ASTM F1249-2006(2011) Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor《用调制红外线传感器测量水蒸气经塑料薄膜和薄片的传输率的标准试验方法》.pdf
《ASTM F1249-2006(2011) Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor《用调制红外线传感器测量水蒸气经塑料薄膜和薄片的传输率的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM F1249-2006(2011) Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated Infrared Sensor《用调制红外线传感器测量水蒸气经塑料薄膜和薄片的传输率的标准试验方法》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: F1249 06 (Reapproved 2011)Standard Test Method forWater Vapor Transmission Rate Through Plastic Film andSheeting Using a Modulated Infrared Sensor1This standard is issued under the fixed designation F1249; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, 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.1. Scope1.1 This test method covers a procedure for determining therate of water v
3、apor transmission through flexible barriermaterials. The method is applicable to sheets and films up to 3mm (0.1 in.) in thickness, consisting of single or multilayersynthetic or natural polymers and foils, including coatedmaterials. It provides for the determination of (1) water vaportransmission r
4、ate (WVTR), (2) the permeance of the film towater vapor, and (3) for homogeneous materials, water vaporpermeability coefficient.NOTE 1Values for water vapor permeance and water vapor perme-ability must be used with caution. The inverse relationship of WVTR tothickness and the direct relationship of
5、WVTR to the partial pressuredifferential of water vapor may not always apply.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 standard to establish appro-priate safety and health practices and determ
6、ine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D374 Test Methods for Thickness of Solid Electrical Insu-lationD1898 Practice for Sampling of Plastics3E96/E96M Test Methods for Water Vapor Transmission ofMaterialsE104 Practice for Maintaining
7、Constant Relative Humidityby Means of Aqueous SolutionsE178 Practice for Dealing With Outlying ObservationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 water vapor permeability coeffcientthe product ofthe permeanc
8、e and the thickness of the film. The permeabilityis meaningful only for homogeneous materials, in which caseit is a property characteristic of bulk material.3.1.1.1 DiscussionThis quantity should not be used unlessthe relationship between thickness and permeance has beenverified in tests using sever
9、al thicknesses of the material. Anaccepted unit of permeability is the metric perm centimeter, or1 g/m2per day per mm Hgcm of thickness. The SI unit is themol/m2sPamm. The test conditions (see 3.1) must be stated.3.1.2 water vapor permeancethe ratio of a barriersWVTR to the vapor pressure difference
10、 between the twosurfaces.3.1.2.1 DiscussionAn accepted unit of permeance is themetric perm, or 1 g/m2per day per mm Hg. The SI unit is themol/m2sPa. Since the permeance of a specimen is generally afunction of relative humidity and temperature, the test condi-tions must be stated.3.1.3 water vapor tr
11、ansmission rate (WVTR)the time rateof water vapor flow normal to the surfaces, under steady-stateconditions, per unit area.3.1.3.1 DiscussionAn accepted unit of WVTR is g/m2perday. The test conditions of relative humidity and temperaturewhere the humidity is the difference in relative humidity acros
12、sthe specimens, must be stated.4. Summary of Test Method4.1 A dry chamber is separated from a wet chamber ofknown temperature and humidity by the barrier material to betested. The dry chamber and the wet chamber make up adiffusion cell in which the test film is sealed. Water vapordiffusing through t
13、he film mixes with the gas in the drychamber and is carried to a pressure-modulated infrared sensor.This sensor measures the fraction of infrared energy absorbedby the water vapor and produces an electrical signal, theamplitude of which is proportional to water vapor concentra-tion. The amplitude of
14、 the electrical signal produced by the test1This test method is under the jurisdiction of ASTM Committee F02 on FlexibleBarrier Packaging and is the direct responsibility of Subcommittee F02.10 onPermeation.Current edition approved Aug. 1, 2011. Published November 2011. Originallyapproved in 1989. L
15、ast previous edition approved in 2006 as F1249 06. DOI:10.1520/F1249-06R11.2For 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
16、 ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.film is then compared to the signal produced by measurementof a calibration
17、film of known water vapor transmission rate.This information is then used to calculate the rate at whichmoisture is transmitted through the material being tested.5. Significance and Use5.1 The purpose of this test method is to obtain reliablevalues for the WVTR of plastic film and sheeting.5.2 WVTR
18、is an important property of packaging materialsand can be directly related to shelf life and packaged productstability.5.3 Data from this test method is suitable as a refereemethod of testing, provided that the purchaser and seller haveagreed on sampling procedures, standardization procedures,test c
19、onditions, and acceptance criteria.6. Apparatus6.1 This method utilizes water vapor transmission appara-tus4(Fig. 1) comprised of the following:6.1.1 Diffusion CellAn assembly consisting of two metalhalves which, when closed upon the test specimen, willaccurately define a circular area. A typical ac
20、ceptable diffusioncell area is 50 cm2. The volume enclosed by each cell half,when clamped, is not critical; it should be small enough toallow for rapid gas exchange, but not so small that anunsupported film that happens to sag or buckle will contact thetop or bottom of the cell. A depth of approxima
21、tely 6 mm(0.250 in.) has been found to be satisfactory for 50-cm2cells.6.1.1.1 Diffusion Cell ORingAn appropriately sizedgroove machined into the humid chamber side of the diffusioncell retains a neoprene Oring. The test area is considered to bethe area established by the inside contact diameter of
22、thecompressed Oring when the diffusion cell is clamped shutagainst the test specimen.6.1.1.2 Diffusion Cell Sealing SurfaceA flat rim aroundthe dry side of the diffusion cell. This is a critical sealingsurface against which the test specimen is pressed; it shall besmooth and without radial scratches
23、.6.1.1.3 Diffusion Cell Air PassagesTwo holes in the dryhalf of the diffusion cell. This is necessary only in the earliermodel WVTR instruments that have a separate conditioningrack and testing chamber. These shall incorporate Oringssuitable for sealing the diffusion cell to the test chamberpneumati
24、c fittings for the introduction and exhaust of airwithout significant loss or leakage.NOTE 2Use of Multiple Diffusion CellsExperience has shown thatarrangements using multiple diffusion cells are a practical way to increasethe number of measurements that can be obtained in a given time. Aseparate co
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