Effect of growing graphene flakes on branched carbon nanofibers based on carbon fiber on mechanical and thermal properties of polypropylene

A one-step process, the chemical vapor deposition method, has been used to fabricate graphene flakes (G) on branched carbon nanofibers (CNF) grown on carbon fibers (CF). In this contribution, the G-CNF-CF fibers have been used as reinforcing fillers in a polypropylene (PP) matrix in order to improve the mechanical and thermal properties of the PP. A bimetallic catalyst (Ni/Cu) was deposited on a CF surface to synthesize branched CNF using C2H2/H-2 precursors at 600 degrees C followed by growing G flakes at 1050 degrees C. The morphology and chemical structure of the G-CNF-CF fibers were characterized by means of electron microscopy, transmission electron microscopy, and Raman spectroscopy. The mechanical and thermal behaviors of the synthesized G-CNF-CF/PP composite were characterized by means of tensile tests and thermal gravimetric analysis. Mechanical measurements revealed that the tensile stress and Young's modulus of the G-CNF-CF/PP composites were higher than the neat PP with the contribution of 76%, 73%, respectively. Also, the thermal stability of the resultant composite increased about 100 degrees C. The measured reinforcement properties of the fibers were fitted with a mathematical model obtaining good agreement between the experimental results and analytical solutions.