ISSN:
0887-6266
Keywords:
starch
;
shear-thickening
;
semidilute solution
;
viscoelastic properties
;
oscillatory shear flow
;
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The shear-thickening behavior of semidilute waxy maize (WM) starch solutions (90/10 DMSO/water) exhibit much of the behavior of classical nonlinear viscoelasticity. Small-amplitude oscillatory shear experiments were used to investigate the network structure formed during the shear-thickening regime. The solution viscoelastic properties of WM starch prior to the shear-thickening region could be described by the GLV model. The macromolecules behave as random coils with a longest relaxation time of 0.58 ± 0.03 s. For WM starch the observed shear-thickening region creates a stable, highly entangled network which resembles the behavior found in solutions in the concentrated regime. The longest relaxation time for the entangled solution is estimated to be 1.4 s. Semidilute solutions of normal maize (NM) starch in 90/10 DMSO/water do not exhibit a shear-thickening regime. The oscillatory shear data obtained before and after a thixotropic loop experiment were identical. The semidilute solution conformational dynamics of NM starch indicate some degree of rigidity in one of the components that constitute NM starch which might be associated with the helical structure obtained by amylose in DMSO. © 1998 John Wiley & Sons, Inc. This article is a US Government work, and, as such, is in the public domain in the United States of America. J Polym Sci B: Polym Phys 36: 2085-2093, 1998
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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