1、Designation: F 88/F 88M 09Standard Test Method forSeal Strength of Flexible Barrier Materials1This standard is issued under the fixed designation F 88/F 88M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the strengthof seals in flexible barrier materials.1.2 The test may be conducted on seal
3、s between a flexiblematerial and a rigid material.1.3 Seals tested in accordance with this test method may befrom any source, laboratory or commercial.1.4 This test method measures the force required to separatea test strip of material containing the seal. It also identifies themode of specimen fail
4、ure.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancew
5、ith the standard.1.6 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 us
6、e.2. Referenced Documents2.1 ASTM Standards:2D 882 Test Method for Tensile Properties of Thin PlasticSheetingE 171 Specification for Atmospheres for Conditioning andTesting Flexible Barrier MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. T
7、erminology3.1 Definitions:3.1.1 average seal strength, naverage force per unit widthof seal required to separate progressively a flexible materialfrom a rigid material or another flexible material, under theconditions of the test.3.1.1.1 DiscussionThe average force normally is calcu-lated by the tes
8、ting machine from the digitized plot of forceversus grip travel. The plot starts from zero force after slackhas been removed from the test strip. The initial ramp-up fromzero to the force level required to peel the seal is not indicativeof seal strength, and data from that part of the curve should n
9、otbe included in the calculation of average strength, nor shouldthe return to zero following complete failure of the specimen.The amount of data actually discarded on each end of themeasured seal-profile curve must be the same for all testswithin any set of comparisons of average seal strength (see6
10、.1.1 and 9.8.1).3.1.2 flexible, adjindicates a material with flexuralstrength and thickness permitting a turn back at an approximate180 degree angle.3.1.3 maximum seal strength, nmaximum force per unitwidth of seal required to separate progressively a flexiblematerial from a rigid material or anothe
11、r flexible material,under the conditions of the test.4. Significance and Use4.1 Seal strength is a quantitative measure for use in processvalidation, process control, and capability. Seal strength is notonly relevant to opening force and package integrity, but tomeasuring the packaging processes abi
12、lity to produce consis-tent seals. Seal strength at some minimum level is a necessarypackage requirement, and at times it is desirable to limit thestrength of the seal to facilitate opening.4.1.1 The maximum seal force is important information, butfor some applications, average force to open the sea
13、l may beuseful, and in those cases also should be reported.4.2 A portion of the force measured when testing materialsmay be a bending component and not seal strength alone. Anumber of fixtures and techniques have been devised to holdsamples at various angles to the pull direction to control thisbend
14、ing force. Because the effect of each of these on testresults is varied, consistent use of one technique (Technique A,1This test method is under the jurisdiction of ASTM Committee F02 on FlexibleBarrier Packaging and is the direct responsibility of Subcommittee F02.20 onPhysical Properties.Current e
15、dition approved June 15, 2009. Published July 2009. Originallyapproved in 1968. Last previous edition approved in 2007 as F 88 07a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
16、tion, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Technique B, or Technique C) throughout a test series isrecommended. Examples of fixtures and techniques are illus-
17、trated in Fig. 1.4.2.1 Technique A: UnsupportedEach tail of the specimenis secured in opposing grips and the seal remains unsupportedwhile the test is being conducted.4.2.2 Technique B: Supported 90 (By Hand)Each tail ofthe specimen is secured in opposing grips and the seal remainshand-supported at
18、a 90 perpendicular angle to the tails whilethe test is being conducted.4.2.3 Technique C: Supported 180The least flexible tailis supported flat against a rigid alignment plate held in onegrip. The more flexible tail is folded 180 over the seal and isheld in the opposing grip while the test is being
19、conducted.5. Interferences5.1 The value obtained for seal strength can be affected byproperties of the specimen other than seal strength. Theseinterferences are discussed in the annex.6. Apparatus6.1 Tensile Testing MachineA testing machine of theconstant rate-of-jaw-separation type. The machine sha
20、ll beequipped with a weighing system that moves a maximumdistance of 2 % of the specimen extension within the rangebeing measured. The machine shall be equipped with a devicefor recording the tensile load and the amount of separation ofthe grips; both of these measuring systems shall be accurate to6
21、2 %. The rate of separation of the jaws shall be uniform andcapable of adjustment from approximately 8 to 12 in. 200 to300 mm/min. The gripping system shall be capable ofminimizing specimen slippage and applying an even stressdistribution to the specimen.6.1.1 If calculation of average seal strength
22、 is required, thetesting machine system shall have the capability to calculate itsvalue over a specified range of grip travel programmable by theoperator. Preferably, the machine shall have the capability alsoto plot the curve of force versus grip travel.6.2 Specimen Cutter, conforming to the requir
23、ements of 5.4of Test Methods D 882, sized to cut specimens to a width of0.984 in. 25 mm, 0.591 in. 15 mm, or 1.00 in. 25.4 mm.Tolerance shall be 60.5 %.7. Sampling7.1 The number of test specimens shall be chosen to permitan adequate determination of representative performance.7.2 Testing of samples
24、with visual defects or other devia-tions from normality may or may not be appropriate dependingon the purpose of the investigation. Indiscriminate eliminationof defects can bias results.8. Aging and Conditioning8.1 In the absence of information showing that heat sealstrength stability of the materia
25、ls under test is reached inshorter times, condition and test sealed materials in accordancewith Specification E 171, with a minimum conditioning time of40 h or longer if shown to be required to reach stability.8.2 Heat seal conditioning periods may be shortened totimes determined by experimentation
26、as sufficient to achieveseal strength stability.8.3 Modification of conditioning practices may be necessaryto meet specific test objectives, such as the measurement ofseal strength at specified storage or handling temperature.9. Procedure9.1 Calibrate the tensile machine in accordance with themanufa
27、cturers recommendations.9.2 Prepare sealed test specimens for testing by cutting tothe dimensions shown in Fig. 2. Edges shall be clean-cut andperpendicular to the direction of seal. Specimen legs may beshorter than shown, depending on the grip dimensions of thetesting machine.9.3 Adhering to one ta
28、il-holding technique, clamp each legof the test specimen in the tensile testing machine. The sealedarea of the specimen shall be approximately equidistant be-tween the grips. Recommended distance between grips (initialunconstrained specimen length) is:FIG. 1 Tail Holding MethodsF 88/F 88M 092Fin and
29、 Hot-Wire SealsHighlyAextensible materials 0.39 in. 10 mmLessAextensible materials 1.0 in. 25 mmLap Seals X + 10 mmBAGrip separation distance is recommended to be limited for highly extensiblematerials(100+%elongation at seal failure) to minimize interferences (seeannex).BRefer to Fig. 2 for definit
30、ion of X.9.4 Center the specimen laterally in the grips. Align thespecimen in the grips so the seal line is perpendicular to thedirection of pull, allowing sufficient slack so the seal is notstressed prior to initiation of the test.9.5 A significant difference in measured seal strength hasbeen shown
31、 to result, depending on the orientation of a fin-sealtail during the test. The test report should indicate the details ofany technique used to control tail orientation.9.6 The seal shall be tested at a rate of grip separation of 8to 12 in./min 200 to 300 mm/min.9.7 For each cycle, report the maximu
32、m force encounteredas the specimen is stressed to failure and identify the mode ofspecimen failure.9.8 If the test strip peels apart in the seal area, either byadhesive failure, cohesive failure, or delamination, the averagepeel force may be an important index of performance andshould be measured by
33、 the testing machine as a part of the testcycle.9.8.1 Follow the machine manufacturers instructions toselect the desired algorithm for calculating average sealstrength. Fig. 3 illustrates the effect of an algorithm that usesdata only from the central 80 % of the curve to calculate theaverage.9.8.2 I
34、f the test strip does not peel significantly in the sealarea and failure is largely by breaking, tearing, or elongation ofthe substrate material, average force to failure may have littlesignificance in describing seal performance and should not bereported in such cases (see Annex A1.1).9.9 Aplot of
35、force versus grip travel may be useful as an aidin interpretation of results. In those cases, the testing machineshould be programmed to generate the plot.9.10 Other properties, such as energy to cause seal separa-tion, may be appropriate in cases where grip travel results onlyin peel. When other fa
36、ilure modes (elongation, break, tear,delamination (when not a designed peel seal separation mode)NOTE 1Seal dimension marked X varies with sealer configuration.FIG. 2 Recommended Specimen DimensionsF 88/F 88M 093or other) are present in addition to peel of the seal, energy, andother functions must b
37、e interpreted with caution.10. Report10.1 Report the following:10.1.1 Complete identification of material being tested.10.1.2 Equipment and test method or practice used to formseals, if known.10.1.3 Equipment used to test seals.10.1.4 Ambient conditions during tests; temperature andhumidity.10.1.5 G
38、rip separation rate.10.1.6 Initial grip separation distance.10.1.7 Seal width.10.1.8 Machine direction of material in relation to directionof pull.10.1.9 Force (strength) values to three significant figures.10.1.10 Technique of holding the tail (TechniqueA, B, or C)and any special fixtures used to h
39、old specimens.10.1.11 If the seal is made between two different materials,record which material is clamped in each grip.10.1.12 Number of specimens tested and method of sam-pling.10.1.13 Any other pertinent information that may affect testresults.10.1.14 Visual determination of mode of specimen fail
40、ure.Frequently more than one mode will occur in the course offailure of an individual strip. Record all modes observed. Asuggested classification of modes is (see Fig. 4):Adhesive failure of the seal; peel.Cohesive failure of the material.Break or tear of material in seal area or at seal edge.Delami
41、nation of surface layer(s) from substrate.Elongation of material.Break or tear of material remote from seal.10.1.15 Maximum force encountered as each specimen isstressed to failure, expressed preferably in Newtons/meter orlbf/in. of original specimen width. Gmf/in. and lbf/in. arecommonly used.10.1.
42、16 Average Peel Force, if applicable (see 9.8)If thismeasurement is reported, a statement of the method or algo-rithm used to calculate the average should be included.10.1.17 Plot of force versus grip travel, if deemed signifi-cant in interpretation of results.FIG. 3 Calculation of Average Seal Stre
43、ngthTABLE 1 Materials and TechniquesTest Series “A”(MAXIMUM Values)Heat Seal Coated 50# Basis Weight Paper sealed to Film (48 ga. PET/2mil LDPE)Supported 90 12 in./minUnsupported 12 in./minUnsupported8in./minTest Series “B”(Both MAXIMUM Values and AVERAGE Peel Values were reported)Uncoated 1073B Tyv
44、ek sealed to Film (48 ga. PET/2 mil LDPE)Supported 90 12 in./minUnsupported 12 in./minSupported 180 12 in./minReverse direction of materials in grips 12 in./minTest Series “C”(MAXIMUM Values)Coex HDPE 3 mil film with peelable sealant layer sealed face-to-faceFoil Composite 5 mil with same peelable s
45、ealant surface sealedface-to-faceUnsupported 12 in./minSupported 180 12 in./minTABLE 2 Test EquipmentManufacturer ModelsLoad Celllb NDillon AFG-50N 11.2 50Instron 4464, 5500R, 5564,5565, S5R1123,4442, MN-441124, 112.4,22.5, 11.2, 25 kN, 500,100, 50, 9Lloyd Instruments 1300-36 22.4 100MTS Sintech Ren
46、ew 4204 25 111.2Test Resources 2000ZR 25 111.2Thwing Albert EJA 11.2 50Vinatoru Enterprises CCT, HST 11.2 50F 88/F 88M 094NOTE 1Schematic representation of seal failure modes for seals between two webs. No diagram is included for systems including an adhesive as athird component.FIG. 4 Test Strip Fa
47、ilure ModesF 88/F 88M 09510.1.18 Other data not compromised by interferences, ifsuch data are relevant to the specific test purpose.10.1.19 Any statistical calculation deemed appropriate(most commonly mean, range, and standard deviation).11. Precision and Bias11.1 PrecisionA round robin was conducte
48、d using Prac-tice E 691 as a guide, involving 18 laboratories measuring atotal of 1980 samples distributed over three different testgroups of six laboratories each.3In order to maintain a focus ontesting the method itself, laboratory samples were used to limitthe amount of variation in the seals pro
49、duced. Description ofmaterials measured and methods used are listed in Table 1.Seven different brands of tensile testing equipment were usedto collect information. The model identifications and load cellsizes are listed in Table 2. Statistical summaries of repeatability(within a laboratory) and reproducibility (between laboratories)are listed in Table 4 for SI units and Table 3 in units of poundsper inch. Fig. 5 is graphical depictions of data.11.2 Concept of “r” and “R” in Tables 4 and 3If SrandSRhave been calculated from
