35.3.2—Some polymers can be degraded by the action

Ultraviolet light can supply enough energy to break polymer bonds or create reactive radicals, causing chains to fragment. This is photodegradation, not necessarily complete biodegradation.

The rate depends on the polymer, light intensity, oxygen and stabilising additives. Fragmentation may produce smaller pieces without converting them fully to CO₂ and water.

A poly(alkene) exposed to sunlight can become brittle as chains break, yet the resulting microfragments can persist.

“Breaks into pieces” does not mean “biodegradable”; physical fragmentation and biological mineralisation are different endpoints.