Effect of hydrogen plasma-mediated surface modification of carbon fibers on the mechanical properties of carbon-fiber-reinforced polyetherimide composites

The surfaces of carbon fibers were modified by hydrogen plasma treatment to investigate the consequent effects on reinforcement of polyetherimide (PEI) composites. The structural surface properties were characterized by Raman spectroscopy, XPS, FT-IR and SEM. The effectiveness of hydrogen and oxygen plasma treatments in improving the surface roughness, structure and mechanical properties of the composites was demonstrated. The results indicated that hydrogen and oxygen plasma treatment modified the carbon bonding structure and the surface roughness differently. Both an increase in the density of functional groups and changes in the carbon bonding contributed to the enhancement of the PEI matrix. SEM imaging confirmed decreased fiber pull-out for PEI reinforced with plasma-treated carbon fibers because of the enhanced adhesion between the carbon fibers and the PEI. Thus, hydrogen plasma treatment of the carbon fibers led to an enhancement of tensile properties at both room temperature and high temperature (150 °C). This study demonstrates that hydrogen plasma treatment is a promising technique for improving the mechanical properties of carbon-fiber-reinforced polymer composites.