Advanced characterization of recycled polyolefins: a holistic approach to study their microstructure and contaminations

Achieving the detailed knowledge of recycled materials composition is a formidable task due to the presence of organic and inorganic contaminations. Additionally, the complexity of the microstructure is far superior to the one of virgin materials where the production process is well controlled. Nonetheless, this task is of paramount importance because properties are affected in crucial ways. In this work we studied recycled polyolefin grades with several techniques, in particular through their adaptation to the analysis of this class of materials, to combine the information and obtain a detailed knowledge of their characteristics. Thermogravimetric Analysis (TGA), X-Ray Fluorescence (XRF), X-Ray Computed Tomography (CT) and Scanning Electron Microscopy (SEM) were used to characterize inorganic contaminations. CT and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterize organic contaminations. Microstructure details were evaluated by Nuclear Magnetic Resonance (NMR) and fractionation and thermal analysis methods. Also the limitations of the various techniques are addressed.