Key indicators in accelerated aging testing mainly include changes in appearance, retention of mechanical properties, changes in physicochemical properties, and functional indicators. These are the core basis for judging product stability and predicting lifespan.
1. Appearance and Sensory Changes (Intuitive Failure Warning)
This is the most direct observation indicator, used for early problem detection.
Color Change: Measured using a colorimeter, ΔE value is generally required to be ≤ 2.0 as acceptable.
Surface Defects: Such as cracks, chalking, blistering, mold, exudates, etc., especially common in plastics and coated materials.
Transparency/Clarity: Applicable to liquids or transparent materials; turbidity or sedimentation indicates performance degradation.
2. Retention of Mechanical Properties (Core of Material Durability)
Key data reflecting the structural integrity of the material, commonly used in the evaluation of materials such as plastics, rubber, and packaging.
Tensile strength retention ≥ 80%
Elongation at break retention ≥ 50%
If below this standard, it indicates that the material has become significantly embrittled or aged.
Flexural strength and impact toughness: Used to assess the structural components' resistance to damage during long-term use.
Industry-standard criteria: Aging coefficient can also be used.
3. Physicochemical performance indicators (deep stability verification)
Revealing chemical or physical changes occurring within the material.
pH changes: Affecting product compatibility and corrosion risk.
Moisture content/loss on drying: Reflecting the loss of hygroscopic or volatile components.
Viscosity changes: Crucial for liquid products (such as adhesives and cosmetics).
Thermal stability parameters: Such as glass transition temperature (Tg) and thermal decomposition temperature, obtained through DSC and TGA analysis.
4. Functionality and safety indicators (application-oriented verification)
Verifying whether the core functions are maintained for specific product types.
Active Ingredient Content: This includes whether the concentration of active substances in pharmaceuticals and sunscreen agents in cosmetics meets standards.
Microbiological Stability: This includes total bacterial count, mold and yeast counts, and sterility testing, especially critical in food and medical devices.
Electrical Performance Changes: This includes changes in volume resistivity, dielectric strength, and leakage current, used for reliability assessment of electronic components.
Packaging Sealing: Leakage is detected using vacuum decay methods to ensure the integrity of the sterile barrier.
5. Key Indicators for Specific Application Scenarios
The focus varies depending on the industry's needs:
|
Application Area |
Key Indicator Examples |
|
Medical Devices |
Sterility, Packaging Sealing, Material Compatibility, Exudate Analysis |
|
Food/Pharmaceuticals |
Main Component Degradation, Related Substances, Dissolution Rate, Shelf Life Prediction |
|
Electronic Materials |
CMTI Immunometry, Insulation Resistance, TDDB Lifetime Model Estimation |
|
Plastics/Coatings |
Gloss Decrease, Chalking Grade, Retention of Mechanical Properties After UV Aging |
In summary, the key to accelerated aging testing lies in "multi-dimensional indicator linkage analysis"-single data is insufficient to determine overall reliability; it is necessary to combine appearance, mechanical, chemical, and functional indicators to accurately extrapolate the true shelf life and ensure product safety.
