SULFONIC ACID POLYIMIDES AND THEIR SALTS: PROPERTIES OF THEIR PARTICLES IN SOLUTION AND SUSPENSION

A high-temperature one-step synthesis resulted in two new polymers PI-I and PI-II (polyimides), which have functional groups as SO 3H and SO 3Na in their chain. Their molecular-mass molecular characterization revealed that PIs are polydisperse systems, and show thermal stability up to 400 degrees C. The dynamic characteristics of polyimide particles in polar and nonpolar media were studied. The particle size of PI-I is significantly affected by the polarity of the medium. Due to intermolecular interactions associated with the free proton, the average particles diameters in dimethylformamide (DMF) was 10 mu m, while in polymethylsiloxane (PMS- 5) it was 1.4 mu m. The size particles of PI-II in different media were 246 and 606 nm. Viscoelastic and mechanical properties of polymer systems were studied using microrheology and classical rheology. Hysteresis loss coefficients (.) at various temperatures (T) were relatively small and stable for PI-I at T < 60 degrees C with insignificant changes at increasing frequency. PI-II coefficient changes markedly but smoothly as a function of. ( angular frequency) at T < 60 degrees C. With increasing temperature, the values of. are almost independent of., taking quite large values compared to the corresponding values for the PI-I. It was determined that the temperature increases the interaction between the particles of the dispersed phase in the electric field. And the decrease in the viscosity of the suspension is due to a decrease in the viscosity of the medium. The electrorheological effect is most pronounced for the PI-I suspension.