| Abstract: | The effect of temperature on the unexpected shear-thickening behavior exhibited by semidilute solutions of waxy maize starch during a repeated shear-loop experiment was evaluated. Shear-thickening behavior, characterized using power law models, was observed for waxy maize starch, but not for normal maize starch at the same concentration. The shear-thickening region was observed for waxy maize starch at temperatures ranging from 25°C to 80°C and shear rates from 2–100 s?1 during the initial part of the shear-loop experiment. For waxy maize starch, the power law exponent, n, was found to be 0.539 ± 0.017 in the shear-thinning region. For normal maize starch, the value of n was found to be equal to 0.751 ± 0.015 and only shear-thinning behavior was observed. The values of n for both waxy maize and normal maize starch were found to be temperature independent within the precision of the experimental measurements. The differences in n indicate the differences in the conformational dynamics of waxy maize and normal maize starches in solution. |
