The effect of temperature on the viscoelastic properties of model and industrial dispersions

This paper discusses the effect of temperature on the dynamic rheological properties of both the model polystyrene gelatin and the industrial photographic coupler dispersions. The time temperature superposition (TTS) was used to bring experimental data at various temperatures together into single master curves. An Arrhenius-type TTS principle, rather than the Williams-Landel-Ferry equation, was used in this work to bring all dynamic moduli and dynamic viscosity curves at different temperatures into single master curves. The present investigation verified that the TTS principle, which was developed for polymeric materials, could also be used for model and industrial photographic coupler dispersions as well. Furthermore, not only was the TTS principle suitable for the dispersions in the sol state, but it could also be used for the data in the gel-like state as well. The TTS allowed the estimation of the rheological properties of the dispersions over the frequency range which is otherwise inaccessible to the range of experimental measurement. Therefore, the linear viscoelastic properties of these model and photographic coupler dispersions at very low frequency (which is useful in predicting the stability of the product), as well as properties at very high frequency (or large deformation, e.g., during coating or pumping processes), could be estimated. (C) 1998 The Society of Rheology.