Poly (vinylidene fluoride) (PVDF) composites with high loadings (50-65 wt%) of waste-derived fillers—alum sludge (AS), an inorganic water treatment residue, and wood dust (WD), a lignocellulosic timber by-product—were prepared via melt compounding and compression moulding without compatibilisers. Mechanical, thermal, and dielectric properties were systematically characterised. Increasing filler loading enhanced Young’s modulus but reduced elongation and impact resistance due to restricted chain mobility and stress concentration. Dielectric behaviour differed markedly between the two systems: AS composites exhibited progressive increases in relative permittivity (up to ~70%) attributed... More >