Barrier Properties of Films: Characteristics and Measurement

A barrier film has a specific purpose: to limit the passage of substances that could compromise the protection of a product.

Oxygen, water vapor and carbon dioxide pass through materials in different ways. For this reason, barrier performance cannot be described by a single measurement. Specific parameters are used to quantify a film’s behavior under defined test conditions.

OTR, WVTR and CO₂TR are the main parameters used to characterize the transmission of oxygen, water vapor and carbon dioxide, respectively.

Measuring these properties helps manufacturers develop new films, optimize multilayer structures and laminates, verify material performance and support quality control.

ExtraSolution offers solutions for measuring these properties in plastic films, barrier materials and multilayer structures.

What Are the Barrier Properties of Films?

Barrier properties describe a material’s ability to limit the passage of specific substances through its structure.

In packaging applications, these properties are particularly important when the transmission of gases or moisture needs to be controlled.

A film may provide an effective barrier against oxygen while behaving differently with respect to water vapor or carbon dioxide. Its performance must therefore be evaluated according to the substance of interest and the requirements of the application.

Barrier properties are influenced by material composition, thickness, structure and the conditions under which the material is tested.

Why Are Barrier Properties Important?

Evaluating barrier properties provides quantitative information that can be used when selecting, developing and qualifying materials.

Measurements can help to:

  • compare different films and materials;
  • evaluate barrier performance;
  • optimize multilayer structures and laminates;
  • assess new materials or changes in composition;
  • support material and supplier qualification;
  • monitor consistency during quality control.

The appropriate measurement depends on the substance to be evaluated and the function the material must perform.

OTR, WVTR and CO₂TR: The Main Parameters

Different parameters are used to characterize the transmission of different substances through a material.

OTR — Oxygen Transmission Rate

OTR describes the rate at which oxygen passes through a material under specified test conditions. It is commonly used to evaluate oxygen barrier performance.

Learn more about Oxygen Permeability and OTR: Measurement and Analysis.

WVTR — Water Vapor Transmission Rate

WVTR describes the rate at which water vapor passes through a material under defined conditions. It is used to characterize moisture barrier performance.

Learn more about Water Vapor Permeability and WVTR: Measurement and Analysis.

CO₂TR — Carbon Dioxide Transmission Rate

CO₂TR describes the rate at which carbon dioxide passes through a material under specified test conditions.

Learn more about CO₂ Permeability and CO₂TR: Measurement and Analysis.

These parameters describe different transmission properties and should be selected according to the material and the intended application.

Barrier Films: Materials and Structures

Barrier performance can be achieved through different materials and film configurations.

Depending on the application, a film may consist of a single layer or combine multiple materials to achieve the required combination of properties.

Common structures include:

  • monolayer plastic films;
  • multilayer films;
  • laminated structures;
  • co-extruded films;
  • metallized films;
  • films with functional coatings.

Each layer can contribute differently to the overall performance of the material. Some layers may primarily provide barrier properties, while others contribute to mechanical strength, processability or heat-sealing performance.

For an overview of materials and structures, see Barrier Films: Characteristics, Materials and Measurement Methods.

Barrier Properties of Multilayer Films

Multilayer films and laminates combine different materials to achieve specific performance characteristics.

The barrier performance of the complete structure depends on the properties and arrangement of the individual layers, as well as on the overall thickness and test conditions.

Measuring the finished structure makes it possible to compare alternative combinations of materials and evaluate the effects of changes in layer composition or thickness.

For more information, see [Permeability Measurement of Multilayer Films and Laminates].

What Influences Film Barrier Performance?

Several factors can influence the barrier properties of a film, including:

  • Material composition: different materials exhibit different transmission characteristics.
  • Thickness: thickness can affect the measured transmission rate.
  • Layer structure: the combination and arrangement of layers influence the performance of multilayer films.
  • Coatings and metallization: additional layers can modify barrier performance.
  • Temperature: temperature can influence transmission behavior.
  • Relative humidity: humidity can affect certain materials and their barrier properties.

Because these factors can influence the measured result, test conditions must be considered when evaluating or comparing materials.

How Are Barrier Properties Evaluated?

Barrier properties are evaluated through tests that measure the transmission of a specific substance through a material under defined conditions.

Depending on the property being investigated, the relevant parameter may be:

  • OTR for oxygen transmission;
  • WVTR for water vapor transmission;
  • CO₂TR for carbon dioxide transmission.

The results provide quantitative information about the material’s performance and can be used to compare alternative materials or structures.

Reliable comparisons require consistent test conditions and appropriate measurement methods.

For more information about the measurement process, see How Is the Permeability of a Plastic Film Measured?.

How to Compare Films with Different Barrier Properties

Comparing films requires more than looking at a single measurement value.

It is important to consider:

  • the substance being measured;
  • the parameter used;
  • sample thickness and structure;
  • temperature and humidity conditions;
  • the measurement method.

A material with a low oxygen transmission rate may not necessarily exhibit the same relative performance for water vapor or carbon dioxide.

Material selection should therefore be based on the specific barrier properties required by the intended application.

Why Characterize Barrier Properties?

Measuring barrier properties turns material performance into quantitative data that can be evaluated and compared.

These measurements can support:

  • the development of new films;
  • the optimization of multilayer structures;
  • the evaluation of alternative materials;
  • material and supplier qualification;
  • quality control and performance verification.

Barrier characterization is therefore useful in both research and development and routine quality control.

Barrier Properties in Packaging

Barrier properties are relevant to a wide range of packaging applications, including food, pharmaceutical and technical packaging.

Depending on the application, testing may be performed on plastic films, laminates, multilayer structures and materials with functional coatings.

The parameter to be measured depends on the function of the packaging material and the conditions under which it will be used.

For application-specific information, see Permeability Measurement in Food Packaging and Permeability Measurement in Flexible Packaging.

ExtraSolution Solutions for Barrier Property Measurement

ExtraSolution offers instruments for characterizing the barrier properties of plastic films, barrier materials and multilayer structures.

Available solutions include systems for measuring individual transmission parameters and integrated systems for evaluating multiple properties.

For example:

  • MultiPerm O2-CO2 measures oxygen and carbon dioxide transmission.
  • MultiPerm O2-H2O measures oxygen and water vapor transmission.
  • MultiPerm H2O-CO2 measures water vapor and carbon dioxide transmission.
  • TotalPerm integrates measurements of oxygen, carbon dioxide and water vapor transmission.
  • PermeH2O is designed specifically for water vapor permeability measurement.

The appropriate solution depends on the material, the parameters to be measured, the expected measurement range and the required test conditions.

Measure the Barrier Properties of Your Films

ExtraSolution provides solutions for measuring OTR, WVTR and CO₂TR to help characterize plastic films, barrier materials and multilayer structures.

Contact ExtraSolution to identify the most suitable solution for your materials and testing requirements.

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