Effect of fiber surface treatment on mechanical properties of carbon fiber reinforced composites

Abstract

In this work, different surface treatments: viz. Acetone desizing, nitric acid treatment, silane treatment, nitric acid treatment followed by silane treatment are performed on carbon fibers. The modified carbon fibers are embedded in epoxy matrix and high quality 2-ply laminated composites are manufactured using vacuum bagging method. The interlaminar shear strength,flexural strength and flexural modulus of composites are improved by treatments. The chemical bonds formed between carbon fibers and epoxy matrix as a result of silanization gave better results as compared to the mechanical interlocking between carbon fibers and matrix induced by etching using nitric acid. A significant improvement in interlaminar shear strength (11 MPa) and flexural strength (488 MPa) of composites is achieved by treating the fibers with nitric acid for 5 minutes followed by silane treatment using 3-Aminopropyltrimethoxy silane. This is attributed to creation of active sites and hydroxyl (-OH) groups on fiber surface by nitric acid treatment which improved bonding between silane and carbon fibers.