The development of improved material, i.e. stronger, lighter, more heat, and impact resistant, has been a general pursuit of mankind. Recently, the development of nanocomposite has shown large potential for new materials with improved properties. However, the process by which nanocomponents modify the physical and thermal properties of the polymer matrix is still far from understood. The present study attempts to shed some light on the mechanism of the interaction between nanocomponents and polymer chains. The effect of a dispersion of TiO₂ nanoparticles on the behavior epoxy resins was investigated to determine the type and amount, if any, of interactions between the nanoparticles and polymers. The goal was to establish whether chemical or physical interactions existed. The study focused on three aspects of the properties of nanocomposites: A) the study of the rate of the curing reaction; B) the determination of the thermodynamic characteristics of the nanocomposite and, especially, of variations in glass transition temperatures (T_g); and C) the investigation of physical properties of the nanocomposite.

Results showed that the addition of nanoparticles to the epoxy resin decreased the rate of curing, suggesting that the TiO₂ particles may not have any interactions but act as obstacles to the proper reptation of chains. However, the glass transition temperature, T_g, of fully cured material was shown to increase with the amount of nanoparticles, indicating that interactions do exist under certain conditions. This conclusion was supported by rheological data, namely the fact that frequency sweep measurements showing that values of shear moduli G' and especially G" are more constant at high temperature in the nanocomposite compared to the epoxy resin, implying a more stable material. Creep and relaxation measurements showed that elastic fluctuations were almost eliminated and recovery to stress was much faster in nanocomposite materials, also at high temperatures. These observations were attributed to the possible existence of a chemical binding of TiO₂ with some part of the polymer chains because the added interactions may help store the energy necessary for recovery. Hence some chemical interactions may be present that are only observable under conditions of high temperature.