Electro-optic decay analysis for polydisperse systems III. Experimental data for rods

The decay of the transient birefringence induced by pulsed electric fields has been recorded and analysed for two different aqueous, polydisperse systems of rod-shaped particles. Attapulgite needles and asbestos fibres were the materials studied. The initial slopes of graphs of the logarithm of the normalised amplitudes during the decay process as a function of time were evaluated for both low and high electric field strengths. By comparing the data with those obtained from a simultaneous electron microscopic study, we verify the predictions of earlier theory from this research group that (i) discrete polydispersity average parameters are obtained from the initial slopes, (ii) from two such averages, which are quickly measured by this method, the sample polydispersity is indicated and (iii) the “peeling” method commonly used hitherto can give misleading size parameters.