Shear-thickening (dilatant) behavior is common in several polymeric systems, but not in pure polymers. There are many theories that can be used to describe shear-thickening and some mathematical models that fit experimental data of three of its six types: dilatant, newtonian-dilatant, newtonian-dilatant-pseudoplastic, viscoplastic-dilatant, pseudoplastic-dilatant and newtonian-pseudoplastic-newtonian-dilatant sequences. This work deals with the behavior of newtonian-dilatant-pseudoplastic sequence behavior and proposes a hybrid, non-linear and viscous model to fit the experimental data from systems that present such rheological behavior. The systems under investigation were: a) solution of alpha,omega poly(t-butylstyrene) in a mineral oil (3g/dl) (sample 1) and b) suspension of styrene -- methyl acrylate copolymer (S-co-MA) particles (15% vol.) in a poly(acrylic acid) (PAA) (1% wt) and water solution (sample 2). The proposed model agrees with the experimental data analysed.
Non-linear rheological model; non-newtonian behavior; shear-thickening; polymeric systems
