Hygrothermal characterization of polyimide–titanium‐based fibre metal laminate

Polyimide‐based composites are currently being used on structures for both military and civilian aircraft. A major concern with these materials is the effect of long‐term exposure to service environments on their physical and mechanical properties. Hygrothermal ageing experiment was performed to understand the long‐term moisture absorption behaviour of carbon‐fibre reinforced polyimide (CF/P) and polyimide–titanium‐based fibre metal laminates (FMLs) in this work. Specimens were hygrothermal conditioned at 85°C, 95% relative humidity (RH) from 250 h to 1,000 h. Then, the moisture absorption of the specimens was determined. It was observed that the moisture absorption in the FMLs was quite slow according to the barrier function of the metal. More significantly, the mechanical properties of the CF/P and FMLs, obtained from flexure and interlaminar shear test, were affected by ageing with the reduction of flexure and interlaminar shear strength. Also, the decay mechanism of the mechanical property caused by hygrothermal ageing was further verified by means of scanning electron microscope (SEM) and dynamic mechanical analysis (DMA) techniques. POLYM. COMPOS., 39:2819–2825, 2018. © 2016 Society of Plastics Engineers