ASTM F2622-08
(Test Method)Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using Various Sensors
Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using Various Sensors
SIGNIFICANCE AND USE
The O2GTR is an important determinant of the packaging protection afforded by barrier materials. It is not, however, the sole determinant, and additional tests, based on experience, must be used to correlate packaging performance with O2GTR. It is suitable as a referee method of testing, provided that the purchaser and the seller have agreed on sampling procedures, standardization procedures, test conditions, and acceptance criteria.
Testing which has compared select instruments with other sensors to the instruments specifically described in Test Method D 3985 is shown in Section 16, Precision and Bias, of this method.
The Precision and Bias section of this method shows results using several instruments with non-coulometric and coulometric sensors.
SCOPE
1.1 This test method covers a procedure for determination of the steady-state rate of transmission of oxygen gas through plastics in the form of film, sheeting, laminates, coextrusions, or plastic-coated papers or fabrics. It provides for the determination of (1) oxygen gas transmission rate (O2GTR), (2) the permeance of the film to oxygen gas (PO2), and (3) oxygen permeability coefficient (P'O2) in the case of homogeneous materials.
1.2 This test method does not purport to be the only method for measurement of O2GTR. There may be other methods of O2GTR determination that use other oxygen sensors and procedures.
1.3 This test method has intentionally been prepared to allow for the use of various sensors, devices, and procedures. The precision and bias of each design needs to be individually established to determine the applicability of that instrument or method to meet the needs of the user.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 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.
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Standards Content (Sample)
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Designation:F2622–08
Standard Test Method for
Oxygen Gas Transmission Rate Through Plastic Film and
Sheeting Using Various Sensors
This standard is issued under the fixed designation F 2622; 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
of the steady-state rate of transmission of oxygen gas through
3. Terminology
plastics in the form of film, sheeting, laminates, coextrusions,
3.1 Definitions:
or plastic-coated papers or fabrics. It provides for the determi-
3.1.1 oxygen permeability coeffıcient (P8O )—the product
nation of (1) oxygen gas transmission rate (O GTR), (2) the
of the permeance and the thickness of film.The permeability is
permeance of the film to oxygen gas (PO ), and (3) oxygen
meaningfulonlyforhomogeneousmaterials,inwhichcaseitis
permeability coefficient (P’O ) in the case of homogeneous
a property characteristic of the bulk material. The oxygen
materials.
permeability coefficient should not be used, unless the relation-
1.2 This test method does not purport to be the only method
ship between thickness and permeance has been verified on
for measurement of O GTR. There may be other methods of
tests using several different thicknesses of the material. The SI
O GTR determination that use other oxygen sensors and
unit of oxygen permeability is the mol/(m·s·Pa). The test
procedures.
conditions (see 3.1.3) must be stated.
1.3 This test method has intentionally been prepared to
3.1.2 oxygen permeance (PO )—the ratio of the O GTR to
2 2
allow for the use of various sensors, devices, and procedures.
the difference between the partial pressure of O on the two
The precision and bias of each design needs to be individually
sidesofthefilm.TheSIunitofpermeanceisthemol/(m ·s·Pa).
established to determine the applicability of that instrument or
The test conditions (see 15.1) must be stated.
method to meet the needs of the user.
3.1.3 oxygen transmission rate (O GTR)—the quantity of
1.4 The values stated in SI units are to be regarded as the
oxygen gas passing through a unit area of the parallel surfaces
standard. The values given in parentheses are for information
of a plastic film per unit time under the conditions of test. The
only.
SI unit of transmission rate is the mol/(m ·s). The test condi-
1.5 This standard does not purport to address all of the
tions, including temperature and oxygen partial pressure on
safety concerns, if any, associated with its use. It is the
both sides of the film must be stated.
responsibility of the user of this standard to establish appro-
3.1.3.1 Discussion—A commonly used unit of O GTR is
priate safety and health practices and determine the applica-
3 2
the cm (STP)/m ·d) at one atmosphere pressure difference
bility of regulatory limitations prior to use.
where 1 cm (STP) is 44.62 µmol, 1 atm is 0.1013 MPa, and
2. Referenced Documents one day is 86.4 3 10 s. The O GTR in SI units is obtained by
-10
multiplying the value in inch-pound units by 5.160 3 10 .
2.1 ASTM Standards:
D 1898 Practice for Sampling of Plastics
4. Summary of Test Method
D 3985 Test Method for Oxygen Gas Transmission Rate
4.1 The oxygen gas transmission rate is determined after the
sample has equilibrated in a controlled test environment.
Control of carrier gas flow rate (for concentration detectors),
This test method is under the jurisdiction ofASTM Committee F02 on Flexible
relative humidity, temperature, and oxygen concentration in
Barrier Packaging and is the direct responsibility of Subcommittee F02.10 on
both the carrier gas and permeant (test) gas chambers is
Permeation.
critical.
Current edition approved April 1, 2008. Published May 2008.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.2 The specimen is mounted as a sealed semi-barrier
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
between two chambers at ambient atmospheric pressure. A
Standards volume information, refer to the standard’s Document Summary page on
stream of nitrogen slowly purges one chamber and the other
the ASTM website.
Withdrawn. chamber contains oxygen. As oxygen gas permeates through
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2622–08
the film into the nitrogen carrier gas, it is transported to the Valves connect the carrier gas side of each individual diffusion
detector where it produces a signal representing the oxygen cell to the sensor in a predetermined pattern. Carrier gas is
transmission rate. continually purging the carrier gas sides of those cells that are
not connected to the sensor. Either test gas or carrier gas, as is
5. Significance and Use appropriate, purges the test gas chamber of any individual cell.
7.1.2 Flow Controller—A flow controller will control the
5.1 The O GTR is an important determinant of the pack-
flow of carrier and test gases with sufficient precision to allow
aging protection afforded by barrier materials. It is not,
determination of the oxygen permeability in instruments which
however, the sole determinant, and additional tests, based on
calculate the oxygen permeability based on the oxygen con-
experience, must be used to correlate packaging performance
centration change in the carrier gas stream. In some instru-
with O GTR. It is suitable as a referee method of testing,
ments (such as the Coulometric), the flow rate does not need to
provided that the purchaser and the seller have agreed on
be controlled as precisely.
sampling procedures, standardization procedures, test condi-
7.1.3 Flow Switching Valves—Valves for the switching of
tions, and acceptance criteria.
the nitrogen and test gas flow streams.
5.2 Testing which has compared select instruments with
7.1.4 Sensor—An oxygen-sensitive sensor with sufficient
other sensors to the instruments specifically described in Test
sensitivity and precision to yield meaningful results can use
Method D 3985 is shown in Section 16, Precision and Bias, of
various operating principles including coulometric, electro-
this method.
chemical and zirconium oxide. Different sensors may have
5.3 The Precision and Bias section of this method shows
different levels of sensitivity. The user should select the
results using several instruments with non-coulometric and
instrument/sensor system which will adequately cover the
coulometric sensors.
oxygen permeation range and degree of precision of interest.
7.1.5 Data Recording System—An appropriate data record-
6. Interferences
ing system shall record all pertinent information. Various
6.1 The presence of certain interfering substances in the
integrated and external computer systems have been found
carrier gas stream may give rise to unwanted electrical outputs
effective.
and error factors. Interfering substances include carbon mon-
oxide, hydrocarbons, free chlorine, and some strong oxidizing
8. Reagents and Materials
agents. Exposure to carbon dioxide should also be minimized
8.1 Nitrogen Carrier Gas shall consist of nitrogen. The
to avoid damage to the sensor through reaction in some sensor
carrier gas shall be dry and contain not more than 5 ppm of
types.
oxygen. If catalysts or other oxygen absorbers are employed, a
higher oxygen level may be found to be acceptable. If other
7. Apparatus
gases are needed to be included in this nitrogen to allow
7.1 Oxygen Gas Transmission Apparatus, with the follow-
catalysts to function they may be incorporated up to 5 %.
ing:
8.2 Oxygen Test Gas shall be dry and contain not less than
7.1.1 Diffusion Cell shall consist of two metal halves,
99 % oxygen (except as provided in 13.8).
which, when closed upon the test specimen, will accurately
8.3 Sealing Grease—For some instrument types, a vacuum
define a circular area. The volume enclosed by each cell half,
or stopcock grease may be required to seal the specimen film
when clamped, is not critical; it should be small enough to
in the diffusion cell.
allow for rapid gas exchange, but not so small that an
8.4 Water for Humidification—For humidification of the
unsupported film which happens to sag or bulge will contact
carrier and permeant gas streams, ultra-high purity water is
the top or bottom of the cell. The diffusion cell shall be
required for some instrument types to prevent plugging of the
provided with a thermometer well for measuring temperature.
humidification system. This water should have a resistivity of
7.1.1.1 O-Ring—Various designs may be included in the at least 18 MV.An example of a suitable type is high-pressure
diffusion cell design. Some systems may require vacuum
liquid chromatography (HPLC) water.
greasetoformaproperseal.Thedesignwilldefinethetestarea
9. Precautions
of the film as it is tested.
7.1.1.2 Diffusion Cell Pneumatic Fittings—The diffusion 9.1 Temperature and relative humidity are critical param-
cell shall incorporate suitable fittings for the introduction and eters affecting the measurement of O GTR. Careful tempera-
exhaust of gases without significant loss or leakage. ture and relative humidity control can help to minimize
7.1.1.3 It is desirable to thermostatically control the diffu- variations due to environmental fluctuations. During testing,
sion cell.Asimple heating or heating/cooling system regulated the temperature shall be monitored to the nearest 0.5°C and the
to 60.5°C, is adequate for this purpose. A thermistor sensor relative humidity to the nearest 0.5 percent. The average
and an appropriate control circuit will serve to regulate the cell conditions and range of conditions experienced during the test
temperature unless measurements are being made close to period shall both be reported.
ambient temperature. In this case, it is desirable to provide 9.2 The sensor may require a relatively long time to
cooling capability to remove some of the heat. stabilize to a low reading characteristic of a good barrier after
7.1.1.4 Experience has shown that arrangements using mul- it has been used to test a poor barrier such as low-density
tiple diffusion cells are a practical way to increase the number polyethylene. For this reason, materials of comparable gas
of measurements that can be obtained from a single sensor. transmission qualities should be tested together.
F2622–08
9.3 Back diffusion of air into the unit is undesirable. Care placed carefully in the diffusion cell taking care to avoid
should therefore be taken to ensure that there is a flow of wrinkles and creases. Clamp the halves of the cell together
nitrogen through the system at all times. This flow can be tightly.
lowered when the instrument is not being used.
13.2.4 Purging the System—Allow the gases to flow to
9.4 Elevated temperatures can be used to hasten specimen purge the system of ambient air before taking any measure-
outgassing, provided that the treatment does not alter the basic
ments
structure of the specimen (crystallinity, density, and so forth).
13.3 The following three flow alternative configurations for
This can be accomplished by the use of the heaters in the
the carrier gas are made using various valves and controls.The
diffusion cells.
oxygen transmission rate in the carrier gas is measured in each
configuration. Typically, the background oxygen transmission
10. Sampling
rate levels are measured first, followed by the measured level
of oxygen transmission rate through the film.
10.1 The sampling units used for the determination of
13.3.1 Background Gas Cylinder Oxygen Transmission
O GTR shall be representative of the quantity of product for
Rate—The gas is flowed directly from the carrier gas source,
which the data are required, in accordance with Practice
through an oxygen reducing catalyst or other oxygen absorber,
D 1898. Care shall be taken to ensure that samples are
if desired, and then to the sensor.
representative of conditions across the width and along the
13.3.2 Background Diffusion Cell Oxygen Transmission
length of a roll of film.
Rate—A stream of carrier gas is directed through the upper
(test gas) side of the diffusion cell) and another stream flows
11. Test Specimens
through the lower (carrier gas) side of the diffusion cell
11.1 Test specimens shall be representative of the material
chambers. The oxygen transmission rate going through the
being tested and shall be free of defects, including wrinkles,
carrier side of the cell is measured.
creases, and pinholes, unless these are a characteristic of the
13.3.3 Measured Diffusion Cell Oxygen Transmission
material being tested.
Rate—The carrier gas is directed to flow through the carrier
11.2 Average thickness shall be determined to the nearest
side of the cell while oxygen (in whatever concentration is
2.5 µm (0.0001 in.), using a calibrated dial gage (or equivalent)
desired) is directed through the oxygen (test gas) side of the
ataminimumoffivepointsdistributedovertheentiretestarea.
diffusion cell and then to the sensor.
Maximum, minimum, and average values shall be recorded. If
13.4 Temperature shall be obtained by monitoring the tem-
this measurement may damage the specimen, it can be done
perature as closely as possible to the specimen.
after permeation has been tested.
13.5 Standby and Shutoff Procedures—Followthemanufac-
11.3 If the test specimen is of an asymmetrical construction,
turer’s instructions in the instrument manual for putting the
the two surfaces shall be marked by appropriate distinguishing
instrumentintostandbymodewhenthesystemwillnotbeused
marks and the orientation of the test specimen in the diffusion
for an extended period.
cell shall be reported (for example, “side II was mounted
13.6 Tests in a Moist Environment—Thistestmethodcanbe
facing the oxygen (test gas) side of the diffusion cell”).
conducted with test and carrier gases at any controlled tem-
perature and relative humidity. Provision to control and moni-
12. Conditioning
tor environmental conditions must be made and validated.
12.1 After the sample has been mounted in the diffusion
Design details to accomplish temperature and humidity control
cell, a sufficient length of time must be allowed for the film to
are beyond the scope of this test method.
reach equilibrium. No conditioning prior to mounting the film
13.7 TheO GTRattemperaturesotherthanambientmaybe
sample in the diffusion cell is needed.
determined by thermostatically controlling the diffusion cell
provided that the tempera
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