Stochastic autooscillations of electrical conductivity of chitosan films swelled in water

The standard vapour permeation (VP) technique and conductometric experiment s 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 no ticed in measuring the electric current passing through the films. Conducto metric data of cellophane swelling in both water vapour and liquid water ha ve been obtained. Swelling in water appeared to be about an order of magnit ude faster, The continuous wavelet transform (CWT) has been applied to the signal and its fractal character could be visualized. Despite of observed c omplex non-linear dynamics it was possible to derive a single parameter - " relative diffusivity" - that characterizes the polymer, (C) 1999 Published by Elsevier Science S.A. All rights reserved.