Stochastic autooscillations of electrical conductivity of chitosan films swelled in water

The standard vapour permeation (VP) technique and conductometric experiments on swelling of chitosan and cellophane films in water vapour under normal conditions have been carried out. Non-linear behaviour of the material has been revealed. A very fast percolation and a chaotic dynamics have been noticed in measuring the electric current passing through the films. Conductometric data of cellophane swelling in both water vapour and liquid water have been obtained. Swelling in water appeared to be about an order of magnitude faster. The continuous wavelet transform (CWT) has been applied to the signal and its fractal character could be visualized. Despite of observed complex non-linear dynamics it was possible to derive a single parameter — “relative diffusivity” — that characterizes the polymer.