Carbon Mesophase/Carbon Nanotubes Nanocomposite - Functional Filler for Conductive Pastes A. M. Bondar*, A. Bara*, D. Patroi*, P.M. Svasta** *National Institute for Research and Development in Electrical Engineering ICPE - Advanced Research, Bucharest, Romania, * *"Polytechnic" University OF Bucharest, Romania Abstract Carbon nanotubes (CNT) have attracted much attention from the researches worldwide, because they show superior physical and electrical potentials, which allow them to be applied in a large field of technologies. In recent years, studies into the practical applications of CNT have focused on polymeric composite for electronic packaging. This paper present the results of our researches for obtaining of conductive pastes based on carbon mesophase/carbon nanotubes nanocomposites like functional filler in a polymeric matrix. The nanocomposites were obtained by adding of single walled carbon nanotubes (SWNT) or multi walled carbon nanotubes (MWNT) in a petroleum pitch. [t was reported that SWNT behave as either a metal or a semiconductor depending on the wrapping angle of the graphene sheet and its diameter, while MWNT are always conductive. Carbonic functional phase, obtained by heat treatment of pitch/nanotubes mixtures at 900°C temperatures, was structural characterized by optical microscopy, SEM, X- ray Diffraction and functional by electrical resistivity measurements. Polymeric composites were obtained by adding carbonic functional phase in an epoxy resin matrix. These were characterized to establish the electrical percolation threshold. Keywords Carbon mesophase nanocomposite, carbon nanotubes, polymer composite Introduction The electrical conductivity of polymers can be increased by the addition of conductive fillers, including various forms of carbon fibers, carbon black, and graphite { 1, 2]. The resulting composites can be used in applications where metals have typically been the materials of choice [3,4]. The advantages of using these materials include lighter weight, resistance to corrosion, and the ability to be readily adapted to the needs of a specific application. The possible applications for electrically conductive resins include electromagnetic and radio frequency interference (EMI/RFI) shielding for electronic devices and electrostatic dissipation (BSD) [6]. The objective of this work was to obtain and to analyze single-filler conductive resins in order to obtain an electrical conductive for the development of conductive carbon-polymer composites. Experiments Materials were chosen based on their commercial availability, cost effectiveness, and their widespread use. The polymer used, an epoxy resin (Diglycidyl ether of bisphenol), is commonly used in a number of applications, including conductive resins. The different carbon fillers used in this work were also chosen based on their ability to impart high conductivity to the composites, while still maintaining a relatively low cost and high availability. The carbon mesophase/carbon nanotubes nanocomposites are expected to have a high electrical conductivity of any of the other fillers. Due to its high surface area, can effectively impart high electrical conductivity at relatively low concentration. This carbon mesophase based composites can also produce good conductivity while generating improved mechanical properties that other fillers cannot provide. Detailed descriptions of the formation processes of the fillers and the conductive polymer composites are giving below, in addition to various physical properties for each material. The processing of polymer composites concern two steps: * filler preparation (carbon nanocomposites); * polymer composites preparation. For filler preparation were used a petroleum pitch as matrix and single walled (SWNT) or multi walled (MWNT) carbon nanotubes as reinforcement. rhe main characteristics of pitch are presented below: TABLE 1, PETROLEUM PITCH (PP) CHARACTERISTICS Characteristics V | B.I.* | Q.l. S.Pt. (R&B), % % % °C PP 45 17.5 0.4 65 volatile matter; benzene insoluble; * quinoline insoluble 215 0-7803-9553-0/05/$20.00 ©2005 IEEE. Polytronic 2005 - 5th International Conference on Polymers and Adhesives in Microelectronics and Photonics