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Fabrication and Electrical Properties Evaluation of PA/CNT Conductive Nanocomposite with Low Percolation Threshold

Shahbazi, Hessam | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52823 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza
  7. Abstract:
  8. Polyamide-6 is a thermoplastic polymer that is classified as electrically non-conductive materials. One way of adding conductivity to the polymer matrices is by utilizing them in a nanocomposite form. Superior mechanical and electrical properties of Carbon Nanotubes make them worthy of being chosen as reinforcement in nanocomposites to extend their operation to a broader range of applications, like conductive nanocomposites, mainly polymer-based matrices. The Nanotubes have chemical affinity and tend to entangle and aggregate. Because of this, to achieve a uniform and remarkable electrical conductivity is hard-to-reach. state of entanglement effects correctly melt methods of polymer blend mixing as a more approached to this industrial method. In other words, final electrical conductivity is affected by the dispersion and distribution of Nanotubes in the polymer matrix. In this study, in order to reach a low percolation threshold in Polymide-6 matrix, Polypropylene was used as a second phase to reach immiscible blend morphology. In the range of 35 to 65 volume percent of Polypropylene, cocontinuity of morphology was investigated by field emission electron microscopy. Octadecyl Triphenyl Phosphonium Bromide was used for non-covalent functionalization of Nanotubes’ surface to control the localization of Nanotubes. Selective Dissolution of one phase in the matrix showed the preferential distribution of Carbon Nanotubes in the sample, which contains surface functions, motivated a significant change in the localization of Nanotubes. Scanning Electron Microscopy and Rheology was used to examine the conductive network-like path formation in the samples. The electrical properties of the nanocomposite of Polyamide/Polypropylene and Carbon Nanotubes, which were fabricated by melt-mixing method, showed a remarkable increase compared to the neat blend and non-optimized nanotube samples. The restriction of nanotubes in one phase caused to achieve a minimum electrical resistance at minimum loading of Carbon Nanotubes. Best sample among the samples, was 35G-2.3F-G from the perspective of electrical conductivity at 500 Volts. Eventually, Double percolation approach reduced the nanoparticles’ loading to 2.3% to avoid the usage of high amount and achieve an improvement of 10 orders of magnitude higher conductivity level from 1015 for neat polymers to 105 for the optimized 35G-2.3F-G sample
  9. Keywords:
  10. Polyamide 6 ; Nanocomposite ; Carbon Nanotubes ; Electrical Properties ; Melt Mixing Conditions ; Electrical Double Percolation

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