Investigating the effect of the amount of solid particles on the rheological behavior of highly filled composites

Highly filled composites have wide applications in military and aerospace systems and consist of two polymer matrix components and different fillers with a weight fraction of more than 30%. The viscosity of highly filled composite slurry with different shear rates in the temperature range of 40 to 50 ˚C after the end of mixing in binder/aluminium, binder/aluminium/ammonium perchlorate composites has been measured using a Brookfield rotary viscometer and it was observed that the viscosity and dependence It corresponds to the shear rate with pseudoplastic fluid behavior. Using the power law equation, determining and analyzing the viscosity index (k) and pseudoplastic index (n) parameters, it was shown that the rheological behavior of the highly filled composite significantly depends on the interactions between the filler and the matrix. Furthermore, it was observed that changes in the type and amount of solid particles during processing lead to unexpected rheological behavior of the highly filled composite. Investigation of three levels of aluminium content 40%, 45%, and 50% at different temperatures in composite slurry showed that aluminium with 50% by weight had better rheological behavior due to more binder system and better wetting between the filler material and polymer matrix. The increase in viscosity is due to the higher load of solid particles, especially smaller particles, and when ammonium perchlorate particles were added to the system, the fluid showed more pseudoplastic behavior. With increasing temperature, viscosity decreased due to increased mobility of polymer molecules.