Chitosan-silver nanoparticles (CS-AgNP’s) composite films have been synthesized by three
different methods. Structure and relaxation properties of nanocomposites films have been analyzed by
scanning electron microscopy, thermo-gravimetry analysis, infrared, dielectric spectroscopy and X-ray
photoelectron spectroscopies. Two relaxation processes have been detected; in the wet films in the temperature
range 25-70°C (with water content between 1-11 wt%, TGA measurements) the α-relaxation associated
with the glass-rubber transition has been observed. The second relaxation was observed in the
temperature range 80-160°C and it has been identified as the σ-relaxation which is often associated with
the hopping motion of ions in the disordered structure of the composite. These relaxation processes and
DC conductivity depend upon the method of preparation and concentration of AgNP’s. Based upon the results, a possible
mechanism of interaction between AgNP’s and chitosan matrix and the influence of nanoparticles concentration on structure,
relaxation and electrical properties have been proposed.
Keywords: Chitosan, dielectric relaxation, glass transition, nanoparticles concentration, silver nanoparticles, sigma relaxation.
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