Quality Loss Rate Testing of Packaging Materials: Standards, Methods, and Applications

Quality loss rate testing measures the percentage of mass that a packaging material loses under controlled heating, drying, or aging conditions, providing a reliable indicator of volatile content, residual moisture, and additive stability. Accurate determination of this parameter is essential for compliance with food-contact regulations, pharmaceutical packaging requirements, and manufacturing quality specifications. This article explains the technical principle, sample types, test items, measurement methods, applicable standards, and practical applications of quality loss rate testing for packaging materials.

Technical Overview

Quality loss rate, also referred to as mass loss rate or weight loss rate, is defined as the relative reduction in the mass of a packaging material after it has been subjected to a specified thermal or environmental treatment, expressed as a percentage of the original mass. The parameter is calculated as follows: Quality Loss Rate (%) = (m0 − m1) / m0 × 100, where m0 is the initial mass of the conditioned specimen and m1 is the mass measured after the specified treatment.

For packaging materials, an excessive mass loss is a critical warning signal. It may indicate high levels of retained solvents from printing or laminating processes, elevated volatile organic compound (VOC) content, unreacted monomers or oligomers, excessive moisture, or the migration and evaporation of plasticizers, stabilizers, and other functional additives. Such losses can degrade mechanical strength, dimensional stability, and barrier performance, and in food-contact or pharmaceutical applications they may result in contaminant transfer to the product.

Quality loss rate testing is therefore embedded in numerous national and international frameworks, including the GB 4806 series for food-contact materials in China, ISO and ASTM methods for plastics and paper-based materials, and general laboratory practice for incoming material inspection, process validation, and product release. Testing is typically performed by accredited third-party laboratories or in-house quality control facilities using gravimetric techniques with high-precision analytical balances.

Testing Samples

Plastic Films and Sheets

Flexible films made from polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA), polyvinyl chloride (PVC), and ethylene-vinyl acetate (EVA) are among the most commonly tested packaging materials. These samples are evaluated for drying loss, residual solvent content, and additive loss, particularly after printing, coating, or lamination processes.

Rigid Plastic Containers and Articles

Bottles, jars, trays, tubs, closures, and injection-molded or thermoformed components are tested to verify cure completeness, additive stability, and compliance with food-contact or pharmaceutical specifications. Specimens are usually cut from the container body or wall at defined locations to ensure representative sampling.

Paper and Paperboard

Carton board, kraft paper, molded pulp trays, paper bags, and paper cups are tested for moisture content and volatile loss. Because cellulosic materials are hygroscopic, strict conditioning before measurement is essential to obtain reproducible results.

Composite and Laminated Materials

Multilayer structures combining plastic films with aluminum foil, paper, or deposited barrier layers are evaluated for total mass loss and interlayer stability. These samples often contain adhesives and printing inks whose residual solvents contribute significantly to the measured loss.

Foam and Cushioning Materials

Expanded polystyrene (EPS), expanded polyethylene (EPE), and expanded polypropylene (EPP) cushioning materials are tested for volatile content and dimensional-mass stability, since excessive loss can indicate residual blowing agents or thermal degradation.

Testing Items

Depending on the material type, the intended application, and the governing specification, quality loss rate testing may cover the following items:

• Total mass loss on drying (loss on drying, LOD) at a specified temperature
• Volatile organic matter content, including residual printing and laminating solvents
• Moisture content and moisture loss under drying conditions
• Loss of plasticizers, stabilizers, and other migratable additives
• Mass loss after dry-heat treatment or sterilization cycles
• Mass loss after accelerated aging or long-term storage simulation
• Water absorption behavior and extractable or soluble matter loss where specified

Testing Methods

Constant-Weight Oven Drying Method

The most widely applied technique places conditioned specimens in a forced-convection oven at a controlled temperature, commonly 105 °C ± 2 °C for general plastics and paper, with alternative temperatures such as 70 °C, 90 °C, or material-specific values selected to avoid thermal degradation. Specimens are dried to constant weight, typically requiring several hours with reweighing intervals until consecutive masses differ by less than a defined tolerance. The specimen is cooled to ambient temperature in a desiccator before each weighing. This approach is consistent with methods such as ASTM D6980 for water content determination by loss in weight and related gravimetric procedures referenced across GB/T and ISO frameworks.

Volatile Loss Methods

For materials in which plasticizer or volatile additive loss is the primary concern, methods based on activated carbon exposure, such as ASTM D1203, or resin volatility methods such as ASTM D889, may be applied. ISO 176 addresses the determination of loss of plasticizers from plastics and is relevant for flexible PVC packaging structures. These methods expose specimens to defined environments and quantify the resulting gravimetric change over a specified period.

Water Absorption and Immersion Methods

Where the specification requires characterization of moisture-related mass change rather than drying loss, immersion and humid-exposure methods such as ISO 62 and ASTM D570 are used, with the corresponding Chinese national method GB/T 1034. Results distinguish between water absorbed, soluble matter extracted, and net mass change, which is important for paper-based and hygroscopic plastic packaging.

Conditioning and Environmental Control

All specimens must be conditioned before baseline weighing, typically at 23 °C ± 2 °C and 50% ± 10% relative humidity in accordance with ISO 291 or GB/T 2918, unless the product standard specifies otherwise. Consistent conditioning, controlled cooling in a desiccator, and minimized handling time are decisive for repeatability and reproducibility.

Equipment and Calculation

Testing requires an analytical balance with a resolution of 0.1 mg, a calibrated forced-convection oven with uniform temperature distribution, a desiccator with an active desiccant, and appropriately sized weighing vessels. The specimen mass, typically sufficient to provide a representative sample while remaining within balance capacity, is recorded before and after treatment, and the quality loss rate is calculated from the gravimetric difference. Reported results should include specimen description, treatment temperature and duration, conditioning parameters, individual and mean values, and the referenced test method.

Applications

Quality loss rate testing supports a broad range of regulatory, quality assurance, and product development activities across the packaging industry:

• Compliance verification for food-contact materials under the GB 4806 series, including plastics, paper, metals, and composites used in direct food contact
• Pharmaceutical packaging qualification, where mass stability under dry-heat sterilization and storage conditions is a core acceptance criterion
• Incoming material inspection and supplier qualification for films, resins, laminates, and converted packaging components
• Process control for printing, coating, adhesives lamination, and curing operations, where residual solvent and drying completeness must be confirmed
• Shelf-life studies and accelerated aging programs that monitor long-term mass stability and additive retention
• Export certification support, where buyers and regulators require documented gravimetric stability data aligned with ISO, ASTM, EN, JIS, or GB standards
• Failure analysis and customer complaint investigation related to odor, migration, brittleness, or barrier degradation in packaged goods

FAQ

What is quality loss rate in packaging materials?

Quality loss rate is the percentage of mass a packaging specimen loses after a defined thermal or environmental treatment, calculated as the difference between the initial and final mass divided by the initial mass and multiplied by 100. It reflects the combined effect of moisture evaporation, volatile release, and additive migration.

What temperature is typically used for the test?

A drying temperature of 105 °C ± 2 °C is common for general plastics and paper-based materials, while lower temperatures such as 70 °C or 90 °C are selected for heat-sensitive materials to prevent degradation. The exact temperature must always follow the governing product standard or client specification.

How long does a test take?

A single determination usually takes from a few hours to a full working day, depending on the drying time required to reach constant weight and the conditioning period required before the baseline weighing. Studies involving accelerated aging or sterilization cycles may extend over several days or weeks.

What sample size and replication are required?

Typically, multiple specimens are cut from different regions of the sample to account for material variability, and the mean result is reported along with individual values. The required number of specimens and the minimum specimen mass depend on the referenced standard and the homogeneity of the material.

What result is considered acceptable?

Acceptance limits depend entirely on the material type and application. For example, food-contact plastics and pharmaceutical packaging grades often impose strict limits on drying loss and volatile content, while industrial packaging may allow broader tolerance. The applicable limit is defined by the relevant GB, ISO, ASTM, EN, or JIS standard or by the contractual product specification.

Which laboratories can perform this testing?

Testing can be carried out by accredited third-party laboratories or by manufacturer quality control laboratories equipped with calibrated balances, ovens, and controlled conditioning facilities, provided that the selected method and the laboratory scope match the applicable regulatory and contractual requirements.