New hybrid method for simultaneous improvement of tensile and impact properties of carbon fiber reinforced composites

For weight savings of automobiles to improve fuel efficiency, tensile and impact strengths of carbon fiber reinforced composites (CFRC) are important properties required for substitution of metallic or ceramic automotive parts by CFRC parts. Effect of surface treatments of carbon fiber (CF) such as plasma, nitric acid, and liquid nitrogen treatments on interfacial bonding and mechanical properties of CF reinforced thermoplastic composites was investigated and nitric acid treatment was the best method to improve the interfacial affinity between the used CF and thermoplastic polymer matrix since the treatment induced acidic functional groups on the surface and increased surface roughness simultaneously. A new hybrid fabrication method was suggested by applying a bi-component two-layer structure to the film insert molding to improve tensile and impact strengths of CFRC simultaneously. Compared with tensile and impact strengths of the base polymer, those of the new hybrid composites filled with rubber particles and CF were improved by about 41.3% and 105.7%, respectively. In particular, tensile and impact strengths of the composite specimen prepared by the hybrid fabrication method were improved by about 15.0% and 36.0%, respectively when compared with those of the composite specimen prepared by the conventional melt mixing.