Analytical pyrolysis optimization for the quali-quantitative determination of polymer mixtures

In recent years, the problem of "microplastics" has become increasingly worrying, as the amount of plastics that will be produced in the future will increase significantly. Microplastics are defined as emerging pollutants, due to the risks they may cause to the environment and especially to human health. The analytical issue behind their quantification in environmental matrices is quite complex. The thermoanalytical Py-GC/MS technique can provide qualitative and quantitative information about the microplastics more accurate than already applied optical techniques. The first aim of this thesis project was to determine the potentialities and limitations of such method for the quali-quantitative determination of polymers such as PET, PA6, PA66, PS, PP, PE and PVC. Particular attention was put on the interaction between polymers’ pyrolysis products. While this aspect has not been widely addressed in literature yet, it could result a limitation to the application of such technique for quantification purposes. Along this work pyrolytic interactions between PET with PA6, PA66 and PVC that lead to the formation of new compounds, were determined. These interferences were thought to be responsible in part for compromising the reproducibility of quantitative analyses.For this reason, polymers derivatisation tests were carried out with TMAH, an already widely used reagent for the analysis of microplastics. BSTFA and HMDS, other more innovative derivatisers in this field of research, were tested. TMAH proved to be very effective in eliminating interferences from a qualitative point of view. It also produced more satisfactory results for quantitative determination. However, the silylating reagents showed limitations in eliminating interactions. This precluded their use for possible quantification tests. The results of this study provides the basis for the development of a robust thermoanalytical technique for microplastic quantification in environmental samples.