1、Designation: F 2622 08e1Standard Test Method forOxygen Gas Transmission Rate Through Plastic Film andSheeting Using Various Sensors1This standard is issued under the fixed designation F 2622; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, 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.e1NOTEResearch Report information was added editorially in July 2008.1. Scope1.1 This test method covers a pr
3、ocedure for determinationof the steady-state rate of transmission of oxygen gas throughplastics in the form of film, sheeting, laminates, coextrusions,or plastic-coated papers or fabrics. It provides for the determi-nation of (1) oxygen gas transmission rate (O2GTR), (2) thepermeance of the film to
4、oxygen gas (PO2), and (3) oxygenpermeability coefficient (PO2) in the case of homogeneousmaterials.1.2 This test method does not purport to be the only methodfor measurement of O2GTR. There may be other methods ofO2GTR determination that use other oxygen sensors andprocedures.1.3 This test method ha
5、s intentionally been prepared toallow for the use of various sensors, devices, and procedures.The precision and bias of each design needs to be individuallyestablished to determine the applicability of that instrument ormethod to meet the needs of the user.1.4 The values stated in SI units are to be
6、 regarded asstandard. No other units of measurement are included in thisstandard.1.5 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 de
7、termine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1898 Practice for Sampling of Plastics3D 3985 Test Method for Oxygen Gas Transmission RateThrough Plastic Film and Sheeting Using a CoulometricSensor3. Terminology3.1 Definitions:3.1.1 oxyg
8、en permeability coeffcient (P8O2)the productof the permeance and the thickness of film. The permeability ismeaningful only for homogeneous materials, in which case it isa property characteristic of the bulk material. The oxygenpermeability coefficient should not be used, unless the relation-ship bet
9、ween thickness and permeance has been verified ontests using several different thicknesses of the material. The SIunit of oxygen permeability is the mol/(msPa). The testconditions (see 3.1.3) must be stated.3.1.2 oxygen permeance (PO2)the ratio of the O2GTR tothe difference between the partial press
10、ure of O2on the twosides of the film. The SI unit of permeance is the mol/(m2sPa).The test conditions (see 15.1) must be stated.3.1.3 oxygen transmission rate (O2GTR)the quantity ofoxygen gas passing through a unit area of the parallel surfacesof a plastic film per unit time under the conditions of
11、test. TheSI unit of transmission rate is the mol/(m2s). The test condi-tions, including temperature and oxygen partial pressure onboth sides of the film must be stated.3.1.3.1 DiscussionA commonly used unit of O2GTR isthe cm3(STP)/m2d) at one atmosphere pressure differencewhere 1 cm3(STP) is 44.62 m
12、ol, 1 atm is 0.1013 MPa, andone day is 86.4 3 103s. The O2GTR in SI units is obtained bymultiplying the value in inch-pound units by 5.160 3 10-10.4. Summary of Test Method4.1 The oxygen gas transmission rate is determined after thesample has equilibrated in a controlled test environment.Control of
13、carrier gas flow rate (for concentration detectors),relative humidity, temperature, and oxygen concentration inboth the carrier gas and permeant (test) gas chambers iscritical.4.2 The specimen is mounted as a sealed semi-barrierbetween two chambers at ambient atmospheric pressure. Astream of nitroge
14、n slowly purges one chamber and the otherchamber contains oxygen. As oxygen gas permeates through1This 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 April 1, 2008.
15、 Published May 2008.2For 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 ASTM website.3Withdrawn.1Copyright ASTM International,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the film into the nitrogen carrier gas, it is transported to thedetector where it produces a signal representing the oxygentransmission rate.5. Significance and Use5.1 The O2GTR is an important determinant of the pa
17、ck-aging protection afforded by barrier materials. It is not,however, the sole determinant, and additional tests, based onexperience, must be used to correlate packaging performancewith O2GTR. It is suitable as a referee method of testing,provided that the purchaser and the seller have agreed onsamp
18、ling procedures, standardization procedures, test condi-tions, and acceptance criteria.5.2 Testing which has compared select instruments withother sensors to the instruments specifically described in TestMethod D 3985 is shown in Section 16, Precision and Bias, ofthis method.5.3 The Precision and Bi
19、as section of this method showsresults using several instruments with non-coulometric andcoulometric sensors.6. Interferences6.1 The presence of certain interfering substances in thecarrier gas stream may give rise to unwanted electrical outputsand error factors. Interfering substances include carbo
20、n mon-oxide, hydrocarbons, free chlorine, and some strong oxidizingagents. Exposure to carbon dioxide should also be minimizedto avoid damage to the sensor through reaction in some sensortypes.7. Apparatus7.1 Oxygen Gas Transmission Apparatus, with the follow-ing:7.1.1 Diffusion Cell shall consist o
21、f two metal halves,which, when closed upon the test specimen, will accuratelydefine a circular area. 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 which happens to sag or bulge w
22、ill contactthe top or bottom of the cell. The diffusion cell shall beprovided with a thermometer well for measuring temperature.7.1.1.1 O-RingVarious designs may be included in thediffusion cell design. Some systems may require vacuumgrease to form a proper seal. The design will define the test area
23、of the film as it is tested.7.1.1.2 Diffusion Cell Pneumatic FittingsThe diffusioncell shall incorporate suitable fittings for the introduction andexhaust of gases without significant loss or leakage.7.1.1.3 It is desirable to thermostatically control the diffu-sion cell. A simple heating or heating
24、/cooling system regulatedto 60.5C, is adequate for this purpose. A thermistor sensorand an appropriate control circuit will serve to regulate the celltemperature unless measurements are being made close toambient temperature. In this case, it is desirable to providecooling capability to remove some
25、of the heat.7.1.1.4 Experience has shown that arrangements using mul-tiple diffusion cells are a practical way to increase the numberof measurements that can be obtained from a single sensor.Valves connect the carrier gas side of each individual diffusioncell to the sensor in a predetermined pattern
26、. Carrier gas iscontinually purging the carrier gas sides of those cells that arenot connected to the sensor. Either test gas or carrier gas, as isappropriate, purges the test gas chamber of any individual cell.7.1.2 Flow ControllerA flow controller will control theflow of carrier and test gases wit
27、h sufficient precision to allowdetermination of the oxygen permeability in instruments whichcalculate the oxygen permeability based on the oxygen con-centration change in the carrier gas stream. In some instru-ments (such as the Coulometric), the flow rate does not need tobe controlled as precisely.
28、7.1.3 Flow Switching ValvesValves for the switching ofthe nitrogen and test gas flow streams.7.1.4 SensorAn oxygen-sensitive sensor with sufficientsensitivity and precision to yield meaningful results can usevarious operating principles including coulometric, electro-chemical and zirconium oxide. Di
29、fferent sensors may havedifferent levels of sensitivity. The user should select theinstrument/sensor system which will adequately cover theoxygen permeation range and degree of precision of interest.7.1.5 Data Recording SystemAn appropriate data record-ing system shall record all pertinent informati
30、on. Variousintegrated and external computer systems have been foundeffective.8. Reagents and Materials8.1 Nitrogen Carrier Gas shall consist of nitrogen. Thecarrier gas shall be dry and contain not more than 5 ppm ofoxygen. If catalysts or other oxygen absorbers are employed, ahigher oxygen level ma
31、y be found to be acceptable. If othergases are needed to be included in this nitrogen to allowcatalysts to function they may be incorporated up to 5 %.8.2 Oxygen Test Gas shall be dry and contain not less than99 % oxygen (except as provided in 13.8).8.3 Sealing GreaseFor some instrument types, a vac
32、uumor stopcock grease may be required to seal the specimen filmin the diffusion cell.8.4 Water for HumidificationFor humidification of thecarrier and permeant gas streams, ultra-high purity water isrequired for some instrument types to prevent plugging of thehumidification system. This water should
33、have a resistivity ofat least 18 MV. An example of a suitable type is high-pressureliquid chromatography (HPLC) water.9. Precautions9.1 Temperature and relative humidity are critical param-eters affecting the measurement of O2GTR. Careful tempera-ture and relative humidity control can help to minimi
34、zevariations due to environmental fluctuations. During testing,the temperature shall be monitored to the nearest 0.5C and therelative humidity to the nearest 0.5 percent. The averageconditions and range of conditions experienced during the testperiod shall both be reported.9.2 The sensor may require
35、 a relatively long time tostabilize to a low reading characteristic of a good barrier afterit has been used to test a poor barrier such as low-densitypolyethylene. For this reason, materials of comparable gastransmission qualities should be tested together.F262208e129.3 Back diffusion of air into th
36、e unit is undesirable. Careshould therefore be taken to ensure that there is a flow ofnitrogen through the system at all times. This flow can belowered when the instrument is not being used.9.4 Elevated temperatures can be used to hasten specimenoutgassing, provided that the treatment does not alter
37、 the basicstructure of the specimen (crystallinity, density, and so forth).This can be accomplished by the use of the heaters in thediffusion cells.10. Sampling10.1 The sampling units used for the determination ofO2GTR shall be representative of the quantity of product forwhich the data are required
38、, in accordance with PracticeD 1898. Care shall be taken to ensure that samples arerepresentative of conditions across the width and along thelength of a roll of film.11. Test Specimens11.1 Test specimens shall be representative of the materialbeing tested and shall be free of defects, including wri
39、nkles,creases, and pinholes, unless these are a characteristic of thematerial being tested.11.2 Average thickness shall be determined to the nearest2.5 m (0.0001 in.), using a calibrated dial gage (or equivalent)at a minimum of five points distributed over the entire test area.Maximum, minimum, and
40、average values shall be recorded. Ifthis measurement may damage the specimen, it can be doneafter permeation has been tested.11.3 If the test specimen is of an asymmetrical construction,the two surfaces shall be marked by appropriate distinguishingmarks and the orientation of the test specimen in th
41、e diffusioncell shall be reported (for example, “side II was mountedfacing the oxygen (test gas) side of the diffusion cell”).12. Conditioning12.1 After the sample has been mounted in the diffusioncell, a sufficient length of time must be allowed for the film toreach equilibrium. No conditioning pri
42、or to mounting the filmsample in the diffusion cell is needed.13. Procedure13.1 Various instruments will have somewhat different op-erating procedures and each instruments specifics are beyondthe scope of this test method.13.2 Regardless of the specific instrument employed, thereare some steps commo
43、n to any system.13.2.1 Instrument Warm-Up PeriodDepending on thesensor and specific system involved some period of timeshould be allowed to insure stability.13.2.2 Diffusion Cell PreparationIn many systems, theseal separating the test area of the film and the surroundingenvironment requires O-rings
44、or finished surfaces. If recom-mended by the instrument manufacturer, apply sealing greaseevenly.13.2.3 Specimen PreparationThe size of the specimenobviously depends on the diffusion cell design. The sample isplaced carefully in the diffusion cell taking care to avoidwrinkles and creases. Clamp the
45、halves of the cell togethertightly.13.2.4 Purging the SystemAllow the gases to flow topurge the system of ambient air before taking any measure-ments13.3 The following three flow alternative configurations forthe carrier gas are made using various valves and controls. Theoxygen transmission rate in
46、the carrier gas is measured in eachconfiguration. Typically, the background oxygen transmissionrate levels are measured first, followed by the measured levelof oxygen transmission rate through the film.13.3.1 Background Gas Cylinder Oxygen TransmissionRateThe gas is flowed directly from the carrier
47、gas source,through an oxygen reducing catalyst or other oxygen absorber,if desired, and then to the sensor.13.3.2 Background Diffusion Cell Oxygen TransmissionRateA stream of carrier gas is directed through the upper(test gas) side of the diffusion cell) and another stream flowsthrough the lower (ca
48、rrier gas) side of the diffusion cellchambers. The oxygen transmission rate going through thecarrier side of the cell is measured.13.3.3 Measured Diffusion Cell Oxygen TransmissionRateThe carrier gas is directed to flow through the carrierside of the cell while oxygen (in whatever concentration isde
49、sired) is directed through the oxygen (test gas) side of thediffusion cell and then to the sensor.13.4 Temperature shall be obtained by monitoring the tem-perature as closely as possible to the specimen.13.5 Standby and Shutoff ProceduresFollow the manufac-turers instructions in the instrument manual for putting theinstrument into standby mode when the system will not be usedfor an extended period.13.6 Tests in a Moist EnvironmentThis test method can beconducted with test and carrier gases at any controlled tem-perature and relative humidity. Provisi
