Why doesn't degradable plastic break down?

Recently, people have started to denounce decomposable plastic, which has two main arguments: if decomposable plastic does not decompose completely, then the decomposable plastic that people have been digging up for years for human use will not decompose completely, and if it is crushed by smaller plastic molecules, the environmental pollution will increase.
 

Myth 1: Mining is sustainable.
 

There is a kind of degradable plastic called photolytic plastic bags, which refers to the addition of initiators in plastic raw materials, so that plastic gradually decomposes under the action of photolysis, which is the early form of degradable plastic. Most of it is photodecomposition. After being buried, there is no light. How do you do that?
 

The breaking of small plastic molecules will increase environmental pollution.
 

It is said that when you harm the interests of others, others will also attack you. Whose interests will decomposable plastics touch? Producers of primary or secondary plastics that are not degradable. Along with Hainan, Guangxi, Hebei and other places have issued bans on the use, sales and production of disposable non-biodegradable plastic products, vigorously promote the use of biodegradable plastic products, there are many plastic manufacturers changed or went bankrupt. Will a crackdown on degradable plastic bags help businesses survive? With the attention of human beings and countries to environmental protection and resource utilization, it is an inevitable trend that degradable plastics replace non-degradable plastics.
 

Faced with many problems that cannot be ignored, biodegradable plastic bags can not only be completely degraded in 1-2 years, but also can be composted. The surprising finding is that it can not only self-degrade but also catalyze other plastic products. The principle is actually quite simple. Using natural polymers (starch, cellulose, shellfish, etc.). Or agricultural by-products, alcohols produced by microorganisms or synthetic biodegradable polymers, such as thermoplastic starch plastics, mylar, starch/polyvinyl alcohol, etc.