Ultimate properties of rubber and core-shell modified epoxy matrices with different chain flexibilities

Preformed polystyrene-co-butylacrylate (PScoBu) core-shell particles and po lystyrene microspheres as well as amine-terminated butadiene nitrile (ATBN) rubber have been used for modification of both rigid and more flexible cro sslinked DGEBA-based epoxy networks having significantly different crosslin k densities. Some variations in cure kinetics have been shown by both therm al and rheological measurements. Independently of the crosslink density of the neat epoxy matrix, function of the cycloaliphatic or aliphatic hardener used, the toughening effect via core-shell modification has been found as good as that for rubber modification but with a better retention of thermal properties. Results are investigated as a function of the morphologies obt ained by scanning electron microscopy (SEM) but also by atomic force micros copy (AFM). Larger fracture toughness was obtained for every-unmodified and modified- epoxy matrices cured with the aliphatic hardener as a consequenc e of the lower crosslink density of the corresponding mixtures. (C) 2001 Kl uwer Academic Publishers.