Structure and properties of vinyl ester resins modified with organophilic synthetic layered silicates bearing non- and co-reactive intercalants

OLS were incorporated in various amounts (0.1 to 5 wt.%) in VE. The intercalants of synthetic fluorohectorite were TMDA and OAE, respectively. The latter quaternary amine was expected to support the intercalation/exfoliation of the silicate by participating in the crosslinking reactions. Both OLS types became intercalated based on X-ray diffractograms. DMTA displayed a slight increase in the stiffness by adding OLS. The glass transition temperature did not change practically with the OLS type and content. Fracture mechanical tests were performed on CT specimens. Both the fracture toughness (K-c, maximum improvement ca. 45%) and fracture energy (G(c), maximum improvement ca. 100%) increased with increasing OLS content. As expected, OAE proved to be a more suitable intercalant than TMDA in respect to the overall property profile. The failure mode of the specimens was studied in a SEM and discussed. The fractographic inspection revealed that the composites contained abundant OLS microparticles triggering crack pinning and crack bifurcations.