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A Study on Mechanical, Electrical Properties and Morphology of Ps/Eoc/Cnt Nanocomposite Blends

Cheraghi, Mohammad Saeed | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52872 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Pircheraghi, Gholamreza; Seyed Reyhani, Morteza
  7. Abstract:
  8. Nowadays, the development of different polymer blend nanocomposites is of great importance for achieving electrical and antistatic properties for various applications such as auto parts and the packaging industry. Immiscible polymer blends with conductive nanoparticles such as carbon nanotube, graphene, etc. can reach the conductivity threshold with low amounts of nanoparticles and produce desired electrical properties. In the present study, we have attempted to develop a polystyrene(PS)/ethylene-octene copolymer(EOC)/carbon nanotube(CNT) blend nanocomposite with suitable electrical conductivity. The compounding was performed by melt mixing at two weight percent of 80/20 and 50/50 (PS/EOC) and different amounts of CNTs in an internal mixer in one step. The effect of the addition of CNTs to PS/EOC blend and the relationship between morphology and electrical, rheological and mechanical properties was investigated. By examining the FE-SEM images, it was observed that the addition of CNTs to the blend changed the morphology from the matrix-droplet to co-continuous and CNTs were selectively localized in the PS continuous phase. This observation is compatible with the results of the oscillatory rheology test, which shows a change in behavior from liquid-like to solid-like at 0.5 wt. % CNTs. The electrical conductivity of both types of blend increased 9 orders of magnitude by adding only 1.5 wt. % CNTs. Also, the electrical percolation thresholds for the 80/20 and 50/50 blend nanocomposites were calculated as 0.15 and 0.25 wt%, respectively, which is much lower than the values obtained from melt mixing in similar studies. Also, the elongation at break of all blends increased compared to neat polystyrene and the yield strength of the blend nanocomposites relative to pure blend increased until the contents of CNTs reached the percolation threshold and decreased thereafter. Overall, the results showed the occurrence of double percolation in these blends due to the addition of EOC and CNT, which is of industrial importance for controlling the morphology and achieving the desired mechanical and electrical properties
  9. Keywords:
  10. Anti-static Coating ; Polymer Blend Nanocomposites ; Selective Localization ; Double Percolation ; Electrical Percolation Threshold

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