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Electrically Conductive Polymer Composites

Rhodes, Susan M.
http://rave.ohiolink.edu/etdc/view?acc_num=akron1194556747

Abstract Details

2007, Doctor of Philosophy, University of Akron, Polymer Science.
Carbon nanofiber composites Carbon nanofiber (CNF) and carbon nanotube (CNT) composites have enhanced mechanical and electrical properties that make these composites desirable for antistatic and electronic dissipation technology. These applications require a homogeneous dispersion of CNF within a polymer matrix. To improve the compatibility/dispersibility of CNF within a polymer matrix, a hyperbranched polyol CNF composite was synthesized by the chemical modification of oxidized CNF with glycidol and boron trifluoride diethyl etherate. The resulting polyol CNF were characterized by TGA, FTIR, TEM/SEM and XPS. The hydroxyl groups were reacted with heptafluorobutyryl chloride to determine the amount of oxidized groups in the sample. The amount of hydroxyl groups increased by 417 % for the polyol CNF compared to the oxidized CNF and an improvement in dispersion ability was observed. Silver- and polyaniline-filled epoxy composites Composites with high electrical conductivity have been formulated from 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (ECC), undoped polyaniline (inherently conductive polymer, ICP), silver particles, and a thermal initiator capable of forming a strong Lewis acid. The incorporation of undoped polyaniline (PANI) into the silver-filled epoxy matrix provided an order of magnitude decrease in electrical resistivity (10-5 ohm-cm) compared to non-ICP matrix (10-4 ohm-cm). Formulations were characterized by SEM, TGA, solid state 13C NMR and 4-point probe conductivity. An interaction between PANI and the surfactant on the silver particles resulted in improved connectivity (aggregation and packing) of the silver particles. Furthermore, formulations using undoped PANI exhibited higher conductivity than doped PANI. Solid state 13C NMR showed that PANI became latently doped from the acid catalyst within the epoxy matrix, as well as the acidic surfactants on the surface of the silver. The ability to better disperse PANI, compared to the doped PANI, within the matrix contributed to the improved performance. Radiation-cured, silver-filled epoxy composites UV radiation curing has gained more popularity for unfilled systems over the past two decades, but is still limited in applications requiring high levels of filler. In this research, silver fillers were investigated to determine which sizes and shapes of silver filler are best suited for UV radiation curing. We revealed a matrix dependency on the ability to cure a silver filled composition, with Ag-filled acrylate-based compositions providing higher cure after light exposure than Ag-filled epoxy-based compositions. Furthermore, some photo-DSC measurements provided preliminary information about the connectivity of Ag particles in a Ag-filled polymer composite. The rate of polymerization of a polymer composite is well known to be dependent upon reaction temperature. In the case of silver-filled composites, we showed a relation between UV curability and percolation of Ag particles in polymer composites. The synergy between silver particles and polyaniline, as described in the previous project, has been found to have a negative impact on the UV curability of these polymer composites. Synthesis of silver nanomaterials It is well known that the use of conductive fillers with higher aspect ratios leads to percolation at lower filler concentration. Researchers have reported high yield syntheses of silver nanowires, but there have been no reports of polymer composites incorporating these materials. In this research, we explored the potential to use silver nanowires as the conductive filler component in polymer composites. Despite numerous attempts, high quantity synthesis of silver nanowires is still an unachieved target. Additional research is required to understand the nucleation and kinetics of silver nanowire synthesis to enable scale-up of silver nanowires.
Roderic Quirk (Advisor)
250 p.
Chemistry, Polymer
polymer; composites; carbon nanofibers; conductive; electrically conductive; inherently conductive polymers; radiation curable; polyaniline

Recommended Citations

Citations

  • Rhodes, S. M. (2007). Electrically Conductive Polymer Composites [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194556747

    APA Style (7th edition)

  • Rhodes, Susan. Electrically Conductive Polymer Composites. 2007. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1194556747.

    MLA Style (8th edition)

  • Rhodes, Susan. "Electrically Conductive Polymer Composites." Doctoral dissertation, University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194556747

    Chicago Manual of Style (17th edition)

akron1194556747
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© 2007, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.