Preparation and Characterization of Carbon Nanotubes/Carbon Fiber/Phenolic Composites on Mechanical and Thermal Conductivity Properties

The properties of fiber-matrix interface pay an important effect on the mechanical properties of carbon fiber-reinforced composites. To improve the interfacial properties in carbon fiber/phenolic resin (CF/PF) composites, CF adhered CNTs (CNTs-CF) were prepared by CVD method. The surface of treated CF and the distribution of CNTs in the interfacial region of CF were detected by scanning electron microscopy (SEM). SEM images identified 700 degrees C being the optimum growth temperature to obtain CNTs-CF, in which CNTs randomly dispersed surrounding the individual fiber surfaces. Compared to crude CF/PF composites, the tensile strength, bending strength, shear strength, impact strength, thermal conductivity at 25 degrees C of CNTs-CF/PF composites increase by 144.5%, 59.2%, 129.0%, 75.9% and 41.7%. The improvement of mechanical properties is due to that the homogenously dispersed CNTs serve as a supplementary reinforcement to the interface and further reduce inter-laminar stress concentration. This represents an important step toward CNT-reinforced polymers with high mechanical properties.