A: Such as photo-oxidative degradation plastics, which are not real biodegradable plastics, but this photodegradable material is the first to popularize the concept of degradation, probably in the 1960s and 1970s. Photooxidation plastics, which are ordinary petroleum-based plastics, add some additives that can cause the breakage of petroleum-based plastic molecular chains by the action of sunlight, so they can become plastic fragments under the action of light. This degradation has relatively large defects: the first photodegradation does not really achieve degradation, and the second decomposes into plastic fragments, which have a very serious impact on plants and microorganisms, and also produce microplastics.