1、Designation: D 3079 94 (Reapproved 2003)Standard Test Method forWater Vapor Transmission of Flexible Heat-Sealed Packagesfor Dry Products1This standard is issued under the fixed designation D 3079; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the amountof water vapor transmission for fle
3、xible heat-sealed packagesunder specified conditions of exposure.NOTE 1Adequate heat-seal efficiency should be determined prior tothis test method.1.2 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 sta
4、ndard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definition
5、:3.1.1 water vapor transmission of a desiccant-filledpackagethe increase in mass after exposure to a specifiedhumid environment (90 6 2 % relative humidity, 100 6 2F(37.8 6 1.1C). The mass increase may be divided by a timeunit to give a rate (for example, grams per 30 days). It isassumed that this m
6、ass increase is due to water vapor trans-mission (through the package) from the test environment to thedesiccant.4. Summary of Test Method4.1 Test samples are filled with desiccant and after sealingare exposed to 100 6 2F (37.8 6 1.1C) and 90 6 2%relative humidity for at least 1 month. Measurements
7、of massare taken at intervals to determine the average rate of masschange. Controls are used to monitor mass gain of packagematerials.5. Significance and Use5.1 This test method determines the water vapor barrierproperties of the package. With proper precautions and back-ground experience, reproduci
8、ble results can be obtained to aidin the selection of proper package materials required to providethe product shelf-life desired. This test method may be used toestablish a performance specification.6. Apparatus6.1 Weighing BalanceAnalytical balance accurate to 1mg.6.2 Test ChamberA test room or cab
9、inet provided withconditioned air that is continuously circulated around thespecimens under test. The conditions in the chamber shall besuch that no condensation occurs on the specimens.7. Materials7.1 DesiccantAnhydrous calcium chloride in the form ofsmall lumps is recommended for this test method.
10、 This shouldpass a No. 8 (2.36-mm) sieve, and be free of fines that will passa No. 30 (600-m) sieve. The desiccant should be dried for atleast 24 h at 200C prior to use.8. Test Specimens8.1 Test specimens shall be representative of the packagesbeing tested, and shall be closed and sealed in the norm
11、almanner.8.2 Review the precision and bias statement to determinethe number of samples required to meet requirements. Gener-ally, three to five samples have been found to be sufficient formost applications.8.3 Each test specimen should be half full of desiccant up to100 g of desiccant. If the half-f
12、ull capacity is greater than 100g of desiccant, the package shall be less than half full, but eachshall contain approximately the same quantity of desiccant.1This test method is under the jurisdiction of ASTM Committee F02 on FlexibleBarrier Materials and is the direct responsibility of Subcommittee
13、 F02.10 onPermeation.Current edition approved Nov. 15, 1994. Published January 1995. Originallypublished as D 3079 72. Last previous edition D 3079 72 (1984)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
14、 ASTMStandards volume information, 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.8.4 If more than one type of package is tested for compari-son purposes, all types sho
15、uld have the same (as close aspossible) surface area and shape, and should contain the samequantity of desiccant.8.5 An appropriate number of identical control packagesshall be prepared, containing no desiccant.9. Procedure9.1 Place the selected quantity of the desiccant inside thetest specimen with
16、 no other contents, but with a suitable liner,if the package normally requires a liner, so that the package canbe handled with the regular automatic packaging machinery.Close and seal the specimens and controls in exactly the samemanner that packages with normal contents are closed andsealed. This t
17、est method may be applied to hand-sealedpackages, but take great care to ensure a complete seal. Notethe use of the hand seal in the report.9.2 Prewarm the sealed packages slowly to a temperature ofapproximately 100F (37.8C).9.3 Place the warmed specimens and controls inside the testroom or cabinet
18、in a position where free access of theconditioned circulating air is provided on all surfaces of thepackages.9.4 Make successive weighings of the packages and con-trols at suitable intervals and plot on arithmetical graph paperthe mass gained against time after subtracting the average massgain of th
19、e controls. Accuracy of the test is adversely affectedby too frequent weighings. For highly permeable packages, aminimum weighing frequently of 3 days is recommended. Forpackages having a low rate of permeability, a weighingfrequency of bi-weekly to monthly is recommended. Allweighings shall prefera
20、bly be made without removing thespecimen from the test chamber. In instances where this is notpossible, remove the specimens and controls from the testchamber and allow them to equilibrate for1hintheweighingarea. Weigh in the same sequence each time. Specimens shouldnot be out of the test chamber fo
21、r more than3hatatime.Continue until a constant rate of gain is attained as indicated byat least three successive points in a straight line. The slope ofthis portion of the curve will furnish a measure of water vaportransmission.10. Report10.1 Report the following information:10.1.1 Identification of
22、 the package including data on films,heat seal equipment, liners, etc.,10.1.2 Desiccant used and quantity,10.1.3 Temperature and relative humidity at which the testwas conducted. If the tolerance of 62 % relative humidity or62F (1.1C) temperature is exceeded, the variation shall bespecified.10.1.4 N
23、umber of specimens tested and number of controls,10.1.5 Weighing frequency,10.1.6 Water vapor transmission reported as grams of waterper 30 days for the period of constant rate of gain,10.1.7 Data on any previous tests to which the specimensmight have been subjected, and10.1.8 A statement to the eff
24、ect that all tests were made inaccordance with this test method.11. Precision and Bias11.1 PrecisionThis round-robin study was carried out inaccordance with Practice E 691. Six laboratories participated ina round-robin study determining weight gain (moisture) forheat-sealed packages. Three materials
25、 were used in the study asfollows:11.1.1 30# MG Bleached Pouch Stock/22# LDPE extrusioncoated,11.1.2 2.2 mil coextrusion 87 % HDPE/13# EVA-MDPE,and11.1.3 25# MG Bleached Kraft Paper/7# LDPE/0.00030 in.Aluminum Foil/22# LDPE extrusion coated.11.2 BiasSince there is no accepted reference materialsuita
26、ble for determining bias for the procedure in this testmethod, bias has not been determined.12. Keywords12.1 flexible packages; water vapor transmissionASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Us
27、ers of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed ever
28、y five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible techni
29、cal committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 3079 94 (2003)2
