Plastic is one of the greatest inventions of the 20th century, but it is now banned or discarded in many fields because it is “not environmentally friendly”. One of the products in its place is “degradable plastics” such as PLA straws or cornstarch lunch boxes. However, is degrading plastic necessarily more environmentally friendly? How does it degrade? How to judge whether a material is environmentally friendly? We try to answer these questions from the classification and degradation conditions of degradable materials.
Degradable plastics refer to substances that can be degraded into environmentally harmless substances under specific natural environment conditions after use, and are a general term for a large class of degradable materials. Degradable plastics first appeared in the 1960s, and have experienced the development stage of mixing with traditional plastics, the stage of degradation through photothermal conditions, and the stage of degradation through microbial enzymatic reactions. Combining degradable plastics with traditional plastics (such as polyethylene, polypropylene) can only make the traditional plastics more easily disintegrated into small fragments, resulting in more microplastics polluting the environment, so it cannot be considered degradable. Photothermal degradable plastics have poor degradability and are constrained by natural conditions such as temperature and light intensity. For example, mulch film buried in the ground will have little effect or cannot be decomposed at all due to lack of light. Therefore, only plastics that are degradable under biological conditions, also known as biodegradable plastics, are truly degradable plastics and have the value of preventing and controlling plastic pollution.
People often have a misunderstanding: degradable plastics can degrade in any natural environment. In fact, degradable plastics have degradable properties only when they enter a specific environment, and are not degradable under any natural conditions.
Different degradable plastics can achieve plastic degradation under conditions such as compost, soil burial, and fresh water. However, compared with the soil environment, the marine environment has the characteristics of high salinity and low microbial density. Those plastic products that can be degraded by microbial enzymatic reactions on land often degrade and fail in the marine environment.
Actively responding to plastic pollution is related to the health of the people. Let us act quickly, start from ourselves, start from now, establish the environmental protection concept of “reducing plastic and limiting plastic”, assume environmental responsibility, and do less damage to the environment and more One point of love! Let us join hands and strive to be the demonstrators and advocates of “plastic reduction and plastic restriction”, and promote plastic pollution control with practical actions.
