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Thermal Degradation and Kinetic Analysis of Polyethylene/Carbon Nanotube Nanocomposites Prepared via in Situ Polymerization

Shariati, Jafar | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42186 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ramazani Saadatabadi, Ahmad; Khorasheh, Farhad
  7. Abstract:
  8. In the preparation of nanocomposites, the multi-walled carbon nanotubes (MWCNTs) functionalized by hydroxyl groups were used. Subsequently, the polyethylene/multi-walled carbon nanotube (PE/MWCNTs) nanocomposites were prepared via in situ polymerization technique. In this study, effect of MWCNTs on the thermal degradation of these PE/MWCNT nanocomposites was investigated; the thermal degradations of pure PE and PE nanocomposites with different concentrations of nanotubes (0.5, 1.5, 3.5 wt %) have been studied by using thermal gravimetric analysis (TGA). Samples were heated to 700˚C at different heating rates (5, 10, 15, and 20˚C/min). TGA was used to investigate the effect of the MWCNTs on the thermal stability of the nanocomposites under a nitrogen atmosphere through study on parameters such as the onset temperature of degradation (T0.1), the decomposition temperature at a 50% weight loss (T0.5), the degradation temperature of maximum rate of the weight loss (Tm) and residual yields (WR) in TGA curves at 700˚C. It was found that the thermal stability of PE/MWCNT nanocomposites were first increased with the content of MWCNT, but then decreased after the content was larger than 1.5 wt % at differing heating rates. Decrease in the thermal stability of PE-MWCNT-3.5(Wt %) nanocomposite could be due to catalytic polymer decomposition because of the presence of hydroxyl groups on the edges of the MWCNT. On the other hand, the residual yields increased for all the content of MWCNT at 700˚C in TGA thermograms. The activation energy of degradation for PE/MWCNT nanocomposites containing higher MWCNT contents (0.5 wt% and 1.5 wt %) were higher than that of PE, while the activation energy decreased with further increasing MWCNT content (3.5 wt %) compared with that of PE. So, can be said that MWCNTs have two opposite effects on the thermal degradation of PE/MWCNT nanocomposites prepared via in situ polymerization
  9. Keywords:
  10. Nanocomposite ; Thermal Damage ; Carbon Nanotubes ; Activation Energy ; Thermal Gravimetric Analysis

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