Effect of an Atmospheric Pressure Plasma Surface Treatment and Humidity Levels on the Interfacial Fracture Toughness of Co-Cured Composite Joints

摘要

In this paper, the effects of an atmospheric pressure plasma surface treatment and humidity storage level on an aerospace grade prepreg material prior to co-curing is examined. Three atmospheric pressure plasmas were investigated; Helium, Helium/Nitrogen & Helium/Oxygen. A Helium/Oxygen plasma at 1600 W was found to give the most efficient, uniform treatment in terms of surface energy. A treatment time of 50 sec in a Helium/Oxygen plasma at 1600W gave the highest increase in mode I fracture toughness, G_(IC). Longer treatment times resulted in lower fracture toughness. Humidity level was found to have an adverse effect on fracture toughness. Fracture toughness deceased as humidity levels increased. The reduction in fracture toughness was accompanied by a drop in the glass transition temperature of the adhesive layer.