Development and optimization of sustainable recycled gypsum composites for high-performance EMI shielding

• Sustainable gypsum, vermiculite, and RPU provide eco-friendly EMI shielding. • Blend-press-sinter composites optimized with RSM and validated via COMSOL simulations. • HR-SEM shows gypsum, vermiculite, and RPU traits enhance composite performance. • FTIR confirms chemical interactions in gypsum composites for better EMI shielding. • Optimized composites achieve -38.240 dB EMI SE, offering sustainable shielding. The growing demand for lightweight, eco-friendly materials with effective electromagnetic interference (EMI) shielding properties necessitates the exploration of sustainable alternatives to conventional shielding solutions. This study investigates gypsum-based composites enhanced with vermiculite and recycled rigid polyurethane (RPU) powder using a blend-press-sinter methodology. The composites were fabricated through controlled mixing, sieving, and compression processes to ensure uniform filler distribution. Optimization was performed using Response Surface Methodology (RSM) with a Central Composite Design (CCD), and shielding effectiveness was evaluated over the 8–12 GHz frequency range using a vector network analyzer. The optimal composition—15 wt.% vermiculite, 15 wt.% RPU powder, and 70 wt.% gypsum—achieved a predicted EMI shielding effectiveness (SE) of –39.653 dB. The experimental SE of the confirmation sample was –38.240 dB, with a 3.70% error from the predicted CCD value and 2.94% from the COMSOL-simulated value (–37.147 dB). HR-SEM and FTIR confirmed the morphological uniformity and chemical interaction among fillers. These lightweight, cost-effective, and potentially biodegradable composites offer a promising sustainable solution for EMI shielding in electronic, aerospace, and telecommunication applications.