Boosting the Performance of CFRP with High Axial Compression Characteristics Fabricated Using the Filament Cover Method: Surface Modification of Sheath Filament PBO Fiber and Improvement of Reinforcing Fiber Volume Fraction

We have proposed the filament cover method for fabricating carbon fiber-reinforced plastic (CFRP) with high axial compression characteristics to address one of the shortcomings of unidirectional CFRP, whose compressive strength is inferior to its tensile strength. In this paper, we attempt to fabricate CFRP with high compressive strength while retaining the high tensile strength of unidirectional CFRP. We propose a method for surface modification of sheath filament PBO fiber (corona discharge treatment followed by silane coupling treatment) and a method for increasing the reinforcing fiber volume fraction of CFRP (flattening reinforcing fiber bundles and shrinking the gaps between them). CFRP prototypes fabricated using them exhibit tensile strength on par with regular CFRP, the effectiveness of the method was confirmed.