Residual strain due to solvent loss from a crosslinked coating

Data show that epoxy coatings cast from a very slow- evaporating solvent have residual internal strain that increases with coating thickness. A theory is presented, which agrees well with experimental results, based on the idea that solvent volume loss from the crosslinked coating is responsible for the strain. The strain depends on solvent evaporation and diffusion rates, as well as the curing reaction kinetics and coating solution concentration. A calculation, using this theory, models the excellent adhesion of epoxy coatings and shows that adhesion may be improved by using a faster evaporating solvent.Des donn\ue9es d\ue9montrent que les rev\ueatements d'epoxy coul\ue9s \ue0 partir de solvants \ue0 \ue9vaporation tr\ue8s lente manifestent une d\ue9formation r\ue9siduelle interne d'autant plus importante que le rev\ueatement est \ue9pais. On pr\ue9sente ice une th\ue9orie qui concorde bien avec les r\ue9sultats exp\ue9rimentaux; elle est fond\ue9e sur l'hypoth\ue8se que cette d\ue9formation est imputable au volume de solvant qui a disparu du rev\ueatement r\ue9ticul\ue9. Cette d\ue9formation d\ue9pend autant des vitesses d'\ue9vaporation et de diffusion du solvant, que de la cin\ue9matique de la r\ue9action de r\ue9ticulation et de la concentration de la solution du rev\ueatement. Un calcul, s'appuyant sur cette th\ue9orie, simule l'excellente adh\ue9rence des rev\ueatements epoxy et montre que celle-ci est meilleure si on utilise un solvant \ue0 \ue9vaporation plus rapide.Peer reviewed: YesNRC publication: Ye