Nanoclay reinforced thermoplastic toughened epoxy hybrid syntactic foam: Surface morphology, mechanical and thermo mechanical properties

Abstract

Epoxy hybrid syntactic foams were prepared with diglycidyl ether of bisphenol A (DGEBA) epoxy resin, diamino diphenyl sulfone (DDS), hydroxyl terminated polyether ether ketone having pendant methyl group (PEEKMOH), microballoon and nanoclay. The density of the foam was maintained between 0.6 and 0.72 g/cc for all compositions. Fracture toughness, tensile, flexural and compressive properties of the foam were evaluated with respect to clay and PEEKMOH concentrations. Morphology by X-ray diffraction revealed that the clay particles within the epoxy resin were intercalated for all the compositions of the syntactic foam. Fracture toughness and mechanical properties of the syntactic foam were significantly improved by the addition of nanoclay. A further enhancement in fracture toughness and mechanical properties was observed by the addition of PEEKMOH. The hybrid epoxy syntactic foam thus prepared exhibited 58%, 77% and 38% improvement in compressive strength, percentage elongation and fracture toughness, respectively, compared to the neat epoxy syntactic foam. The specific mechanical properties were found to be higher for the epoxy hybrid syntactic foam containing 3 wt% nanoclay and 3 wt% of PEEKMOH combination. The storage and loss modulus of the syntactic foam were also increased by the addition of nanoclay and PEEKMOH. A marginal improvement in T g was observed with clay incorporated syntactic foam. SEM analysis revealed that increased microcracking, crack path deflection, matrix deformation, plastic deformation, rupture of microballoons and debonded microspheres influencing on fracture toughness and mechanical properties of epoxy hybrid syntactic foam.