Mechanical properties of boron nitride nanotube / epoxy polymer composites

Abstract

Boron nitride nanotubes (BNNTs) have attracted significant interest of the scientific world due to their remarkable mechanical and thermal properties. They have high modulus and high strength similar to carbon nanotubes. In addition they are highly resistant to oxidation and structurally stable and inert to most chemicals. All these outstanding properties of BNNTs, as well as their low density and high aspect ratio make them an ideal candidate for the reinforcement of polymer composites. In this study, BNNT/epoxy polymer composites with different nanotube concentrations were fabricated after a BNNT dispersion prepared by ultrasonication in dimethylformamide (DMF). Properties and structure of BNNT/epoxy composites were investigated by mechanical testing, thermal analysis and scanning electron microscopy. A good nanotube dispersion was achieved for composites with 0.1 wt. per cent of BNNTs, but presence of agglomerates in composites with 0.2 wt. per cent and 0.4 wt. per cent of BNNTs were determined by the examination of fracture surfaces. The tensile strength of the composites reinforced with 0.1 wt. per cent of BNNTs is 10.6% greater than that of the neat epoxy and onset of thermal degradation is delayed for 32 ºC with 0.1 wt. per cent of BNNT loading. The improvements in mechanical and thermal properties of composites are attributed to good dispersion of BNNTs in epoxy matrix and high interfacial shear stress between BNNTs and the epoxy matrix.