Experimental study and theoretical analysis on the mechanical properties of SWNTs/phenolic composites

In this study, single-walled carbon nanotubes (SWNTs) synthesized through the floating catalyst chemical vapor deposition (CVD) method were used to reinforce the phenolic resin. The effects of SWNT loading on the mechanical properties of the composites were investigated. It is found that a small loading of SWNTs can enhance significantly the mechanical properties of the composites. Young’s modulus increases 29.7% and the tensile strength increases 20.3% when 0.75 wt% and 2.0 wt% SWNTs were introduced to the phenolic matrix, respectively. The modified Halpin–Tsai equations were adopted to fit the experimental data of the tensile strength and Young’s modulus of the SWNTs/phenolic composites. Based on the equation, the effective modulus and the effective tensile strength in the ranges of 988–1600 GPa and 6.8–10.0 GPa, respectively, of the SWNT bundle were calculated. The tensile fracture surfaces of SWNTs/phenolic composites were examined using a field emission scanning electron microscope (FESEM). It is found that bundle bridging, SWNT loading, uniform dispersion of SWNTs, and the wetting at interface are the key parameters for strengthening the composites.