ASTM D1922-2008 Standard Test Method for Propagation Tear Resistance of Plastic Film and Thin Sheeting by Pendulum Method.pdf

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1、Designation: D 1922 08Standard Test Method forPropagation Tear Resistance of Plastic Film and ThinSheeting by Pendulum Method1This standard is issued under the fixed designation D 1922; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio

2、n, the year of 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 This test method2cove

3、rs the determination of theaverage force to propagate tearing through a specified length ofplastic film or nonrigid sheeting after the tear has been started,using an Elmendorf-type tearing tester. Two specimens arecited, a rectangular type, and one with a constant radius testinglength. The latter sh

4、all be the preferred or referee specimen.1.2 Because of (1) difficulties in selecting uniformly iden-tical specimens, (2) the varying degree of orientation in someplastic films, and (3) the difficulty found in testing highlyextensible or highly oriented materials, or both, the reproduc-ibility of th

5、e test results may be variable and, in some cases, notgood or misleading. Provisions are made in the test method toaddress oblique directional tearing which may be found withsome materials.1.3 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for inform

6、ationonly.1.4 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 practices and determine the applica-bility of regulatory limitations prior to use. Spec

7、ific precau-tionary statements are given in 13.1.NOTE 1This standard and ISO 6383-2 are technically equivalent.2. Referenced Documents2.1 ASTM Standards:3D 374 Test Methods for Thickness of Solid Electrical Insu-lationD 618 Practice for Conditioning Plastics for TestingD 689 Test Method for Internal

8、 Tearing Resistance of PaperD 1004 Test Method for Tear Resistance (Graves Tear) ofPlastic Film and SheetingD 4000 Classification System for Specifying Plastic Mate-rialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 6383-2 Plast

9、icsFilm and SheetingDeterminationof Tear ResistancePart 2 Elmendorf Method43. Summary of Test Method3.1 The force in grams required to propagate tearing acrossa film or sheeting specimen is measured using a preciselycalibrated pendulum device. Acting by gravity, the pendulumswings through an arc, te

10、aring the specimen from a precut slit.The specimen is held on one side by the pendulum and on theother side by a stationary member. The loss in energy by thependulum is indicated by a pointer. The scale indication is afunction of the force required to tear the specimen.4. Significance and Use4.1 Thi

11、s test method is of value in ranking relative tearingresistance of various plastic films and thin sheeting of compa-rable thickness. Experience has shown the test to have its bestreliability on relatively less extensible films and sheeting.Variable elongation and oblique tearing effects on the moree

12、xtensible films preclude its use as a precise production-controltool for these types of plastics. This test method should be used1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.19 on Film and Sheeting.Current edition a

13、pproved Nov. 1, 2008. Published November 2008. Originallyapproved in 1961. Last previous edition approved in 2006 as D 1922 - 06a.2This test method has been adapted from TAPPI Standard Method T 414M-49,Internal Tearing Resistance of Paper. In testing certain plastic films, problems ofreproducibility

14、 and interpretation of results are encountered which require specialtreatment to make the test method of most value. This test method is revised herespecifically for use with plastic film and thin sheeting. For more completeexplanation of certain aspects of the equipment, its calibration and adjustm

15、ent, referto TAPPI Standard Method T 414M-49.The following additional references may be of interest in connection with thistest method:Painter, E. V., Chu, C. C., and Morgan, H. M., “Testing Textiles on the ElmendorfTear Tester,” Textile Research Journal, Vol XX, No. 6, June 1950, pp. 410417.Elmendo

16、rf, A., “Strength Test for Paper,” Paper, Vol 26, April 21, 1920, p. 302.3For referenced ASTM standards, 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 A

17、STM website.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*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.

18、for specification acceptance testing only after it has beendemonstrated that the data for the particular material areacceptably reproducible. This test method should be used forservice evaluation only after its usefulness for the particularapplication has been demonstrated with a number of different

19、films.4.2 This test method has been widely used as one index ofthe tearing resistance of plastic film and thin sheeting used inpackaging applications. While it may not always be possible tocorrelate film tearing data with its other mechanical or tough-ness properties, the apparatus of this test meth

20、od provides acontrolled means for tearing specimens at straining ratesapproximating some of those found in actual packaging ser-vice.4.3 Due to orientation during their manufacture, plasticfilms and sheeting frequently show marked anisotropy in theirresistance to tearing. This is further complicated

21、 by the fact thatsome films elongate greatly during tearing, even at the rela-tively rapid rates of loading encountered in this test method.The degree of this elongation is dependent in turn on filmorientation and the inherent mechanical properties of thepolymer from which it is made. These factors

22、make tearresistance of some films reproducible between sets of speci-mens to 65 % of the mean value, while others may show nobetter reproducibility than 650 %.4.4 Data obtained by this test method may supplement thatfrom Test Method D 1004, wherein the specimen is strained ata rate of 50 mm (2 in.)

23、per minute. However, specimengeometry and testing speed of the two test methods aredissimilar. The rate of tearing in this test method, while varyingas a function of resistance to tear, is in the range from 7.6 to 46m (300 to 1800 in.)/min.4.5 There is not a direct, linear relationship between teari

24、ngforce and specimen thickness. Data from this test method areexpressed as tearing force in millinewtons (or grams-force, ifdesired), with specimen thickness also reported. But sets ofdata from specimens of dissimilar thickness are usually notcomparable. Therefore, only data at the same thickness ca

25、n becompared.4.6 For many materials, there may be a specification thatrequires the use of this test method, but with some proceduralmodifications that take precedence when adhering to thespecification. Therefore, it is advisable to refer to that materialspecification before using this test method. T

26、able 1 of Classi-fication System D 4000 lists theASTM materials standards thatcurrently exist.5. Apparatus5.1 Pendulum Impulse-Type Testing Apparatus,5consistingof the following:5.1.1 Stationary Clamp.5.1.2 Movable Clamp, carried on a pendulum, preferablyformed by a sector of a wheel or circle, free

27、 to swing on a ballbearing or other substantially frictionless bearing.5.1.3 Stop Catch, for holding the pendulum in a raisedposition and for releasing it instantaneously.5.1.4 Indicating Device, for registering the maximum arcthrough which the pendulum swings when released. Thependulum shall carry

28、a circumferential scale, graduated from 0to 100 % of the machine capacity so as to read against thepointer the average force required to tear a specimen 43 mm(1.7 in.). The pointer and scale may be replaced by anelectronic digital readout. Digital readouts are available whichwill give test results d

29、irectly in millinewtons, directly ingrams-force, or in percent of pendulum capacity. With thependulum in its initial position ready for test, separate the twoclamps by an interval of 2.54 mm (0.10 in.). So align them thatthe specimen clamped in them lies in a plane perpendicular tothe plane of oscil

30、lation of the pendulum with the edges of thejaws gripping the specimen in a horizontal line, a perpendicularto which through the axis of suspension of the pendulum is102.7 6 0.05 mm (4.044 6 0.002 in.) in length and makes anangle of 27.5 with the plane of the film specimen. Theclamping surface in ea

31、ch jaw shall be at least 25.4 mm (1 in.)in width and at least 12.7 mm (0.5 in.) in depth.5.1.5 CapacityInstruments of several capacities, 1960,3920, 7840, 15 600, 31 360, 62 720 mN (200, 400, 800, 1600,3200, 6400 gf), and perhaps others are available. Thesecapacities can be achieved by individual in

32、struments, inter-changeable pendulum sectors, or augmenting weights.5.2 Template, Die, or Shear-Type Cutter5,6, for cuttingspecimens.5.3 Razor Blades, single-edged, for cutting specimenswhere a template is used.5.4 Thickness-Measuring DeviceA suitable micrometer,or other thickness gauge, reading to

33、0.0025 mm (0.0001 in.) formeasuring the thickness of test specimens. The pressureexerted by the gauge on the specimen being measured shall notdistort or deform the specimen. For thin films, #0.025 mm(0.001 in.), or films that exhibit visual deformation duringmeasurement, a maximum pressure of 70 kPa

34、 (10 psi) isrecommended. For thicker or stiffer films, the pressure shall bebetween 160 and 185 kPa (23 and 27 psi), in accordance withMethod C of Test Methods D 374.6. Test Specimens6.1 Test specimens shall be cut using a die or template, asshown in Fig. 1, to form a constant-radius testing length.

35、 Thisshall be the preferred or referee specimen type since itsgeometry is intended to compensate to some degree for theproblem of oblique tearing (Note 2 and Note 3). Alternatively,specimens shall be cut to form a rectangle 76 mm (3 in.) ormore in width by 63 mm (2.5 in.) in length and plainly marke

36、dto denote intended direction of tear. The 63-mm specimendimension shall be the direction of tear. Two sets of specimens5The sole source of supply of the apparatus known to the committee at this timeis Thwing-Albert Instrument Co., Philadelphia, PA 19144. If you are aware ofalternative suppliers, pl

37、ease provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.6The TA63 Sample Cutter, Catalog No. 98, available from the Thwing-AlbertInstrument Co., Philadelphia, PA 19144,

38、has been found satisfactory for cuttingspecimens.D1922082shall be cut from each sample so that their sides are parallel to(1) the machine direction and (2) the transverse direction,respectively, of the material being tested. Enough specimensshall be cut in each direction to provide a minimum of ten

39、tearstrength determinations.NOTE 2Specimens having constant-radius testing lengths are de-signed to correct for oblique directional tearing encountered in certainanisotropic, elastomeric films, and nonrigid sheeting. For purposes ofspecimen selection, oblique tearing is defined as tearing in a curve

40、d orstraight line that deviates more than 9.5 mm (38 in.) from the vertical lineof intended tear.NOTE 3Certain film and sheeting specimens showing oblique tearingmay yield data of poor reproducibility because the axis of maximumorientation varies as much as 30 from the nominal machine direction.When

41、 this is suspected, the sample may be examined by crossed Polaroidplates to determine this direction of maximum orientation and thespecimens cut along the axis of anisotropy for testing parallel and normalto it.6.2 Where a metal template is used, the film or sheetingshall be placed on a hard surface

42、. The template shall be heldover it and the specimens cut out using a single-edged razorblade.6.3 When the specimen is cut out, a slit 20 mm (0.8 in.) deepmay be made at the center of the edge perpendicular to thedirection to be tested. This leaves exactly 43 mm (1.7 in.) oftearing length between th

43、e end of the slit and the opposite edgeof the specimen. This slit may be cut into the specimen after ithas been placed in the testing apparatus.NOTE 4The pendulum apparatus may be fitted with a sharp-loadedknife to make this slit in the specimen after it has been clamped in theapparatus. The action

44、of the knife must be such as to make a clean slitexactly 20 mm (0.8 in.) into the specimen from the edge.6.4 The test specimens shall conform to the dimensions inFig. 1 for the constant-radius specimen or to the dimensionsnoted in 6.1 for rectangular specimens and shall not vary morethan 0.5 % from

45、these dimensions.7. Adjustment of Apparatus7.1 Pendulum Friction:7.1.1 Older InstrumentsTo check the pendulum swing forfreedom from excess friction, level the apparatus and draw apencil line on the base or stop mechanism 25.4 mm (1 in.) tothe right of the edge of the sector stop. With the sector rai

46、sedto its initial position and the pointer set against its stop, onreleasing the sector and holding the stop down, the sectorshould make at least 20 complete oscillations before the edgeof the sector that engages with the stop no longer passes to theleft of the pencil line. Otherwise, oil and adjust

47、 the bearing.7.1.2 Newer InstrumentsIn recent years, a new type offrictionless bearing made of synthetic material has been used.This bearing will not necessarily allow the pendulum sector tomake 20 complete oscillations as the older one did. This doesnot mean that there is excess friction in the pen

48、dulum swing.These newer bearings should not be oiled. Consult the instruc-tions supplied with the instrument for guidance.7.2 Pointer FrictionCheck the pointer friction as follows:Set the pointer at zero reading on the scale before releasing thesector, and after release see that the pointer is not p

49、ushed morethan three scale divisions beyond zero. A reading of more thanthree divisions indicates excessive pointer friction and thepointer should be removed, the bearing wiped clean, and atrace of oil or petroleum jelly applied. When the pointerfriction has been reduced, finally adjust the pointer stop.7.3 Pointer Zero ReadingTo check the pointer for its zeropoint, level the apparatus so that, with the sector free, the lineon the sector indicating the vertical point of suspensioncoincides with a corresponding point on the base of theapparatus, usually placed on the st