Low velocity impact properties of carbon nanofibers integrated carbon fiber/epoxy hybrid composites manufactured by OOA-VBO process

A nano-modified prepreg system was fabricated by impregnating T-300 carbon fiber with 1 wt.% oxidized carbon nanofibers (O-CNFs) modified EPON 862 epoxy resin system. The O-CNFs modified carbon fiber reinforced polymer (CFRP) prepregs were then molded and cured into CFRP laminates via an Out of Autoclave and Vacuum Bag Only (OOA-VBO) process. Samples of 100 × 100 mm were subjected to low velocity impact test using an instrumented falling weight impact machine at three different energy levels of 10, 20 and 30 J. Fracture surface analysis and projected damage area after low velocity impact test were evaluated by scanning electron microscopy and ultrasonic C-scan, respectively. Experimental analysis indicates that the incorporation of O-CNFs into carbon fiber/epoxy laminates has improved impact resistance in terms of enhanced peak load, damage initiation energy and reduced damage area in comparison to control laminates. However, the ductility index was found to be decreased with the increase of O-CNFs loading. Micrographs revealed uniform dispersion of O-CNFs in epoxy, good adhesion between O-CNFs and epoxy polymer, and improved interfacial bonding between fiber/matrix that lead to the stronger shift of the impact resistance of the hybrid composites.