Thermal stability and water uptake of high performance epoxy layered silicate nanocomposites

Intercalated and ordered exfoliated layered silicate nanocomposites based on three different epoxy resins of different structures and functionalities were synthesized using an octadecyl ammonium modified smectite clay. Water uptake properties of series of each nanocomposite system with different organoclay concentrations were determined by gravimetric measurements over a period of time. The diffusion coefficients were determined and the effect of the absorbed water on the thermal relaxations investigated. The equilibrium water uptake of all nanocomposites was reduced compared to the neat epoxy system but the rate of water diffusion remained unaffected. Further, the thermal stability of the different nanocomposites was determined using thermogravimetric analysis. The nanocomposites showed slightly reduced thermal stability, as indicated by a slight decrease in onset of degradation, whilst the final char concentration increased for greater organoclay concentrations. (C) 2003 Elsevier Ltd. All rights reserved.