Performance Assessment of Mechanically Recycled EPS

This study investigates the influence of mechanically recycled EPS on the mechanical and thermal properties of EPS composites for use in thermal insulation. Composites containing 5%, 10%, 25%, and 50% recycled EPS were produced using two recycled sources (construction EPS and packaging EPS). The tested properties included density, compressive strength at 10% deformation, bending strength, and thermal conductivity. Results show that increasing recycled content leads to a decline in density, with a more pronounced drop at higher recycled levels, particularly above 10% recycled content in the S1–25 series and 25% in the other series. Compressive strength correlates closely with density regardless of recycled content or origin and the behavior largely aligns with EN 13163 predictive models for virgin EPS. Thermal conductivity remains unchanged at lower recycled contents, with minor increases (up to 6%) observed at 50% recycled content. Bending strength decreases with increasing recycled content with greater losses noted in specimens containing packaging EPS. However, despite containing recycled materials, the empirical equations stated in EN 13163:2016 for predicting thermal conductivity and compressive stress at 10% deformation remain closely correlated regardless of recycled material content, indicating that density remains the main parameter for predicting the tested properties. These findings suggest that EPS with moderate recycled content can meet performance expectations, though further research on microstructure is recommended to understand property degradation mechanisms at higher recycled levels.