How to Distinguish Degradable, Biodegradable and Compostable?

When designing a new product, it is important to consider its ecological behavior, which relates to how it is ultimately handled. Of particular concern are those used in single-use packaging and consumer products. Designing these materials to be biodegradable and ensuring they end up being properly systematically disposed of is good for the environment and ecology.

In the past, polymers were designed to be non-degradable materials. Today, the challenge is to design polymers that have the desired function during use, but decompose after use. More importantly, the degradation products cannot be toxic and cannot persist in the environment for a long time, but can be completely digested by soil microorganisms within a certain period of time like food. To ensure market acceptance of biodegradable food packaging products, there is no doubt that these eco-friendly food packaging materials need only be demonstrated to be biodegradable within a short period of a few weeks in a waste management infrastructure. However, these are not sufficient to clearly explain the difference between "degradable", "biodegradable" and "compostable" plastics. Further explanation will be given below.

1. Eco-friendly food packaging degradable materials

Eco-friendly food packaging degradable materials include plastics that can be degraded by physical and biological factors (light or heat, or the action of microorganisms). So-called oxodegradable (that is, accelerated degradation by catalysts or activators at high temperatures) or photodegradable starch-polyethylene plastics pose some environmental concerns. These materials do not degrade as quickly as compostable plastics and can also leave debris. The hydrophobic fragments formed by these degradation have a large surface area and may migrate into groundwater and soil, adsorb and retain some hydrophobic highly toxic substances such as PCB and DDT on their surfaces, making the toxic substance content up to 1% of the background content. A million times, enough to be a delivery system for toxic substances in the environment. Therefore, it must be ensured that the product is fully biodegradable within a very short period of time determined by the processing facility.

2. Eco-friendly food packaging biodegradable materials

Biodegradable materials for food packaging eco are those plastics that can be fully digested by the microorganisms in the processing system as food for energy (entering the food chain). The determination of this complete microbial digestion and utilization is measured by testing whether the carbon element of the test plastic can be completely converted into CO2 through the microbial processes that take place in the cells.

3. Eco-friendly food packaging compostable materials

In addition to being microbially degradable, there is a time requirement for a plastic to be called "compostable". For example, the specification for compostable plastics, the specification for biodegradable plastics for surface coating of paper or other compostable media, or the standard for compostable clamshell packaging states that these materials should biodegrade within 180 days in an industrial composting environment. An industrial composting environment refers to a specified temperature of about 60°C and the presence of microorganisms. By this definition, eco-food packaging compostable plastic leaves no debris in the residue for longer than about 12 weeks, contains no heavy metals or toxic substances, and supports plant life.