Effect on Surface Modification of Carbon Fiber by Cold Plasma to Mechanical Properties of CFRP and C/C composites

Abstract

Surface modification of pitch based high modulus carbon fiber (CF) by cold plasma was investigated to give high compativility between CF and matrix in CF/resin composites (CFRP) and CF/carbon composites (C/C). The surface treatment of CF filament was carried out with O2 plasma generated by radio frequency (13.56 MHz). The CF surface was analyzed by ESCA. It was found that the acidic group on the CF surface was formed by O2 plasma. The unidirectinally CFRP plates (4 mm in thickness) were prepared by orientating CF prepreg coated with phenolic resin, and carbonizing at 1000°C under nitrogen.These CFRP and C/C plates showed the bulk density of 1.7 g/cm3 and the CF contents of 60-70vol%. The fractured behavior and mechanical strength of CFRP and C/C plates were changed with input power of O2 plasma. The flexural strength and compressive strtength of CFRP and C/C plates prepared from CF filament treated in O2 plasma at 50 W with input power, Was the largest of all.The cold O2 plasma treatment for CF is recommended as an ingenious method for the surface modification of CF.