Photodegradable plastics

Photodegradable plastics refer to plastics that can undergo degradation under the action of light.
1. Examples of photodegradable plastics
According to the manufacturing method, photodegradable plastics can be divided into synthetic degradable plastics and additive degradable plastics.
(1) Synthetic degradable plastics
a. Ethylene/carbon monoxide copolymer (E/CO)
Photodegradation is characterized by main chain breakage. The photodegradation rate and degree of E/CO are related to the amount of ketone groups contained in the chain. The higher the content, the faster the degradation rate and the greater the degree. Scientists in Texas, USA have conducted outdoor exposure experiments on E/CO, and in sunny June, E/CO can degrade as quickly as a few days.
b. Ethylene/vinyl ketone copolymers (Ecolyte)
The ketone groups on the side chains of Ecolyte molecules can undergo decomposition under natural light. Ecolyte has better photodegradation performance than E/CO, but its cost is also higher.
The disadvantage of this type of polymer is that it begins to degrade upon exposure to light, with almost no induction period. Antioxidants need to be added to regulate the induction period.
(2) Additive type photodegradable plastics
Additive type photodegradable plastics are polymers that add a small amount of photosensitizer and act as a photocatalytic degradation catalyst at low concentrations. They undergo a reaction under sunlight (ultraviolet light) irradiation, causing the polyolefin polymer to break.
Adding photosensitizers such as ketones and amines to polymers such as PE and PP can achieve good photodegradation performance.
Additive type photodegradable plastics have low costs, simple production processes, and good results when used as covering films. But its degradation characteristic is that the exposed surface degrades more thoroughly, while the part buried in the soil degrades worse. The degradation induction period of this type of photodegradable plastic can be controlled within two months or more. But the controllability of degradation time is poor.