Creep resistance of PI/SiO2 hybrid thin films under constant and fatigue loading

This paper presents an experimental study on creep resistance of PI/SiO2 hybrid thin films with silica-fillers weight varying in the range of 0–8%. Creep deformation, creep rate and creep compliance are utilized to evaluate the thin films’ characteristics under constant stress (creep) and tension–tension fatigue tests. The effects of silica doping level, stress amplitude and force pattern (constant or sinusoidal) are also analyzed in the experiments. The results show that the existence of nano-silica can improve the creep resistance both under constant and fatigue loading. Compared with constant loading, fatigue loading can accelerate the creep deformation and creep rate, and significantly increase the creep compliance of PI/SiO2 hybrid thin films in the primary creep stage. As the creep develops into the secondary stage, the stress amplitude will replace the stress pattern and play a dominated role, which is due to the different deformation mechanisms in different creep stages.