Influence of aging and colorants on environmental degradation of polyolefins

Plastic litter breaks down into microplastics (MPs) and nanoplastics over time, but their environmental lifespan remains largely unknown. Understanding the degradation of plastic litter in the environment remains a fundamental question in MP research. This study highlights the significant role of colorants in the degradation process by analyzing forty-four naturally aged polyethylene (PE) lobster trap tags collected from the marine environment and an old, heavily degraded polypropylene (PP) product. The lobster trap tags, marked with their production year, indicate their time in the marine environment, with the oldest dating back to 1983, while the PP tub, over forty years old, had undergone extensive photodegradation in sunlight. Chemical, thermal, mechanical and surface property analyses revealed that the aging of PE tags is not directly proportional to their environmental degradation. Among the eight different tag colors, blue and green were the least degraded, while red showed the most degradation, emphasizing the influence of colorants. In contrast, the PP sample exhibited severe surface degradation, with significant fragmentation leading to MP formation, while its interior remained relatively intact. These findings underscore the complex interactions between environmental factors and material properties in plastic degradation.