Repair effects of offcut-carbon-fiber-powder-modified PU-PMMA copolymer on flexure-after-impact behaviors of composite laminate

Polymer matrix composites are popular for their lightweight and high strength. Poly (methyl methacrylate) (PMMA), known for its transparency, can be toughened with polyurethane (PU) to expand its applications. This study further strengthened PU-PMMA by adding carbon fiber powder from offcut fabrics (oCFP), enhancing mechanical and adhesion properties. Tensile, flexural, and lap-shear tests were conducted to investigate the effects of the oCFP on the mechanical and adhesion properties of the PU-PMMA resin. The oCFP-modified PU-PMMA was then used in scarf repair to assess its effectiveness on the impacted composite laminates. Tensile and flexural tests showed that 1 wt% oCFP improved tensile strength from 38 MPa to 43.31 MPa and flexural strength from 56.02 MPa to 82.21 MPa, while further addition of oCFP led to reductions in these strengths. Although oCFP-modified PU-PMMA did not significantly restore the impacted laminates' flexural strength, the repairing effect was still more pronounced than that of a commercial epoxy adhesive, demonstrating potential as a repair or structural adhesive.