[Fourier transform infrared spectroscopy data] - Photodegradation of macroplastics in the marine environment: fourier transform infrared spectroscopy (EAGER: Collaborative Research: NSF2026: Is Plastic Degradation Occurring in the Deep Ocean Water Column?)

Here, we investigated the weathering of commercially available plastics (tabs 1.3 × 4.4 × 0.16 cm), including high-density polyethylene, low-density polyethylene, polypropylene, polystyrene, and polycarbonate, in seawater under laboratory-simulated ultraviolet A radiation for 3–9 months, equivalent to 25–75 years of natural sunlight exposure without considering other confounding factors.

After the exposure, the physical integrity and thermal stability of the tabs remained relatively intact, suggesting that the bulk polymer chains were not severely altered despite strong irradiation, likely due to their low specific surface area. In contrast, the surface layer (∼1 μm) of the tabs was highly oxidized and eroded after 9 months of accelerated weathering. Several antioxidant additives were identified in the plastics through low temperature pyrolysis coupled with gas chromatography/mass spectrometry (Pyr-GC/MS) analysis.