Designation:D1709–04
Standard Test Methods for
Impact Resistance of Plastic Film by the Free-Falling Dart Method1
This standard is issued under thefixed designation D1709;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.
1.Scope*
1.1These test methods cover the determination of the energy that causes plasticfilm to fail under specified conditions of impact of a free-falling dart.This energy is expressed in terms of the weight(mass)of the missile falling from a specified height which would result in50%failure of speci-mens tested.
1.2Two test methods are described:
1.2.1Test Method A employs a dart with a38.1060.13-mm[1.50060.005-in.]diameter hemispherical head dropped from a height of0.6660.01m[26.060.4in.].This test method may be used forfilms whose impact resistances require masses of about50g or less to about2kg to fracture them.
1.2.2Test Method B employs a dart with a50.8060.13-mm[2.00060.005-in.]diameter hemispherical head dropped from a height of1.5060.03m[60.0+0.25,−1.70in.].Its range of applicability is from about0.3kg to about2kg. 1.3Two testing techniques are described:
1.3.1The standard technique is the staircase method.By this technique,a uniform missile weight increment is employed during test and the missile weight is decreased or increased by the uniform increment after test of each specimen,depending upon the result(fail or not fail)observed for the specimen.
1.3.2The alternative technique provides for testing speci-mens in successive groups of ten.One missile weight is employed for each group and missile weight is varied in uniform increments from group to group.
1.3.3The staircase technique and the alternative technique give equivalent results both as to the values of impact failure weight which are obtained and as to the precisions with which they are determined.
1.4The values stated in SI units are to be regarded as standard.The values stated in parentheses are for information only.
腕表式激光仪
N OTE1—Tests on materials that do not break,for any reason,are not considered to be valid.It has been noted that certain materials may stretch so far as to bottom out at the base of certain test instruments without actually rupturing.Subcommittee D20.19is currently considering meth-ods for testing these materials.Anyone interested in participating in a Task Group should contact the Chairman of Subcommittee D20.19through ASTM International Headquarters.
N OTE2—This test method is technically equivalent to ISO7765-1: 1988,with the exception of a larger tolerance on the drop height in Test Method B.Also,the ISO method does not allow the alternat
ive testing technique described in Section11of this test method.
1.5This standard does not purport to address the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2.Referenced Documents
2.1ASTM Standards:2
D374Test Methods for Thickness of Solid Electrical Insu-lation
D618Practice for Conditioning Plastics for Testing
D883Terminology Relating to Plastics
D1248Specification for Polyethylene Plastics Extrusion Materials for Wire and Cable
D3420Test Method for Dynamic Ball Burst(Pendulum) Impact Resistance of Plastic Film
D4272Test Method for Total Energy Impact of Plastic Films by Dart Drop
E177Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2ISO Standard:
ISO7765:1988Plastic Film and Sheeting—Determination of Impact Resistance by the Free Falling Dart Method—Part1:Staircase Method3
3.Terminology
3.1Definitions—For definitions related to plastics,see Terminology D883.
1These test methods are under the jurisdiction of ASTM Committee D20on Plastics and are the direct responsibility of Subcommittee D20.19on Film and Sheeting.
Current edition approved October1,2004.Published October2004.Originally approved in1959.Last previous edition approved in2003as D1709–03.
2For referenced ASTM standards,visit the ASTM website,,or contact ASTM Customer
Service at For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.
3Available from American National Standards Institute(ANSI),25W.43rd St., 4th Floor,New York,NY10036.
1
*A Summary of Changes section appears at the end of this standard. Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.
3.2Definitions of Terms Specific to This Standard:
3.2.1failure—any break through thefilm that can be ob-served readily by feeling or by viewing the specimen under backlighted condition.
3.2.2impact failure weight—that missile weight,estimated statistically,at which50%of the specimens would fail in the specified test.
3.2.3missile weight—the weight(mass)of the dart plus the total value of incremental weights attached plus the locking collar.
4.Significance and Use
4.1Test Methods A and B are used to establish the weight of the dart when50%of the specimens fail under the conditions specified.Data obtained by one test method cannot be com-pared directly with the other test method nor with those obtained from tests employing different conditions of missile velocity,impinging surface diameter,effective specimen diam-eter,and thickness.The values obtained by these test variables are highly dependent on the method offilm fabrication.
4.2The results obtained by Test Methods A and B are greatly influenced by the quality offilm under test.The confidence limits of data obtained by this procedure can, therefore,vary significantly,depending on the sample quality, uniformity offilm gage,die marks,contaminants,etc.(see Section15).
4.3Test Methods A and B have been found useful for specification purposes.Correlation between test results and field performance can usually be established.
4.4The impact resistance of plasticfilm,while partly dependent on thickness,has no simple correlation with sample thickness.Hence,impact values cannot be normalized over a range of thickness without producing misleading data as to the actual impact resistance of the material.Data from these test methods are comparable only for specimens that vary by no more than625%from the nominal or average thickness of the specimens tested.
4.5Several impact test methods are used forfilm.It is sometimes desirable to know the relationships among test results derived by different test methods.A study was con-ducted in which fourfilms made from two resins(polypropy-lene and linear low-density polyethylene),with twofilm thicknesses for each resin,were impacted using Test Methods D1709(Method A),D3420(Procedures A and B),and D4272.The test results are shown in the Appendix.Differ-ences in results between Test Methods D1709and D4272may be expected since Test Methods D1709represents failure initiated energy,while Test Method D4272is initiation plus completion energy.Somefilms may show consistency when the initiation energy is the same as the total energy.This statement and the test data also appear in the significance sections and appendixes of Test Methods D3420and D4272.
5.Apparatus
5.1The apparatus shall be constructed essentially as shown in Fig.1,using the following components common to both test methods:
5.1.1Dart Well—If the dart impact machine utilizes an enclosed dart well,it must contain a single unobstructed vent with a minimum area of625mm2(~1in.2)to provide adequate venting.
N OTE3—Some dart impact machine designs utilize enclosed dart wells that do not permit adequate venting to the atmosphere during impact.Data have shown that this has a significant effect on the observed impact value, especially withfilms that exhibit high elongation during testing,resulting in atypically high impact values.
N OTE4—The use of smaller,multiple vents is permitted if it can be demonstrated that the venting efficiency is comparable and has no statistically significant effect on the values obtained.
5.1.2Specimen Clamp—A two-piece annular specimen clamp having an inside diameter of12562.0mm[5.0+0.0,−0.15in.]and conforming to the following requirements: 5.1.2.1The lower or stationary half of the clamp shall be mounted rigidly so that the plane of the specimen is horizontal.
5.1.2.2The upper or movable part of the clamp shall be designed to maintain positive and plane cont
act with the lower part of the clamp when in position.The clamps shall be provided with suitable means of maintaining sufficient contact to hold thefilm samplefirmly in place during the test. Pneumatically operated clamps have been successfully em-ployed.
5.1.2.3Rubber-like gaskets may be affixed to the specimen contact surfaces of both clamps to provide a cushion which minimizes thickness variation effects.Rubber gasketing
3.061mm[0.125+0.025,−0.04in.]thick,of50to60Shore
A durometer hardness,12562.0mm[5.00+0.00,−0.15in.] in inside diameter and15063.0mm[6.0+0.02,−0.2in.]in outside diameter has been found satisfactory for this purpose.
5.1.2.4Slippage offilms greater than0.10mm[0.004in.]in thickness may be minimized or eliminated by securing crocus cloth or50D garnet abrasive paper to the gaskets with double sensitive tape so that the abrasive surface is in direct contact with thefilm.There should be sufficient clamping force to eliminate detectable slippage.Other means of reducing slip-page such as additional clamping devices or positive clamping surfaces may be used provided that thefilm is not weakened at the inside wall of the specimen clamps and that the effective diameter of12562.0mm[5.00+0.00,−0.15in.]of thefilm is not changed.
5.1.3Dart Release Mechanism,capable of supporting a 2-kg weight shall be used for supporting and releasing the dart assembly.It shall be equipped with a centering device,such as a removable plumb bob,to ensure a reproducible drop.Either an electromagnetic-or pneumatic-operated release mechanism may be used.
5.1.4Positioning Device—The apparatus shall be able to drop the dart from heights of0.6660.01m[2
6.060.4in.] for Test Method A and1.5060.03m[60.0+0.25,−1.70in.] for Test Method B.The distance between the impinging surface of the dart head and the surface of the test specimen is considered to be the drop height.The dart shall be positioned vertically above the center of the test specimen.
5.1.5Micrometer,accurate to60.0025mm[60.0001in.] in the range from0.0025mm[0.0001in.]to1mm[0.4in.]for measuring specimen thickness(see Test Methods D
374).
5.1.6Cushioning and Shielding Devices ,to protect person-nel and to avoid damaging the impinging surface of the dart.These devices shall not interfere with the dart or the specimen prior to penetrating the specimen.
5.1.7Collar with inside diameter of approximately 7mm [0.28in.]and with set screw for securing collar to dart shaft.5.2Darts for Test Methods A and B shall have hemispheri-cal heads,each fitted with a
6.561-mm [0.25+0.04,−0.03-in.]diameter shaft at least 115mm [4.5in.]long to accommo-date removable incremental weights.Each dart weight shall be known to 60.5%relative.Dart head surfaces shall be free of nicks,scratches,or other irregularities.The shaft shall be attached to the center of the flat surface of the head with its
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longitudinal axis perpendicular to the surface.If an electro-magnet is used,the shaft shall be made of material that is not magnetic and shall have a steel tip 12560.2mm [0.50+0.00,−0.02in.]long at the end held by the electromagnet. 5.2.1For Test Method A,the dart head shall be 38.1060.13–mm [1.50060.005–in.]in diameter.It may be constructed of smooth,polished aluminum,phenolic,or other low-density material of similar hardness.
5.2.2For Test Method B,the dart head shall be 50.8060.13–mm [2.00060.005in.]in diameter.It may be constructed of smooth,polished stainless steel or other material of similar
durability.
N OTE 1—Values for tolerances in SI units are to be regarded as standard.The numbers in parentheses reflect the allowable tolerance range of older equipment and are only provided for information and,in many cases,do not correspond directly to the tolerances in SI units.The differences are not expected to have a significant effect on the results but the dimensions in SI units shall be used in cases of dispute.N OTE 2—Legend Dart Assembly:黑龙江北开职业技术学院
A.Steel shaft tip 6.561mm [0.25+0.04,−0.03in.]OD by 12.560.2mm [0.50+0.00,−0.02in.]long.
B.Dart shaft:6.561mm [0.25+0.04,−0.03in.]OD and at least 115mm [4.5in.]long:1⁄4–20thd.(N.
C.)12.560.2mm [0.50+0.00,−0.02in.]long on bottom:No.5–40thd.(N.F.)for steel tip.
C.Hemispherical head:Method A—38.1060.13–mm [1.50060.005–in.]in diameter.Method B—50.8060.13–mm [2.00060.005in.]in diameter.
D.Removable weights.
E.Collar and screw.
FIG.1Apparatus for Free-Falling Dart Impact Test for Plastic
Film
5.3The material of construction of the dart head shall be referenced in the report using the following designations: Material Construction Designation
Stainless Steel A
Aluminum B
Phenolic C
Composite D
鱼肝油丸是哪一种维生素Other E
N OTE5—Data have shown a sensitivity of impact results related to the material of construction andfinish of the dart head used.The differences have been especially significant when testingfilms exhibiting high impact, or high elongation characteristics,or both.This issue,together with related concerns,is currently under study in Subcommittee D20.19.
5.4Incremental Weights for Test Methods A and B shall be of stainless steel or brass and cylindrical in shape.Each shall have a center hole
6.6+1.0,−0.00mm[0.26+0.03,−0.00in.] in diameter.The thickness of each shall be adjusted to obtain the specified weight within60.5%.The diameter of the weights shall not exceed the diameter of the dart head. Suggested combination of weights for the specified diameters are as follows:
5.4.1For Test Method A,31.561-mm[1.25+0.03,−0.05-in.]diameter weights.
Number Weight,g
2or more5
815
830
860
5.4.2For Test Method B,45.061-mm[1.75+0.06,−0.02-in.]diameter weights.
Number Weight,g
2or more15
845
890
5.4.3Optionally,additional weights,each120g60.5% for Test Method A or180g60.5%for Test Method B,may be constructed for use if it is necessary to extend the missile weight beyond that attainable when using all weights in the standard set.
6.Test Specimen
6.1Test specimens shall be large enough to extend outside the specimen clamp gaskets at all points.The specimens shall be representative of thefilm under study and shall be taken from the she
et or tube in a manner representative of sound sampling practice.This is to ensure that the whole of the sheet be represented in the test unless such sampling constitutes a variable under study.
6.2The specimens shall be free of pinholes,wrinkles,folds, or other obvious imperfections,unless such imperfections constitute variables under study.
7.Conditioning
7.1Conditioning—Follow the conditioning requirements specified in the materials specification for the material that is being tested.Otherwise,condition the test specimens at 2362°C[70to77°F]and5065%relative humidity for not less than40h prior to test in accordance with Procedure A of Practice D618,for those tests where conditioning is required. In cases of disagreement,the tolerances shall be61°C [61.8°F]and62%relative humidity.
7.2Test Conditions—Conduct tests in the standard labora-tory atmosphere of2362°C[73.463.6°F]and5065% relative humidity unless otherwise specified in the materials specification.In cases of disagreement,the tolerances shall be 61°C[61.8°F]and62%relative humidity.
8.Preparation of Apparatus
8.1Set up the apparatus for testing by Test Method A or by Test Method B.
8.1.1For Test Method A select a dart with a38.1060.13-mm[1.50060.005-in.]diameter hemispherical head.For Test Method B,select a dart with a50.8060.13-mm [2.00060.005-in.]diameter hemispherical head.
8.1.2Activate the dart release mechanism and insert the steel shaft tip into the mechanism.The dart should be held in place by the dart release mechanism.Adjust the drop height (the vertical distance from the plane of a clamped specimen to the bottom surface of the dart head)to0.6660.01m [26.060.4in.]for Test Method A or to 1.5060.03m [60.0+0.25,−1.70in.]for Test Method B.(Warning—For safety reasons,remove the dart while making position adjust-ments.)
8.1.3With a trialfilm specimen clamped between the specimen clamps and with no added weights on the dart, release the dart and observe the point at which the dart impacts the specimen,catching the dart after it bounces off thefilm surface.If necessary,adjust the dart release mechanism so that, in repeated trials,the dart reproducibly impacts the center of the clamped portion of thefilm.
8.2Check the apparatus periodically to make sure specimen slippage during testing is not occurring.If slippage occurs,this is reason to reject the results.The likelihood of occurrence of slippag
e increases with increasing dart weight and with in-creasing drop height and is greater with some materials than with others.Slippage may be checked conveniently during the course of testing of a routine sample at a missile weight wherein both failures and non-failures are being observed. Either of the following procedures is effective.
8.2.1Before dropping the missile on a clamped specimen, draw a circle on thefilm using a ball-point pen in contact with the inside wall of the upper clamp.Apply only the pressure of the pen itself to thefilm.After the dart is dropped and prior to removing the plasticfilm,draw another circle using a ball-point pen of another color.If the lines are drawn,distinct double lines at any point on the circumference show that slippage has occurred.(Warning—For safety reasons,the dart should not be in the dart release mechanism while drawing the circle.)
8.2.2If crocus cloth or sandpaper is affixed to the gaskets to effect greater gripping,determine slippage simply by inspect-ing the clampedfilm area after impact for evidence of scratch marks produced as slippage蒋维平
occurred.
STAIRCASE TESTING TECHNIQUE
战前战后
9.Procedure
9.1By this technique,a uniform missile weight increment is employed during test and the missile weight is changed after test of each specimen.
9.2Select Test Method A or Test Method B for use,as desired,or as required by the relevant material specification.Set up the apparatus for testing as described in 8.1.If desired,carry out a slippage check as described in 8.2at some point during the course of testing.
9.3Measure and record the average thickness of the test specimens in the area of impact to the nearest 0.0025mm [0.0001in.].
9.4For a starting point,select a missile weight near the expected impact failure weight.Add the necessary number of incremental weights onto the dart shaft and put the locking collar into place so that the weights are held securely in place.9.5Select a missile weight increment D W appropriate to the impact strength of the sample:The value chosen for D W should be such that three to six (but at least three)missile weights will be employed in the determination.A D W value equal to some 5to 15%of W F ,the impact failure weight,is usually appropriate.
9.6Place the first test specimen over the bottom part of the clamp,making sure that it is uniformly flat,free of folds,and that it covers the gasket at all points.Clamp in place with the top part of the annular clamp.
9.7Activate the dart release mechanism and put the dart into position.Release the dart.If the dart bounces off the specimen surface,catch the dart after it bounces to prevent both multiple impact with the specimen surface and damage to the hemispherical contact surface of the dart resulting from impact with metal parts of the apparatus.
9.8Examine the test specimen for any evidence of slippage.If slippage occurs,this is reason to reject the results.
9.9Examine the specimen to determine whether it has or has not failed.Record the result on a form such as that shown in Fig.2,using a 0to denote non-failure and an X to denote failure,or any other similar convention to indicate non-failure or failure.
9.10If the first specimen failed,decrease the missile weight by D W .If the first specimen did not fail,increase the missile weight by D W .Test the second specimen.Continue testing successive specimens,decreasing or increasing the missile weight by D W between drops depending upon whether the preceding specimen did or did not fail.
9.11After 20specimens have been tested,count the total number,N ,of failures,(X ’s).If N =10at this point,testing is complete.If not,complete testing as follows:
9.11.1If N <10,continue testing additional specimens until N =10,then stop
testing.
N OTE —
W F 5W o 1[D W ~A/N 21/2!#51201[15~15/1021/2!#51201[15~1.520.5!#
5135g .
FIG.2Determination of Dart Impact Failure
Weight
