*3.1.2 Thermal degradation*

Plastic waste litters on the coastal shorelines are exposed to elevated temperatures, leading to a thermo-oxidative breakdown of the plastic. Thermal degradation of plastics involves absorption of heat and breaking of polymeric chains thus releasing radicals that react with atmospheric oxygen to produce hydroperoxide, which eventually cleaves into hydroxyl and alkoxy free radicals. These radicals result in the formation of aldehydes, ketones, esters, or alcohols, causing plastic degradation [69]. Chain scission and cross-linking of the polymers are responsible for the thermal degradation process [70, 71]. In the environmental matrix related to beaches and coastal shorelines, slow thermal degradation of plastics may occur concurrently with photodegradation (due to the presence of sunlight), resulting in enhanced plastic degradation [72].
