Plastic is known as the main culprit of “white pollution” because it is not easy to degrade, can last a long time, and seriously pollute the environment. But why can't plastic be degraded?
First of all, there are two main types of plastics: thermoplastic and thermosetting. Thermoplastic plastics can be heated and then made through a molding process, while thermoset plastics are unchangeable once molded. The structure of both types of plastics consists of macromolecules, which are interlocked with each other to form a three-dimensional network structure that is difficult to break down.
Thermoplastics have a looser structure, which means that there is less interlocking between the chains, so this type of plastic breaks down more easily, but not completely. Thermoset plastics have a much tighter structure, which makes them more difficult to break down.
Second, plastics are biochemically inert. In biology, “inert” refers to an organism's lack of reactivity to a biochemical reaction, meaning that it is unable to serve as a substrate for a biochemical reaction. Plastics have a similar biochemical inertness. Plastics do not contain nutrients and lack elements such as oxygen and carbon that microorganisms need for decomposition. As a result, microorganisms lack sufficient nutrients and energy to break them down. Strength of polymer bonds in plasticsThe polymer bonds in plastics are very strong and difficult to hydrolyze by microorganisms and enzymes, and are not easily broken by other chemicals. Because of the amazing stability of the chemical structure of these polymer bonds, plastics can be stored for long periods of time without breaking down.
In summary, the inability of plastics to be degraded is due to their polymer structure, biochemical inertness, and polymer bond strength. We need to actively explore ways to biodegrade polymers, improve the conversion efficiency of resource recycling, and reduce the impact of plastic pollution on the environment.
