Effect of UV Exposure on Mechanical Properties of POSS Reinforced Epoxy Nanocomposites

Epoxy nanocomposites containing 5 wt% glycidyl Polyhedral Oligomeric Silsesquioxane (POSS) by weight is prepared. Elastic and viscoelastic properties of the neat epoxy and epoxy/POSS nanocomposite has been studied using nanoindentation technique. Elastic modulus of the polymer systems are determined using modified Oliver-Pharr method taking creep rate into account. Creep compliance properties of the studied systems are determined by fitting a standard linear solid model to the creep plot. Both neat epoxy and epoxy/POSS nanocomposite showed an increase in elastic modulus and a decrease in creep compliance as a function of UV exposure time; although, the effect of UV exposure is more pronounced in case of epoxy/POSS nanocomposite. It is speculated that the excess epoxide groups present in the glycidyl POSS is going through further crosslinking during the UV exposure leading to the observed higher rate of property change compared to neat epoxy.