Plastic degradation refers to the process where polymer materials reach the end of their lifecycle, resulting in reduced molecular weight. This manifests as brittleness, cracking, softening, hardening, or loss of mechanical strength. Conventional plastic bags can take decades or even centuries to degrade, and if disposed of in landfills or incinerated, they contribute to environmental pollution. To address this issue, degradable plastic bags were developed.
Degradable plastic bags are manufactured by incorporating specific additives-such as starch, modified starch, cellulose, photosensitizers, or biodegradation agents-that reduce their stability and accelerate decomposition in natural environments.
Types of Degradable Plastic Bags
Photodegradable Plastic Bags
1.Contain light-sensitive additives that break down the plastic when exposed to sunlight.
2.Disadvantage: Degradation time is unpredictable due to varying sunlight exposure and weather conditions.
Biodegradable Plastic Bags
1.Decompose entirely into low-molecular compounds through microbial action.
2.Advantages:
Easy to store and transport only requires dry conditions, no need to avoid light.
Widely used in agricultural films, packaging, and medical applications.
3.With advancements in biotechnology, biodegradable plastics have become a major focus in sustainable material research.
Photo/Biodegradable Plastic Bags
1.A hybrid of photodegradable and biodegradable plastics, combining the degradation mechanisms of both.
Water-Soluble Plastic Bags
1.Contain water-absorbing additives that dissolve when discarded in water.
2.Primarily used in medical supplies for easy disposal and sterilization.
How to Identify Degradable Plastic Bags
Certification Marks
1.For food-grade bags, check for the QS (Quality Safety) mark and the label "For Food Use."
Shelf Life & Degradation Characteristics
1.Degradable plastic bags typically have a short shelf life (around 3–5 months).
2.Even unused bags may start degrading naturally after five months, developing a "snowflake" texture by the sixth month.
3.Under composting conditions, they can fully degrade in just three months.
Conclusion
Degradable plastic bags offer a more sustainable alternative to traditional plastics, but their environmental benefits depend on proper disposal systems. Consumers should verify certifications and handle them according to guidelines to maximize eco-friendliness.