(84c) Investigation of the Carbon Nanotube Interfacial Tailoring Effects On the Mechanical and Viscoelastic Properties of Carbon Nanotube Epoxy Nanocomposites

Nanocomposites represent a class of functional materials with tailored properties that include enhanced thermal and mechanical stability, electrical conductivity and EMI shielding, diffusion and transport properties, and anti-vibration and damping. They have applications such as actuators, adaptive and smart materials, and highly stable light weight structural materials for aircraft components. The final properties of the nanocomposites are controlled by the characteristics of the host polymer matrix but more importantly by the properties of the nanophase constituent such as its inherent physical and mechanical properties, dimensionality and aspect ratio, extremely large interfacial area, and three-dimensional spatial orientations.

The interfacial characteristics of the carbon nanotubes (CNTs) were manipulated using covalent bonding of a series of diamines including linear aliphatic, aromatic and flexible ether linkage in epoxy resin matrix. The objectives were to examine the effects of the rigidity and the polarity of the interface on the final characteristics of the epoxy carbon nanotube nanocomposites. Surface treatments of CNTs were performed by acid oxidation of CNT (mixture of sulfuric/nitric acid in a 3:1 (v/v ratio)) and converting the carboxylic groups to acyl chloride. This was followed by condensation of the carboxylic groups with the diamines molecules. CNTs surface modifications were studies using FT-IR, XPS, and TGA. Surface modified carbon nanotubes were dispersed in the epoxy resin matrix with the aid of solvent and sonication. Dynamic mechanical analyses of the nanocomposites were performed to examine the storage shear moduli and the damping characteristics of the nanocomposites. Nanocomposites containing CNT modified with higher initial oxygenated functional groups exhibited larger increase in the storage shear moduli. Surface examination of the nanocomposites with SEM exhibited formation of nanoropes.