Preparation and characterization of conductive polymer composites, and their assessment for electromagnetic interference shielding materials and capacitors

Köysüren, Özcan
The aim of this study was to improve electrical properties of conductive polymer composites. For this purpose, various studies were performed using different materials in this dissertation. In order to investigate the effect of alternative composite preparation methods on electrical conductivity, nylon 6/carbon black systems were prepared by both in-situ polymerization and melt-compounding techniques. When compared with melt compounding, in-situ polymerization method provided enhancement in electrical conductivity of nylon 6 composites. Furthermore, it was aimed to improve electrical conductivity of polymer composites by modifying surface chemistry of carbon black. 1 wt. % solutions of 3-Aminopropyltriethoxysilane and formamide were tried as chemical modifier, and treated carbon black was melt mixed with low-density polyethylene (LDPE) and nylon 6. According to electron spectroscopy for chemical analysis (ESCA), chemicals used for surface treatment may have acted as doping agent and improved electrical conductivity of polymer composites more than untreated carbon black did. Formamide was more effective as dopant compared to the silane coupling agent. In order to investigate electromagnetic interference (EMI) shielding effectiveness and dielectric properties of conductive polymer composites, 1, 2 and 3 wt. % solutions of formamide were tried as chemical modifier and treated carbon black was melt mixed with poly(ethylene terephthalate) (PET). Composites containing formamide treated carbon black exhibited enhancement in electrical conductivity, EMI shielding effectiveness and dielectric constant values compared to composites with untreated carbon black. In order to enhance electrical conductivity of polymer composites, the selective localization of conductive particles in multiphase polymeric materials was aimed. For this purpose, carbon nanotubes (CNT) were melt mixed with polypropylene (PP)/PET. Grinding, a type of solid state processing technique, was applied to PP/PET/CNT systems to reduce the average domain size of blend phases and to improve interfacial adhesion between these phases. Grinding technique exhibited improvement in electrical conductivity and mechanical properties of PP/PET/CNT systems at low PET compositions. To investigate application potential of conductive polymer composites, polyaniline (Pani)/carbon nanotubes (CNT) composites were synthesized and electrochemical capacitance performances of these systems, as electrode material in electrochemical capacitors, were studied. Polyaniline/carbon nanotubes composites resulted in a higher specific capacitance than that of the composite constituents. Pseudocapacitance behavior of Pani might contribute to the double layer capacitance behavior of nanotubes. Additionally, as an alternative to Pani/CNT systems, polyaniline films were deposited on treated current collectors and electrochemical capacitance performances of these electrode systems were investigated. The highest specific capacitance of polyaniline/carbon nanotubes composites was 20 F/g and this value increased to 35.5 F/g with polyaniline film deposited on treated current collector.


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Doğan, Mehmet; Bayramlı, Erdal; Department of Polymer Science and Technology (2011)
The main objective of this study was to produce flame retardant polyamide-6 (PA-6) and polypropylene (PP) composites and fibers containing boron compounds. The synergistic effect on flame retardancy of boron compounds (boron silicon containing oligomer (BSi), zinc borate (ZnB), boron phosphate (BPO4), metal oxide doped BPO4 and lanthanum borate (LaB)) with conventional flame retardants were investigated. The synergistic effect of nano-clay with commercial flame retardants was also investigated in order to r...
Composition-property relationship of PCL based Polyurethanes
Güney, Aysun; Hasırcı, Nesrin; Department of Polymer Science and Technology (2012)
The desirable properties of polyurethanes (PUs) such as mechanical flexibility associated with chemical versatility make these polymers attractive in the development of biomedical devices. In this study, various segmented polyurethanes were synthesized through polymerization reactions between polycaprolactone (PCL) diol or triol and excess hexamethylene diisocyanate (HDI) with varying NCO/OH ratios and the effect of composition on the properties of the resultant polyurethane films were examined. Initially, ...
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In this research, diazophenylene and diazodiphenylene bridged metal-phthalocyanine polymers were produced from diazonium salt of diaminophenylene/bensidin and pre-synthesized tetraamino metal phthalocyanines. Tetraamino metal phthalocyanine complexes of Co, Ni, Cu, Ce, and Er were obtained by reducing tetranitro metal phthalocyanine complexes synthesized from 3-nitrophthalic anhydride, urea, metal salt, and ammonium molybdate catalyst. Complexes and polymers were characterized by Fourier Transform Infrared ...
Synthesis and characterization of polypropylene based ion-exchange resin
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The synthesis of ion-exchange resin which can be used in various separation and chemical purposes, such as diffusion dialysis, electro dialysis, electrolysis and fuel cells has of considerable interest. For all these applications, the interactions of the ionic groups and the resulted morphologies are critical for establishing the unique properties. Considerable researches have been continued to understand the microstructure of these materials. The aim of this study is to synthesize polypropylene (PP) based ...
Citation Formats
Ö. Köysüren, “Preparation and characterization of conductive polymer composites, and their assessment for electromagnetic interference shielding materials and capacitors,” Ph.D. - Doctoral Program, Middle East Technical University, 2008.