Effect of atmospheric pressure plasma treatment for repair of polymer matrix composite for aerospace applications

This paper investigates the repair of polymer matrix composites and validates the repair by static testing. Scarf repair is carried out on the laminates and cured under vacuum. It is observed that 80% of tensile strength is recovered due to this process. Therefore, this investigation highlights the significance of atmospheric pressure plasma treatment on repair of graphite epoxy laminate. It is observed that the surface energy of graphite epoxy laminate has improved significantly due to atmospheric pressure plasma treatment. Atmospheric pressure plasma treatment results in noteworthy increase in oxygen functionalities as detected by X-ray photoelectron spectroscopy, as well as surface roughness as detected by atomic force microscopy. The improvement in adhesion properties is correlated with lap shear strength of adhesive bonded joints and mode of failure has been analyzed by scanning electron microscopy. The plasma-treated laminates, when used for repair, provided an additional 12% in the tensile strength and thereby retaining a strength increase up to 92%.