Steady shear and transient properties of starch in dimethylsulfoxide

B. Kapoor, M. Bhattacharya

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

The effect of starch composition (amylose to amylopectin ratio) and concentration (2, 4, 6, and 8%) on the steady shear (η), transient (G(t),η+(γ,t)η-(γ,t), and J(t)) properties of starch in a mixed solvent (10% water-90% DMSO) was investigated. High amylose corn starch containing 70% amylose and 30% amylopectin, common corn starch containing 25% amylose and 75% amylopectin, and waxy corn starch containing about 99% amylopectin were the three starch types used. Changes in the concentration or the amylose to amylopectin ratio in the starch changed the behavior from Newtonian liquid to semidilute solution to viscoelastic solid. Shear thinning occurred at lower shear rate with increasing concentration. Time-strain separability was found to be applicable for concentrations of 2 and 4% and stresses were found to relax monotonically to zero. Waxy corn starch at higher concentration (6 and 8%) had a high magnitude of recovered strain typical of gels. High amylose corn starch samples were in the semi-dilute concentration regime. A single integral constitutive equation (K-BKZ) was proposed to model rheological data for 2, 4, and 6% common corn starch, and 2 and 4% waxy corn starch and gave an acceptable fit to the data. A more complex behavior was observed for 8% common corn starch and 6 and 8% waxy corn starch, with changes in network structure manifested in the lack of reproducibility of data.

Original languageEnglish (US)
Pages (from-to)217-231
Number of pages15
JournalCarbohydrate Polymers
Volume44
Issue number3
DOIs
StatePublished - Mar 2001

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