Effect of humidity on the microstructure and energy storage properties of polyetherimide

The linear polymer, polyetherimide (PEI), has attracted much attention in recent years due to its high energy storage efficiency and high operating temperature. In this work, the effect of humidity on the relevant properties of PEI is investigated by changing the ambient humidity during electrostatic spinning. The results show that humidity affects the microscopic morphology of PEI after spinning and the dielectric energy storage properties of PEI films. Microstructure images show that the humidity of the spinning environment not only affects the morphology of the PEI filament, but also has an effect on the surface morphology of the PEI film after hot pressing. The experimental test results demonstrate that humidity has a significant effect on the energy storage performance. The reasons for this change were analyzed by molecular dynamics and x-ray photoelectron spectroscopy (XPS). It was found that the attraction of hydroxyl groups may hinder the rotation of the phthalimide rings reducing the polarization rate causing a decrease in polarization.