Electrical and Dielectrical Properties of Composites Based on Alumina and Cyclic Olefin Copolymers

• Published in: Materials Vol. 17; no. 21; p. 5349
• Main Authors: Ionete, Eusebiu Ilarian, Visse, Artur, Andrei, Radu Dorin, Petreanu, Mirela Irina, Spiridon, Stefan Ionut, Ionete, Roxana Elena
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.11.2024
• Subjects: Acid resistance; Alumina; Aluminum compounds; Aluminum oxide; Composite materials; Copolymers; Cryoforming; Cryogenic temperature; Dielectric properties; Dielectrics; Electric fields; Electric properties; Electric vehicles; Electrical conductivity; Electrical insulation; Electrical properties; Electrical resistivity; Electromagnetism; Extrusion molding; Force and energy; Formulations; Mechanical properties; Melt blending; Moisture absorption; Moldings; Olefins; Physical properties; Polymers; Polyolefins; Room temperature; Surface stability; Surface treatment; Temperature; Tensile strength; Water absorption; Germany; Japan; composites; dielectrics; cyclic olefin copolymer; alumina; conductivity; cryogenics
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17215349

Understanding the performance of polymer dielectrics at different temperatures is becoming increasingly important due to the rapid development of electric cars, electromagnetic devices, and new energy production solutions. Cyclic olefin copolymers (COCs) are an attractive material due to their low water absorption, good electrical insulation, long-term stability of surface treatments, and resistance to a wide range of acids and solvents. This work focused on the dielectric and electrical properties of cyclic olefin copolymer (COC)/Al2O3 composites over a wide range of temperature and frequency domains, from room temperature to cryogenic temperatures (around 125 K). Permittivity, electrical conductivity, and electrical modulus are given consideration. A composite of up to 50% Al2O3 mixed with COC was prepared via a conventional melt-blending method. The final samples were formed in sheets and processed using injection and extrusion moldings. It was found that formulations with Al2O3 concentrations ranging from 10 to 50% resulted in higher electrical conductivity while maintaining the viscosity of the composite at a level acceptable for polymer-processing machinery. Our data show that COC/alumina composites present substantial potential as materials for high-frequency applications, even at the regime of cryogenic temperatures.