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EVA /BT/MWCNT Hybrid Composites: Morphology, Electrical and Mechanical Properties

Khodsetan, Haniyeh | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54627 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Frounchi, Masoud
  7. Abstract:
  8. In this research, the EVA/BT/MWCNT nanocomposites were prepared via the solution casting method in the various weight fractions of Barium titanate (BT) and multi-walled carbon nanotubes (MWCNT). Barium titanate-based ceramic material has a high dielectric constant, and it is used in the manufacture of sensors, capacitors, and electrical memories. On the other hand, multi-walled carbon nanotubes, due to electric charges on their surface and high electrical conductivity, can affect the dielectric properties combined with barium titanate and the hybrid of these two materials a polymer matrix suitable for special applications. In this study, ethylene-vinyl acetate (EVA) copolymer was used as a polymer matrix. An ultrasonic bath was used to disperse the nanomaterials. Characterization of the samples by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD), which showed the homogeneous distribution of nanomaterials in the polymer matrix. The results of the mechanical tensile test showed that the mechanical properties of nanocomposites were improved in the presence of barium titanate and multi-walled carbon nanotubes. Measurement of piezoelectric response and electrical conductivity of nanocomposites showed that an increase in the weight percentage of barium titanate nanoparticles increased the output voltage. Because the more electric charge is generated by the impact on nanoparticles and their transfer to the sides of the polymer matrix causes a more significant potential difference. Also, the increase of barium titanate nanoparticles, which have a high dielectric constant, led to more of these nanoparticles being dispersed per unit volume of the sample. Consequently, electrical conductivity decreased. However, the electrical conductivity increased due to increasing the content of carbon nanotubes. The piezoelectric behavior of nanocomposite showed that the peak-to-peak open-circuit voltage in the EVA / 20BT / 0.5MWCNT nanocomposite is at its maximum by mechanical impact stimulation (10 N). This behavior can be due to the rapid transfer of electrical charge between the nanocomposite surfaces and thus increase the piezoelectric response. Capacitance test by LCR meter showed that by increasing barium titanate nanoparticles to the polymer matrix due to the high dielectric constant of these nanoparticles and as a result of their low electrical conductivity, the electrical conductivity of nanocomposites decreased. While the capacitance increased which shows a behavior similar to the piezoelectric behavior of nanocomposites. By increasing the content of multi-walled carbon nanotubes to the polymer matrix, the electrical conductivity of nanocomposites increased and capacitance decreased. Finally, the contact angle test showed that the addition of nanomaterials to the polymer matrix causes the resulting nanocomposite to become hydrophobic and achieves self-cleaning properties of the surface, which expands its application in various industries
  9. Keywords:
  10. Piezoelectric ; Conductance ; Ethylene Vinyl Acetate (EVA) ; Nanocomposite ; Multi-Walled Carbon Nanotube ; Barium Titanat ; Structural Properties

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