ASTM F1927-98(2004)
(Test Method)Standard Test Method for Determination of Oxygen Gas Transmission Rate, Permeability and Permeance at Controlled Relative Humidity Through Barrier Materials Using a Coulometric Detector
Standard Test Method for Determination of Oxygen Gas Transmission Rate, Permeability and Permeance at Controlled Relative Humidity Through Barrier Materials Using a Coulometric Detector
SCOPE
1.1 This test method covers a procedure for determination of the rate of transmission of oxygen gas, at steady-state, at a given temperature and %RH level, through film, sheeting, laminates, co-extrusions, or plastic-coated papers or fabrics. This test method extends the common practice dealing with zero humidity or, at best, an assumed humidity. Humidity plays an important role in the oxygen gas transmission rate (O2GTR) of many materials. This test method provides for the determination of oxygen gas transmission rate (O2GTR), the permeance of the film to oxygen gas (P'O2), and oxygen permeability coefficient (P''O2) in the case of homogeneous materials at given temperature and %RH levels(s).
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 9.
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Designation:F 1927–98(Reapproved2004)
Standard Test Method for
Determination of Oxygen Gas Transmission Rate,
Permeability and Permeance at Controlled Relative Humidity
Through Barrier Materials Using a Coulometric Detector
This standard is issued under the fixed designation F 1927; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Through Plastic Film and Sheeting Using a Coulometric
Sensor
1.1 This test method covers a procedure for determination
E 104 Practice for Maintaining Constant Relative Humidity
of the rate of transmission of oxygen gas, at steady-state, at a
by Means of Aqueous Solutions
given temperature and %RH level, through film, sheeting,
E 691 Practice for Conducting an Interlaboratory Study to
laminates, co-extrusions, or plastic-coated papers or fabrics.
Determine the Precision of a Test Method
This test method extends the common practice dealing with
zerohumidityor,atbest,anassumedhumidity.Humidityplays
3. Terminology
an important role in the oxygen gas transmission rate (O GTR)
3.1 Definitions:
of many materials. This test method provides for the determi-
3.1.1 oxygen permeability coeffıcient (P9O )—the product
nation of oxygen gas transmission rate (O GTR), the per-
of the permeance and the thickness of the film. The permeabil-
meance of the film to oxygen gas (P8O ), the permeation
ity is meaningful only for homogeneous materials, in which
coefficient of the film to its thickness (PO ), and oxygen
case it is a property characteristic of the bulk material. This
permeability coefficient (P9O ) in the case of homogeneous
quantity should not be used unless the relationship between
materials at given temperature and %RH level(s).
thickness and permeance has been verified on tests using
1.2 The values stated in SI units are to be regarded as the
several different thicknesses of the material. The SI unit of
standard.
oxygen permeability is the mol/m·s·Pa.The test conditions
1.3 This standard does not purport to address all of the
(see 3.1.4) must be stated.
safety concerns, if any, associated with its use. It is the
3.1.2 oxygen permeance (P8O )—the ratio of O GTR to the
2 2
responsibility of the user of this standard to establish appro-
difference between the partial pressure of O on the two sides
priate safety and health practices and determine the applica-
ofthefilm.TheSIunitofpermeanceisthemol/m · s · Pa.The
bility of regulatory limitations prior to use. Specific precau-
test conditions (see 3.1.4) must be stated.
tionary statements are given in Section 9.
3.1.3 oxygen permeation coeffıcient (PO )—the ratio of
2. Referenced Documents O GTR to the thickness of the film. The SI unit of permeance
isthemol/m · s · cm.Thepermeationcoefficientismeaningful
2.1 ASTM Standards:
only for homogeneous materials, in which case it is a property
D 1434 Test Method for Determining Gas Permeability
characteristic of the bulk material. This quantity should not be
Characteristics of Plastic Film and Sheeting
3 used unless the relationship between thickness and transmis-
D 1898 Practice for Sampling of Plastics
sion rate is known.
D 3985 Test Method for Oxygen Gas Transmission Rate
3.1.4 oxygen transmission rate—at a given temperature and
%RH (O GTR), the quantity of oxygen gas passing through a
unit area of the parallel surfaces of a plastic film per unit time
This test method is under the jurisdiction ofASTM Committee F02 on Flexible
under the conditions of test. The SI unit of transmission rate is
Barrier Materials and is the direct responsibility of Subcommittee F02.10 on
the mol/m · s. The test conditions, including temperature,
Permeation.
%RH and oxygen partial pressure on both sides of the film
Current edition approved Oct. 10, 1998. Published March 1999.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
must be stated.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.1.5 transmission rate(O GTR)—acommonlyusedmetric
Standards volume information, refer to the standard’s Document Summary page on
3 2
unit of O GTR is the cm (STP)/m · d at one atmosphere
the ASTM website.
Withdrawn. pressure differential where: 1 cm (STP) is 44.62 µmol, 1 atm is
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1927–98 (2004)
0.1013 MPa, and one day is 86.4 3 10 s. O GTR in SI units 6. Interferences
is obtained by multiplying the value in metric units by
6.1 The presence of certain interfering substances in the
-10 3
5.165 3 10 or the value in inch-pound units [(cm /STP/100
carrier gas stream may give rise to unwanted electrical outputs
2 -9
in. · d)] by 8.005 3 10 .
and error factors. Interfering substances include free chlorine
and some strong oxidizing agents. Exposure to carbon dioxide
4. Summary of Test Method
should also be minimized to avoid damage to the sensor
4.1 Theoxygengastransmissionrateisdeterminedafterthe
through reaction with the potassium hydroxide electrolyte.
sample has equilibrated in a given temperature and humidity
7. Apparatus
environment.
4.2 The specimen is mounted as a sealed semi-barrier
7.1 Oxygen Gas Transmission Apparatus, as diagramed in
between two chambers at ambient atmospheric pressure. One Fig. 1 and described following.Alternative systems need to be
chamber is slowly purged by a stream of nitrogen at a given
evaluated to ensure equivalent performance.
temperature and %RH and the other chamber is purged by a 7.1.1 Diffusion Cell, consisting of two metal halves, that,
stream of oxygen at the same temperature as the N stream but
when closed upon the test specimen, will accurately define a
may have a different %RH than the N stream. In this case the circular area. Typical acceptable diffusion cell areas are 100
environment would more closely simulate actual shelf condi-
and 50 cm . The volume enclosed by each cell half, when
tions. As oxygen gas permeates through the film into the clamped, is not critical: it should be small enough to allow for
nitrogen carrier gas, it is transported to the coulometric
rapid gas exchange, but not so small that an unsupported film
detector where it produces an electrical current, the magnitude
which happens to sag or bulge will contact the sides of the cell.
of which is proportional to the amount of oxygen flowing into
The diffusion cell shall be provided with a temperature
the detector per unit time.
measuring and controlling capability and a means to measure
and control relative humidity.
5. Significance and Use
7.1.1.1 Temperature control is critical because RH can vary
5.1 O GTRatagiventemperatureand%RHisanimportant
as much as 5 % RH/°C in certain temperature regions. A
determinant of the packaging protection afforded by barrier compact design of the diffusion cell structure with associated
materials. It is not, however the sole determinant, and addi-
controls would lend itself to better temperature control. The
tional tests, based on experience, must be used to correlate temperature should be controlled to 60.5°C or better.
packaging performance with O GTR. It is suitable as a referee 7.1.1.2 O-Ring—An appropriately sized groove, machined
method of testing, provided that purchaser and seller have into the oxygen (or test gas) side of the diffusion cell, retains a
agreed on sampling procedures, standardization procedures, neoprene O-ring. The test area is considered to be that area
test conditions and acceptance criteria. established by the inside contact diameter of the compressed
FIG. 1 A Practical Arrangement of Components for the Measurement of Oxygen Transmission Rate Under Precise Relative Humidity
Conditions Using the Coulometric Method
F 1927–98 (2004)
O-ring when the diffusion cell is clamped shut against the test 7.1.7.2 The RH detectors should periodically be calibrated
specimen.Thearea,A,canbeobtainedbymeasuringtheinside against saturated salt solutions (see Practice E 104) or NIST
diameter of the imprint left by the O-ring on the specimen after traceable devices.
it has been removed from the diffusion cell.
8. Reagents and Materials
7.1.1.3 Thenitrogen(orcarriergas)sideofthediffusioncell
shall have a flat raised rim. Since this rim is a critical sealing
8.1 Nitrogen Carrier Gas, consisting of a nitrogen and
surface against which the test specimen is pressed, it shall be
hydrogen mixture in which the percentage of hydrogen shall
smooth and flat, without radial scratches.
fall between 0.5 and 3.0 volume %.The carrier gas shall be dry
7.1.1.4 Diffusion Cell Pneumatic Fittings—Each half of the
andcontainnotmorethan100ppmofoxygen.Acommercially
diffusion cell shall incorporate suitable fittings for the intro-
available mixture known as “forming gas” is suitable.
duction and exhaust of gasses without significant loss or
8.2 Oxygen Test Gas, shall be dry and contain not less than
leakage.
99.5 % oxygen (except as provided in 14.10).
7.1.1.5 Experience has shown that arrangements using mul-
8.3 Water to Generate %RH—Double or triple-distilled
tiple diffusion cells are a practical way to increase the number water is recommended (not deionized water) for precise
of measurements which can be obtained from a coulometric
relative humidity generation and to avoid scale build up.
sensor.Avalving manifold shall connect the carrier gas side of
8.4 Sealing Grease—A high-viscosity hydrocarbon grease
each individual diffusion cell to the sensor in a preselected
(preferred) or a high-vacuum grease is required for sealing the
pattern. Carrier gas is continually purging the carrier gas sides
specimen film in the diffusion cell.
of those cells that are not connected to the sensor. Either test
9. Precautions
gasorcarriergas,asisappropriate,purgesthetestgaschamber
of any individual cell.
9.1 Temperature is a critical parameter affecting the mea-
7.1.2 Catalyst Bed—Should be used on the carrier gas (N )
surement of O GTR. Careful temperature control will help to
side of the diffusion cell assembly to provide an essentially
minimize variations due to temperature fluctuations. During
oxygen free carrier gas. Palladium catalyst on alumina con-
equilibration and testing the temperature shall be monitored
verts O molecules into H O, thus virtually eliminating O
2 2 2 periodically. Should this temperature exceed 60.5°C after
molecules in the carrier gas.
reaching the desired temperature, report the average tempera-
7.1.3 Oxygen gas transmission apparatus shall have the
ture and the range of temperatures found during the test.
capability of measuring, at a variety of relative levels includ-
9.2 Thesensorwillrequirearelativelylongtimetostabilize
ing, zero RH to 90 % RH at a wide range of temperatures.
to a low reading characteristic of a good barrier after it has
7.1.4 Package testing at given temperature and %RH levels
been used to test a poorer barrier such as low density
to be optional if it is not included in the basic configuration.
polyethylene. For this reason, materials of comparable gas
7.1.5 Coulometric Sensor—An oxygen-sensitive coulomet-
transmission qualities should be tested together.
ric sensor operating at an essentially constant efficiency shall
9.3 Back diffusion of air into the unit is undesirable. Care
be used to monitor the quantity of oxygen transmitted.
should be taken to ensure that there is a flow of nitrogen
7.1.6 With computer controlled systems, the results are
through the system at all times. This flow can be low when the
printed out giving final results, time-history of equilibration,
instrument is not being used.
ambient conditions of test, material being tested and date.
9.4 Elevated temperatures to hasten specimen out gassing is
Shouldafailureoccur,thetimeofthisoccurrenceanditscause
not recommended. RH is a function of temperature and,
and correction taken should be documented for operator
therefore, equilibrating at some other temperature than the test
analysis as to the validity of continued testing.
temperature would expose the sample to an incorrect RH
7.1.7 RH Detectors—Water sensitive solid-state devices are
during the equilibration process. The entire test should be run
used to monitor the relative humidity of the gases directly in
at constant temperature and constant RH.
the upper and lower halves of the cell.
7.1.7.1 Placement of the RH detectors in the diffusion cells 10. Sampling
is important because relative humidity will change whenever
10.1 The samples used for the determination of O GTR
the temperature of the relative humidity source and diffusion
shall be representative of the quality of product for which the
cells differ.
data are required, in accordance with Practice D 1898. Care
shall be taken to ensure that film samples are representative of
conditions across the width and along the length of the film
The sole source of supply of the apparatus, a suitable catalyst, known to the
being tested.
committee at this time is Englehard Industries Division, Chemical Department, 429
DelanceyStreet,Newark,NJ07105.Ifyouareawareofalternativesuppliers,please
provide this information to ASTM Headquarters. Your comments will receive
careful consideration at a meeting of the responsible technical committee that you Hasegawa, S. (NIST) “National Basis of Accuracy in Humidity Measure-
may attend. ments,” ISA Transactions, Vol 25, No. 3, 1986, pp. 15–24.
5 7
Thesolesourceofsupplyofsuitableapparatussuchasthatembodiedinseveral The sole source of supply of the apparatus, a suitable hydrocarbon grease such
later OX-TRAN models known to the committee at this time is available from as Apiezon T, known to the committee at this time is, Biddle Instruments, 510
MOCON/Modern Controls, Inc. 7500 Boone Ave N, Minneapolis, MN 55428. If Township Road, Blue Bell, PA 19422. If you are aware of alternative suppliers,
you are aware of alternative suppliers, please provide this information to ASTM pleaseprovidethisinformationtoASTMHeadquarters.Yourcommentswillreceive
Headquarters.Your comments will receive careful consideration at a meeting of the careful consideration at a meeting of the responsible technical committee that you
responsible technical committee that you may attend. may attend.
F 1927–98 (2004)
11. Test Specimen 13. Conditioning
13.1 Trim the test specimen to a size appropriate for the
11.1 Test specimens shall be representative of the material
diffusion cell in which it will be mounted. In
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