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ISSN:2394-3661 | Crossref DOI | SJIF: 5.138 | PIF: 3.854

International Journal of Engineering and Applied Sciences

(An ISO 9001:2008 Certified Online and Print Journal)

Conductivity Degradation Study of polypyrrole and polypyrrole/5% w/w TiO2 nanocomposite under Heat Treatment in Helium and Atmospheric Air

( Volume 3 Issue 6,June 2016 ) OPEN ACCESS
Author(s):

E. Vitoratos, S. Sakkopoulos, E. Dalas, K. Emmanouil

Abstract:

The thermal aging of the d.c. electrical conductivity σ in pure polypyrrole (PPy) and in the nanocomposite PPy/5%w/w TiO2 was investigated for thermal treatment times from 0 to 50 hours at different temperatures Τ = 100, 300 and 380 K under atmospheric air and inert He gas. In both materials the fluctuation induced tunneling of charge carriers was followed revealing a granular metal structure. The isothermal variation of σ with time under atmospheric air and inert He indicates the coexistence of two antagonistic mechanisms, the one increasing and the other decreasing σ. In XRD patterns from PPy and PPy/5%w/w TiO2 the sharp peaks of rutile and anatase crystallographic types of TiO2 coexist with the broad peak of amorphous PPy. The latter shifts to smaller angles with the addition of TiO2 indicating a greater separation of pyrrole rings, which turns up to be about equal to the diameter of O2- indicating the diffuse of oxygen from TiO2 into PPy. SEM pictures confirm the removal of Cl- in the form of HCl during thermal aging, a process which decreases the conductive part of the polymer and at the same time rearranges the chains. These represent two antagonistic mechanisms the first decreasing, the second increasing conductivity.  

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