THE EFFECT OF TEMPERATURE ON THE VISCOELASTIC PROPERTIES OF MODEL ANDINDUSTRIAL DISPERSIONS

This paper discusses the effect of temperature on the dynamic rheologi cal properties of both the model polystyrene gelatin and the industria l photographic coupler dispersions. The time temperature superposition (TTS) was used to bring experimental data at various temperatures tog ether into single master curves. An Arrhenius-type TTS principle, rath er than the Williams-Landel-Ferry equation, was used in this work to b ring all dynamic moduli and dynamic viscosity curves at different temp eratures 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 dispe rsions as well. Furthermore, not only was the TTS principle suitable f or 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 rang e which is otherwise inaccessible to the range of experimental measure ment. Therefore, the linear viscoelastic properties of these model and photographic coupler dispersions at very low frequency (which is usef ul 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 Rheolo gy.