Study on morphology and mechanical properties of PMMA-based nanocomposites containing POSS molecules or functionalized SiO 2 particles

Abstract

Nanocomposites of octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) and functionalized SiO₂ were investigated in order to determine the effect of particles on the morphology and mechanical properties of PMMA. The outcome of the study suggested that functionalized SiO₂ and octavinylPOSS molecule had different morphology. As proved by X-ray diffraction and transmission electron microscopy analysis, the crystal structure of OVPOSS molecule was significantly different from amorphous aggregates of functionalized SiO₂. With the additional particles in the nanocomposites, the sizes of octavinylPOSS and functionalized SiO₂ began to reduce. This illustrated that the separation of aggregates led to the formation of irregular POSS molecules and amorphous SiO₂ particles varied. Differential scanning calorimetry analysis indicated that PMMA-POSS nanocomposites had a homogeneous system. However, there was a significant phase separation at 3 wt.% SiO₂. PMMA-SiO₂ nanocomposites displayed lower reinforcing effects than expected, based on the mechanical properties of nanocomposites containing OVPOSS molecules.