Effects of Electric Discharge Plasma Treatment on the Thermal Conductivity of Polymer–Metal Nitride/Carbide Composites LEVENT PARALI, 1,3 MIRZA A. KURBANOV, 2 AZAD A. BAYRAMOV, 2 FARIDA N. TATARDAR, 2 RAMAZANOVA I. SULTANAKHMEDOVA, 2 and HUSEYNOVA GULNARA XANLAR 2 1.—Department of Electronics and Automation, Celal Bayar University, Turgutlu, 45400 Manisa, Turkey. 2.—Academy of Science of Azerbaijan, Institute of Physics, Baku, Azerbaijan. 3.—e-mail: levent.parali@cbu.edu.tr High-density polymer composites with semiconductor or dielectric fillers such as aluminum nitride (AIN), aluminum oxide (Al 2 O 3 ), titanium carbide (TiC), titanium nitride (TiN), boron nitride (BN), silicon nitride (Si 3 N 4 ), and tita- nium carbonitride (TiCN) were prepared by the hot pressing method. Each powder phase of the composites was exposed to an electric discharge plasma process before composite formation. The effects of the electric discharge plasma process and the filler content (volume fraction) on the thermal con- ductivity, volt–ampere characteristics, thermally stimulated depolarization current, as well as electrical and mechanical strength were investigated. The results of the study indicate that, with increasing filler volume fraction, the thermal conductivity of the samples also increased. Furthermore, the thermal conductivity, and electrophysical and mechanical properties of the high-den- sity polyethylene + 70% BN composite modified using the electric discharge plasma showed improvement when compared with that without electric dis- charge plasma treatment. Key words: Thermal conductivity, polymer–metal nitride/carbide composites, electric discharge plasma INTRODUCTION Nowadays, with the increasing use of microelec- tronic circuits, overheating of electronic components has become an important issue. Such overheating must be distributed efficiently and quickly, there- fore requiring that materials such as packaging materials, the circuit board, heat exchangers, and machinery must have good thermal conductivity, in addition to their traditional physical and mechani- cal properties. 1–3 As electronic systems require fast and efficient signal distribution, these materials should have high thermal conductivity, high elec- trical resistance, and low dielectric permittivity and loss tangent values. 4 Polymers such as high-density polyethylene (HDPE), polypropylene (PP), polyvinylidene fluo- ride (PVDF), and polyvinylchloride (PVC) are widely used in electronic systems, but their thermal conductivity and high thermal expansion coefficient limit their use in many applications. By addition of fillers to such plastics, their thermal behavior can be significantly improved. To produce polymers offering both thermal conductivity and electrical insulation, various thermally conductive fillers, such as diamond, boron nitride (BN), aluminum nitride (AIN), silicon carbide (SiC), and mica, have been used as doping materials to improve polymer- based composites. 5–9 The thermal conductivity of polymer-based composites is influenced by the filler packing density, 10 particle size and size distribu- tion, 11,12 surface treatment, 13 and mixing method. 14 The degree of surface dispersion of the filler par- ticles determines their interaction with the poly- mer, also determining the thermal conductivity of the system. Strong surface interaction (so-called (Received February 1, 2015; accepted August 9, 2015) Journal of ELECTRONIC MATERIALS DOI: 10.1007/s11664-015-4010-3 Ó 2015 The Minerals, Metals & Materials Society Author's personal copy