1、Designation: F88/F88M 09F88/F88M 15Standard Test Method forSeal Strength of Flexible Barrier Materials1This standard is issued under the fixed designation F88/F88M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of the strength of seals in flexible barrier materials.1.2 The test may be conducted
3、 on seals between a flexible material and a rigid material.1.3 Seals tested in accordance with this test method may be from any source, laboratory or commercial.1.4 This test method measures the force required to separate a test strip of material containing the seal. It also identifies the modeof sp
4、ecimen failure.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non
5、-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations
6、 prior to use.2. Referenced Documents2.1 ASTM Standards:2D882 Test Method for Tensile Properties of Thin Plastic SheetingE171 Practice for Conditioning and Testing Flexible Barrier PackagingE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminolog
7、y3.1 Definitions:3.1.1 average seal strength, naverage force per unit width of seal required to separate progressively a flexible material froma rigid material or another flexible material, under the conditions of the test.3.1.1.1 DiscussionThe average force normally is calculated by the testing mac
8、hine from the digitized plot of force versus grip travel. The plot startsfrom zero force after slack has been removed from the test strip. The initial ramp-up from zero to the force level required to peelthe seal is not indicative of seal strength, and data from that part of the curve should not be
9、included in the calculation of averagestrength, nor should the return to zero following complete failure of the specimen. The amount of data actually discarded on eachend of the measured seal-profile curve must be the same for all tests within any set of comparisons of average seal strength (see6.1.
10、1 and 9.8.1).3.1.2 flexible, adjindicates a material with flexural strength and thickness permitting a turn back at an approximate 180 degreeangle.3.1.3 maximum seal strength, nmaximum force per unit width of seal required to separate progressively a flexible materialfrom a rigid material or another
11、 flexible material, under the conditions of the test.1 This test method is under the jurisdiction of ASTM Committee F02 on Flexible Barrier Packaging and is the direct responsibility of Subcommittee F02.20 on PhysicalProperties.Current edition approved June 15, 2009Nov. 1, 2015. Published July 2009D
12、ecember 2015. Originally approved in 1968. Last previous edition approved in 20072009 asF88 07a.F88/F88M 09. DOI: 10.1520/F0088_F0088M-09.10.1520/F0088_F0088M-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book o
13、f ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technical
14、ly possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
15、700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 Seal strength is a quantitative measure for use in process validation, process control, and capability. Seal strength is not onlyrelevant to opening force and package integrity, but to measuring the packaging processes a
16、bility to produce consistent seals. Sealstrength at some minimum level is a necessary package requirement, and at times it is desirable to limit the strength of the sealto facilitate opening.4.1.1 The maximum seal force is important information, but for some applications, average force to open the s
17、eal may be useful,and in those cases also should be reported.4.2 Aportion of the force measured when testing materials may be a bending component and not seal strength alone.Anumberof fixtures and techniques have been devised to hold samples at various angles to the pull direction to control this be
18、nding force.Because the effect of each of these on test results is varied, consistent use of one technique (Technique A, Technique B, orTechnique C) throughout a test series is recommended. Examples of fixtures and techniques are illustrated in Fig. 1.4.2.1 Technique A: UnsupportedEach tail of the s
19、pecimen is secured in opposing grips and the seal remains unsupported whilethe test is being conducted.4.2.2 Technique B: Supported 90 (By Hand)Each tail of the specimen is secured in opposing grips and the seal remainshand-supported at a 90 perpendicular angle to the tails while the test is being c
20、onducted.4.2.3 Technique C: Supported 180 The least flexible tail is supported flat against a rigid alignment plate held in one grip. Themore flexible tail is folded 180 over the seal and is held in the opposing grip while the test is being conducted.5. Interferences5.1 The value obtained for seal s
21、trength can be affected by properties of the specimen other than seal strength. Theseinterferences are discussed in the annex.6. Apparatus6.1 Tensile Testing MachineAtesting machine of the constant rate-of-jaw-separation type.The machine shall be equipped witha weighing system that moves a maximum d
22、istance of 2 % of the specimen extension within the range being measured. Themachine shall be equipped with a device for recording the tensile load and the amount of separation of the grips; both of thesemeasuring systems shall be accurate to 62 %. The rate of separation of the jaws shall be uniform
23、 and capable of adjustment fromapproximately 8 to 12 in. 200 to 300 mm/min. The gripping system shall be capable of minimizing specimen slippage andapplying an even stress distribution to the specimen.6.1.1 If calculation of average seal strength is required, the testing machine system shall have th
24、e capability to calculate its valueover a specified range of grip travel programmable by the operator. Preferably, the machine shall have the capability also to plotthe curve of force versus grip travel.6.2 Specimen Cutter, conforming to the requirements of 5.4 of Test Methods D882, sized to cut spe
25、cimens to a width of 0.984in. 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 permit an adequate determination of representative performance.7.2 Testing of samples with visual defects or other deviations from norma
26、lity may or may not be appropriate depending on thepurpose of the investigation. Indiscriminate elimination of defects can bias results.FIG. 1 Tail Holding MethodsF88/F88M 1528. Aging and Conditioning8.1 In the absence of information showing that heat seal strength stability of the materials under t
27、est is reached in shorter times,condition and test sealed materials in accordance with Specification E171, with a minimum conditioning time of 40 h or longerif shown to be required to reach stability.8.2 Heat seal conditioning periods may be shortened to times determined by experimentation as suffic
28、ient to achieve sealstrength stability.8.3 Modification of conditioning practices may be necessary to meet specific test objectives, such as the measurement of sealstrength at specified storage or handling temperature.9. Procedure9.1 Calibrate the tensile machine in accordance with the manufacturers
29、 recommendations.9.2 Prepare sealed test specimens for testing by cutting to the dimensions shown in Fig. 2. Edges shall be clean-cut andperpendicular to the direction of seal. Specimen legs may be shorter than shown, depending on the grip dimensions of the testingmachine.9.3 Adhering to one tail-ho
30、lding technique, clamp each leg of the test specimen in the tensile testing machine. The sealed areaof the specimen shall be approximately equidistant between the grips. Recommended distance between grips (initial unconstrainedspecimen length) is:NOTE 1Seal dimension marked X varies with sealer conf
31、iguration.FIG. 2 Recommended Specimen DimensionsF88/F88M 153Fin and Hot-Wire SealsHighlyA extensible materials 0.39 in. 10 mmLessA extensible materials 1.0 in. 25 mmLap Seals X + 10 mmBA Grip separation distance is recommended to be limited for highly extensible materials (100 + % elongation at seal
32、 failure) to minimize interferences (see annex).B Refer to Fig. 2 for definition of X.9.4 Center the specimen laterally in the grips. Align the specimen in the grips so the seal line is perpendicular to the directionof pull, allowing sufficient slack so the seal is not stressed prior to initiation o
33、f the test.9.5 A significant difference in measured seal strength has been shown to result, depending on the orientation of a fin-seal tailduring the test. The test report should indicate the details of any technique used to control tail orientation.9.6 The seal shall be tested at a rate of grip sep
34、aration of 8 to 12 in./min 200 to 300 mm/min.9.7 For each cycle, report the maximum force encountered as 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 by adhesive failure, cohesive failure, or delamination, the
35、 average peelforce may be an important index of performance and should be measured by the testing machine as a part of the test cycle.9.8.1 Follow the machine manufacturers instructions to select the desired algorithm for calculating average seal strength. Fig.3 illustrates the effect of an algorith
36、m that uses data only from the central 80 % of the curve to calculate the average.9.8.2 If the test strip does not peel significantly in the seal area and failure is largely by breaking, tearing, or elongation of thesubstrate material, average force to failure may have little significance in describ
37、ing seal performance and should not be reportedin such cases (see Annex A1.1).9.9 A plot of force versus grip travel may be useful as an aid in 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
38、separation, may be appropriate in cases where grip travel results only in peel.When other failure modes (elongation, break, tear, delamination (when not a designed peel seal separation mode) or other) arepresent in addition to peel of the seal, energy, and other functions must be interpreted with ca
39、ution.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 form seals, if known.10.1.3 Equipment used to test seals.10.1.4 Ambient conditions during tests; temperature and humidity.10.1.5 Grip separation rate
40、.10.1.6 Initial grip separation distance.10.1.7 Seal width.10.1.8 Machine direction of material in relation to direction of pull.pull may be noted, if known and relevant to the test outcome.10.1.9 Force (strength) values to three significant figures.FIG. 3 Calculation of Average Seal StrengthF88/F88
41、M 15410.1.10 Technique of holding the tail (Technique A, B, or C) and any special fixtures used to hold 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 sampling.10.1.13 Any other per
42、tinent information that may affect test results.10.1.14 Visual determination of mode of specimen failure. Frequently more than one mode will occur in the course of failureof an individual strip. Record all modes observed. A suggested classification of modes is (see Fig. 4):Adhesive failure of the se
43、al; peel.Cohesive failure of the material.Break or tear of material in seal area or at seal edge.Delamination 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 is stressed to failure, expressed pref
44、erably in Newtons/meter or lbf/in.of original specimen width. Gmf/in. and lbf/in. are commonly used.10.1.16 Average Peel Force, if applicable (see 9.8)If this measurement is reported, a statement of the method or algorithmused to calculate the average should be included.10.1.17 Plot of force versus
45、grip travel, if deemed significant in interpretation of results.10.1.18 Other data not compromised by interferences, if such 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 Bia
46、s11.1 PrecisionA round robin was conducted using Practice E691 as a guide, involving 18 laboratories measuring a total of1980 samples distributed over three different test groups of six laboratories each.3 In order to maintain a focus on testing themethod itself, laboratory samples were used to limi
47、t the amount of variation in the seals produced. Description of materialsmeasured and methods used are listed in Table 1. Seven different brands of tensile testing equipment were used to collect3 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Res
48、earch Report RR:F02-1023.TABLE 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./minUnsupported 8 in./minTest Series “B”(Both MAXIMUM Values and AVERAGE Peel Values were repo
49、rted)Uncoated 1073B Tyvek 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 sealant surface sealedface-to-faceUnsupported 12 in./minSupported 180 12 in./minTABLE 2 Test EquipmentManufacturer Models Load Celllb NDillon AFG-50N 11.2 50Instron 4464, 5500R, 5564,5565, S5R1123,4442, MN
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