AUTHOR=Tang Chih-Cheng , Chen Ying-Ting , Zhang Yi-Ming , Chen Huey-Ing , Brimblecombe Peter , Lee Chon-Lin 

TITLE=Cracking and Photo-Oxidation of Polyoxymethylene Degraded in Terrestrial and Simulated Marine Environments

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.843295

DOI=10.3389/fmars.2022.843295

ISSN=2296-7745

ABSTRACT=Marine plastic debris is an environmental problem, and its degradation into microplastics (0.1-5000 μm) introduces them into the food chain. However, little is known about the mechanisms by which plastic waste ages in the environment. In this study, small polyoxymethylene (global production ~3000 Tg per year) pellets were exposed in terrestrial and simulated marine environments to heat and light, resulting in cracking during decay with increasing IR absorption (OH-bonds). Furthermore, sunlight over three years reduced pellet mass and diameter (~10% and ~40%), initially yielding 100-300 μm fragments. Changes under UV irradiation were smaller as it could not penetrate into particle interiors. Characteristic spacing of surface striations (100-300 µm) initiated radial cracks to pellet interiors, and breakdown ultimately meant 95% of particles were <300 µm, which are potentially incorporated in marine turbidites. The fragmentation of polyoxymethylene in sunlight forms microplastics which are increasingly difficult to retrieve, so mitigation should focus on reduced use of plastics and preventing their release into the environment.