Electrical conductivity and optical properties of polypropylene glycol composites with multiwall carbon nanotubes
Alieksandrov M.A.1, Gaponov А.М1, Pinchuk-Rugal Т.М.1, Dmytrenko О.P.1, Poprugko V.M.1, Kulish М.P.1
1 Taras Shevchenko National University of Kyiv, Faculty of Physics, Chair of Physics of Functional Materials, 64/13 Volodymyrska str., 01601 Kyiv, Ukraine
E-mail: mrmarafom@gmail.com 

Polypropylene glycol (PPG) composite films with multi-walled carbon nanotubes (MWCNT) were fabricated using the Doctor blade coating method. The percolation dependences of electrical conductivity, Raman scattering (Raman scattering), photoluminescence emission (PL), photoluminescence excitation of PPG-BVNT film composites in a wide range of carbon nanotube concentrations before and after the percolation threshold was performed. 

Fig. 1. Percolation conductivity curve for PPG+MWCNT samples with different concentration of nanotubes.
It was found that for PPG-MWCNT composites the percolation threshold is φc(PPG-MWCNT) = 0.0002 vol. frac. The conductivity behavior indicates the presence of tunnel jumps of charge carriers, which is associated with complexation in composites, Fig. 1. The presence of such complexes affects the intra-combinational and intercombination transitions of the excitation energy, which is manifested in the Raman spectra, PL emission of polymers, and Van How singularities of nanotubes.