3-APTES-Functionalized Epoxidized Castor Oil-Epoxy Biocomposite: A Sustainable High Voltage Insulator with Enhanced AC Breakdown Strength

This study developed 3-aminopropyltriethoxysilane-functionalized epoxidized castor oil-epoxy biocomposite as a viable environmental friendly alternative to conventional non-eco-friendly epoxy resin insulators. While the integration of epoxidized castor oil (ECO) into epoxy matrix has shown potential enhancement in some aspects, the incorporation of silane-functionalized ECO into epoxy remains unexplored. In this study, the integration of 3-aminopropyltriethoxysilane-functionalized epoxidized castor oil (AECO) into epoxy resin was investigated, aiming at enhancing AC breakdown strength with eco-friendly modifier. Fourier transform infrared spectrometer confirmed the successfully epoxidation of castor oil with emerging of epoxy associated functional groups, while the successful 3-aminopropyltriethoxysilane (APTES) functionalization of ECO was confirmed through the introduction of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{N}-\mathrm{H}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{S i - O}-\text{S i}$</tex> functional groups into ECO. The relative permittivity was examined by a Novocontrol spectrometer, revealing an increase in dielectric constant of biocomposites up to 3.68018 from 3.15643 exhibited by pure epoxy resin. The biocomposite from AECO and epoxy resin demonstrated the optimal enhancement in breakdown strength of 11.44 % at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$30 \text{wt} \%$</tex> of AECO relative to epoxy resin, attributed to increase in trap density to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4.22 \times 10^{20} \text{eV}^{-1} ~\mathrm{m}^{-3}$</tex> and introduction of deep traps of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{1. 0 1 5 6 ~ e V}$</tex> in the matrix, which limited carrier mobility within the material. APTES functionalization of ECO was confirmed to be essential as ECO-based epoxy biocomposite demonstrated low breakdown strength. These findings highlighted the potential of AECO-epoxy resin biocomposite as a promising eco-friendly high voltage insulator, simultaneously reducing petroleum content in epoxy-based insulators which is finite and depleting resource.