L-P Sung, S.S. Jhang, S. Rostampour, R. Cook
National Institute of Standards and Technology,
Keywords: microplastics, weathering, spectroscopic databases, environmental impact
Summary:Considering the massive plastic materials in commercial products and the scale of plastic waste in the environments, the impacts are global. Plastic waste incompletely degrades due to environmental factors (such as sunlight and temperature). The weathered plastics can be chemically and physically different from the pristine plastic material. Identification of chemically transformed plastics can be a challenge, as spectroscopic databases (e.g., infrared spectroscopy, Raman spectroscopy) are not available for weathered plastic materials at different, well-controlled stages of weathering. As weathered plastic particles become smaller, they become theoretically more abundant and toxic, and certainly more difficult to detect and characterize. This objective of this project is to generate systematically degraded plastic particles for use as research grade test materials (RGTM). RGTMs will enable researchers to investigate the environmental impacts of plastic waste in a consistent manner. Current research focus at NIST (National Institutes of Standards and Technology) is to generate weathered plastic particles with the NIST SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) using both top-down and bottom-up approaches, where macro-samples of plastic are UV-weathered while immersed in water (and simulated ocean water) or pristine polymer submicron particles are suspended in water and UV-weathered, respectively. The outcome of this project would provide spectral database (FTIR) of weathered plastics, generation of more relevant, weathered microplastic particles. These weathered plastic particles will be used to evaluate key toxicological assays, and develop microplastic and nanoplastic characterization methods (e.g., microscopy, pyrolysis GC-MS) in collaboration with other NIST researchers.