Gas permeability is a key property for evaluating the barrier performance of films, membranes, plastic materials and structures used across a wide range of industrial sectors.
Measuring gas permeability means determining how readily a gas passes through a material under specific temperature, pressure and humidity conditions. This information helps characterize the material’s performance and determine whether its barrier properties meet the requirements of a given application.
ExtraSolution develops and supplies solutions for gas permeability measurement and analysis, with instruments designed to characterize materials and packaging and evaluate their barrier properties.
What Is Gas Permeability?
Gas permeability describes the ability of a gas to pass through a material.
This phenomenon is particularly important when a material is intended to act as a barrier. For example, packaging film may need to limit the passage of oxygen, carbon dioxide or other gases to help preserve the characteristics of the packaged product.
Gas permeability depends on several factors, including:
- the nature and structure of the material;
- sample thickness;
- temperature;
- the partial pressure difference of the gas;
- humidity conditions;
- the properties of the gas being tested;
- film structure, particularly in multilayer materials and laminates.
For this reason, knowing the type of material alone is not always enough to predict its barrier performance. Experimental testing provides quantitative data that can be used for comparison.
Why Measure Gas Permeability?
Permeability characterization is important in applications where gas exchange through a material can affect the preservation, protection or performance of a product.
In packaging, for example, barrier properties can help control the exchange of gases between the contents of a package and the external environment.
Gas permeability measurement can be used to:
- characterize new materials;
- compare different films or structures;
- evaluate the performance of barrier materials;
- monitor production quality;
- support research and development activities;
- optimize multilayer structures and laminates;
- assess the effects of formulations, treatments or manufacturing processes;
- select the most suitable material for a specific application.
Permeability data can therefore be used both during the development of new materials and for production monitoring and verification.
How Is Gas Permeability Measured?
Gas permeability is generally measured by placing a sample between two environments with different conditions and monitoring the gas passing through the material.
Depending on the measurement technique, the test gas is introduced on one side of the sample, while the gas that passes through the material is detected on the other side.
The instrument measures the amount of gas permeating through the sample over time and processes the data according to the conditions defined for the test.
Accurate analysis therefore requires not only suitable equipment but also clearly defined and controlled test conditions.
Parameters that may affect the result include temperature, relative humidity, pressure and sample characteristics.
Which Gases Can Be Tested?
Gas permeability can be investigated using different gases, depending on the material being tested and its intended application.
The gases most commonly considered when characterizing the barrier properties of materials include:
- oxygen (O₂);
- carbon dioxide (CO₂);
- water vapor;
- other gases, depending on the specific testing requirements.
The choice of test gas depends on the objective of the analysis and the material behavior to be characterized. In some applications, it may be necessary to evaluate how effectively a material limits oxygen transmission, while in others the focus may be on water vapor or carbon dioxide transmission.
Measurement methods, test conditions and relevant parameters may vary according to the gas being tested and the method used.
It is therefore important to select a testing solution that matches the material, the gas of interest and the required operating conditions.
Oxygen, Water Vapor and CO₂ Permeability
Some of the most widely used measurements for characterizing the barrier properties of materials concern oxygen, water vapor and carbon dioxide.
Oxygen permeability is commonly assessed using the OTR (Oxygen Transmission Rate) parameter, which describes the rate at which oxygen passes through a material under specified test conditions.
Water vapor transmission is characterized using the WVTR (Water Vapor Transmission Rate) parameter, which describes the rate at which water vapor passes through a sample.
For carbon dioxide, the CO₂TR (Carbon Dioxide Transmission Rate) parameter is used to describe the rate of CO₂ transmission through a material.
These parameters relate to distinct measurement applications. ExtraSolution therefore provides dedicated solutions and technical information for each type of analysis.
Barrier Properties and Materials
Gas permeability measurement is closely related to the evaluation of a material’s barrier properties.
A material with high barrier performance can limit the passage of specific gases, while materials with different characteristics may exhibit higher permeability.
Barrier performance does not depend solely on the raw material. Thickness, material structure, the combination of different layers and environmental conditions can all influence the behavior of a sample.
This is particularly important for:
- plastic films;
- multilayer films;
- laminated materials;
- co-extruded structures;
- flexible packaging;
- membranes and technical materials.
Experimental measurement makes it possible to evaluate the actual performance of the structure being tested.
Permeability Measurement in Films and Packaging
In the packaging industry, permeability characterization is used to evaluate films and structures intended for packaging applications.
Material selection may depend on the ability of a structure to limit the passage of specific substances between the external environment and the packaged product.
Measurements can be performed on different materials and structures, making it possible to compare alternative solutions during research, development and quality control.
Testing can also help assess the effects of changes to a material’s structure, such as variations in thickness or the addition of new barrier layers.
For further information on specific applications, see also Plastic Film Permeability: Measurement and Testing, Permeability Measurement of Multilayer Films and Laminates and Permeability Measurement in Flexible Packaging.
Gas Permeability Measurement Instruments
The choice of analyzer depends on the type of measurement required, the gas being tested, the material and the intended test conditions.
ExtraSolution offers solutions for characterizing permeability and barrier properties, with different configurations to meet specific testing requirements.
The product range includes systems dedicated to measuring specific permeability parameters, as well as multisensor systems for characterizing multiple barrier properties.
For combined oxygen and CO₂ measurements, ExtraSolution offers MultiPerm O2-CO2. MultiPerm O2-H2O and MultiPerm H2O-CO2 allow different types of analysis to be combined. For comprehensive characterization of O₂, CO₂ and water vapor, TotalPerm is available. PermeH2O is specifically designed for water vapor permeability measurement.
Applications of Gas Permeability Measurement
Gas permeability characterization is used in a wide range of industrial and research applications.
Key applications include:
Characterizing the barrier properties of films, laminates and other materials used in packaging.
Plastic Films and Flexible Packaging Materials
Comparing different materials and structures and evaluating their barrier performance.
Evaluating the barrier properties of materials used to protect products and formulations.
Multilayer Materials and Laminates
Analyzing the performance of complete structures and comparing different combinations of materials.
Research and Development
Supporting the design and optimization of new materials and high-performance solutions.
Quality Control
Verifying that barrier properties meet internal specifications or product requirements.
Standards and Test Conditions
Permeability measurements should be performed according to defined procedures and under controlled conditions to obtain meaningful, comparable results.
Depending on the gas, material and method used, different technical standards may apply to the determination of permeability or transmission rates.
When selecting a test method, it is important to consider the applicable standard, the characteristics of the material and the conditions under which the results will be used.
ExtraSolution can support the selection of a suitable measurement solution based on the test requirements and the laboratory’s needs.
How to Choose a Gas Permeability Measurement Solution
No single instrument is suitable for every application.
Selection should start with the type of characterization required and the characteristics of the sample. A preliminary assessment of testing needs helps identify the most suitable configuration, rather than relying solely on the type of material being tested.
Important factors to consider include:
- Which gas needs to be measured?
- What permeability range is expected?
- What type of sample will be tested?
- At what temperature and humidity should the test be performed?
- Which standard or test method must be followed?
- How frequently will measurements be performed?
The answers to these questions help determine the required analyzer specifications and measurement procedure.
Explore the Main Types of Measurement
To learn more about the individual measurement techniques, visit the dedicated pages:
- Oxygen Permeability and OTR: Measurement and Analysis
- Water Vapor Permeability and WVTR: Measurement and Analysis
- CO₂ Permeability and CO₂TR: Measurement and Analysis
- Barrier Properties of Films: Measurement and Characteristics
For information about our instruments and help identifying the most suitable solution for your laboratory, contact ExtraSolution.
ExtraSolution Solutions for Permeability Analysis
ExtraSolution offers instruments and systems for characterizing barrier properties and measuring the permeability of different materials.
Available solutions can be configured according to the gas being tested and the laboratory’s requirements, from research and development to quality control.
To identify the most suitable solution, start by selecting the specific type of measurement you need:
- Oxygen Permeability and OTR: Measurement and Analysis
- Water Vapor Permeability and WVTR: Measurement and Analysis
- CO₂ Permeability and CO₂TR: Measurement and Analysis
- Barrier Properties of Films: Measurement and Characteristics
Contact ExtraSolution to discuss your testing requirements and identify the most suitable solution.