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Data System Unification for Barrier Capability Testing
: The problem of data inconsistency among barrier property tests still exists. Minor differences can lead
to significant economical losses, even safety problems of products. This paper mainly talks about the methods of
unifying barrier property testing data system and the demands in choosing standard film.
: barrier property, oxygen transmission rate, water vapor transmission rate, calibration, standard film
From the laboratory capability validation of “barrier property of plastic packaging material test，testing of
oxygen penetration amount and vapor penetration amount”, we can see that the inconsistency among different
testing methods really exists. Minor differences can lead to significant economical losses, even safety problems
of products. After the capability validation, experts in the relative fields began to pay attention to barrier property
testing unification. We wil further discuss the probability of realization and method of implementation.
1. Analysis of the available methods of unifying barrier property testing data
There are difficulties in unifying barrier property testing data system because of the differences in testing
theories of barrier property testing. For example, pressure difference method in air penetration test compute
testing data by measuring the changes in testing cavities, and isopiestic method get testing data by inspecting
oxygen content in airflow. Likewise, as for moisture permeability test, parameters also vary greatly, weighting
method use weight, while electrolysis sensor method and infrared sensor method use gas content in airflow, and
humidity sensor method choose times. So the direct calibrating methods adopt by those barrier property tests are
different, such as isopiestic method using standard air in calibration while pressure difference method using
But those direct calibration methods can not be used to unify data system of barrier property test. First, these
calibration methods only calibrate key test parameters but other parameters are also calculated in testing result.
Second, calibrate objects differ in different calibration methods and these methods can not be used in other
situations. So we must find a current and reliable method to satisfy the need.
After studying calibration methods in other test indexes, in order to unify data system of barrier property test,
we must find a kind of substance that can calibrate test data of barrier property test instruments, just as using
standard blocks which calibrate the thickness of instruments, to complement the calibrate of different thickness
gauges. And as for barrier property testing, the standard substance appears to be standard films which have
acknowledgeable, robust barrier properties. User can find out whether the experimental data is within the
promising range by comparing the barrier property data of film and testing data of instrument. Generally speaking,
the standard film calibration method which has been widely used is the first consideration to unify data system of
2. Standard Film and Selection
2.1 Introduction to Standard Film calibration
Standard film calibration is the most commonly used calibrating method in barrier property testing. The
calibrating which deal with testing data instead of experimental parameters, could be used to calibrate
instruments in air penetration test, moisture permeability test and organic compounds permeability test, the
There are many advantages in standard film calibration. First, it is easy to use, the standard substance is the
only need. Second, it conforms accuracy and consistency of testing data. Other calibrating methods calibrate one
testing parameter only and can not eliminate the effects of other factors. Third, it can be used in frequent
operating and periodical calibrating. Multi-cavity testing instrument need not to break its normal testing work
when determining if the instrument is working in condition.
Standard film calibration has been widely used. The property testing needs to be strengthened to qualify to
the unification of data system of barrier property. It is important to make sure that errors would not happen when
testing the same index using the same instrument under the same experimental condition. The focus is whether
film is stable and keeps its barrier property after a certain period of storage, transportation and so on. So the
barrier property of film includes good uniformity and stability.
First, select films of good uniformity and stability.
Second, uniform is the first consideration. Uniform films such as standard film published by NIST and used in
air penetration instrument testing. The more kinds of materials involve in films, the more factors that affect the
uniformity and stability of testing data.
Third, the universality of testing data of selected material, the data should not too close to the limit of testing
instruments. A data of mid-level is fairly receivable. For if the testing data is too close to the limit of testing
instruments, other factors such as environment would have more influences on the testing data.
Forth, materials that keep good barrier property after strength enforcement is the priority choice. Although
uniformity and stability of barrier property is keystone in material selection, other factors in material transportation
should also be considered. So, materials with good barrier property are the prior chooses on the basis of
In fact, there many materials that meet the demands of standard film selection, such as PET. PET is the most
commonly used material in flexible packaging with moderate barrier property and stability. The specimen that
used in laboratory capability validation of “barrier property of plastic packaging material test，testing of oxygen
penetration amount and vapor penetration amount” , are PET with slight differences in thickness and have a
barrier property of good uniformity and stability. We can see from list1 that it keeps good barrier property after
enforced on external forces in kneading experiment by labthink, counteracting the effect of external forces in
ps：1. The unit of WVTR is：g/m2·24h.
Relevant institutes of our nation are trying to unify testing data of barrier property, for example, the national
test standards of pressure difference method and weighing method have already been instituted, we can manage
the testing data system by controlling testing methods. However, with the development of national barrier
property testing, we have isopiestic method and electrolysis sensor method later and non-standard instruments
are also used sometimes. We can not control the stability of testing data system by controlling testing methods,
so it is urgent to find a new way to unify data system of barrier property testing. Standard film calibration that has
been commonly used is competent for unifying data system of barrier property and getting rid of obstacles in data
comparison of different testing methods.
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