Why are special storage conditions required?
Biodegradable plastics PLA and PBAT are designed to decompose under specific conditions. While this characteristic contributes to environmental protection, it also necessitates special storage methods for preservation. Proper storage conditions not only maintain material properties but also ensure that the degradation process only begins when necessary, preventing premature failure.
I. Temperature Control: Preventing Unplanned Degradation
Biodegradable plastics are extremely sensitive to temperature. To ensure stable performance and prevent premature degradation, the storage environment temperature should be strictly controlled between 15-25℃. If the temperature is consistently above 30℃, the material’s molecular chains may undergo accelerated hydrolysis, leading to decreased strength and shortened lifespan; if the temperature is below 5℃, it is prone to embrittlement and deformation. Drastic temperature fluctuations should be avoided in particular to prevent inducing internal stress in the material, affecting the reliability of the finished product. It is recommended that warehouses be equipped with temperature and humidity monitoring equipment, with enhanced ventilation and cooling in summer and adequate insulation and antifreeze measures in winter.
1. Suitable Temperature Range
(1) Optimal Storage Temperature: 15-25℃
(2) Critical Temperature: Avoid prolonged exposure to environments above 30℃
(3) Low Temperature Limit: Not below 5℃ to prevent material embrittlement
2. Effects of Temperature Fluctuations
Research has found that for every 10℃ increase in temperature, the degradation rate of PLA may increase by 2-3 times. In high-temperature environments during summer, improper storage may cause the product to begin to show performance degradation within 6 months.
II. Humidity Management: Controlling Hydrolysis Reactions
The chemical structures such as ester bonds in biodegradable plastics are extremely sensitive to moisture. The relative humidity of the storage environment must be strictly controlled below 50% to avoid moisture triggering material hydrolysis, leading to molecular chain breakage and performance degradation. It is recommended to use moisture-proof sealed packaging with built-in desiccants (such as silica gel) and monitor the ambient humidity regularly. The warehouse should be far away from water sources and avoid condensation caused by temperature fluctuations to ensure the material remains stable during storage and prevent premature degradation.
1. Key Indicator Requirements
(1) Relative Humidity: Should be controlled below 50%
(2) Packaging Protection: Moisture-proof and sealed packaging must be used
(3) Desiccant Use: It is recommended to place silica gel desiccant inside the packaging.
2. Water Activity Control
For starch-based biodegradable plastics, when the ambient humidity exceeds 60%, the material may undergo premature hydrolysis, resulting in a decrease in mechanical strength of more than 20% within 3 months.
III. Light Protection: Avoid Photodegradation
Light, especially ultraviolet light, accelerates the breakage of molecular chains in biodegradable plastics, triggering photo-oxidation reactions, leading to premature aging, discoloration, or embrittlement. Direct sunlight and strong fluorescent light must be strictly avoided during storage. It is recommended to use opaque packaging or store in a light-protected environment. Experiments show that effective light protection can extend the material’s lifespan by more than 40%, ensuring that degradation only begins under pre-set composting conditions and avoiding performance loss during storage.
1. Impact of Ultraviolet Radiation
(1) Direct Sunlight: Avoid exposure to direct sunlight.
(2) Artificial Light Sources: Reduce lighting with strong ultraviolet radiation, such as fluorescent lamps.
(3) Packaging Requirements: Use opaque packaging materials or those with added UV stabilizers.
2. Storage Environment Selection
Studies show that, under the same conditions, biodegradable plastics stored away from light can have a lifespan that is more than 40% longer than products exposed to light.
IV. Ventilation and Air Quality Control
The storage environment should maintain adequate ventilation, avoiding stagnant air or strong convection, to balance temperature and humidity and prevent localized condensation. At the same time, air quality should be strictly controlled, keeping the area away from pollutants such as volatile chemical substances and acidic gases to prevent oxidation or corrosion of the materials. Warehouses should be equipped with low-velocity air circulation systems and air filtration devices to ensure stable oxygen concentrations and that the concentration of harmful substances is below safe limits, providing a neutral and clean storage environment for biodegradable plastics.
1. Ventilation Requirements
(1) Moderate Ventilation: Maintain air circulation but avoid strong convection.
(2) Air Quality: Avoid pollutants such as chemical gases and acidic substances.
2. Oxygen Control
Although biodegradable plastics require oxygen for degradation, high-concentration oxygen environments should be avoided during storage to prevent premature oxidation reactions.
V. Packaging and Storage Standards, Storage Period Management
To ensure the stable performance of biodegradable plastics, their packaging must use moisture-proof and light-proof sealed materials. The storage environment must be kept cool, dry, and well-ventilated, strictly adhering to the principles of storage away from walls and the ground, and “first-in, first-out.” Storage periods vary depending on the material type: PLA products are typically 12-18 months, PBAT products are approximately 18-24 months, and starch-based materials are generally limited to 6-12 months. The integrity of the packaging and the condition of the materials must be checked regularly, and an expiration date warning mechanism must be established to avoid performance degradation or premature degradation due to over-expiration storage.
1. Packaging Material Selection
Moisture-proof layer: Aluminum foil composite material or high-barrier plastic
Cushioning material: To prevent mechanical damage
Sealing performance: To ensure the packaging remains intact
2. Warehouse Management
Goods should be stored at least 15cm off the ground
Maintain a distance of at least 30cm from walls
Follow the “first-in, first-out” principle
3. Storage Period Management
Recommended storage periods for different materials:
PLA products: 12-18 months
PBAT products: 18-24 months
Starch-based materials: 6-12 months
4. Quality Control
Establish a regular inspection system, including:
Monthly inspection of packaging integrity
Quarterly sampling and testing of performance indicators
Establish emergency plans for abnormal situations
VI. Special Requirements for Special Materials
Different biodegradable materials have different storage requirements: PLA materials require special attention to moisture and light protection, and the storage temperature should not exceed 25℃; PBAT has good temperature resistance but needs to be protected from direct ultraviolet radiation; starch-based materials must strictly control humidity below 50% and avoid high-temperature environments. Cellulose composite materials need attention to mold and insect prevention, while composite materials with added natural fibers also need additional light protection. Each material should have a specific storage plan tailored to its chemical properties to ensure optimal performance throughout its shelf life.
1. Storage Considerations for PLA Materials
(1) Sensitive to humidity, requiring careful moisture control
(2) Poor heat resistance, requiring strict temperature control
(3) Avoid contact with alkaline substances
2. Storage Characteristics of PBAT Materials
(1) Relatively resistant to damp heat
(2) Storage conditions still need to be controlled
(3) Pay attention to UV protection
3. Special Considerations for Starch-Based Materials
(1) Strict moisture and mold prevention
(2) Control storage temperature
(3) Shorten the shelf life
VII. Conclusion: Scientific storage is key to ensuring performance.
The unique characteristics of biodegradable plastics determine the importance of their storage conditions. Proper storage not only extends product lifespan but also ensures optimal performance during use. Enterprises, distributors, and consumers should all prioritize controlling storage conditions to jointly maintain the environmental value of the product.
Through scientific storage management, we can ensure that biodegradable plastics play their due role when needed, rather than “retiring prematurely” during storage. This requires the joint efforts of all links in the industrial chain. From production to use, proper storage management must be done at every stage to truly maximize the value of environmentally friendly materials.
