THE CURE AND DIFFUSION OF WATER IN HALOGEN-CONTAINING EPOXY AMINE THERMOSETS/

Dielectric measurements were performed to determine the effect of chlo rine, methyl and trifluoromethyl substituents on the cure of bis[N,N-b is(2,3-epoxypropyl)-4-aminophenyl]methane with 4,4'-diaminodiphenylsul fone and s(1-methylethylidene)]-bis[2,6-dimethyl]benzamine, and the da ta were analysed to give gelation and vitrification points. Infra-red measurements were also carried out during the cure process to monitor the consumption of epoxy groups. Dynamic mechanical thermal analysis a nd density measurements were carried out on the N,N-diglycidylaniline system and a reduction in the glass transition temperature was observe d to occur with the incorporation of a trifluoromethyl group into the resin structure. Dielectric and gravimetric studies are reported on th e absorption of water by these resins. In agreement with gravimetric d ata for water absorption, dielectric data obtained at 10 Hz showed tha t trifluoromethyl substitution increases the diffusion coefficient whe reas chlorine substitution decreased it. The chlorinated resin exhibit ed a higher than expected initial dielectric increment, which has been attributed to the effect of a micro-porous surface structure of the r esin. Atomic force microscopy of the resins surfaces indicates that th e chlorinated and fluorinated resins have greater surface roughness th an the protonated analogues, consistent with the dielectric observatio ns. Analysis of the amount of 'bound' and 'free' water in the resin sy stems shows that the halogenated resins have a lower percentage of bou nd water and more of the water is in the 'free' state. (C) 1997 Elsevi er Science Ltd.