Preparation of raspberry-like SiO2 nanoparticles and thermo-mechanical properties of its epoxy composites

Raspberry-like SiO₂ (R-SiO₂) nanoparticles were prepared by electrostatic self-assembly of two different sizes SiO₂ nanoparticles under the help of polyelectrolytes, which would be removed by further calcination. The R-SiO₂/epoxy composites were fabricated then by a solvent-free curing process. The morphology of R-SiO₂ and fracture morphology of their epoxy composites were observed by scanning electron microscopic (SEM). Thermo-mechanical properties including storage modulus, glass transition temperature (T_g) and coefficient of thermal expansion (CTE) are critical properties for SiO₂/epoxy composites. To observe these parameters, dynamic mechanical analysis (DMA) and thermomechanical analysis (TMA) were used, respectively. The results showed that the R-SiO₂ particles could be used as effective fillers on increasing T_g and decreasing CTE of the epoxy composites.