RSM-based optimization of mechanical and moisture resistance properties of ternary polymer nanocomposites

Abstract Epoxy-based polymer Nanocomposites are widely investigated for electrical insulation applications due to their exceptional mechanical and dielectric properties; however, moisture absorption and brittleness remain major challenges. This study aimed to develop and optimize Epoxy/ Ethylene Propylene Diene Monomer (EPDM) /nano-silica ternary nanocomposites with increased tensile strength and reduced water absorption using Response Surface Methodology (RSM) based on Central Composite Design (CCD). The effects of EPDM concentration, nano-silica loading, and sonication time were evaluated through 20 experimental runs. Water absorption was measured according to ASTM D570 after 240-hour immersion, while tensile strength was determined using ASTM D638 standard. The statistical analysis showed that all three processing parameters significantly affected the measured responses within the investigated experimental ranges, with nano-silica loading showing the largest statistical effect. The developed linear models showed satisfactory fit and predictive statistics, with non-significant lack-of-fit results. Increasing nano-silica loading and sonication time was associated with increased tensile strength and reduced water absorption within the experimental design space. These response trends may be related to changes in the polymer–filler environment and the processing-dependent state of the silica-containing phase. The optimized formulation exhibited a tensile strength of 90.9 ± 0.46 MPa and water absorption of 0.0441 ± 0.0003% under the investigated test conditions. Overall, the results demonstrate the potential of the Epoxy/EPDM/nano-silica system as a candidate for further investigation in electrical-insulation applications.