Research Article
SG Prolongo, MR Gude and A
Abstract
Polystyrene-b-polybutadiene-b-poly (methyl methacrylate) block copolymer (SBM) was incorporated into epoxy resin to access the nanostructures in epoxy thermosets, knowing the different miscibility of polymeric blocks on epoxy matrix during the curing treatment. The morphology of modified SBM/epoxy resins was examined by Transmission and Field Emission Gun Scanning Electron Microscopy (TEM and FEG-SEM), reveling a nanostructured epoxy matrix with a dispersed micro-scale phase. The modified resins presented enhanced flexural properties, which were dependent on the composition of blend. The resin reinforced with low SBM contents (2.5 and 5 wt%) presented high values of flexural modulus and strength, while the blend reinforced with higher SBM load (10 wt%) showed higher elongation ability. This different behavior was explained by SEM analysis of fracture surfaces, which showed different toughening mechanisms. The adhesive strength and toughness were determined using carbon fiber/epoxy laminates with peel ply surface treatment as adherends. The results showed a dramatic enhancement of both properties for modified SBM/epoxy adhesives. The highest increases measured were 50 and 70% for lap shear strength and mode-I adhesive fracture energy, respectively.