Synergetic effects of silicon nanoparticles and multi-walled carbon nanotubes on the structural and dielectric properties of polystyrene-based nanocomposites

In the present study, high-impact polystyrene (HIPS) nanocomposites filled with nano-silicon In the present study, high-impact polystyrene (HIPS) nanocomposites filled with nano-silicon particles (Si) and multi-walled carbon nanotubes (MWCNTs) were prepared, their structural, dielectric, and mechanical properties were investigated. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of Si nanoparticles and the preservation of the MWCNTs’graphitic (002) structure. Atomic Force Microscope (AFM) analysis confirmed that the addition of hybrid fillers leads to changes in the surface morphology. It was determined that the root mean square (RMS) surface roughness decreased from approximately 85 nm for pure MWCNTs to about 30 nm for the HIPS + Si + MWCNT nanocomposite. Dielectric measurements showed that the HIPS+1.5 wt.%Si+1.5 wt.%MWCNT nanocomposite exhibited the highest dielectric response. The dielectric constant increased by approximately 3.5 times at 1 kHz compared to neat HIPS. A relaxation maximum observed at 125 Hz and was corresponding to an effective relaxation time of τ = 1.27 m. At 200 kHz, the AC conductivity was calculated as σ ≈ 10 –8 S/cm, consistent with near-percolation behavior. Mechanical testing revealed that tensile strength increased from 14.06 MPa to 17.49 MPa with hybrid filler incorporation, while relative elongation decreased from 82% to 17.88%, indicating the typical stiffness–ductility trade-off. The results demonstrate that hybrid Si/MWCNT fillers induce synergistic effect on dielectric and mechanical performance in HIPS-based nanocomposites.