1、Designation: F3136 15Standard Test Method forOxygen Gas Transmission Rate through Plastic Film andSheeting using a Dynamic Accumulation Method1This standard is issued under the fixed designation F3136; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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 determinationof the transmission rate of oxygen
3、 gas through plastics in theform of film, sheeting, laminates, coextrusions, coated oruncoated papers or fabrics.1.2 This test method is not the only method for measure-ment of the oxygen transmission rate (OTR). There are othermethods of OTR determination that use other oxygen sensorsand procedures
4、.1.3 The values stated in SI units are to be regarded asstandard. Commonly used metric units used to report OxygenTransmission Rate are included in Terminology, Procedure,Precision and Bias sections and in the Calculation section ofthe Appendix.1.4 This standard does not purport to address all of th
5、esafety 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 use.2. Referenced Documents2.1 ASTM Standards:2D3985 Test Method for Oxyge
6、n Gas Transmission RateThrough Plastic Film and Sheeting Using a CoulometricSensorE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF2622 Test Method for Oxygen Gas Transmission Rat
7、eThrough Plastic Film and Sheeting Using Various SensorsF2714 Test Method for Oxygen Headspace Analysis ofPackages Using Fluorescent Decay3. Terminology3.1 Definitions:3.1.1 Oxygen Transmission Rate (OTR)the quantity ofoxygen gas passing through a unit area of the parallel surfacesof a plastic film
8、per unit time under the conditions of test. TheSI unit of transmission rate is the mol/(m2s). The test condi-tions including temperature, relative humidity and oxygenpartial pressure on both sides of the film must be stated in thereport.3.1.1.1 DiscussionA commonly used unit of OTR is thecm3(STP)/(m
9、2day) at one atmosphere pressure differencewhere 1 cm3(STP) is 44.62 mol, 1 atmosphere is 0.1013MPa, and one day is 86.4 103s. The OTR in SI units isobtained by multiplying the value in commonly used units by5.160 10-10.4. Summary of Test Method4.1 The specimen is mounted as a sealed semi-barrierbet
10、ween two chambers, which together make up the perme-ation apparatus. The sensing well which contains the oxygensensor is slowly purged by a stream of pure nitrogen or otheroxygen deficient gas mixture until the oxygen concentrationrepresents that of the purge gas. A commercial grade ofcompressed nit
11、rogen containing less than 0.05% oxygen isrecommended.Agas of known oxygen concentration, typicallyair or pure oxygen, is directed into the opposite chamber, thedriving well. Oxygen concentration in the sensing well con-taining the oxygen sensor is measured periodically and theaccumulating oxygen co
12、ncentration recorded. The OxygenTransmission Rate (OTR) parameter is determined from theslope of the logarithm of accumulated oxygen concentration inthe sensing well versus time as described in 14.2.5. Significance and Use5.1 The Oxygen Transmission Rate is an important deter-minant of packaging fun
13、ctionality afforded by packagingmaterials for a wide variety of packaged products includingfood, pharmaceuticals and medical devices. In someapplications, sufficient oxygen must be allowed to permeateinto the package. In others, the oxygen ingress must beminimized to maintain product quality.1This t
14、est method is under the jurisdiction ofASTM Committee F02 on FlexibleBarrier Packaging and is the direct responsibility of Subcommittee F02.10 onPermeation.Current edition approved April 1, 2015. Published April 2015. DOI: 10.1520/F3136-15.2For referenced ASTM standards, visit the ASTM website, www.
15、astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Oth
16、er ASTM Standard Methods to measure the oxygentransmission rate are described in Standard Test Method D3985and Standard Test Method F2622.6. Interferences6.1 Any leakage within the permeation apparatus ormounted packaging film will affect results. A means to assessleakage is described in paragraph 9
17、.2.6.2 The condition of the sample film must be noted such aswrinkles or other defects can affect results.7. Apparatus7.1 Oxygen Gas Transmission Apparatus, as diagrammed inFig. 1 with the following:7.1.1 Permeation Apparatus (diffusion cell) shall consist oftwo metal halves, which, when closed upon
18、 the test specimen,will define a known gas transmission area. The volume of thesensing well containing the oxygen sensor must be accuratelyknown.7.1.1.1 O-ringA circular transmission area permits appli-cation of a static O-ring in a properly constructed O-ringgroove in the side of the permeation app
19、aratus that does notcontain the oxygen sensor. The test area of the sensing well isconsidered to be that area established by the inside contactdiameter of the compressed O-ring when the permeationapparatus is clamped shut. The area, A, can be obtained bymeasuring the inside diameter of the imprint l
20、eft by the O-ringon the specimen after it has been removed from the permeationapparatus.7.1.1.2 The sensing well of the permeation apparatus shallhave a flat raised rim. Since this rim is a critical sealing surfaceagainst which the test specimen is pressed, it shall be smoothand flat without radial
21、scratches.7.1.1.3 The sensing well of the permeation apparatus shallhave a low-permeability window transparent to wavelengthsused to activate and read the oxygen sensor which is mountedwithin the sensing well.7.1.1.4 The oxygen sensor incorporates a fluorophore thatfluoresces in response to a certai
22、n wavelength of light, but isquenched in the presence of oxygen. The oxygen quenchingeffect is calibrated to oxygen concentration. This sensingtechnology is identical to the sensing technology described inASTM F2714.7.1.1.5 The permeability apparatus shall incorporated suit-able fittings for the int
23、roduction and exhaust of gases withoutsignificant loss or leakage.7.2 It is necessary to control the temperature of the perme-ability apparatus during the test period. A simple heating/cooling chamber regulated to 60.5C, is adequate for thispurpose in which the apparatus is housed during the test pe
24、riod.7.3 Flow meters having an operating range from 1 to 100cm3/min are required to monitor the flow rate of the nitrogenpurge stream and, if used, the oxygen or compressed aircirculation stream. Sufficiently low flow rates and/or balancedpressures on each side of the film are required to avoidstret
25、ching the specimen which would modify the effectivesensing well volume.7.4 An external light source provides sufficient light in theappropriate wavelength to activate the oxygen sensor.7.5 A light detector, and associated electronics, determinesthe fluorescence decay constant, which is proportional
26、tooxygen concentration.7.6 A computer is used to calculate the oxygen concentra-tion at specified time intervals based on decay rates. Theoxygen transmission rate of the film is calculated from thatdata.8. Reagents and Materials8.1 Nitrogen enriched purge gas shall contain a knownconcentration of ni
27、trogen. Commercial grade compressed ni-trogen (0.05% oxygen), certified pure nitrogen gas, cryogeni-cally stored nitrogen or nitrogen enriched gas produced usingon-site generators may be used.8.2 Transmission gas shall be of a known oxygen concen-tration with an oxygen concentration at least 10% gre
28、ater thanthe purge gas. Typically, commercial grade compressedoxygen, certified gas or air is used.Also, regulated compressedair can be used or the driving well can simply be left open toambient air.FIG. 1 A Practical Arrangement of Components for the Measurement of Oxygen Transmission Rate Using an
29、 Optical Florescent OxygenSensor and a Permeation ApparatusF3136 1528.3 Sealing GreaseHigh-viscosity silicone stop cockgrease or high-vacuum grease is required for sealing thespecimen film in the diffusion cell.9. Precautions9.1 Temperature is a critical parameter affecting the mea-surement of OTR.
30、Careful temperature control can help tominimize variations due to temperature fluctuations. Duringtesting, the temperature shall be monitored and controlled to 60.5C. Temperature variations should be minimized. Theaverage temperature and a range of temperatures during a testshall both be recorded.9.
31、2 Oxygen that leaks into the sensing well through faultyvalves, fittings, or through an improperly sealed window cansignificantly affect the accuracy of the measurement. Periodicleak checks using impervious films such as metal foils withthicknesses 25 m (with their expected permeations of zero)shoul
32、d be taken to identify suspected system leaks. Leak checkpermeation tests should be run at least every 3-6 months andeach test should be run for a minimum of 12 hours.10. Sampling10.1 Film samples used for the determination of OTR shallbe representative of materials for which the data are required.C
33、are shall be taken to ensure that samples are representative ofconditions across the width and along the length of a roll offilm.11. Test Specimens11.1 Test specimens shall be representative of the materialand shall be free of defects including wrinkles, creases, andpinholes, unless these are charac
34、teristics of the material beingtested and included in the material description.11.2 Average thickness shall be determined 6 3 m using acalibrated dial gage (or equivalent) at a minimum of five pointsdistributed over the entire test area. Maximum, minimum, andaverage values shall be recorded. Sample
35、thickness need not bemeasured for determination of sample OTR only.11.3 If the test specimen is of an asymmetrical construction,the two surface shall be marked by appropriate distinguishingmarks and the orientation of the test specimen within thepermeation apparatus shall be reported.12. Calibration
36、12.1 General ApproachThe oxygen sensor fluoresceswhen exposed to certain wavelengths of light. Oxygenquenches the fluorescent decay response. The sensor apparatusutilizes a light source to deliver light to the oxygen sensorwhich, in turn, fluoresces. This light is measured by thedetector. The detect
37、or determines the exponential fluorescentresponse decay constant, which is calibrated to oxygen con-centration.12.2 CalibrationThe sensor system is calibrated by mea-suring oxygen concentration at two known values, typically air(20.9% oxygen) and pure nitrogen (0% oxygen). These valuesdefine a calib
38、ration curve from which unknown oxygen levelsmay be determined. Alternatively, 2 gases of known concen-trations nearer to the level under test may prove to yield abetter calibration value (perhaps 3% and 0% oxygen).13. Procedure13.1 Apply a thin layer of sealing grease (see 8.3) aroundthe raised rim
39、 of the sensing well opposite the O-ring. Place thespecimen on the greased surface, taking care to avoid wrinklesor creases. Close and secure the permeation apparatus.An acceptable Permeation Apparatus (aka Diffusion Cell) is available from OxySense, Inc., 6000 S. Eastern Ave., Suite 14G, Las Vegas,
40、 NV 89119, USA.FIG. 2 Permeation Apparatus as described in this method (film specimen is shown adhered to the sensing well)F3136 15313.2 The system can be calibrated with the test specimen inplace.13.2.1 Open both the inlet and outlet valves connected to thesensing well of the permeation apparatus.
41、If using air as theupper oxygen level calibration gas, there is no need to purgethe sensing well as it already contains air and readings from thesensor can be taken immediately. If using other than air as theupper oxygen level calibration gas, then the sensing well mustbe purged with that gas. Purge
42、 the sensing well with the higheroxygen level calibration gas at 5-10 cm3/min. Note thatwhenever purging with a sample in the chamber, care must betaken to avoid stretching or bulging the film. A flow rate of5-10 cm3/min with valves open has been determined to notcause undue sample bulging or stretc
43、hing. Oxygen concentra-tion should be monitored until the reported value does notchange. Expect to purge with at least 5 chamber volumes of gas(typically 5-10 minutes). Once the indicated concentrationremains steady, calibrate the oxygen sensor to this knownvalue.13.2.2 Purge the sensing well with t
44、he lower oxygen levelcalibration gas (typically nitrogen) at a flow rate of 5-10cm3/min. Again, observe the indicated oxygen concentrationuntil it does not change. Once the concentration reading issteady, calibrate the oxygen sensor to this known value. Fromthese two readings of calibrated/known gas
45、 concentrations, thesystem can determine the calibration curve parameters (seeSection 14 below). By purging the sensing well with the loweroxygen concentration lastly, the step also serves to prepare thechamber for the commencing of the test.13.3 Initiate the test with the specimen mounted as a seal
46、edsemi-barrier between the two halves of the permeation appa-ratus.13.3.1 The sensing well which contains the oxygen sensor isslowly purged (5-10 cm3/min) by a stream of nitrogen until thesensing well is either essentially free of oxygen or to a knownreduced oxygen level (based on indicated oxygen c
47、oncentra-tion reading shown by the instrument). Close the inlet valve ofthe sensing well prior to the outlet valve to eliminate pressurewithin the sensing well.13.3.2 A gas of known oxygen concentration, typically100% oxygen, is applied to the driving well at a rate ofapproximately 5-10 cm3/min for
48、5-10 minutes. The drivingwell may be sealed off after flushing by closing the inlet valvefirst then the outlet valve. Alternatively, if air (20.9% oxygen)is to be used as the driving gas, the valves can be left open. Asstated previously, care must be taken to prevent any pressuredifferential on eith
49、er side of the film specimen which maydistort it, changing the sensing well volume.13.3.3 Oxygen concentration in the sensing well is mea-sured periodically at time increments sufficient to indicate asmall gain in oxygen with each reading (changes of 0.05%oxygen have been found satisfactory between readings).13.3.4 The test should continue until such time as theexperimenter is satisfied that the indicated increase in oxygenconcentration during the test period is consistent with resultsobtained from previous periods.13.4 Start/End PointsThe permeation of the sample
