A Comprehensive Investigation of Waste Expanded Polystyrene Recycling by Dissolution Technique combined with Nanoprecipitation

Abstract In this work, an environmentally friendly and value-added technique was employed to obtain polystyrene (PS) nanoparticles from expanded polystyrene (EPS) waste. The waste was dissolved in ethyl acetate and nanoprecipitated in ethyl alcohol, which are green and renewable solvents. The EPS concentration, stirring speed and solvent/non-solvent ratio (S/N) were evaluated in obtaining nanoparticles. The precipitated nanomaterial was characterized by Dynamic Light Scattering (DLS), Field Emission Gun Scanning Electron Microscopy (FEG-SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TG), Differential Scanning Calorimetry (DSC) and Gel Permeation Chromatography (GPC). It was verified that the smaller nanoparticles were obtained with lower PS concentration (1 wt.%), greater stirring speed (2500 RPM), and higher S/N ratio (1:30). The observed morphology was spherical and no change in the chemical structure of the sample was verified, the glass transition temperature (Tg) was similar (101 °C) and there was no change in the crystalline structure of the sample. Regarding the efficiency and sustainability of the process, all used solvents can be easily recovered by distillation process.