The strategies for toughening lightly crosslinked epoxies are relatively well-known and one of the most widely studied model epoxy systems is bisphenol A based epoxy (DGEBA) cured with piperidine (PIP). This epoxy system can be toughened by various types of modifiers and fillers as well as a combination of modifiers and fillers. In this study, the DGEBA/PIP system was cured for 6 hours at 160 C to amplify the toughening effect. Various nanoscale modifiers and fillers were examined. In general, the soft rubber-based modifiers were found to be the most effective for toughening. Scanning Electron Microcopy (SEM) images of the fracture surface revealed that every single rubber particle cavitated at the crack tip, whereas, only a small fraction of the silica nanoparticles debonded. Toughening models suggest that the toughness could be improved if the fraction of debonded particles is increased. Unfortunately, strategies to modify the surfaces of silica nanoparticles could not increase the fraction of debonded nanoparticles. Therefore, a hybrid silica nanoparticle containing a silica core, a butyl acrylate rubbery layer and a methyl methacrylate outer layer was tried. Preliminary results are encouraging.

Model epoxy resin toughened with nanoscale toughening agents

256th National Meeting (2018)

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