Fragmentation (Plastic)

Plastic fragmentation is the breakdown of larger plastic debris into smaller particles through UV photodegradation, mechanical abrasion by waves and sand, thermal stress, and partial biodegradation, while the polymer backbone persists. Fragmentation drives the size cascade from macroplastic (over 5 mm) through microplastic (under 5 mm) toward nanoplastic, generating secondary microplastics that dominate marine particle counts. Embrittled surface layers crack and shed, so a single weathered item produces thousands of fragments. Because fragmentation increases particle number and surface area without removing polymer mass, it raises bioavailability to filter feeders and zooplankton and seeds the plastisphere with colonizable surfaces.