Properties of Poly(carbonate) Containing Oxide Nanoparticles

Nanocomposites composed of poly(carbonate) (PC) and oxide nanoparticles have been studied. For BaTiO$_{\mathrm{3}}$ both as-received and surface-treated (3-aminopropyl-trimethoxysilane) nanoparticles were utilized. The complex relative permittivity, $\varepsilon $*$= \varepsilon $'-j$\varepsilon $'', at audio frequencies from 5K to about 500K and the room temperature breakdown strength have been determined. Also, SEM, DSC and TGA studies have been carried out. $\varepsilon '$ is 11 for PC containing 59 wt-{\%} of untreated 50-70 nm diameter BaTiO$_{\mathrm{3}}$ and $\varepsilon '$ vs. nanoparticle content is larger than would be expected on the basis of the modified Hanai equation. Also, the breakdown strength is low and decreases as nanoparticle content increases. However, $\varepsilon '$ is low and the breakdown strength is high for PC containing the surface-treated nanoparticles. The gamma relaxation (200K and 1000 Hz) does not change as nanoparticle content increases to 59 wt-{\%}. Also, a low temperature relaxation region (in the vicinity of 20K) associated with the nanoparticles is found in the nanocomposites. Next, the breakdown strength increases as BaTiO$_{\mathrm{3\thinspace }}$nanoparticle size increases from 50 nm to 500 nm.