Submitted to: National Institute of Standards & Technology - Kyoto International Polymer Science Symposium on Polymer Science
Publication Type: Abstract only
Publication Acceptance Date: 1/1/2003
Publication Date: 3/22/2003
Citation: Kim, S., Xu, J., Carriere, C.J., Willett, J.L. 2003. Phase behavior, shear effect, and rheology of starch solutions [abstract]. National Institute of Standards & Technology - Kyoto International Polymer Science Symposium on Polymer Science. Paper No.27. Interpretive Summary:
Technical Abstract: Starches are composed of two components, branched carbohydrate with high molar mass amylopectin and linear carbohydrate with lower molar mass amylose. Conventionally, fractionation of the two components has been achieved by aqueous dispersion or aqueous leaching of granules, and selective retrogradation or alcohol precipitation of one component from starch dispersion. In our laboratory, we found that starch solutions show phase separation provided that the concentration of starch, temperature, and solvent medium are properly chosen. In general, starch solutions behave in the same way as a pseudo-binary system like a synthetic polymer solution, polystyrene/poly(butadiene)/dioctylphthalate and show upper critical solution temperature behavior. The construction of phase diagram provides us with a new simple method for isolating amylose from starch solutions. As shear fields were applied to the starch solution, shear-induced aggregation was observed at higher than ca. 100 s-1. This behavior was investigated with a custom-built shear microscope and a rheometer. It was found that the aggregates are formed as functions of shear rate (fourth power) and time.