Water Transport in Densely Crosslinked Networks: a omparison between Epoxy Systems Having Different Interactive Character

Water transport in a densely crosslinked epoxy network, TGDDM-HHPA, was investigated by coupling time-resolved FTIR spectroscopy and gravimetric measurements. Vibrational anal. yielded information on the different water species present in the system and allowed a quant. estn. of their population at sorption equil. The transport of water mols. was found to follow a Fickian behavior characterized by an effective diffusion coeff. which increases with total water concn. The dependence of the effective diffusion coeff., D eff(C), on concn., as obtained from integral sorption curves, was interpreted by introducing a concn. dependent term, D(C), and an "interaction factor", j, which accounts for the effect of the mol. interactions which effectively slow down the diffusion process. The results were compared with those obtained on another epoxy network, TGDDM-DDS, characterized by the presence of stronger interacting sites. Differences and similarities of the spectroscopic and gravimetric results are critically discussed in the light of the structure of the two networks.