Excellent mechanical performance and enhanced dielectric properties of OBC/SiO2 elastomeric nanocomposites: Effect of dispersion of the SiO2 nanoparticles

Abstract

Two kinds of fumed SiO2 nanoparticles with the same average diameter but distinct surface characteristics (hydrophilic A200 and hydrophobic R974) were incorporated into an ethylene-α-olefin block copolymer (OBC) to prepare high-performance thermoplastic elastomeric nanocomposites via simple melt mixing. Hydrophilic A200 exhibits a particular chain-like distribution while hydrophobic R974 shows a homogenous dispersion in the nanocomposites. The rheological percolation threshold of OBC/A200 nanocomposites was much lower than that of OBC/R974 nanocomposites, showing a more developed nanoparticle network in OBC/A200 nanocomposites. Thermodynamic analysis revealed that the particular chain-like distribution of A200 and more developed network structure are due to the selective localization of hydrophilic A200 in the melt. The reinforcement effect of hydrophilic A200 in OBC/A200 nanocomposites is always higher than that of hydrophobic R974 in OBC/R974 nanocomposites at the same filler loading, and even better, the increments in the tensile modulus of OBC/A200 nanocomposites are almost four times higher than that of OBC/R974 nanocomposites at the same silica loading. Besides, the dielectric permittivity of the OBC/A200 composite at low frequency was also higher than that of the OBC/R974 composite with the same loading of filler at the same frequency. These results provide guidance for the preparation of high-performance elastomeric nanocomposites with both excellent mechanical performance and enhanced dielectric properties.