Determination of Barrier Properties of Packaging Materials: Testing Standards, Methods, and Applicat

Barrier property testing measures how effectively packaging materials resist the permeation of oxygen, water vapor, and other gases, providing essential data for shelf-life prediction and quality assurance. Accurate determination of oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) helps manufacturers select the right materials, validate packaging designs, and comply with international standards such as ASTM, ISO, and GB. This article provides a comprehensive technical overview of barrier performance testing, including sample types, test items, standardized methods, industry applications, and frequently asked questions.

Technical Overview

Barrier properties refer to the ability of a packaging material to retard the transmission of gases, water vapor, and volatile organic compounds through its structure. For products such as foods, pharmaceuticals, medical devices, and electronics, the ingress of oxygen or moisture is a primary driver of degradation, including oxidation, rancidity, hydrolysis, microbial growth, corrosion, and loss of sterility. Determining barrier performance is therefore a cornerstone of package development, shelf-life modeling, and regulatory compliance.

Permeation through polymer-based packaging follows the solution–diffusion mechanism: permeant molecules are adsorbed on the high-concentration side of the material, dissolve into the polymer matrix, diffuse through it along a concentration gradient, and desorb on the low-concentration side. The measured transmission rate depends on the intrinsic permeability of each layer, total material thickness, layer architecture, temperature, relative humidity, and the presence of defects such as pinholes, cracks, or poor lamination.

Quantitative barrier characterization is typically expressed as oxygen transmission rate (OTR) in cm³/(m²·24h·atm), water vapor transmission rate (WVTR) in g/(m²·24h), or permeability coefficients that normalize for thickness and pressure difference. These measurements are performed in accredited third-party laboratories or in-house facilities using instruments and procedures defined by standards organizations including ISO, ASTM, DIN, JIS, and GB (Chinese national standards).

Testing Samples

Monolayer Plastic Films and Sheets

Common test articles include single-polymer films such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyamide (nylon, PA), polyvinylidene chloride (PVDC), ethylene-vinyl alcohol copolymer (EVOH), cyclic olefin polymer (COP), and polylactic acid (PLA). These materials span a wide barrier range from moderate (PE, PP) to high barrier (EVOH, PVDC).

Multilayer Laminates and Coated Structures

Flexible packaging is usually a laminate combining several functional layers, for example PET/Al/PE, OPP//PVDC, PA/EVOH/PE, or metallized PET (VMPET) structures. Barrier testing of laminates evaluates the combined performance of the full structure, including adhesives and coating continuity.

Paper, Paperboard, and Biodegradable Materials

Coated or laminated papers, wax-treated boards, and compostable films based on PLA, PBAT, or cellulose are tested to verify moisture and grease resistance for cartons, sachets, and sustainable packaging formats.

Rigid Containers and Finished Packages

Bottles, jars, closures, blister packs, thermoformed trays, and sealed pouches can be tested as whole packages. Whole-package testing captures the influence of seams, seals, closures, and liners, which often dominate real-world barrier performance.

Testing Items

Barrier performance determination covers a family of measurable parameters, each addressing a specific permeant or product requirement:

• Oxygen transmission rate (OTR) of films, sheets, laminates, and finished packages.
• Water vapor transmission rate (WVTR), also called moisture vapor transmission rate (MVTR).
• Carbon dioxide and nitrogen gas transmission rates for modified atmosphere packaging (MAP) design.
• Permeability coefficient, diffusion coefficient, and solubility coefficient for material science evaluation.
• Aroma and organic vapor permeation (e.g., flavors, fragrances, solvents) using specialized detector configurations.
• Grease and oil resistance for fatty food and cosmetic packaging.
• Whole-package gas and moisture ingress for sealed containers, bottles, and blister packs.

Testing Methods

Oxygen Transmission Testing

Two principal methods are used. The coulometric (equal-pressure) sensor method, described in ASTM D3985, ASTM F1927, ISO 15105-2, and GB/T 19789, passes carrier gas through a chamber and measures oxygen permeated to a coulometric sensor; it offers high sensitivity suited to medium and high barrier films. The manometric (differential-pressure) method, covered by ASTM D1434, ISO 15105-1, GB/T 1038, and JIS K 7126, measures pressure increase in an evacuated downstream chamber and can be extended to gases other than oxygen. Finished packages are tested per ASTM F1307 using package-adapted coulometric fixtures.

Water Vapor Transmission Testing

The gravimetric cup method (ASTM E96/E96M, ISO 2528, GB/T 1037, JIS Z 0208) seals the specimen over a desiccant or water reservoir and tracks mass change over time; it is simple and widely accepted. The infrared sensor method (ASTM F1249, ISO 15106-2, GB/T 21529) uses modulated infrared detection of permeated water vapor and delivers fast, highly repeatable results, including at low transmission levels. Electrolytic and gas-chromatographic detector variants are covered under ISO 15106-3 and ISO 15106-4.

High-Barrier and Whole-Package Testing

For ultra-high barrier structures such as foil laminates, SiOx- or AlOx-coated films, and pharmaceutical blister foils, extended conditioning periods, low-range sensors, and careful leak checking are required to reach equilibrium and achieve reliable detection limits. Whole-package methods may use static or dynamic accumulation of permeated oxygen inside a sealed test chamber, providing realistic ingress data for MAP products and sensitive dosage forms.

Test Conditions and Conditioning

Standard climates include 23 °C at 0% or 50% RH for oxygen testing and 38 °C at 90% RH for tropical-condition water vapor testing. Because barrier properties of hydrophilic polymers such as EVOH and nylon are strongly humidity-dependent, testing at multiple humidity levels is recommended for products distributed across diverse climates. Specimens must be conditioned before measurement, and results must always report the temperature and relative humidity at which they were obtained.

Applications

Barrier property data directly support product protection and regulatory decisions across many industries:

• Food and beverage: shelf-life modeling, MAP gas-ratio selection for snacks, coffee, dairy, oils, and processed meats, and validation of foil and metallized structures.
• Pharmaceuticals: moisture and oxygen protection for tablets and capsules, blister foil qualification, and support of ICH stability studies for moisture-sensitive dosage forms.
• Medical devices: verification of sterile barrier systems in terminally sterilized packaging consistent with ISO 11607 requirements.
• Electronics: moisture barrier qualification for moisture-sensitive components, desiccated packaging, and humidity-controlled storage bags.
• Cosmetics and chemicals: aroma retention, prevention of oxidation of active ingredients, and compatibility assessment of sachets and tubes.
• Packaging development: material screening, supplier comparison, conversion-process evaluation (e.g., effect of orientation, metallization, or lamination), and quality control lot release.

FAQ

What is the difference between transmission rate and permeability coefficient? Transmission rate (e.g., OTR, WVTR) describes flux through a specific specimen of given thickness under stated conditions, whereas the permeability coefficient is a material property normalized for thickness and pressure difference, allowing comparison between different materials.

Why do OTR and WVTR results depend on temperature and humidity? Higher temperature increases polymer chain mobility and permeant diffusivity, while humidity can plasticize polar polymers such as EVOH and nylon, dramatically raising their oxygen transmission. Results are only comparable when obtained under identical conditions.

Should I test flat film or the finished package? Flat-film testing is ideal for material selection and specification, while whole-package testing reflects the influence of seals, creases, closures, and material deformation during forming. A complete evaluation often includes both.

How long does barrier testing take? Moderate-barrier films typically reach equilibrium within several hours to one day. High-barrier structures may require several days of conditioning and measurement to achieve a stable, validated result at the required detection limit.

Which standards should be specified on a test report? Reports should identify the method standard (e.g., ASTM D3985, ASTM F1249, ISO 15105-2, GB/T 21529), test temperature and humidity, specimen thickness, test area, and results with measurement uncertainty where applicable.