Rheological Behavior of the Composites of Carboxymethylcellulose-Zinc Oxide/Starch

Abstract

The rheological behavior of the carboxymethylcellulose (CMC) / starch blends with and without zinc oxide (ZnO) have been investigated by controlled shear rate testing ramps. All blends showed high shear thinning flow behavior, (n=0,10 - 0,32) without ZnO and (n=0,10-0,29) with ZnO. The consistency index (K) and apparent viscosity (ηa,100 ) decreased with increasing amount of starch and with the addition of 1% wt ZnO. The results also showed that occurs an inversion in the elastic and viscous modulii behavior between 25 and 700C, obeying the Arrhenius equation. The study of activation energy showed that ZnO acts in the CMC phase, increase of viscosity of mixtures. The creep and recovery test indicated a decrease in the viscosity zero shear rate, indicating an increase of viscous character.  The phase angle results also confirm an increase of viscosity with addition of ZnO.