ASTM D3985 Testing: Determining Oxygen Transmission Rate (OTR) of Plastic Films and Packaging Materials
What is ASTM D3985 Testing?
ASTM D3985 describes a standard method for measuring the oxygen gas transmission rate through plastic film and sheeting using a coulometric sensor.
This test measures the amount of oxygen passing through a film as a function of time, under controlled temperature and humidity conditions.
The method provides a quantitative measure of oxygen barrier performance, making it crucial in assessing packaging materials that protect against oxidation-sensitive products, such as food, pharmaceuticals, and electronics.
In other words, ASTM D3985 helps manufacturers estimate how well packaging prevents oxygen from permeating through it and spoiling the shelf life, stability, and quality of packaged goods.
Why is ASTM D3985 Testing Important?
Controlling oxygen exposure is vital in maintaining the quality and safety of oxygen-sensitive products. ASTM D3985 testing plays a key role by:
- Determining the oxygen barrier properties of films and coatings used in packaging.
- Ensuring product freshness, flavor retention, and prevention of spoilage.
- Supporting regulatory compliance and performance specifications required by the food and pharmaceutical industries.
- Enabling material selection and quality assurance during product development.
- Helping identify the effect of environmental factors (temperature, humidity) on barrier performance.
This test is crucial for industries that seek to ensure packaging integrity and meet consumer and regulatory expectations for durability, safety, and extended shelf life.
Which Materials Can Be Tested Under ASTM D3985?
ASTM D3985 is suitable for a wide range of polymeric materials and films, including:
- Single-layer and multi-layer plastic films
- Coated papers and laminates
- Flexible packaging materials
- Plastic containers and sheets
- Barrier coatings and metallized films
Common materials tested include:
Polyethylene (PE), Polypropylene (PP), Polyethylene Terephthalate (PET), Polylactic Acid (PLA), Nylon, and EVOH-based multilayer films.
Specimens are typically tested in film or sheet form, although some adaptations permit the testing of molded articles or coated materials.
What Information Do ASTM D3985 Test Results Provide?
The test provides key oxygen transmission and permeability data, as summarized below:
| Parameter | Unit | Description |
| Oxygen Transmission Rate (OTR) | cc/m²·day | Volume of oxygen passing through a unit area of film per day |
| Permeability | cc·mm/m²·day·atm | Oxygen transmission normalized for film thickness and pressure |
| Steady-State Time | hours | Time taken for oxygen flow to stabilize |
| Temperature & Humidity Dependence | — | Effect of environmental conditions on transmission rate |
These results provide a clear indication of how well a packaging material resists oxygen permeation, guiding material selection and process optimization.
What Industries Use ASTM D3985 Testing?
This test method is extensively used in industries where oxygen control is critical, including:
- Food & Beverage Packaging: To maintain freshness and prevent rancidity in snacks, dairy, meat, and beverages.
- Pharmaceuticals: Ensures drug stability by minimizing oxygen exposure.
- Medical Devices: Protects sensitive instruments and sterile packaging.
- Electronics: Prevents oxidation and moisture damage in protective films.
- Agriculture: Used for films in modified atmosphere packaging (MAP).
- R&D & Material Science: For evaluating new barrier materials and coatings.
What Equipment Is Used for ASTM D3985 Testing?
The core test setup includes:
- Oxygen Transmission Analyzer (Coulometric Sensor System): Measures oxygen passing through the film.
- Test Cell: Holds the film sample between two chambers—one containing oxygen, the other nitrogen.
- Temperature and Humidity Control Unit: Maintains standard test conditions.
- Flow Controllers: Regulate gas streams on both sides of the specimen.
- Data Acquisition System: Automatically records and calculates OTR values.
How Is the ASTM D3985 Test Performed?
Step-by-Step Procedure:
- Sample Preparation:
Film specimens are cut to the required size and thickness. Any pinholes or defects are avoided. - Conditioning:
Samples are pre-conditioned at the test temperature and relative humidity (commonly 23°C and 0–100% RH, as specified by the test). - Mounting:
The specimen is clamped in the test cell, separating two gas chambers — one with pure oxygen and the other with nitrogen. - Testing:
Oxygen permeates through the film and is detected by a coulometric sensor on the nitrogen side. - Measurement:
The instrument records the steady-state oxygen flow rate, which is used to calculate the OTR. - Data Analysis:
The OTR is reported as the volume of oxygen (cc) transmitted per square meter of film per day, normalized for test conditions.
What Are the Standard Test Conditions?
| Parameter | Typical Condition |
| Temperature | 23°C ± 2°C |
| Relative Humidity (RH) | 0%, 50%, or as specified |
| Test Gas (Upper Chamber) | 100% Oxygen |
| Carrier Gas (Lower Chamber) | Nitrogen (O₂-free) |
| Pressure Differential | 1 atm |
| Sample Thickness | Measured before testing |
| Duration | Until steady-state oxygen flow is achieved |
Stable conditions are crucial for ensuring consistent and reproducible results.
Key Properties Measured
ASTM D3985 quantifies the rate of oxygen transmission through polymeric films under defined temperature and humidity.
The key property measured — Oxygen Transmission Rate (OTR) — indicates a material’s ability to protect contents from oxidation.
A lower OTR value indicates better barrier performance and an extended shelf life for packaged products.
Related Testing Methods
Complementary or alternative methods include:
- ASTM F1927: Oxygen transmission rate using a coulometric sensor for thin films
- ASTM F2622: Oxygen transmission through packages
- ASTM F1307: Oxygen transmission rate for rigid containers
- ISO 15105-2: Oxygen transmission rate using coulometric sensor method
- ASTM F1249: Water vapor transmission rate (WVTR) using infrared detection
These related methods help evaluate comprehensive barrier properties against both oxygen and moisture.
Conclusion
ASTM D3985 is a scientifically robust and industrially accepted test method to determine the oxygen transmission rate of plastic films and sheets.
The test quantifies oxygen permeability, thus ensuring the attainment of performance, durability, and shelf-life requirements in packaging, medical, and electronic applications.
With the growing emphasis on product preservation and sustainability, ASTM D3985 helps manufacturers select high-barrier materials, validate quality control, and ensure conformance to international standards in packaging.
It remains the cornerstone in barrier property testing: so vital to designing packaging that guarantees the freshness, stability, and integrity of the product’s shelf life.
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FAQs on ASTM D3985 – Oxygen Transmission Rate (OTR) Testing
What does the ASTM D3985 test measure? ASTM D3985 measures the rate at which oxygen gas permeates through a plastic film or sheet under controlled temperature and humidity conditions. The result, known as the Oxygen Transmission Rate (OTR), indicates how effectively the material blocks oxygen.
Why is OTR testing important in packaging? OTR testing helps ensure that packaging materials maintain product freshness and quality by limiting oxygen ingress. For food, it prevents spoilage and rancidity; for pharmaceuticals, it provides stability and potency; and for electronics, it prevents oxidation and degradation.
What units are used to express OTR? The OTR is typically reported in cc/m²·day (cubic centimeters of oxygen per square meter per day) at a specified temperature and relative humidity.
