Comparisons of volatile organic compounds emitted from pure and weathered polyethylene and polyethylene terephthalate

It is well documented that microplastics and synthetic microfibers are present in large quantities in the environment across the globe. Large plastic items break down into smaller fragments, many below 5 mm in size, which are then classified as microplastics. The long-term weathering of these microplastics in the environment alters their chemical make-up and structure, but the details of these changes are not well known. To simulate and study the long-term, natural, radical-induced weathering of microplastics in aqueous environments, specific microplastics, polyethylene (PE) and polyethylene terephthalate (PET), have been exposed to ionizing radiation (Cobalt-60 gamma emitter) in water and salt water. The changes in chemical composition of these microplastics can be probed directly and indirectly. One indirect method is the analysis of volatile organic compounds (VOCs) emitted upon heating. The released organics have been collected using solid phase microextraction fibers, then separated and identified using gas chromatography - mass spectrometry. Significant differences between the irradiated and pure polymers have been identified. The full analysis of compounds will be presented and related to the chemical changes induced by the radicals created in natural environments.