Designation:D1922–03a
Standard Test Method for
Propagation Tear Resistance of Plastic Film and Thin Sheeting by Pendulum Method1
This standard is issued under thefixed designation D1922;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.
1.Scope*
1.1This test method2covers the determination of the average force to propagate tearing through a specified length of plasticfilm or nonrigid sheeting after the tear has been started, using an Elmendorf-type tearing tester.Two specimens are cited,a rectangular type,and one with a constant radius testing length.The latter shall be the preferred or referee specimen.
1.2Becau of(1)difficulties in lecting uniformly iden-tical specimens,(2)the varying degree of orientation in some plasticfilms,and(3)the difficulty found in testing highly extensible or highly oriented materials,or both,the reproduc-ibility of the test results may be variable and,in some cas,not good or misleading.Provisions are made in the test method to compensate for oblique directional tearing which may be found with some materials.
1.3The values stated in SI units are to be regarded as the standard.The values given in brackets are for information only.
1.4This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to u.Specific precau-tionary statements are given in13.1.
N OTE1—This standard and ISO6383-2are technically equivalent.2.Referenced Documents
2.1ASTM Standards:3
D374Test Methods for Thickness of Solid Electrical Insu-lation
D618Practice for Conditioning Plastics for Testing
D689Test Method for Internal Tearing Resistance of Paper D1004Test Method for Initial Tear Resistance of Plastic Film and Sheeting
D4000Classification System for Specifying Plastic Mate-rials
E691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2ISO Standard:
ISO6383-2Plastics—Film and Sheeting—Determination of Tear Resistance—Part2Elmendorf Method4
3.Summary of Test Method
3.1The force in grams required to propagate tearing across afilm or sheeting specimen is measured using a precily calibrated pendulum device.Acting by gravity,the pendulum swings through an arc,tearing the specimen from a precut slit. The specimen is held on one side by the pendulum and on the other side by a stationary member.The loss in energy by the pendulum is indicated by a pointer.The scale indication is a function of the force required to tear the specimen.
4.Significance and U
4.1This test method is of value in ranking relative tearing resistance of various plasticfilms and thin sheeting of compa-rable thickness.Experience has shown the test to have its best reliability on relatively less extensiblefilms and sheeting. Variable elongation and oblique tearing effects on the more extensiblefilms preclude its u as a preci production-control
1This test method is under the jurisdiction of ASTM Committee D20on Plastics and is the direct responsibility of Subcommittee D20.19on Film and Sheeting.
Current edition approved November1,2003.Published January2004.Originally approved in1961.Last previous edition approved in2003as D1922–03.
2This test method has been adapted from TAPPI Standard Method T414M-49, Internal Tearing Resistance of Paper.In testing certain plasticfilms,problems of reproducibility and interpretation of results are encountered which require special treatment to make the test method of most value.This test method is revid here specifically for u with plasticfilm and thin sheeting.For more complete explanation of certain aspects of the equipment,its calibration and adjustment,refer
to TAPPI Standard Method T414M-49.
The following additional references may be of interest in connection with this test method:
Painter,E.V.,Chu,C.C.,and Morgan,H.M.,“Testing Textiles on the Elmendorf Tear Tester,”Textile Rearch Journal,V ol XX,No.6,June1950,pp.410–417.
Elmendorf,A.,“Strength Test for Paper,”Paper,V ol26,April21,1920,p.302.
3For referenced ASTM standards,visit the ASTM website,www.astm,or contact ASTM Customer Service at rvice@astm.For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.
4Available from American National Standards Institute(ANSI),25W.43rd St., 4th Floor,New York,NY1
0036.
1
*A Summary of Changes ction appears at the end of this standard. Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.
tool for the types of plastics.This test method should be ud for specification acceptance testing only after it has been demonstrated that the data for the particular material are acceptably reproducible.This test method should be ud for rvice evaluation only after its ufulness for the particular application has been demonstrated with a number of different films.
4.2This test method has been widely ud as one index of the tearing resistance of plasticfilm and thin sheeting ud in packaging applications.While it may not always be possible to correlatefilm tearing data with its other mechanical or tough-ness properties,the apparatus of this test method provides a controlled means for tearing specimens at straining rates approximating some of tho found in actual packaging r-vice.
4.3Due to orientation during their manufacture,plastic films and sheeting frequently show marked anisotropy in their resistance to tearing.This is further complicated by the fact that somefilms 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 onfilm orientation and the inherent mechanical properties of the polymer from which it is made.The factors make tear resistance of somefilms reproducible between ts of speci-mens to65%of the mean value,while others may show no better reproducibility than650%.
4.4Data obtained by this test method may supplement that from Test Method D1004,wherein the specimen is strained at a rate of50mm[2in.]per min.However,specimen geometry and testing speed of the two test methods are dissimilar.The rate of tearing in this test method,while varying as a function of resistance to tear,is in the range from7.6to46m[300to 1800in.]/min.
4.5There is not a direct,linear relationship between tearing force and specimen thickness.Data from this test method are expresd as tearing force in millinewtons(or grams-force,if desired),with specimen thickness also reported.But ts of data from specimens of dissimilar thickness are usually not comparable.Therefore,only data at the same thickness can be compared.
4.6For many materials,there may be a specification that requires the u of this test method,but with some procedural modifications that take precedence when adhering to the specification.Therefore,it is advisable to refer to that material specification before using this test method.Table1of Classi-fication System D4000lists the ASTM materials standards that currently exist.
5.Apparatus
5.1Pendulum Impul-Type Testing Apparatus,5consisting of the following:
5.1.1Stationary Clamp.
5.1.2Movable Clamp,carried on a pendulum,preferably formed by a ctor of a wheel or circle,free to swing on a ball bearing or other substantially frictionless bearing.
5.1.3Stop Catch,for holding the pendulum in a raid position and for releasing it instantaneously.
5.1.4Indicating Device,for registering the maximum arc through which the pendulum swings when relead.The pendulum shall carry a circumferential scale,graduated from0 to100%of the machine capacity so as to read against the pointer the average force required to tear a specimen43mm [1.7in.].The pointer and scale may be replaced by an electronic digital readout.Digital readouts are a
vailable which will give test results directly in millinewtons,directly in grams-force,or in percent of pendulum capacity.With the pendulum in its initial position ready for test,parate the two clamps by an interval of2.54mm[0.10in.].So align them that the specimen clamped in them lies in a plane perpendicular to the plane of oscillation of the pendulum with the edges of the jaws gripping the specimen in a horizontal line,a perpendicular to which through the axis of suspension of the pendulum is 102.760.05mm[4.04460.002in.]in length and makes an angle of27.5°with the plane of thefilm specimen.The clamping surface in each jaw shall be at least25.4mm[1in.] in width and at least12.7mm[0.5in.]in depth.
5.1.5Capacity—Instruments of veral capacities,1960, 3920,7840,15600,31360,62720mN[200,400,800,1600, 3200,6400gf],and perhaps others are available.The capacities can be achieved by individual instruments,inter-changeable pendulum ctors,or augmenting weights.
5.2Template,Die,or Shear-Type Cutter,6for cutting specimens.
5.3Razor Blades,single-edged,for cutting specimens where a template is ud.
5.4Thickness-Measuring Device—A suitable micrometer, or other thickness gage,reading to0.0025m
m[0.0001in.]for measuring the thickness of test specimens.The pressure exerted by the gage on the specimen being measured shall not distort or deform the specimen.For thinfilms,#0.025mm [0.001in.],orfilms that exhibit visual deformation during measurement,a maximum pressure of70kPa[10psi]is recommended.For thicker or stifferfilms,the pressure shall be between160and185kPa[23and27psi],in accordance with Method C of Test Methods D374.
炒山药的做法6.Test Specimens
6.1Test specimens shall be cut,as shown in Fig.1,to form
a constant-radius testing length.This shall be the preferred or referee specimen type since its geometry automatically com-pensates for the problem of oblique tearing(Note2and Note 3).Alternatively,specimens shall be cut to form a rectangle76 mm[3in.]or more in width by63mm[2.5in.]in length and plainly marked to denote intended direction of tear.The63-mm specimen dimension shall be the direction of tear.Two ts of specimens shall be cut from each sample so that their sides are parallel to(1)the machine direction and(2)the transver direction,respectively,of the material being tested.Enough specimens shall be cut in each direction to provide a minimum of ten tear strength determinations.
5Equipment available from the Thwing-Albert Instrument Co.,Philadelphia,PA 19144,meets the requirements for this apparatus.
6The TA63Sample Cutter,Catalog No.98,available from the Thwing-Albert Instrument Co.,Philadelphia,PA19144,has been found satisfactory for cutting
specimens.
N OTE 2—Specimens having constant-radius testing lengths are de-signed to correct for oblique directional tearing encountered in certain anisotropic,elastomeric films,and nonrigid sheeting.For purpos of specimen lection,oblique tearing is defined as tearing in a curved or straight line that deviates more than 9.5mm [3⁄8in.]from the vertical line of intended tear.
N OTE 3—Certain film and sheeting specimens showing oblique tearing may yield data of poor reproducibility becau the axis of maximum orientation varies as much as 30°from the nominal mac
hine direction.When this is suspected,the sample may be examined by crosd Polaroid plates to determine this direction of maximum orientation and the specimens cut along the axis of anisotropy for testing parallel and normal to it.
简体字什么时候开始6.2Where a metal template is ud,the film or sheeting shall be placed on a hard surface.The template shall be held over it and the specimens cut out using a single-edged razor blade.
6.3When the specimen is cut out,a slit 20mm [0.8in.]deep may be made at the center of the edge perpendicular to the direction to be tested.This leaves exactly 43mm [1.7in.]of tearing length between the end of the slit and the opposite edge of the specimen.This slit may be cut into the specimen after it has been placed in the testing apparatus.
N OTE 4—The pendulum apparatus may be fitted with a sharp-loaded knife to make this slit in the specimen after it has been clamped in the apparatus.The action of the knife must be such as to make a clean slit exactly 20mm [0.8in.]into the specimen from the edge.
7.Adjustment of Apparatus 7.1Pendulum Friction :
7.1.1Older Instruments —To check the pendulum swing for freedom from excess friction,level the ap
paratus and draw a pencil line on the ba or stop mechanism 25.4mm [1in.]to the right of the edge of the ctor stop.With the ctor raid to its initial position and the pointer t against its stop,on releasing the ctor and holding the stop down,the ctor should make at least 20complete oscillations before the edge of the ctor that engages with the stop no longer pass to the left of the pencil line.Otherwi,oil and adjust the bearing.
7.1.2Newer Instruments —In recent years,a new type of frictionless bearing made of synthetic material has been ud.This bearing will not necessarily allow the pendulum ctor to make 20complete oscillations as the older one did.This does not mean that there is excess friction in the pendulum swing.The newer bearings should not be oiled.Consult the instruc-tions supplied with the instrument for guidance.
7.2Pointer Friction —Check the pointer friction as follows:Set the pointer at zero reading on the scale before releasing the ctor,and after relea e that the pointer is not pushed more than three scale divisions beyond zero.A reading of more than three divisions indicates excessive pointer friction and the pointer should be removed,the bearing wiped clean,and a trace of oil or petroleum jelly applied.When the pointer friction has been reduced,finally adjust the pointer stop.
7.3Pointer Zero Reading —To check the pointer for its zero point,level the apparatus so that,with the ctor free,the line on the ctor indicating the vertical point of suspension coincides with a corresponding point on the ba of the apparatus,usually placed on the stop mechanism.After level-ing,operate the apparatus veral times with nothing in the jaws,the movable jaw being clod,to ascertain whether the pointer registers zero with no load.If zero is not registered,adjust the position of the pointer stop by means of the pointer stop thumb screw until a zero reading is obtained.
8.Verification of Scale
8.1The scale may be verified either by the procedure described in Test Method D 689and repeated here,or by the method which us the Elmendorf check weights obtainable from the manufacturer.The method in Test Method D 689is relatively time-consuming and complicated.The check weight method is relatively simple.
啊弥陀佛8.2Test Method D 689Procedure :
8.2.1To verify the scale,first mark the center of gravity of the weight (including means of attaching)by a punched dot on the face of the weight.Then clamp a known weight in grams,W,to the radial edge of the ctor beneath the jaws.
8.2.2Rai and t the ctor as for tearing a specimen and,by means of a suitable scale,measure the height in centimetres,h ,of the center of gravity of the weight above the surface upon which the apparatus rests.Then relea the ctor,allow it to swing,and note the pointer reading.Without touching the pointer,rai the ctor until the edge of the pointer just meets with its stop,in which position again determine the height in centimetres,H ,of the center of gravity of the weight above the surface.
8.2.3The work done is W (H −h )gram-centimetres.The pointer reading noted above should be the same as that calculated as follows:感到意外
W ~H 2h !/137.6
8.2.4Five weights from 75to 400g form a suitable range for calibration of the apparatus,one or more being clamped on the edge of the ctor in different positions.Calculate the work done in raising each and add together.
8.2.5Make a record of deviations of the pointer from the calculated readings and make corresponding corrections in the test results at the proper points on the
scale.
FIG.1Constant-Radius Test Specimen for Tear Resistance
Test
8.2.6It is unnecessary to repeat the calibration of the instrument provided it is kept in adjustment and no parts become changed or worn.8.3Check Weight Method 7:
8.3.1U a t of three check weights calibrated for scale values of 20,50,and 80%of the pendulum capacity.Sets of check weights of the values are available for each pendulum capacity.The weights should be so constructed that each weight can be inrted in the clamps by the procedure ud for a test specimen.
8.3.2With the pendulum in the raid position,open the clamp of the pendulum.Slide the tang of the
weight into position,and fasten it curely into the clamp.The body of the weight must be beneath the clamp.Depress the pendulum stop,thus releasing the pendulum.Hold down the stop until after the tear is completed and catch the pendulum on the return swing.Read the indicating device to the nearest division.
8.3.3Repeat this procedure with each of the check weights.8.4Alternative Methods —A variety of new techniques have been developed for scale verification of newer instruments including optical encoders utilizing a single check weight.For instruments that are capable of being verified using the techniques,the specific procedures recommended by the in-strument supplier shall be followed.
9.Conditioning
9.1Conditioning —Condition the test specimens at 2362°C [73.463.6°F]and 5065%relative humidity for not less than 40h prior to test in accordance with Procedure A of Practice D 618for the tests where conditioning is required.In cas of disagreement,the tolerances shall be 61°C [61.8°F]and 62%relative humidity.
9.2Test Conditions —Conduct tests in the standard labora-tory atmosphere of 2362°C [73.463.6°F]a
nd 5065%relative humidity,unless otherwi specified in the test method.In cas of disagreement,the tolerances shall be 61°C [61.8°F]and 62%relative humidity.
10.Procedure
10.1Test not less than ten specimens in each of the principal film or sheeting directions.Measure and record the thickness of each specimen as the average of three readings across its center in the direction in which it is to be torn.Read the thickness to a precision of 0.0025mm [0.0001in.]or better except for sheeting greater than 0.25-mm [10-mils]thickness,which is read to a precision of 0.025mm [0.001in.]or better.
10.2One thickness determination per specimen or the average thickness determined by a continuous scanning instru-ment is acceptable if it can be demonstrated that the overall thickness of the ction of the roll from which the specimens were taken does not deviate >610%from the average.
10.3With the pendulum in its raid position,place the specimen midway in the clamps so that its upper edge is parallel to the top of the clamps and the initial slit (if it was
made when the specimen was cut)is at the bottom of and between the clamps at right angles to their top.
10.4Slit the firmly clamped specimen with the sharp spring-loaded knife if it has not been slit during cutting.Lay the upper testing portion of the specimen over in the direction of the pendulum pivot.
N OTE 5—The work done in tearing a specimen includes a certain amount of work to bend continuously the film or sheeting as it is torn,to provide for the rubbing of the torn edges of the specimen together,and to lift the specimen against the force of gravity.Conquently,it is necessary to specify certain empirical requirements for both the apparatus and the method to keep the additional work not ud for tearing to approximately a definite quantity.
10.5Relea the ctor stop and tear the specimen.As the ctor completes its return swing,catch it with the thumb and forefinger of the left hand,being careful not to disturb the position of the pointer.
10.6Examine the specimen.If it tore through the constant-radius ction within an approximate angle of 60°on either side of the vertical line of intended tear,record the pointer reading to the nearest 0.5unit.If the line of tear was more than approximately 60°from the vertical,reject the reading and test an extra specimen in its place.If rectangular specimens are tested,reject all specimens that tear obliq
uely more than 9.5mm [3⁄8in.]from the vertical line of intended tear.Test extra specimens to replace tho rejected.When oblique tearing is frequent,the test may be performed along and normal to the axis of maximum orientation (e Note 3)instead of along machine and transver directions.
N OTE 6—In addition to tearing in a curved or oblique direction,some specimens may elongate along the line of tear to such an extent that the actual tearing length may be considerably more than the standard 43-mm [1.7-in.]dimension.As the degree or length of this elongation cannot be measured,the data cannot be corrected for its effect.However,when this has occurred,a note should be included in the report of data.This elongation tendency of certain films may cau poorer reproducibility.N OTE 7—The maximum accuracy of the pendulum apparatus lies in the scale range from 20to 60.When thin specimens are being tested,it may be advisable to test enough specimens sandwiched together to produce a scale reading between 20and 60.However,certain specimens in the same sandwich may tear obliquely in opposite directions,which may lead to fally high results.When this tearing behavior is encountered,single specimens must be tested,even though scale readings may be in the range below 20.If tearing loads are in excess of 60,the augmenting weight attachment may be ud to double the capacity of the apparatus or a higher-capacity pendulum may be ud.For thin film,it is recommended that single specimens and a lower-capacity t
ester be ud rather than veral specimens and a higher capacity machine.If the scale reading is below 10on a 200-g pendulum,multiple plies may be ud.The number of plies ud should be the number required to bring the reading above 10.
猜谜11.Calculation
11.1Calculate the average tearing force in millinewtons and,if desired,in grams-force as follows:
11.1.1If the standard 1600-gf instrument with a 0to 100scale is ud,calculate as follows:
Average tearing force,mN 5
1639.813average scale reading
刍怎么读n Average tearing force,gf 5
163average scale reading
n
7
Elmendorf calibration check weights are available from the Thwing-Albert Instrument Co.,Philadelphia,PA 19144.U of the weights will permit direct calibration of the apparatus in a shorter
time.
where:
n=1,or number of plies,if ud.See Note6.
11.1.2If an instrument of different grams-force capacity with a0to100scale is ud,calculate as follows:
Average tearing force,mN5
1639.813average scale reading3gf2capacity
n31600gf
Average tearing force,gf5
163average scale reading3gf2capacity
n31600gf
where:
n=1,or number of plies,if ud.See Note6.
11.1.3If an instrument has an SI metric scale(for example, 0to1000graduations),calculate as follows:
Average tearing force,mN5
163average scale reading3capacity,N
n315.7N
Average tearing force,gf5
163average scale reading3capacity,N
9.813n315.7N
where:
n=1,or number of plies,if ud.See Note6.
11.1.4If an instrument has a direct-reading scale(for example,digital readout)in millinewtons,calculate as follows:
Average tearing force,mN5average scale reading
n
Average tearing force,gf5average scale reading
9.813n
where:
n=1,or number of plies,if ud.See Note6.
11.1.5If an instrument has a direct-reading scale(for example,digital readout)in grams-force,calculate as follows:
Average tearing force,mN5average scale reading39.81
n
Average tearing force,gf5average scale reading
n
where:
形容雪的句子
n=1,or number of plies,if ud.See Note6.
A direct proportionality may not always exist between tearing force and specimen thickness.Therefore,this test method provides for reporting data in millinewtons,or,if desired, grams of force required to propagate tearing with specimen thickness reported parately.
11.2Calculate the arithmetic mean,X,tearing resistance in each principal direction of thefilm or sheeting.
11.3Calculate the standard deviation of the tearing resis-tance in each principal direction to two significantfigures as follows:
s5=~(X22nX¯2!/~n21!
where:
s=estimated standard deviation,
X=value of a single obrvation,
n=number of obrvations,and
X¯=arithmetic mean of the t of obrvations
11.4The average,standard deviation,maximum,and mini-mum values of the tearing resistance may be obtained from the digital readout device,if applicable.
12.Report
12.1Report the following information:
12.1.1Complete identification of the sample tested includ-ing source,manufacturer’s name and code number,method of fabrication,roll or lot number,and date received or made, 12.1.2Type and direction of specimens tested:rectangular or constant radius,parallel or normal to the machine direction of thefilm.If tests were performed with reference to an axis of maximum orientation that did not coincide with the machine or transver direction of thefilm,the report should also include the location of this axis relative to the latter directions,
12.1.3Number of specimens tested at one time,and the number tested in each principal direction of thefilm,
12.1.4Average,maximum,and minimum values for speci-men thickness and for machine and transver tearing resis-tance(if data are obtained from specimens in both principal directions),expresd in millinewtons,or grams-force,if desired to the nearest whole number,
12.1.5Standard deviation from the average(s)of the tearing resistance in the machine and transver directions,if both directions are tested,and
12.1.6Capacity of the tester.
13.Precision and Bias8
13.1Table1and Table2are bad on a round robin conducted between1986and1990in accordance with Practice E691,involving ven materials tested by ven laboratories. For each material,all the samples were prepared at one source, and randomized ctions offilm were nt to each of the laboratories which prepared the test specimens and tested them.Each“test result”was the average of ten determinations.
8Supporting data are available from ASTM Headquarters.Request RR:D20-1177.
TABLE1Propagation Tear Resistance(Elmendorf Tear)Machine
裁员门
Direction
Material
Values Expresd in Units of Grams–Force
Average S r A S R B r C R D Polystyrene 3.440.740.78 2.06 2.17 HDPE No.111.51 1.15 2.56 3.227.18 HDPE No.213.69 1.11 3.13 3.098.76 Polypropylene15.46 1.50 1.93 4.19 5.41 Polyester53.45 1.34 3.60 3.7410.09 LDPE—LD104333.019.5761.8854.79173.3 LLDPE377.412.3552.2834.58146.4
A S
r
=within-laboratory standard deviation for the material stated.It is obtained by pooling the standard deviations of the test results from each laboratory:
S r5[@(~S1!21~1~S n!2#/n]1/2(1) B S
R
=between-laboratories standard deviation for the material stated.It is a pooling of the amounts by which the average of the test results for each laboratory deviate from the overall average for that material.
C r=within-laboratory repeatability limit=2.83S
r
.
D R=between-laboratories reproducibility limit=2.83S
R
.
