Dynamic Mechanical Response in Epoxy Nanocomposites Incorporating Various Nano-Silica Architectures

This paper is a continuation of the previous work where the dielectric response (BDS) of epoxy nanocomposites filled with three types of nano-silica architectures, namely core (SiO
2
), core-shell (SiO
2
)-(SiO
2
) and hollow (h-SiO
2
). was investigated. These samples were filled based on their respective nanoparticle surface area, keeping it theoretically constant across all samples. The aim is to better understand the molecular dynamics and physical mechanisms in dielectric nanocomposites to contribute towards developing materials with tailored properties. The samples were characterised based on their dynamic mechanical behaviour (DMA) and their T
g
was measured by DSC. Unlike BDS, there is no additional relaxation peak observed in DMA thermographs besides the conventionally known $\alpha$ and $\beta$. The T
g
of the samples increases as the size of the nanoparticles decreases. Analysis of the height, width and intensity of the tan $\delta$ of $\alpha$ relaxation peak suggests reduction in the localised modes of motion as the size of the nanoparticles reveals a internally plasticised nanocomposite system. The T
g
values obtained from DSC do not vary significantly across the samples. These key findings are discussed in details and demonstrate by providing further evidence that the additional relaxation observed in BDS measurements is potentially due to the presence of hydrogen bond interactions between the polymer matrix and the fillers. However, no significant impact on the viscoelastic-mechanical properties of the nanocomposites is evident.