Out-of-plane shear properties of glass/epoxy composites enhanced with carbon-nanofibers

The role of adding carbon-nanofibers (CNFs) to glass/epoxy composites and their effects on the out-of-plane shear properties of CNF/glass/epoxy composites have been studied. Neat glass/epoxy and 0.25 wt% CNF/glass/epoxy composite specimens were fabricated using vacuum assisted hand layup, and were subsequently evaluated in terms of shear strength and modulus by means of short beam bending (SBB) and Isopescu shear testing methods. In order to achieve a uniform dispersion of nanoparticles in the resin, online monitoring of suspension viscosity as a function of the sonication time was used. The experimental findings revealed that, at a level of 0.25 wt% CNF, the value of shear strength S13 was improved by 18% and 19.5% in the SBB and Isopescu shear testing methods, respectively. Also, the values of shear modulus G13, shear strength S23 and shear modulus G23 were increased by 38%, 18% and 34%, respectively. FESEM photographs confirmed that roughness enhancement of the resin due to the CNFs addition was the main source of properties improvement in out-of-plane directions.