Green polymeric composites based on construction and packaging waste: toward advanced insulating materials

This study explores the development of sustainable polymeric composites using waste polystyrene (WPS) as the base matrix reinforced with sawdust (SD), red brick waste (RbW), and ceramic waste (CW). Composites were prepared with hybrid filler loadings of 0-40 wt% relative to 100 g of the total composite. Chemical composition and particle size of the solid waste were characterized by X-ray fluorescence (XRF) and Transmission electron microscope (TEM) to evaluate the probability of using these waste powders as novel alternative fillers for polymeric composites. XRF results showed high SiO₂ and Al₂O₃ content in CW and RbW, while SD exhibited a high loss on ignition, confirming its organic nature. TEM results showed that the particle size of all solid inorganic wastes is in the nano size range, which makes them suitable for use as novel alternative fillers instead of traditional fillers. Mechanical tests and water absorption were measured for prepared blends, and the results revealed that tensile strength increased significantly with the addition of hybrid fillers, reaching a maximum of 25.45 MPa for the WPS/CW composite, while WPS/SD had the lowest tensile strength, which was 17.41 MPa. Elongation at break was slightly decreased with the addition of CW or RbW. Also, water absorption decreased with increasing demolition waste content, showing superior resistance to water absorption for WPS filled with CW after 15 days. Thermo gravimetric analysis, dynamic mechanical analysis (DMA), dielectric, and electrical conductivity measurements were employed to understand the thermal stability and physical properties of the composites under investigation. Dielectric measurements indicated that WPS composites filled with CW had higher permittivity and lower dielectric loss, making them recommended for electrical insulation applications. DMA also illustrated that storage modulus and glass transition temperature (Tg) enhanced with addition CW confirming enhanced thermal-mechanical stability.