ASTM F1769-97
(Test Method)Standard Test Method for Measurement of Diffusivity, Solubility, and Permeability of Organic Vapor Barriers Using a Flame Ionization Detector (Withdrawn 2004)
Standard Test Method for Measurement of Diffusivity, Solubility, and Permeability of Organic Vapor Barriers Using a Flame Ionization Detector (Withdrawn 2004)
SCOPE
1.1 This test method covers the measurement of volatile organic-vapor-barrier properties of films, plastic sheeting, coated papers, and laminates. The specific material properties measured include diffusivity, solubility, and permeability coefficients; parameter values which are required for the solution of mass transfer problems associated with nonsteady state and steady state conditions.
1.2 Applicable test vapors include volatile organic compounds which are detectable by a flame ionization detector. Examples of applicable permeation compounds include solvents, organic film additives, flavor compounds, and aroma compounds.
1.3 This test method assumes the material being measured exhibits Fickian behavior and uses the solutions to Fick's Laws for a planar surface as the data regression model. (See Annex A1.)
1.4 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.
WITHDRAWN RATIONALE
This test method covers the measurement of volatile organic-vapor-barrier properties of films, plastic sheeting, coated papers, and laminates. The specific material properties measured include diffusivity, solubility, and permeability coefficients; parameter values which are required for the solution of mass transfer problems associated with nonsteady state and steady state conditions.
Formerly under the jusrisdiction of Committee F02 on Flexible Barrier Materials, this test method was withdrawn in June 2004.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F 1769 – 97
Standard Test Method for
Measurement of Diffusivity, Solubility, and Permeability of
Organic Vapor Barriers Using a Flame Ionization Detector
This standard is issued under the fixed designation F 1769; 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.
P 5 P exp ~–E /RT! (1)
1. Scope
0 P
1.1 This test method covers the measurement of volatile D 5 D exp ~–E /RT! (2)
0 D
organic-vapor-barrier properties of films, plastic sheeting,
S 5 S exp ~–E /RT! (3)
0 S
coated papers, and laminates. The specific material properties
where:
measured include diffusivity, solubility, and permeability coef-
P, D, and S 5 permeability, diffusion, and solubility co-
ficients; parameter values which are required for the solution of
efficients,
mass transfer problems associated with nonsteady state and
P , D , and S 5 Arrhenius fit intercepts,
0 0 0
steady state conditions.
R 5 gas constant,
1.2 Applicable test vapors include volatile organic com-
T 5 temperature, and
pounds which are detectable by a flame ionization detector.
E ,E and E 5 activation energy values.
P D S
Examples of applicable permeation compounds include sol-
2.1.1.2 The intercept and activation energy values are es-
vents, organic film additives, flavor compounds, and aroma
sential to an understanding of a material’s temperature depen-
compounds.
dence, and may be used to estimate a material’s diffusion,
1.3 This test method assumes the material being measured
solubility, and permeability values at any given temperature
exhibits Fickian behavior and uses the solutions to Fick’s Laws
within the region of measurement. They may also be employed
for a planar surface as the data regression model. (See Annex
to estimate values outside of the region of measurement if the
A1.)
fit is sufficiently precise and a glass transition point has not
1.4 This standard does not purport to address all of the
been crossed. Methods of estimating the extrapolation error are
safety concerns, if any, associated with its use. It is the
available in current software packages and may also be
responsibility of the user of this standard to establish appro-
obtained from standard references on statistics.
priate safety and health practices and determine the applica-
2.1.2 diffusion coeffıcient—a kinetic coefficient specific to a
bility of regulatory limitations prior to use.
given material and compound that describes the relationship
between molecular flux and molecular concentration change. D
2. Terminology
is defined by Fick’s First Law:
2.1 Definitions:
F 5 –DdC/dx (4)
2.1.1 activation energy—the thermodynamic property that
describes the relationship of P, D and S to temperature. The
where:
relationship is Arrhenius and the parameters may be obtained
F 5 molecular flux,
by a linear fit of the natural log of the measurement value
D 5 diffusion coefficient, and
versus inverse temperature, K.
dC/dx 5 change in concentration in the direction of x. The
2.1.1.1 Arrhenius parameters of a material are dependent on
SI units for D are m /s.
the glass transition point of the material, and measurements
2.1.3 permeability coeffıcient—an empirical coefficient spe-
spanning a glass transition point will therefore require multiple
cific to a given material and compound that describes the
solutions (Fig. 1). The parameters of the fit are defined by the
relationship of steady state molecular flux to the partial
following equations:
pressure difference across a planar medium. P is defined by the
relation:
This test method is under the jurisdiction of ASTM Committee F-2 on Flexible
F 5 P p – p !/L (5)
~
e 1 2
Barrier Materials and is the direct responsibility of Subcommittee F02.30 on Test
Methods.
Current edition approved Feb. 10, 1997. Published September 1997.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1769
NOTE 1—The log of a mass transfer parameter such as diffusion, solubility, or permeability is expected to be linear with inverse temperature. At the
glass transition point, the slope of the fit will change.
FIG. 1 Arrhenius Parameters of Hypothetical Experiment
where: where:
F 5 the vapor flux at equilibrium, L 5 barrier thickness, and
e
p and p 5 the vapor partial pressures on each side of the p and p 5 opposing gas vapor pressures.
1 2 1 2
medium, and
2.1.6 sample solubility coeffıcient, S —the solubility coeffi-
s
L 5 barrier thickness. The SI units for P are
cient for a specific sample structure and test vapor pressure. S
s
kg/s·m·Pa
is equal to F /D and is in units kg/m .
e s
2.1.4 sample diffusion coeffıcient, D —the diffusion coeffi-
2.1.7 solubility coeffıcient—a coefficient value specific to a
s
cient for a specific sample structure. The material diffusion
given material and compound defining the relationship of
coefficient may be calculated from the sample diffusion coef-
concentration to partial pressure. S is defined by Henry’s Law:
ficient by the equation:
C 5 Sp (8)
D 5 L D (6)
s
where:
where L 5 thickness of the barrier layer.
C 5 concentration within the medium,
The SI units for D are 1/s. D is therefore a frequency value
S 5 solubility coefficient, and
s 2
related to equilibrium time requirements. p 5 vapor pressure of the permeating compound. The SI
units for S are kg/m ·Pa.
2.1.5 sample permeability flux, F —a value describing the
e
steady state permeation flux for the test structure and test gas
3. Summary of Test Method
partial pressure in kg/m ·s. The material permeability coeffi-
cient P may be calculated from F by:
e
3.1 A specific gas entity or mixture is exposed to one side of
P 5 F L/~p – p ! (7) a planar sample by means of a constant gas flow within a
e 1 2
F 1769
controlled temperature cell. The test gas may be comprised of 5. Apparatus
a single compound or multiple compounds (including mois-
5.1 Impinger or Bubbler, for production of the permeant test
ture). Compounds which diffuse across the sample are swept
gas at the desired concentration.
by a carrier gas to a flame ionization detector. The resulting
NOTE 1—Other methods of permeant generation include the use of a
current signal from the detector is then amplified and tabulated
packed column (for granular compounds) and gas cylinders containing a
in accordance with the time of exposure.
mixture of compounds. These are acceptable test gases if the permeant
3.2 Although multiple compounds and mixtures may be
concentration values remain constant during the course of the test.
employed as the test permeant, the analysis of multiple
5.2 Thermal Dewars or a Cold Temperature Bath, capable
diffusion values is beyond the scope of this method. The
of maintaining the permeant bubbler at a room temperature
employment of multiple compounds and mixtures will be
condition or lower.
appropriate if the compound detected by the sensor is singular
5.3 Two Stage Regulators, for each of the required gas
and is known and the interaction effects of other compounds
supplies which include a carrier gas such as helium or nitrogen,
are desired.
and detector fuels which include hydrogen and air (or oxygen).
3.3 The diffusion and permeability coefficients for a given
5.4 Means to Precisely Control the Flow of Each Required
sample and permeant combination are determined by a non-
Gas—As gas flow is critical to the precision of the measure-
linear regression on the transient solution to Fick’s Laws. (See
ment, a flow rate precision of at least 60.1 mL/min is required.
Annex A1.)
5.5 Temperature-Controlled Test Cell, as diagrammed in
3.4 The solubility coefficient is determined from the defini-
Fig. 2 consisting of two chambers diametrically opposed and
tion of the permeability coefficient and the application of
with a means of supporting the measurement sample so as to
Henry’s Law (see Annex A1). These imply the following
separate the two chambers without leakage. Test cell param-
relationship:
eters critical to the measurement process include the following:
S 5 P/D (9)
5.5.1 O-Ring, constructed of Viton (or another known inert
3.5 The diffusion and permeability coefficients for a given
material) for sealing the film is mounted within the cell to
sample and permeant combination are evaluated at a number of
prevent leakage. The O-ring is to be mounted on the test
temperatures to yield the Arrhenius parameters. These values
permeant side of the cell so as to eliminate its effect on the
provide a measure of the temperature dependence of the
detection of compounds diffusing across the test sample.
permeant’s transient and solubility in a given material.
5.5.2 Cell Chamber Volumes, in the range of 10 to 15 cc.
Larger volumes are known to interfere with the measurement
4. Significance and Use
process as they incorporate a significant delay time in test gas
concentration changes.
4.1 Values obtained may be used to estimate the mass
5.5.3 Film Sample Area, as defined by the O-ring diameter
transfer rate of volatile organic compounds permeating into
in the range of 80 to 100 cm .
and through a medium such as a plastic film or coating. Since
5.5.4 Means to Control the Temperature, on both sides of
the rate of transfer can sometimes be extremely slow, steady
the cell (exposure and detector sides) to a precision of
state conditions may not be achieved during the course of the
60.05°C.
experiment or in the intended end use of the material. In these
5.6 Valving and Stainless Steel Plumbing, allowing operator
situations, a reasonable estimate of the total mass transferred or
selection of the permeant chamber gas (either the test permeant
absorbed requires estimates of the diffusion and solubility
or the carrier gas) and transport of the selected gas into the
coefficients. In steady state situations, mass transfer may be
permeant chamber and away from the permeant chamber to an
estimated from the permeability coefficient. (These solutions
exhaust.
are addressed in The Mathematics of Diffusion .)
5.7 Flame Ionization Detector and Amplifier, capable of
4.2 Test measurement values are applicable to a number of
detecting gas concentration differences to at least 1 ppm and
issues associated with the interaction of a packaging material
the means to record the resulting signal with respect to time.
with volatile organic compounds. Examples include shelf life
5.8 Flow Controls and Stainless Steel Plumbing, allowing
estimation when used in conjunction with other information;
the maintenance of a constant flow of carrier gas into the
the evaluation of solvent release rates in a converting process;
detector chamber and then out to the detector. As the measure-
the evaluation of ingredient scalping into a packaging material.
ment signal is dependent on flow rate changes, a flow rate
4.3 Activation energy values may be employed to estimate
precision of at least6 0.1 mL/min is required.
the dependence of the measured mass transfer parameters on
5.9 Injection Port, located prior to the test cell detector
temperature. Since product end use conditions often vary, the
chamber for injections of known calibration compounds.
effect of temperature on a material’s performance can be
5.10 Syringes, of varying size (10 to 1000 μL) for injection
critical to assessing a material’s ability to meet its required
of gas calibration samples. Syringe needles will need to be of
function. These values also allow construction of a database by
a side port type in order to prevent plugging of the syringe and
which materials may be compared for a wide range of end use
to assure consistent calibration values.
temperature conditions.
5.11 Septum Vials, with a volume capacity of 50 to 100 mL
for preparation of calibration standards. The septum material
will be TFE-fluorocarbon or another material known to not
The Mathematics of Diffusion, J. Crank, Clarendon Press, Oxford, 1975. interact with the calibration compound.
F 1769
FIG. 2 Equipment Diagram
6. Reagents and Materials nearest degree centigrade by means of a thermometer, thermo-
couple, or other temperature probe.
6.1 Gas Supplies, of a GC grade or better to include nitrogen
8.1.1 Maintaining a constant bubbler temperature is critical
as a carrier gas (or helium), and flame ionization detector fuels
to minimize variation in the test vapor pressure. In most
of hydrogen and air.
experimental situations, an ice bath will be the preferred means
6.2 Vapor Generation Compounds or Mixtures, for generat-
of temperature control in order to produce a vapor pressure
ing the test gas stream and to prepare calibration standards.
more typical of end use applications and to avoid condensation
in the plumbing from the bubbler to the test cell. Obtain the
7. Sampling
vapor pressure of the compound at the temperature of genera-
7.1 Select samples representative of the lot or the material to
tion from a standard reference manual (CRC Handbook of
be tested. Samples should be free of wrinkles or pinholes and
Chemistry and Physics ) or evaluate by GC analysis.
of a size sufficient for placement within the test cell area.
8.2 Prepare septum vials containing 10 mL of the compound
to be evaluated for use as calibration standards. These vials
8. Permeant Preparation
should be kept in a controlled temperature water bath at a
8.1 Fill the bubbler or impinger to a specified level with the
temperature equal to or less than room temperature. Note the
compound to be evaluated and place in a dewar of ice water or
vial specification, fill level, and temperature.
a controlled temperature bath. Note the fill level and the
bubbler specification. Maintain the bubbler at a constant
temperature and level and record the temperature value to the Handbook of Chemistry and Physics, CRC Press, Inc., Boca Raton, FL.
F 1769
9. System Calibration Fick’s law by a nonlinear regression analysis (see Annex A1).
The regression model to be employed in this analysis is as
9.1 Place an aluminum foil sheet sample into the test cell
follows:
and allow the temperatures and the detector signal to stabilize.
Record the detector signal at stabilization. Q 5 Q ~4/ p! x~exp ~–x! 1 exp ~–9x!! (13)
= =
e
9.2 Sample a headspace of the test compound from the
where:
septum vial using the appropriately sized syringe and inject the
Q 5 detector signal, A,
sample into the injection port. Note the injection volume, the
Q 5 steady state detector signal, A, and
e
vial temperature, the calibration compound, and the c
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