6 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 1.52 6 0.03 m (60.0 + 0.25,1.70 in.). Its range of applicability is from about 0.3 kg toabout 6 kg.1.3 Two testing techniques are described:1.3.1 The standard technique is
6、 the staircase method. Bythis technique, the missile weight employed during the test isdecreased or increased by uniform increments after the testingof each specimen, depending upon the result (fail or not fail)observed for the specimen.1.3.2 The alternative technique provides for testing speci-mens
7、 in successive groups of ten. One missile weight isemployed for each group and the 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 failureweight which are obtained and
8、 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 been noted that certain mate
9、rials 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 Subcommittee D20.19 throughAS
10、TM 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 regulatorylimitations prior to
11、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 tolerances on the dart diamet
12、ers 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 Plastics for TestingD883 Termino
13、logy 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 of Thickness of Plastic FilmT
14、est 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 edition approved April 15, 2016
15、. Published April 2016. Originallyapproved in 1959. Last previous edition approved in 2015 as D1709 15a. DOI:10.1520/D1709-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
16、 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 Conducting an Interlaboratory Study to
17、Determine 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 D883.3.2 Definitions of Terms S
18、pecific 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 fail in thespecified test.3.2.3
19、 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. Data obtained by one test m
20、ethod 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, material construction and finish of the dart head, andfilm thickness. The values obtained by thes
21、e test variables arehighly 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 quality,
22、uniformity of film gage, die marks, contaminants, etc. (seeSection 15).4.3 Test Methods A and B have been found useful forspecification purposes.NOTE 4With sufficient data, correlation between test results and fieldperformance can usually be established.4.4 The impact resistance of plastic film, whi
23、le partlydependent on thickness, 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
24、vary by nomore than 625 % 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 r
25、esins (polypropyl-ene and linear low-density polyethylene), 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 are no
26、tunusual since Test Methods D1709 represents failure initiatedenergy, while Test Method D4272 is initiation plus completionenergy. Some films exhibit consistency when the initiationenergy is the same as the total energy. This statement and thetest data also appear in the significance sections and ap
27、pen-dixes of Test Methods D3420 and D4272.5. 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 ventwit
28、h a minimum area of 625 mm2(1 in.2) to provide adequateventing.NOTE 5Some 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 t
29、hat exhibit high elongation during testing, resultingin atypically high impact values.NOTE 6The 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-p
30、iece annular specimenclamp 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 cl
31、amp shall bedesigned 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
32、em-ployed.5.1.2.3 Rubber-like gaskets can be affixed to the specimencontact surfaces of both clamps to provide a cushion whichminimizes thickness variation effects. Rubber gasketing 3.186 1 mm (0.125 + 0.025, 0.04 in.) thick, of 50 to 60 Shore Adurometer hardness, 125 6 2.0 mm (5.00 + 0.00, 0.15 in.
33、) ininside diameter and 152 6 3.0 mm (6.0 + 0.02, 0.2 in.) inoutside diameter has been found satisfactory for this purpose.5.1.2.4 To minimize or eliminate slippage of films greaterthan 0.10 mm (0.004 in.) in thickness, crocus cloth or 50Dgarnet abrasive paper can be secured to the gaskets withdoubl
34、e-sided tape so that the abrasive surface is in directcontact with the film. The clamping force shall be sufficient toeliminate any detectable slippage. Other means of reducingslippage such as additional clamping devices or positiveclamping surfaces are also acceptable provided that the film isnot w
35、eakened at the inside wall of the specimen clamps andthat the effective diameter of 125 6 2.0 mm (5.00 + 0.00,0.15 in.) of the film is not changed.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.D1709 1625.1.3 Dart Releas
36、e Mechanism, capable of supporting theheaviest weight utilized for testing (up to 6 kg) shall be usedfor supporting and releasing the dart assembly. It shall beequipped with a centering device, such as a removable plumbbob, to ensure a reproducible drop. Either an electromagnetic-or pneumatic-operat
37、ed release mechanism is acceptable.5.1.4 Positioning DeviceThe 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 1.52 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
38、of the test specimen isconsidered to be the drop height. The dart shall be positionedvertically 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
39、person-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 Tes
40、t Methods A and B shall have hemispheri-cal heads, each fitted with a 6.4 6 1-mm (0.25 + 0.04, 0.03-in.) diameter shaft at least 114.3 mm (4.5 in.) long toaccommodate removable incremental weights. Each dartweight shall be known to 60.5 % relative. Dart head surfacesshall be free of nicks, scratches
41、, or other irregularities. Theshaft shall be attached to the center of the flat surface of thehead with its longitudinal axis perpendicular to the surface. Ifan electromagnet is used, the shaft shall be made of materialNOTE 1Values for tolerances in SI units are to be regarded as standard. The numbe
42、rs 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 the dimensions in SI units sha
43、ll 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 6 0.2 mm (0.50 + 0.00, 0.02
44、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.E. Collar and screw.FIG. 1 Apparatus for Free-Falling Dart Impact Test for Plastic FilmD1709
45、163that is not magnetic and shall have a steel tip 12.7 6 0.2 mm(0.50 + 0.00, 0.02 in.) long 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. Accept-able materials of construction include smooth, polishedaluminum, phe
46、nolic, or other low-density material of similarhardness and durability.5.2.2 For Test Method B, the dart head shall be50.80 6 0.13mm (2.000 6 0.005 in.) in diameter. Acceptablematerials of construction include smooth, polished aluminum,phenolic, or other low-density material of similar hardness andd
47、urability.5.2.3 The material of construction of the dart head shall bereferenced in the report using the following designations:Material Construction DesignationStainless Steel AAluminum BPhenolic CComposite DOther ENOTE 7Data have shown a sensitivity of impact results related to thematerial of cons
48、truction and finish of the dart head used. The differenceshave been especially significant when testing films exhibiting high impact,or high elongation characteristics, or both.This issue, together with relatedconcerns, is currently under study in Subcommittee D20.19.5.3 Incremental Weights for Test
49、 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 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:5.3.1 For Test Method A, 31.75 6 1-mm (1.25 + 0.03,0.05-in.) diameter weights.Number Weight, g2 or more 581830865.3.2 For Test Method B, 44.5 6
