1. Basic definition
Degradable materials: refers to materials that can gradually decompose into natural substances (such as water, carbon dioxide, methane, etc.) under specific environmental conditions (such as microorganisms, light, humidity, etc.), avoiding long-term accumulation and pollution.
Compared with traditional plastics (which take hundreds of years to degrade), degradable materials can decompose within a few months to a few years under ideal conditions.
2. Degradation Principle
Biodegradation: Enzymes secreted by microorganisms (such as bacteria and fungi) decompose materials into small molecules.
Photodegradation: The chemical structure of materials is broken by ultraviolet rays or sunlight.
Oxidative degradation: Chain reactions occur under the action of oxygen, and eventually break down.
Note: Different degradation methods need to match specific environments. Not all "degradable" materials can be quickly decomposed in the natural environment.
3. Common types
PLA (polylactic acid): derived from corn starch, commonly used in packaging and tableware, requires industrial composting conditions (high temperature and humidity + microorganisms).
PHA (polyhydroxyalkanoate): synthesized by microorganisms, can also be degraded in the marine environment, but the cost is relatively high.
Starch-based materials: improved products mixed with traditional plastics, may have residual microplastics.
PBAT (polybutylene adipate/terephthalate): good flexibility, used in plastic bags, requires a composting environment.
4. Key misunderstandings
"Degradable" ≠ "discarded at will": most require specific industrial composting facilities (such as 50-60℃ high temperature), and the degradation efficiency in the natural environment is extremely low.
"Fully degradable" and "partially degradable": some materials only break into microplastics, which still need to be distinguished.
Confusion in logos: international standards (such as EU EN 13432 and US ASTM D6400) need to be recognized.
5. Realistic challenges
Cost: The price of biodegradable materials is usually 2-3 times that of traditional plastics.
Recycling system: They need to be classified separately. If they are mixed with ordinary plastics, they will interfere with the recycling process.
Performance limitations: Heat resistance and strength may be insufficient, which limits the application scenarios.
6. Application examples
Food packaging, agricultural mulch, disposable tableware, medical sutures and other short-term use products.
Replacement of traditional plastics in "high pollution areas" (such as express bags and straws).
7. Future Directions
Develop materials with lower cost and wider environmental adaptability (such as seawater degradable plastics).
Improve degradation infrastructure (such as community composting stations).
Policy promotion (such as plastic ban + degradable subsidies).
If you want to go deeper into a certain aspect (such as details of a certain material, policy cases, etc.), you are welcome to discuss further!
