Publication

Abstract : This investigation highlights the performance of epoxy-novolac interpenetrating polymer network (IPN) adhesive bonding of surface-modified polyether imide (PEI) to titanium (Ti) under elevated temperatures and an aggressive chemical environment as well as humid conditions. The results of physical and thermomechanical properties reveal that epoxy-novolac (4∶14∶1) IPN adhesive is the best combination. X-ray photoelectron spectroscopic (XPS) analysis demonstrates formation of oxide functional groups due to low-pressure plasma treatment onto the surface PEI and formation of oxide as well as nitride functional groups due to anodization and plasma nitriding on the titanium surfaces. Surface energy of the anodized titanium is relatively higher in comparison to plasma-nitrided titanium due to the high polarity of oxygen compared to nitrogen, and it consequently shows higher adhesive joint strength. Epoxy-novolac (4∶14∶1) IPN adhesive bonding of polyether imide to titanium reveals that anodized titanium to plasma-treated polyether imide adhesive joints show higher bond strength in ambient conditions. However, when exposed to an aggressive environment, the plasma-nitrided titanium to polyether imide adhesive joint shows higher bond strength because the nitride layer is more stable than the oxide layer and consequently results in a durable interface between titanium and adhesive, leading to cohesive failure of the adhesive joints.