The difference between degradable, biodegradable and compostable
The white pollution of the environment caused by traditional plastic bags is becoming more and more serious. With the continuous improvement of people’s environmental awareness, degradable plastic bags, fully biodegradable plastic bags, fully degradable plastic bags, and various new types of degradable plastic bags have come out one after another. Both base plastics and biodegradable plastics are new materials that are conducive to environmental protection and sustainable replacement of traditional plastics currently mainly made of petroleum. "Degradable", "biodegradable" and "compostable" are terms that people often refer to when talking about these materials. It is easy to confuse them. They are similar but different. So what is the difference between them?
1. Degradable plastic bags
Degradable plastic bags include plastic bags that can be degraded by physical and biological factors (light or heat, or microorganisms). The so-called aerobic degradation (that is, accelerated degradation by catalysts or activators at high temperatures) or photodegradable starch-polyethylene plastics will cause some environmental problems. These degradable plastic bag materials do not degrade as fast as compostable plastics and may leave debris. These degraded fragments have a large surface area and may migrate to groundwater and soil. Some highly toxic substances, such as PCB and DDT, are adsorbed and retained on the surface. The content of toxic substances is as high as 1 million times the background content, which is enough Become a delivery system for toxic substances in the environment. Therefore, it is necessary to ensure that the product is completely biodegradable in a very short time determined by the treatment facility.
2. Biodegradable plastic bags
Biodegradable plastic bags are those plastic bags that can be completely digested by the microorganisms in the processing system as food for energy (entering the food chain). The determination of this complete microbial digestion/utilization is measured by testing whether the carbon element of the test plastic can be completely converted into CO2 through the microbial process occurring in the cell.
3.Compostable plastic bags
In addition to being biodegradable by microorganisms, there must be a time requirement for a plastic bag to be called "compostable" plastic. For example, ASTM 6400 (specification for compostable plastics), ASTM D6868 (specification for biodegradable plastics used for surface coating of paper or other compostable media) or EN 13432 (compostable packaging) standards stipulate that these materials are used in industrial composting environments It should be biodegraded within 180 days. The industrialized composting environment refers to the prescribed temperature of about 60°C and the presence of microorganisms. According to this definition, compostable plastics will not leave fragments longer than about 12 weeks in the residue, contain no heavy metals or toxic substances, and can sustain plant life.