Polymers in the ocean: understanding long-term durability and degradation—a review

Polymers are employed extensively in marine environments due to their resistance to corrosion, reduced weight compared to metals, and lower maintenance costs. However, the harsh marine environment, characterized by seawater, oxygen, UV radiation, and mechanical stresses, significantly affects the long-term performance of polymer-based structures. This study describes the impact of water interaction on polymer ageing and the consequences for mechanical behavior. While oxidative and biodegradation mechanisms are known to have significant effects, this review concentrates on the ubiquitous interaction between water and polymers. The paper examines water absorption mechanisms, the factors that influence them, and the resulting physical and chemical effects on polymers. It provides insights into the relationship between water-polymer interactions and the mechanical performance of marine polymers, offering a foundation for the design of more durable materials and improved service life prediction in challenging aqueous environments, as well as the understanding of plastic fragmentation in the ocean. The findings underline the need for accelerated ageing studies to predict polymer durability in service, emphasizing the importance of replicating natural degradation pathways for reliable lifetime estimations.