Effect of moisture on the dielectric properties of polyimine-based recyclable polymer with self-healing ability

Highly recyclable materials are increasingly demanded in electrical engineering, and new approaches are being found to produce polymer materials with the required properties, including good dielectric properties. The formation of a reversible covalent network in polymer materials is possible for efficient and repeated recycling of these materials, enabling a good self-healing effect under specific ambient conditions. These materials, e.g., based on polyimines, are not new. Still, their dielectric properties, which are crucial for potential applications in electrical engineering, have not yet been sufficiently explored. This contribution primarily evaluates the influence of varying humidity and direct immersion in water on selected dielectric properties. Tested polyimine samples were conditioned in a hot air oven, desiccator and water bath, and then dielectric properties were measured by broadband dielectric spectroscopy (BDS). Conclusions defined based on the dielectric properties measurements by BDS are also supported by the results of differential scanning calorimetry, and the measurement of dielectric strength as an essential parameter for electrical insulating materials is added. The chemical structure of polyimines suggests that these materials would be relatively polar and unsuitable in tested versions for standard electrical insulation systems, even though this would be convenient due to their self-healing ability. Still, they could be used in special applications where relatively high and very moisture-dependent relative permittivity and dissipation factor can be utilized.