Dielectric characteristics of polyimide CP2

Synthesis of Superheat-Resistant Polyimides with Enhanced Dielectric Constant by Introduction of Cu(ΙΙ)-Coordination

To achieve polyimide-metal complexes with enhanced properties, 5-amine-2-(5-aminopyridin-2-yl)-1-methyl-benzimidazole (PyMePABZ) that contains stiff 2-(2'-pyridyl)benzimidazole (PyBI) was synthesized and exploited to construct the Cu(ΙΙ)-crosslinked polyimides (Cu-PIs). These Cu-PIs exhibited higher dielectric, thermal, and mechanical properties with an increase in Cu2+ content. Among them, their dielectric constants (εrS) were up to 43% superior to that of the neat PI, glass transition temperatures (Tgs) were all over 400 °C, and 5% weight loss temperature (T5%) maintained beyond 500 °C. These data indicate that the metal coordination crosslinking provided a useful guide to develop high performance PIs which possess potential application as useful high temperature capacitors.

Polymer Capacitor Dielectrics for High Temperature Applications

Much effort has been invested for nearly five decades to identify and develop new polymer capacitor dielectrics for higher than ambient temperature applications. Simultaneous demands of processability, dielectric permittivity, thermal conductivity, and dielectric breakdown strength dictated by increasing high power performance criteria limit the number of available materials. The present review first explains the advantages of metallized polymer film capacitors over the film-foil, ceramic, and electrolytic counterparts and then presents a comprehensive review on both past developmental effort of commercial resins and recent research progress on new polymers targeted for operating temperature above 150 °C. Some historical background and discussion on the limitation of the commercially available polymer film dielectrics for high temperature applications are also given. In many cases, further development of promising polymers that appear to possess all or most of the important criteria is limited by lack of large scale market incentives but could be of great value to niche applications in the military or aerospace realm.

Dielectric and gas transport properties of highly fluorinated polyimides blends

The physicochemical properties of highly fluorinated polyimide blends were studied in order to highlight the advantages of employing a high content of fluorine atoms to tailor the properties of polyimide materials. Thus, dynamo-mechanical analysis was used to evidence the physical phenomena taking place during heating. The trend of storage modulus, loss modulus and loss factor tangent with temperature during and after the α relaxation was explored. The dielectric spectroscopy was carried out to investigate the dielectric behaviour at different temperatures and frequencies and to evaluate the values of dielectric constant, dielectric loss and electrical resistance. The dielectric spectroscopy data were corroborated with the dynamo-mechanical analysis to highlight the sub-glass transitions encountered in these blend films. Dielectric loss diagrams showed sub-glass transitions in the form of γ and β relaxations mainly due to the segmental mobility of the polymer chain components. The gas separation performance of some of the investigated blends was assesed, and their ability to achieve simultaneously higher gas permeability and higher selectivity was demonstrated.

Rationally designed polyimides for high-energy density capacitor applications

Development of new dielectric materials is of great importance for a wide range of applications for modern electronics and electrical power systems. The state-of-the-art polymer dielectric is a biaxially oriented polypropylene (BOPP) film having a maximal energy density of 5 J/cm(3) and a high breakdown field of 700 MV/m, but with a limited dielectric constant (∼2.2) and a reduced breakdown strength above 85 °C. Great effort has been put into exploring other materials to fulfill the demand of continuous miniaturization and improved functionality. In this work, a series of polyimides were investigated as potential polymer materials for this application. Polyimide with high dielectric constants of up to 7.8 that exhibits low dissipation factors (<1%) and high energy density around 15 J/cm(3), which is 3 times that of BOPP, was prepared. Our syntheses were guided by high-throughput density functional theory calculations for rational design in terms of a high dielectric constant and band gap. Correlations of experimental and theoretical results through judicious variations of polyimide structures allowed for a clear demonstration of the relationship between chemical functionalities and dielectric properties.