Characterization of mechanical properties of epoxy resin reinforced with submicron-sized ZnO prepared via in situ synthesis method

In this paper, ZnO/epoxy composites with homogeneous dispersion were prepared via two simple steps: firstly, in situ preparation of zinc hydroxide (Zn(OH)2)/epoxy from the reaction of aqueous zinc acetate (Zn(Ac)2·2H2O) and sodium hydroxide (NaOH) at 30 °C in the presence of high viscosity epoxy resin; secondly, thermal treatment of the as-prepared Zn(OH)2/epoxy hybrid into ZnO/epoxy composites. Meanwhile, the structure, composition and mechanical properties of the resultant products were successfully investigated. From the result of characterization we found that the composite had the optimal mechanical property at ZnO fraction of 5 wt.%. Compared to pure epoxy resin, the improvement of ultimate tensile stress, elongation at break, tensile modulus and flexural strength achieved about 40.84%, 24.35%, 27.27% and 51.43%, respectively. The crack arresting mechanisms included particle matrix debonding, plastic void growth, in the composites with a stronger interface, significant plastic deformation of the matrix around the well bonded particles. At the same time, the possible reactive mechanism of the preparation of ZnO/epoxy composite was discussed in this paper.

The proposed route has at least four obvious advantages:
► It does not need to pre-prepare the ZnO particles which are easy to aggregate.
► The epoxy resin plays an essential role in the formation of Zn(OH)2 particles.
► The ZnO/epoxy can be obtained by the thermal treatment of the Zn(OH)2/epoxy.
► No usage of any organic solvent and no release of toxic byproducts.