Investigation of the impact of microwave treatment on the aging of polypropylene microplastics

The aging process of microplastics (MPs) is significantly influenced by temperature, and MPs are susceptible to thermal degradation by heating, drying, and cooking. Microwave (MW) ovens in households are frequently used for heating/cooking food in plastic containers, potentially affecting the properties of MPs. We utilised polypropylene (PP) MPs, commonly used as takeaway material to understand the effects of MW treatment. PP MP solutions were prepared in deionised water and deposited on glass slides for analysis using optical photo-thermal infrared spectroscopy (O-PTIR). This novel method enables the detection of submicron particles with 500 nm spatial resolution, and addresses challenges posed by fluorescence interference in Raman and the limited spatial resolution of FTIR. Following initial characterization, PP MPs were subjected to MW treatment for 3-15 min at 1000 W. Additionally, imaging analysis of optical images of samples was employed for measuring morphological properties. The area of MW-treated samples decreased but was not statistically significant. The intensity of the peak at 1016 cm-1 associated with C-C bond stretching increased after 9 and 15 min of MW treatment, suggesting potential bond breakage induced by MW energy. Furthermore, peaks within the 1500 - 1350 cm-1 range exhibited slight shifts after 15 min of exposure, indicative of molecular rearrangements within the polymer structure due to MW radiation. PCA was employed and PC1 loading explained 60 Also see: https://micro2024.sciencesconf.org/557690/document