Methods of Recycling Expanded Polystyrene Waste: Synthesis and Characterization

This work reports the recycling of waste polystyrene that was expanded by homgeneous sulfonation reactions using different methods. The obtained sulfonates polystyrenes (PSS) were identified using various techniques such as FTIR spectrometry, Thermogravimetric Analysis (TGA), and X-ray diffraction (XRD). The FTIR spectrometry showed the appearance of the S-O band at 1050 cm-1 and S=O at 1180 cm-1 of the sulfur trioxide, which confirmed the polystyrene’s modification. It is important to note that great thermal stability happened for the material which was modified at T=445°C, compared with the starting one T=400°C. In addition, the average macromolecular masses (Mv) were obtained by viscosity. The polymer exhibited polyelectrolyte behavior. The results showed an increase up to 69% in the degree of sulfonation due to the essentially higher time, beside a positive correlation between the degree and the color during synthesis. This outcome ultimately indicated a high percentage of changing benzene rings and the results were confirmed by the potentiometric dosage method.