Oxygen Permeability and OTR: Measurement and Analysis

Oxygen permeability is an important property when evaluating the barrier performance of films, packaging materials and multilayer structures. Measuring oxygen transmission helps determine how effectively a material limits the passage of oxygen under defined test conditions.

The Oxygen Transmission Rate (OTR) is a key parameter used to characterize oxygen transmission through a material. It provides quantitative information that can support material development, comparison and quality control.

ExtraSolution offers solutions for measuring oxygen transmission and characterizing the barrier properties of films and other materials.

What Is Oxygen Permeability?

Oxygen permeability describes the ability of oxygen to pass through a material. It is an important characteristic of materials designed to provide a barrier against oxygen transmission.

The oxygen barrier performance of a film depends on several factors, including its composition, thickness, structure and the conditions under which it is tested.

In packaging applications, evaluating oxygen permeability can help compare different materials and determine whether their barrier performance meets the requirements of a specific application.

What Is OTR?

OTR stands for Oxygen Transmission Rate. It indicates the rate at which oxygen passes through a material under specified test conditions.

OTR is commonly used to characterize plastic films, barrier films, laminates and multilayer materials.

In general, a lower OTR indicates that less oxygen passes through the tested material under the specified conditions. However, OTR values should only be compared when the relevant test conditions and reporting units are consistent.

OTR is therefore an important measurement parameter for evaluating and comparing the oxygen barrier performance of materials.

Why Measure OTR?

OTR measurement provides quantitative data on the oxygen barrier performance of a material. This information can be useful throughout material development, qualification and production.

OTR testing can help to:

  • compare different films and packaging materials;
  • evaluate the performance of barrier films;
  • support the development of new materials;
  • optimize multilayer structures and laminates;
  • assess changes in material composition or thickness;
  • qualify materials and suppliers;
  • monitor product consistency during quality control.

Measuring OTR allows laboratories to assess oxygen transmission using defined procedures and comparable data.

How Is Oxygen Permeability Measured?

Oxygen transmission is typically measured using a permeation cell in which the sample separates two environments under controlled conditions.

One side of the sample is exposed to oxygen, while the instrument detects the oxygen that passes through the material to the other side.

The system measures oxygen transmission over time and determines the OTR according to the selected test method.

Reliable measurements require appropriate sample preparation and control of relevant test conditions, including temperature and, where applicable, relative humidity.

The measurement procedure depends on the instrument, the material being tested and the applicable testing standard.

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

Which Materials Can Be Tested Using OTR?

OTR testing can be used to characterize a wide range of materials in which oxygen transmission is an important property.

Common examples include:

  • plastic films;
  • barrier films;
  • multilayer films;
  • laminated materials;
  • metallized films;
  • co-extruded structures;
  • membranes and other technical materials suitable for the selected test method.

The choice of measurement configuration depends on the sample characteristics, the expected OTR range and the required test conditions.

OTR and the Barrier Properties of Films

OTR is one of the main parameters used to characterize the oxygen barrier performance of films.

However, the barrier properties of a material cannot always be described by a single parameter. Oxygen transmission, water vapor transmission and carbon dioxide transmission represent different characteristics and may need to be evaluated separately.

For this reason, material characterization should focus on the specific property relevant to the intended application.

For an overview of barrier properties and the factors that influence them, see Barrier Properties of Films: What They Are and How They Are Evaluated.

Oxygen Permeability in Barrier Films

Barrier films are designed to limit the transmission of specific substances through their structure. Their performance depends on the materials used and how the film is constructed.

Oxygen barrier properties may be achieved using different material combinations, coatings, metallized layers or multilayer structures.

OTR testing can help compare these solutions and evaluate the performance of the complete structure rather than relying solely on the characteristics of individual layers.

To learn more about barrier film materials and structures, see Barrier Films: Characteristics, Materials and Measurement Methods.

Factors That Influence OTR

The measured OTR can be affected by several factors, including:

  • Material composition: different polymers and barrier materials can exhibit different oxygen transmission characteristics.
  • Thickness: changes in thickness can affect the measured transmission rate.
  • Film structure: multilayer films and laminates may behave differently depending on the combination and arrangement of their layers.
  • Temperature: temperature can influence the transmission behavior of a material.
  • Relative humidity: humidity can affect the barrier performance of certain materials.
  • Test conditions: the measurement method and conditions must be considered when interpreting the result.

When comparing OTR values, it is important to ensure that the measurements have been performed under consistent conditions.

OTR in Packaging Applications

Oxygen transmission measurement is relevant to many packaging applications in which the oxygen barrier performance of a material must be characterized.

OTR testing can be used to evaluate films, laminates and multilayer structures during material selection, packaging development and quality control.

The appropriate test depends on the packaging material, its intended function and the requirements of the application.

Standards and Test Methods for OTR Measurement

OTR measurements should be performed according to an appropriate test method and under defined conditions.

The applicable standard depends on the material, the measurement technique and the requirements of the test. Temperature, humidity, sample preparation and reporting units should be considered when interpreting results or comparing measurements.

Where a specific standard is required, the instrument configuration and test procedure should be selected accordingly.

How to Choose an OTR Tester or Analyzer

Selecting an OTR analyzer starts with identifying the material to be tested and the measurement requirements.

Important factors include:

  • sample type and dimensions;
  • expected OTR range;
  • required temperature control;
  • humidity control requirements;
  • number of samples to be tested;
  • applicable test methods and standards;
  • whether other permeability parameters must also be measured.

The most suitable configuration depends on the laboratory’s testing objectives and the characteristics of the materials being analyzed.

ExtraSolution Instruments for OTR Measurement

ExtraSolution offers solutions for measuring oxygen transmission through films and barrier materials.

Depending on the required measurements, available systems include:

  • MultiPerm O2-CO2 — for oxygen and carbon dioxide transmission measurements;
  • MultiPerm O2-H2O — for oxygen and water vapor transmission measurements;
  • TotalPerm — for characterizing oxygen, carbon dioxide and water vapor transmission using an integrated system.

The appropriate instrument depends on the required measurement parameters, sample characteristics and operating conditions.

Applications of OTR Measurement

OTR testing can support a range of activities, including:

  • research and development of new materials;
  • characterization of plastic and barrier films;
  • evaluation of multilayer films and laminates;
  • packaging material qualification;
  • comparison of alternative material structures;
  • quality control and verification of material performance.

Measure Oxygen Transmission with ExtraSolution

ExtraSolution provides solutions for OTR measurement and the characterization of oxygen barrier properties in films and other materials.

Contact ExtraSolution to identify the most suitable configuration for your materials, measurement range and test requirements.

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