Experimental torsional shear properties of carbon fiber reinforced epoxy composites containing carbon nanotubes

The in-plane and torsional shear properties directly relevant to specific applications of carbon fiber-reinforced composites (CFRPs), such as sporting goods and wind turbine blades, are studied. Multiscale composites are fabricated using carbon fiber prepregs containing carbon nanotube (CNT) modified epoxy matrix. The interlaminar shear strength (ILSS) of the composites with 0.5 wt.% CNTs increases by 12% compared to the neat CFRP composites, whereas the torsional shear modulus and strength determined using tubular specimens present corresponding improvements of 17% and 19.5%, respectively. The enhanced interfacial adhesion between the modified matrix and carbon fibers, and the increases in matrix modulus/strength arising from the well-dispersed functionalized CNTs are mainly responsible for the above observations. An increase in CNT content beyond 0.5 wt.% has moderately negative effects on these properties, indicating potential agglomeration at a high CNT content.