Water sorption-desorption-resorption and swelling were studied for a model epoxy system based on DGEBA resin and triamine curing agent. Four types of carbon nanofillers were incorporated into the epoxy matrix: multiwall carbon nanotubes, graphite nano-platelets, expanded graphite platelets, and carbon black. Two-stage sorption and swelling behaviour was observed for all types of nanocomposites. An extent of the anomalous sorption depends on temperature, time and history of the test, and type of the filler. Diffusion-relaxation model of Berens and Hofenberg finely described sorption and resorption experimental curves, while desorption of all samples obeyed the Fick's law. The only additional parameter - relaxation time of polymer network - was introduced into general equations. The relaxation time increased with the addition of nanofillers and decreased with temperature increase. Dynamic mechanical thermal analysis was done to evaluate the plasticizing effect due to the absorbed water and to give an insight into the structural changes of the nanocomposites caused by their hydrothermal ageing. Water absorption resulted in plastification of the polymer that appeared in drop of glass transition temperature and lowering and broadening of tan δ peak, while after-cure and physical ageing effects appeared in the increased storage modulus.
