Stress-Dependent Water Uptake Behavior of Clay Reinforced Nanocomposite Epoxy
Layered silicate nanolayers can be used as alternative inorganic components for the construction of nanostructured hybrid composites. The clay silicate nanolayers possess stable Si-O bonds and high particle aspect ratios comparable to conventional fibers. Their interlayer surface is easily modified by ion-exchange reaction, and the gallery can be intercalated by organic polymer precursors for the formation of organic-inorganic nanocomposites. Exfoliated clay composites contain single, 1 nm thick layers of clay dispersed in the polymer matrix. Owing to the platy morphology of the silicate layers, exfoliated clay nanocomposites can exhibit dramatically improved properties such as barrier and mechanical properties that are not available for conventional composite materials. Since the clay particles scavenge water, the nanocomposite samples initially absorb slightly higher amounts of water in comparison to the no-clay samples, with the water molecules congregating around the clay particles. On the other hand, the presence of these clay particles still hinders diffusion of water through the sample, thus protecting the structural interfaces. In this work, low viscosity liquid aromatic diglycidyl ether of bisphenol A (DGEBA) epoxy resin Epon 815C was mixed with nanoclay at 60°C for 6 hours. The epoxy-clay mixture was then mixed with curing agent DETA (Diethylenetriamine) at 80°C for 4 minutes and cured at 120°C for 3 hours to produce exfoliated clay — epoxy resin system. These samples were used to first optimize the percent clay level for lowest water uptake, and subsequently immersed in water in stressed condition (flexural stress) to assess the effect of stress on nanocomposite epoxy system for its water uptake behavior. The results revealed up to 33% reduction in water uptake for the stressed samples.
ASME 2005 International Mechanical Engineering Congress and Exposition
Sancaktar, Erol and Kuznicki, J., "Stress-Dependent Water Uptake Behavior of Clay Reinforced Nanocomposite Epoxy" (2005). Polymer Engineering Faculty Research. 1564.